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Dissertations / Theses on the topic 'Modulus elasticity'
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1
Ip, Felix. "Compressive strength and modulus of elasticity of masonry prisms." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0019/MQ48451.pdf.
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Ip, Felix (Mong Kau Felix) Carleton University Dissertation Engineering Civil and Environmental. "Compressive strength and modulus of elasticity of masonry prisms." Ottawa, 1999.
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Akhi, Taohida Parvin. "Experimental investigation of effective modulus of elasticity and shear modulus of brick masonry wall under lateral load." ISIS Canada Research Network, 2011. http://hdl.handle.net/1993/5304.
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The primary objective of this research program was to investigate the effective modulus of elasticity and shear modulus of brick masonry walls under lateral load, and to to justify using the Jaeger and Mufti method to calculate the effective modulus of elasticity and shear modulus of brick masonry walls. The experimental program involved the testing of three unreinforced brick masonry walls under in-plane and vertical loads. Linear Variable Differential Transducers were used to record the horizontal and vertical displacements of the walls. The experimental results were used to evaluate the modulus of elasticity and the shear modulus of walls under flexure. The experimental results were compared to the finite element analysis results. It was found that the finite element analysis yields similar results to the experimental results. It was also found that the Jaeger and Mufti method to calculate effective modulus of elasticity and shear modulus of brick masonry walls is effective for design purposes.
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Busch, Amanda J. "Vacuum-Assisted Wet Shaping of Paper." Thesis, Georgia Institute of Technology, 2006. http://hdl.handle.net/1853/10567.
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Premium absorbent paper products (e.g., two-ply towel and tissue) can achieve higher fluid holding capacity per unit dry weight by means of increasing their void volume per unit weight. In turn, high void volume can be attained by increasing the overall thickness of each ply through molding the paper into a three-dimensional ("mini-egg-crate") structure before drying it.
This research investigates the effect of three types of parameters: mold geometrical, operational, and paper parameters. These variables are examined with respect to their effect on the resulting overall thickness. Because the experimental research is fundamental in nature, it employs molding structures of a simplified geometry (produced via rapid prototyping techniques) rather than the geometrically complex molding fabrics used commercially.
A goal of the project is the understanding of the physics of the wet shaping process, in which vacuum is used to deform the wet paper web into the openings in the molding structure. Another goal is identification of limitations or boundaries of the wet shaping
process (e.g., conditions for which "pinholes" occur in the paper). Supporting theoretical analysis of the shaping/molding problem is performed, to provide bases for correlating experimental data and for the optimization of molding geometrical parameters. The result of this study provides quantitative information for some variables that affect the final sheet thickness.
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Bhattacharjee, Chandan. "Bayesian prediction of modulus of elasticity of self consolidated concrete." [College Station, Tex. : Texas A&M University, 2007. http://hdl.handle.net/1969.1/ETD-TAMU-2467.
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Vukovic, Nikola. "Comparison of laboratory and field modulus of elasticity of rocks." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape11/PQDD_0001/MQ44047.pdf.
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Schoppe, Brett Michael. "SHRINKAGE & MODULUS OF ELASTICITY IN CONCRETE WITH RECYCLED AGGREGATES." DigitalCommons@CalPoly, 2011. https://digitalcommons.calpoly.edu/theses/500.
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This paper presents results on experimental research for concrete produced using recycled coarse aggregates (RCA). Five types of coarse aggregates were used in this study, four of which were RCA. The main purpose of this research was to examine how different types and properties of coarse aggregate affected compressive strength, modulus of elasticity, and shrinkage in concrete when natural coarse aggregates were replaced with RCA. Concrete batches were made with water-cement (w/c) ratios of 0.30, 0.45, and 0.60, and substitution percentages ranged from 0% to 100% of natural aggregate with RCA. Test results clearly show that compressive strength, modulus of elasticity, and shrinkage greatly depend on the quality and type of coarse aggregate used. In addition to testing of hardened concrete, predictive models for elasticity and ultimate shrinkage were developed to formulate and reinforce proposed conclusions about the properties and performance for the different RCA.
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Maknickas, Algirdas. "Modelling of elasticity properties of solids by the discrete element method." Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2009. http://vddb.library.lt/obj/LT-eLABa-0001:E.02~2009~D_20090713_142127-91304.
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Development of numerical methods and computation environments opened the possibility of new, more sophisticated mechanical objects modelling. In this context it is natural desire of the researchers to describe macroscopic mechanical characteristics of the materials
by their microstructure, which can be adapted for simulation of the existing and future materials. For this purpose researchers are using intensively experimental
and numerical methods for the development of which the highest priority is given. Numerical experiments are used because they are cheaper and allow the interpretation of already known results of experiments and provide information
to new investigations. One of the methods used for modelling of macroscopic properties modelling is based on microscopic properties of material is discrete element
method (DEM). The DEM traditionally was applied for the granular materials. The basic idea of DEM is that any physical structure could be described as a system of moving particles. This idea could be also applied to the description of solid deformable body. Particles forming solid body and existing interaction between them are of different nature than the granular materials because their
models are often the result of physical and mathematical abstraction. The modelling of solid deformable body with the discrete elements is just at the initial stage and the unified approach to discrete elements models doesn’t exist. There are several versions of models, based on... [to full text]<br>Tobulėjant skaitiniams metodams ir kompiuterinei technikai atsivėrė galimybė naujų, sudėtingesnių mechaninių objektų modeliavimui. Turėdami naujus sudėtingesnių objektų modelius tyrėjai gali pritaikyti aprašytas ir sumodeliuotas šių objektų savybes su mikro struktūros ypatumais esamų ar busimų savybių nustatymui bei naujų medžiagų kūrimui. Tam intensyviai naudojami kaip eksperimentiniai taip ir skaitiniai metodai, kurių tobulinimui šiuo metu yra skiriamas labai didelis dėmesys. Skaitinis eksperimentas, kaip medžiagos tyrimo būdas pasitelkiamas dar ir todėl kad yra pigesnis ir leidžia interpretuoti jau žinomus eksperimentų rezultatus, o taip suteikia žinių naujiems tyrimams.
Vienas iš metodų, kuris modeliuoja makroskopines medžiagų savybes remdamasis medžiagos mikro savybėmis yra diskrečiųjų elementų metodas (DEM). DEM metodas remiasi idėja, kad bet kokia fizikinė struktūra gali būti aprašyta kaip judančių dalelių sistema. Ši idėja pradėta taikyti ir vientisam deformuojamam kūnui aprašyti. Skirtingai nuo biriųjų medžiagų, vientiso kūno dalelės ir tarp jų egzistuojančios sąveikos yra kitokios prigimties, o jų modeliai yra fizikinės ir matematinės abstrakcijos rezultatas.
Vientiso deformuojamo kūno modeliavimas diskrečiais elementais yra tik pradinėje stadijoje, o vientiso požiūrio į diskrečių elementų modelius dar nėra. Yra kelios hipotetinės versijos, grindžiamos skirtingais požiūriais. Taikant DEM kūnui, pirmas žingsnis būtu tampriųjų savybių modeliavimas. Tai yra... [toliau žr. visą tekstą]
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Nortemann, Markus. "Characterisation of Young's modulus and loss factor of damping materials." Thesis, Nelson Mandela Metropolitan University, 2014. http://hdl.handle.net/10948/d1021036.
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Given the importance of simulation techniques in automotive engineering, there is a lack of implementation regarding these techniques in the acoustics of damping materials for air-borne sound. Biot’s calculations have proven its abilities to simulate the acoustic characteristics of these damping materials. However, the characterisation of essential structural parameters, such as Young’s modulus and loss factor, in order to conduct Biot’s calculations have been inconclusive. Thus, the primary research objective of this study is to propose a new measurement system for the structural Biot parameters. After a comprehensive literature review has been undertaken on damping materials, as well as measurement apparatuses for Young’s modulus and loss factor of damping materials, two causes of measurement errors have been identified. Unknown stresses in measurement apparatuses and inhomogeneous, polytrophic and viscoelastic behaviour of specimens. A new measurement system that does not affect the specimens with unknown stresses and accounts for their complex behaviour required investigation. Non-contact ultrasound had been selected as a solution to determine the aforementioned parameters, since these methods do not necessarily touch or compress the specimen, which led to unknown stresses and neglection of the complex specimen behaviour with the aforementioned techniques. Although ultrasound had been used to determine structural parameters on various types of materials, it has never been used to measure soft porous damping materials. In order to find possible solutions, various sources using ultrasonics to investigate struc- tural parameters had been reviewed. In order to calculate structural parameters, the longitudinal and transversal wave velocity inside the specimen had to be determined. The main findings showed that non-contact ultrasound will be able to evaluate the Young’s modulus, loss factor as well as Poisson’s ratio. Consequently, it was shown that longitudinal velocity measurements could be conducted using well known transmission measurements. However, well known approaches would not be sufficient measuring the transversal wave velocity in soft damping materials. This problem was addressed with a special gas to be used, with lower sound speed velocity in the fluid than in the solid. Moreso, a new method determining the transversal wave velocity had been found, as it would enable the use of an even larger range of damping materials, especially ones with heavy frames and lower porosity. It will use refracted waves inside the specimen and the determination of the convertion position of the transversal to the longitudinal wave at the rear specimen surface. At the end of the study, hardware components were selected and a test rig was constructed, which should be able to prove that a determination of structural Biot parameters with non-contact ultrasound is possible with less errors instead of using mechanical transfer function systems. The development of measurement software as well as the testing of the measurement system and its validation was not under investigation in this dissertation. This study has expanded on the body of literature knowledge regarding non-contact ultrasound. Furthermore, a significant contribution has been made towards a new measurement system measuring Young’s modulus and loss factor which circumvents errors in mechanical transfer function systems. This will contribute to more precise simulations of damping materials and damped enclosures, which may ultimately result in enhanced efficiency of damping materials as well as the acoustic packaging of cars.
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Bert, Stephen M. "Using Maturity to Predict Girder Camber." Thesis, Virginia Tech, 2005. http://hdl.handle.net/10919/32852.
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The objective of this research was to determine if differential camber of prestressed concrete girders could be reduced by accurate prediction of initial camber at release of prestress. Maturity at prestress transfer was used to calculate modulus of elasticity for predicting camber at release. The research consists of a literature review of maturity methods, testing of a standard concrete mix to determine strength and modulus functions and measurement of girder camber and maturity.
Both the Nurse-Saul and the Arrhenius maturity models were evaluated. Maturity relationships were developed for concrete mixes containing Type II and Type III cements. A relationship of modulus as a function of maturity was developed. Seven girders were tested. Camber predictions within 0 to ¼ in. of actual camber were obtained using modulus of elasticity calculated from a maturity based function. Comparison was made between maturity based modulus and standard strength based modulus models. Camber predictions based on modulus calculated based on field cured cylinder strengths were within 0 to ½ in.<br>Master of Science
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Wang, Xin. "Elasticity of Lipid Membrane Leaflets: Determining Pivotal Plane and Tilt Modulus in Computer Simulations." Research Showcase @ CMU, 2017. http://repository.cmu.edu/dissertations/960.
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This thesis introduces a novel protocol to measure two elastic quantities of lipid membranes, the pivotal plane of a single leaflet and the lipid tilt modulus. The key setup relies on the simulation of a buckled membrane, a configuration that had been previously proposed to measure a membrane's bending rigidity. Since this method solely depends on the geometrical analysis of the membrane shape, and can hence even be applied to existing simulation trajectories of buckled membranes, it can provide two additional physical quantities at no extra simulation cost. Due to the high precision of its result, many technical subtleties are considered throughout the derivation, pertaining for instance to higher order corrections due to Poisson ratio effects. This calculation, as shown in this thesis, can be used to provide both a reference for other study as well as deeper insight into the nature of lipid models, especially the limitation of the coarse-grained ones.
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Gao, Liang. "Ultrasound Elasticity Imaging of Human Posterior Tibial Tendon." Diss., The University of Arizona, 2014. http://hdl.handle.net/10150/338897.
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Posterior tibial tendon dysfunction (PTTD) is a common degenerative condition leading to a severe impairment of gait. There is currently no effective method to determine whether a patient with advanced PTTD would benefit from several months of bracing and physical therapy or ultimately require surgery. Tendon degeneration is closely associated with irreversible degradation of its collagen structure, leading to changes to its mechanical properties. If these properties could be monitored in vivo, it could be used to quantify the severity of tendonosis and help determine the appropriate treatment. Ultrasound elasticity imaging (UEI) is a real-time, noninvasive technique to objectively measure mechanical properties in soft tissue. It consists of acquiring a sequence of ultrasound frames and applying speckle tracking to estimate displacement and strain at each pixel. The goals of my dissertation were to 1) use acoustic simulations to investigate the performance of UEI during tendon deformation with different geometries; 2) develop and validate UEI as a potentially noninvasive technique for quantifying tendon mechanical properties in human cadaver experiments; 3) design a platform for UEI to measure mechanical properties of the PTT in vivo and determine whether there are detectable and quantifiable differences between healthy and diseased tendons. First, ultrasound simulations of tendon deformation were performed using an acoustic modeling program. The effects of different tendon geometries (cylinder and curved cylinder) on the performance of UEI were investigated. Modeling results indicated that UEI accurately estimated the strain in the cylinder geometry, but underestimated in the curved cylinder. The simulation also predicted that the out-of-the-plane motion of the PTT would cause a non-uniform strain pattern within incompressible homogeneous isotropic material. However, to average within a small region of interest determined by principal component analysis (PCA) would improve the estimation. Next, UEI was performed on five human cadaver feet mounted in a materials testing system (MTS) while the PTT was attached to a force actuator. A portable ultrasound scanner collected 2D data during loading cycles. Young's modulus was calculated from the strain, loading force and cross sectional area of the PTT. Average Young's modulus for the five tendons was (0.45±0.16GPa) using UEI. This was consistent with simultaneous measurements made by the MTS across the whole tendon (0.52±0.18GPa). We also calculated the scaling factor (0.12±0.01) between the load on the PTT and the inversion force at the forefoot, a measurable quantity in vivo. This study suggests that UEI could be a reliable in vivo technique for estimating the mechanical properties of the human PTT. Finally, we built a custom ankle inversion platform for in vivo imaging of human subjects (eight healthy volunteers and nine advanced PTTD patients). We found non-linear elastic properties of the PTTD, which could be quantified by the slope between the elastic modulus (E) and the inversion force (F). This slope (ΔE/ΔF), or Non-linear Elasticity Parameter (NEP), was significantly different for the two groups: 0.16±0.20 MPa/N for healthy tendons and 0.45±0.43 MPa/N for PTTD tendons. A receiver operating characteristic (ROC) curve revealed an area under the curve (AUC) of 0.83±0.07, which indicated that the classifier system is valid. In summary, the acoustic modeling, cadaveric studies, and in vivo experiments together demonstrated that UEI accurately quantifies tendon mechanical properties. As a valuable clinical tool, UEI also has the potential to help guide treatment decisions for advanced PTTD and other tendinopathies.
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Zoric, Branislav. "Modelling the influence of stocking on longitudinal and radial variation in wood properties of Pinus radiata on a warm Northland site." Thesis, University of Canterbury. School of Forestry, 2009. http://hdl.handle.net/10092/2564.
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The objective of this study was to determine how final stocking influences tree growth and radial and longitudinal variation in wood properties at a Pinus radiata D. Don plantation located at one of the warmest forest sites in New Zealand, Forsyth Downs forest in Northland. This thesis addressed both the effect of stocking on stand basal area, height, diameter and branch diameter and the effect of stocking on wood properties microfibril angle (MFA), module of elasticity and density. Finally, how ring width influences wood properties and whether this variable accounts for the treatment effects was investigated.
Stocking, height and ring number and all interactions between these variables significantly affected ring width. Ring width by itself was significant as a predictor of density, but when it was combined with other class level variables it was insignificant (i.e. does not account for treatment effects), and it did not add anything to a model with only class effects. There was a significant impact of ring number on density while ring width was insignificant in the same model.
MFA was significantly affected by ring width, height and ring number in the tree, and all interactions, apart from the three way interaction, but not by stocking. Ring width was significant in the MFA model both by itself and when it was combined with other variables. Ring width accounted for the stocking effect.
The best model of MOE included the class level effects of stocking, height and ring number within the tree, and all interactions between these variables, and ring width, as a continuous variable. While there was a significant effect between stockings this was relatively weak compared to the other main effects. Ring width largely accounted for the effect of stocking, but not that of ring number, or height.
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Adem, Hana Hussin. "Modulus of Elasticity Based Method for Estimating the Vertical Movement of Natural Unsaturated Expansive Soils." Thesis, Université d'Ottawa / University of Ottawa, 2015. http://hdl.handle.net/10393/31910.
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Expansive soils are widely distributed in arid and semi-arid regions around the world and are typically found in a state of unsaturated condition. These soils are constituted of the clay mineral montmorillonite that is highly active and contributes significantly to volume changes of soils due to variations in the natural water content conditions. The volume changes of expansive soils often cause damage to lightly loaded structures. The costs associated with the damage to lightly loaded structures constructed on expansive soils in the United States alone were estimated as $2.3 billion per year in 1973, which increased to $13 billion per year by 2009. In other words, these damages have increased more than five fold during the last four decades. Similar trends in damages were also reported in other countries (e.g., Australia, China, France, Saudi Arabia, United Kingdom, etc.).
Numerous methods have been proposed in the literature over the past 50 years for the prediction of the volume change movement of expansive soils. However, the focus of these methods has been towards estimating the maximum potential heave, which occurs when soils attain the saturation condition. The results of heave estimation considering saturated soil conditions are not always useful in engineering practice. This is because most of damages due to expansive soils often occur prior to reaching the saturation condition. A reliable design of structures on expansive soils is likely if the anticipated soil movements in the field can be reliably estimated over time, taking into account the influence of environmental factors. Limited studies are reported in the literature during the past decade in this direction to estimate/predict the expansive soil movements over time. The existing methods, however, suffer from the need to run expensive and time consuming tests. In addition, verification of these studies for different natural expansive soils has been rather limited.
A simple approach, which is referred to as a modulus of elasticity based method (MEBM), is proposed in this study for the prediction of the heave/shrinkage movements of natural expansive soils over time. The proposed MEBM is based on a simplified constitutive relationship used for the first time to estimate the vertical soil movements with respect to time in terms of the matric suction variations and the corresponding values of the modulus of elasticity. The finite element program VADOSE/W (Geo-Slope 2007) for simulating the soil-atmospheric interactions is used as a tool to estimate the changes in matric suction over time. A semi-empirical model that was originally proposed by Vanapalli and Oh (2010) for fine-grained soils has been investigated and extended for unsaturated expansive soils to estimate the variation of the modulus of elasticity with respect to matric suction in the constitutive relationship of the proposed method. The MEBM has been tested for its validity in five case studies from the literature for a wide variety of site and environmental conditions, from Canada, China, and the United States. For each case study, factors influencing the volume change behavior of soils, such as climate conditions, soil cracks, lawn irrigation, and cover type (pavement, vegetation), are successfully modeled over the period of each simulation. The proposed MEBM provides good predictions of soil movements with respect to time for all the case studies. The MEBM is simple and efficient for the prediction of vertical movements of natural expansive soils underlying lightly loaded structures.
In addition, a new dimensionless model is also proposed, based on the dimensional analysis approach, for the estimation of the modulus of elasticity which can also be used in the constitutive relationship of the MEBM. The dimensional model is rigorous and takes into account the most significant influencing parameters such as matric suction, net confining stress, initial void ratio, and degree of saturation. This model provides a comprehensive characterization of the modulus of elasticity of expansive soils under unsaturated conditions for different scenarios of loading conditions (i.e., both lightly and heavily loaded structures).
The results of the present study are encouraging for proposing guidelines based on further investigations and research studies for the rational design of pavements, shallow and deep foundations placed on/in expansive soils using the mechanics of unsaturated soils.
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Waghorn, Matthew J. "Effect of initial stand spacing and breed on dynamic modulus of elasticity of Pinus radiata." Thesis, University of Canterbury. Forestry, 2006. http://hdl.handle.net/10092/1129.
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Wood stiffness or modulus of elasticity (MOE) is one of the most important wood properties for solid timber applications, and as such, the efficacy of wood use, especially for structural timber is strongly related to MOE. MOE in Pinus radiata is highly variable and poorly understood. In this study, the effect of initial stand spacing and breed on outerwood MOE and the vertical distribution of MOE of Pinus radiata was assessed. Understanding positive or negative influences of growth caused by initial stand spacing and genetic material on MOE is appealing because it could enable us to better comprehend how forest growers could adapt silvicultural operations to the demands of wood processing. Physical characteristics of different breeds and propagation methods of Pinus radiata were assessed at a variety of initial stand spacings. Stem diameter, crown height, stem slenderness and branch size were all heavily influenced by stand spacing. Breed had a marginally significant influence on diameter and stem slenderness. Internode length was not affected by stand spacing, but showed sizeable differences, especially between the long internode 870 breed and the remaining growth and form (GF) breeds. Outerwood MOE was significantly (P<0.0001) influenced by stand spacing and breed, but not their interaction (P>0.05). MOE scaled positively with stand spacing. MOE increased by 39% from 5.4 GPa at 209 stems ha-1 to 7.5 GPa at 2551 stems ha-1. The majority of this increase (33%) occurred between 209 and 835 stems ha-1. Physiologically aged cuttings of greater maturation status exhibited greater MOE, with the three-year-old cuttings being stiffer than the one-year-old cuttings, seedlings from the 870, 268 and 850 series, by 15, 17, 22 and 27%, respectively. Stem slenderness exhibited the strongest significant (P<0.0001) relationship with MOE (r2=0.49), followed by green crown height (r2=0.46) and diameter (r2=0.44). Stem slenderness and green crown height had a direct influence on MOE that explained 53% of the variance in MOE. MOE was also significantly (P<0.0001) influenced by spacing and breed when using the resonance technique to assess whole stem MOE. The vertical distribution of MOE showed that the lowest portion of the stem (bolt 1) was approximately 30% less stiff than bolts 2 and 3. After the greatest MOE value had been obtained at bolt 3, MOE gently declined to the top of the measured stem. Variation of MOE within trees was significant (58%) at the high stockings of 1457 and 2551 stems ha-1, but somewhat lower (36%) at the lower stockings. The 870 breed was approximately 8% and 16% stiffer than the 268 and 850 breeding series respectively, across all stockings, with the three-year-old cuttings being 7% stiffer than the one-year-old cuttings. At stockings of 481 stems ha-1 and less, the proportional height at which MOE was greatest within a tree was between 25% and 50% of stem height. At stockings above 481 stems ha-1 the proportional height at which maximum MOE was obtained was between 15% and 40% of stem height. Bolt slenderness was found to be the most significant factor impacting on MOE of the bolt. Regression of critical buckling height against diameter at ground level yielded a scaling exponent of 0.55, which was lower than the scaling exponent of 0.67 predicted with constant density-specific stiffness. There was a tendency for some bolts with lower mean diameter to display significantly higher safety margins than bolts with higher mean diameter, suggesting that the largest bolts, which occur at the base of tree, are the point of most likely critical failure.
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Torres, Donna Schulz 1972. "Effects of modulus of elasticity of collagen sponges on their cell-mediated contraction in vitro." Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/50056.
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Kocáb, Dalibor. "Experimentální stanovení faktorů ovlivňujících statický modul pružnosti betonu s využitím nedestruktivních zkušebních metod." Doctoral thesis, Vysoké učení technické v Brně. Fakulta stavební, 2016. http://www.nusl.cz/ntk/nusl-355639.
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The Ph.D. thesis deals with one of the most important characteristics of hardened concrete; i.e. the modulus of elasticity. The thesis aims to describe and evaluate the important factors that affect the final value of concrete modulus of elasticity, especially those that can be influenced during construction. Another aim is to find ways to determine the static modulus of elasticity of concrete by non-destructive means (primarily ultrasonic pulse method, resonance method and use of electronic rebound hammers), thus to determine the possibility of creating calibration curve for NDT determination of the modulus of elasticity.
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Brunetti, Carlotta. "Frequency-dependent response of snow in uniaxial compression and comparison with numerical simulation." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2014. http://amslaurea.unibo.it/7820/.
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La determinazione del modulo di Young è fondamentale nello studio della propagazione di fratture prima del rilascio di una valanga e per lo sviluppo di affidabili modelli di stabilità della neve. Il confronto tra simulazioni numeriche del modulo di Young e i valori sperimentali mostra che questi ultimi sono tre ordini di grandezza inferiori a quelli simulati (Reuter et al. 2013). Lo scopo di questo lavoro è stimare il modulo di elasticità studiando la dipendenza dalla frequenza della risposta di diversi tipi di neve a bassa densità, 140-280 kg m-3. Ciò è stato fatto applicando una compressione dinamica uniassiale a -15°C nel range 1-250 Hz utilizzando il Young's modulus device (YMD), prototipo di cycling loading device progettato all'Istituto per lo studio della neve e delle valanghe (SLF). Una risposta viscoelastica della neve è stata identificata a tutte le frequenze considerate, la teoria della viscoelasticità è stata applicata assumendo valida l'ipotesi di risposta lineare della neve. Il valore dello storage modulus, E', a 100 Hz è stato identificato come ragionevolmente rappresentativo del modulo di Young di ciascun campione neve. Il comportamento viscoso è stato valutato considerando la loss tangent e la viscosità ricavata dai modelli di Voigt e Maxwell. Il passaggio da un comportamento più viscoso ad uno più elastico è stato trovato a 40 Hz (~1.1•10-2 s-1). Il maggior contributo alla dissipazione è nel range 1-10 Hz. Infine, le simulazioni numeriche del modulo di Young sono state ottenute nello stesso modo di Reuter et al.. La differenza tra le simulazioni ed i valori sperimentali di E' sono, al massimo, di un fattore 5; invece, in Reuter et al., era di 3 ordini di grandezza. Pertanto, i nostri valori sperimentali e numerici corrispondono meglio, indicando che il metodo qui utilizzato ha portato ad un miglioramento significativo.
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Hermawan, Vera. "Experimental techniques to determine the Young's Modulus of the trachea thesis submitted in partial fulfilment of the degree of Master of Engineering, Auckland University of Technology, September 2004." Full thesis. Abstract, 2004.
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Werner, Jörn. "The influence of composition, processing and temperature on the Young's modulus of elasticity of carbon-bonded refractories." Doctoral thesis, Technische Universitaet Bergakademie Freiberg Universitaetsbibliothek "Georgius Agricola", 2014. http://nbn-resolving.de/urn:nbn:de:bsz:105-qucosa-155296.
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Thermal shock resistance is a key property of refractory materials. Its determination and prediction is essential for the design of structural refractories as well as lining materials. Young’s modulus of elasticity (E) is a crucial parameter for the calculation of thermal shock resistance.
For all investigated carbon-bonded alumina composition a significant increase of E was observed. This increase was attributed to a mismatch of the coefficient of thermal expansion of the composite constituents. Besides others, the graphite content as well as the maximum alumina particle size were identified as crucial factors influencing E(T). Furthermore, the influence of the porosity on E was shown and existing models were fitted to the experimental data for future predictions of E. Finally a metal melt filter structure was investigated to investigate the relationship between its strut Young’s modulus and the structures’ E at high temperatures. Further research should address the filter topic since it was uncertain how to find the normal modes of those structures.
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Potočková, Michaela. "Vliv vícenásobného cyklického zatěžování na hodnotu statického modulu pružnosti betonu v tlaku v konstrukcích." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2016. http://www.nusl.cz/ntk/nusl-240134.
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This thesis deals with the dependence of static modulus of elasticity of concrete in compression on number of load cycles. The deformation of test specimens during multiple cyclic loading was measured with resistive strain gages. Up to 1600 load cycles was conducted. Static modulus of elasticity in compression was determined from measured deformations. The aim of this thesis is assessment changes in the values of static modulus of elasticity depending on the number of load cycles.
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Briggert, Andreas. "Fibres orientation on sawn surfaces : Can fibre orientation on sawn surfaces be determined by means of high resolution scanning." Thesis, Linnéuniversitetet, Institutionen för byggteknik (BY), 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-34979.
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In 2013 the European journal of wood and wood products published an article regarding a new method to predict strength in structural timber (Olsson et al 2013). By determining the fibres orientation on all four surfaces of each board in sample of timber using a high resolution scanner the authors were able to achieve a coefficient of determination, R2, as high as 0.71 between bending strength and a new indicating property (IP). For the same sample of timber Olsson et al (2013) determined the R2 by axial dynamic excitation as 0.59. However, all boards used in their investigation were planed before scanning. This study examines if a high resolution scanner could be used to determine the fibre orientation on the surfaces of sawn timber boards of Norway spruce. Both band sawn surfaces and circular sawn surfaces were examined. The procedure in this investigation is described as follows. Firstly, both the band sawn and the circular sawn boards were scanned by a WoodEye® scanner and together with dimensions, weight and the first longitudinal resonance frequency, a modulus of elasticity (MOE) profile was calculated for each board. The MOE profiles were calculated according to Olsson et al (2013) i.e. by a transformation matrix based upon the fibres orientation and a compliance matrix based on material parameters for Norway spruce. Secondly, the corresponding MOE profiles were then determined after the boards had been planed. As a result two MOE profiles were determined for each board. An indicating property (IP) was defined as the lowest value along each MOE profile. To compare the results a regression analysis was performed in which the IPs defined before planing worked as predictor variable and IPs defined after planing worked as response variable. The band sawn band boards yielded an R2 = 0.94 and the circular sawn boards an R2 = 0.93. Further the standard error of estimate was SEE = 829.1 MPa and SEE = 640.9 MPa respectively. As a last step in this investigation the SEE values achieved in this study where implemented on to the sample Olsson et al (2013) used in their investigation.
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Axson, Daniel Peter. "Ultimate Bearing Strength of Post-tensioned Local Anchorage Zones in Lightweight Concrete." Thesis, Virginia Tech, 2008. http://hdl.handle.net/10919/33711.
Full textAbstract:
Currently, NCHRP Report 356 has published an equation to estimate the ultimate strength of the
local zone in normal weight concrete. The local zone is the area of concrete directly ahead of the
bearing plate. The equation can be broken into two distinct parts: unconfined bearing strength of
concrete enhanced by the A/Ab ratio and the enhancement of strength due to the presence of
confining. Research has shown that the strength enhancement of the A/Ab ratio and confining
reinforcing is less in lightweight concrete than in normal weight concrete.
To determine the strength of the local zone in lightweight concrete 30 reinforced prisms, 2
unreinforced prisms, and concrete cylinders were tested. The dimensions of the prisms were 8
in. x 8 in. x 16 in. and the cylinders were 4 in. x 8 in. cylinders. The simulated reinforcing in the
prisms extended only through the top 8 in. of the prism and consisted of either ties or spirals with
different spacing or pitch, respectively. To determine the effect of the A/Ab ratio for each
spacing or pitch arrangement of the reinforcing, one of two different size bearing plates were
used.
From the testing performed in this research and other research, it is apparent that the NCHRP
equation is unconservative when estimating the ultimate strength of the local zone in lightweight
concrete. By modifying both parts of the NCHRP equation it is possible to conservatively
predict the ultimate strength of the local zone in lightweight concrete.
Also investigated in this thesis are equations to predict the splitting cylinder strength and
modulus of elasticity of lightweight concrete. For a sand-lightweight concrete, as defined by
ACI 318-05 Building code and Commentary, the splitting tensile strength can be accurately
predicted by multiplying the square root of the compressive strength by 5.7.<br>Master of Science
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Maknickas, Algirdas. "Deformuojamo erdvinio kūno tampriųjų savybių modeliavimas diskrečiųjų elementų metodu." Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2009. http://vddb.library.lt/obj/LT-eLABa-0001:E.02~2009~D_20090713_142112-78540.
Full textAbstract:
Tobulėjant skaitiniams metodams ir kompiuterinei technikai atsivėrė galimybė naujų, sudėtingesnių mechaninių objektų modeliavimui. Turėdami naujus sudėtingesnių objektų modelius tyrėjai gali pritaikyti aprašytas ir sumodeliuotas šių objektų savybes su mikro struktūros ypatumais esamų ar busimų savybių nustatymui bei naujų medžiagų kūrimui. Tam intensyviai naudojami kaip eksperimentiniai taip ir skaitiniai metodai, kurių tobulinimui šiuo metu yra skiriamas labai didelis dėmesys. Skaitinis eksperimentas, kaip medžiagos tyrimo būdas pasitelkiamas dar ir todėl kad yra pigesnis ir leidžia interpretuoti jau žinomus eksperimentų rezultatus, o taip suteikia žinių naujiems tyrimams.
Vienas iš metodų, kuris modeliuoja makroskopines medžiagų savybes remdamasis medžiagos mikro savybėmis yra diskrečiųjų elementų metodas (DEM). DEM metodas remiasi idėja, kad bet kokia fizikinė struktūra gali būti aprašyta kaip judančių dalelių sistema. Ši idėja pradėta taikyti ir vientisam deformuojamam kūnui aprašyti. Skirtingai nuo biriųjų medžiagų, vientiso kūno dalelės ir tarp jų egzistuojančios sąveikos yra kitokios prigimties, o jų modeliai yra fizikinės ir matematinės abstrakcijos rezultatas.
Vientiso deformuojamo kūno modeliavimas diskrečiais elementais yra tik pradinėje stadijoje, o vientiso požiūrio į diskrečių elementų modelius dar nėra. Yra kelios hipotetinės versijos, grindžiamos skirtingais požiūriais. Taikant DEM kūnui, pirmas žingsnis būtu tampriųjų savybių modeliavimas. Tai yra... [toliau žr. visą tekstą]<br>Development of numerical methods and computation environments opened the possibility of new, more sophisticated mechanical objects modelling. In this context it is natural desire of the researchers to describe macroscopic mechanical characteristics of the materials by their microstructure, which can be adapted for simulation of the existing and future materials. For this purpose researchers are using intensively experimental and numerical methods for the development of which the highest priority is given. Numerical experiments are used because they are cheaper and allow the interpretation of already known results of experiments and provide information to new investigations.
One of the methods used for modelling of macroscopic properties modelling is based on microscopic properties of material is discrete element method (DEM). The DEM traditionally was applied for the granular materials. The basic idea of DEM is that any physical structure could be described as a system of moving particles. This idea could be also applied to the description of solid deformable body. Particles forming solid body and existing interaction between them are of different nature than the granular materials because their models are often the result of physical and mathematical abstraction.
The modelling of solid deformable body with the discrete elements is just at the initial stage and the unified approach to discrete elements models doesn’t exist. There are several versions of models, based... [to full text]
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Mao, Baimin. "Predicting resilient modulus of highway subgrade soils in Ohio." Ohio : Ohio University, 1995. http://www.ohiolink.edu/etd/view.cgi?ohiou1179257407.
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Perrenot, Gilles. "Etude experimentale et theorique d'assemblages metalliques en forme de sifflet colles avec une resine epoxyde." Reims, 1988. http://www.theses.fr/1988REIMS008.
Full textAbstract:
Etude de la liaison entre deux toles epaisses, a l'aide d'un joint de colle. Assemblage du type : sifflet avec butee. Mesure du module d'elasticite de l'adheresif. Influence du maillage du joint de colle. Modelisation et acquisition numerique par ordinateur
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Bayoglu, Flener Esra. "Soil-structure interaction for integral bridges and culverts." Licentiate thesis, KTH, Civil and Architectural Engineering, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-1715.
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Callaghan, Andree. "The influence of weed control, clone, and stem dimensions on wood quality of 17 year old stems of Pinus radiata which has been grown on the Canterbury Plains." Thesis, University of Canterbury. School of Forestry, 2013. http://hdl.handle.net/10092/9926.
Full textAbstract:
This study determined whether variation in clone, weed control treatment, or stem dimensions, could have an impact upon outerwood stiffness in 17 year old Pinus radiata stems. An experiment located south west of the Dunsandel township in Canterbury, New Zealand, was used to collect measures of acoustic velocity (windward and downward sides) from each of the 278 trees. Diameter at breast height, tree height, and height to live crown were also recorded for each tree. Findings from this research were compared with previous research carried out when the trees were ages eight and eleven.
Assuming a green density of 1,000 kg/m3, Young’s Modulus equation was used to convert acoustic velocity to wood stiffness, or, Modulus of Elasticity (MOE). The effect of wind direction upon mean wood stiffness was not significant (α = 0.05). Consequently, one measure of wood stiffness was calculated per tree.
Mean stem slenderness and mean wood stiffness values were calculated by block, weed control treatment, and clone. Weed control treatments had a significant impact upon mean wood stiffness in comparison to the control treatment (0.03 m2 area of weed control). Significant differences did not exist between different levels of weed control, ie., 0.75 m2, 3.14 m2 and 9 m2 chemical spot spray area.
Clonal variation and stem slenderness significantly affected mean wood stiffness measures. Stem slenderness appeared to be correlated with clonal variation (interaction between clone and slenderness was not significant), however, according to Dr. Euan Mason, this finding is not corroborated by findings from other research on the wood quality of clones in Canterbury (personal communication, September 16, 2013). An analysis of covariance (ANCOVA) determined that mean height to the live crown was not a significant predictor of wood stiffness. Comparison with earlier research showed no change in the ranking of wood stiffness values by clone or treatment.
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Bawcombe, Jonathan. "A study of Douglas-fir anatomical and mechanical properties and their interactions." Thesis, University of Bath, 2012. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.558893.
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Low embodied energy, ability to act as a carbon store and ease of recycling gives forest products an important role within a low carbon built environment. Almost 25 % of the coniferous resource within the South West of England is Douglas-fir, a species reputed for producing high quality timber. Despite this, the region is facing challenges in delivering the resources full potential, a contributing factor to which is a loss of knowledge regarding its quality. The aim of the work presented is to gain an improved understanding of the quality of Douglas-fir grown within the region, from the perspective of uses in structural applications, the factors which influence material quality and their interrelationships. Flexural modulus of elasticity, flexural and compressive strength were determined utilising small clear specimens derived from 1.3 and 8 m heights within 27 trees from six sites across the South West. Results showed a rise in the magnitude of properties with increasing cambial age, particularly so at younger ages. Differences in values were also recorded between stem heights and with rate of growth. These were however less than age related variations. Results compared favourably to those reported in other studies conducted on the species. Utilising SilviScan-3, anatomical properties including density, microfibril angle and cellular dimensions were measured. Significant variations were recorded with cambial age, and in some instances sampling height. The influence of growth rate on anatomical properties was small. Through statistical and composite modelling, microfibril angle was found to be strongly associated with changes in modulus of elasticity within juvenile wood. Within mature wood and for strength properties, density was the controlling factor. It was shown that a moderate proportion of variations in mechanical properties can be accounted for utilising visually identifiable wood characteristics. The new understanding that has been gained through this work presents opportunities for improved utilisation, the implementation of effective management practices and the development of more efficient visual grading techniques.
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Kocuba, Robert. "Diagnostika a hodnocení prefabrikované železobetonové konstrukce." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2018. http://www.nusl.cz/ntk/nusl-372269.
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This thesis deals with inspection and constructionally technical research of reinforced concrete prefabricated construction from the second half of 20th century. In theoretical part, the research of literature, documents and valid standards is performed, with a focus on production and construction of prefabricated elements and also on the metodology of research. In practical part, the detection of reinforcement of individual elements of the construction and concrete properties is performed. The result of this work is the assessment of the state of the construction, static calculation of the ceiling panel and idea proposal for eventual reconstruction.
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Al-Darwash, Mustafa, and Emanuel Nuss. "Mechanical characterization of DuraPulp by means of micromechanical modelling." Thesis, Linnéuniversitetet, Institutionen för byggteknik (BY), 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-43732.
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Södra DuraPulp is a relatively new eco-composite, made from natural wood fibers and polylactic acid (PLA), which comes from corn starch. Until now, there are only few applications for DuraPulp, mainly in the area of design. To find new fields of application, more knowledge about its mechanical material properties are of great interest.This study deals with characterizing the mechanical properties of DuraPulp in an analytical way by means of micromechanical modelling and evaluation with help of Matlab. The mechanical properties for PLA were taken from scientific literature. Not all properties of the wood fibers could be found in literature (particularly Poisson’s ratios were unavailable). Therefore, they partly had to be assumed within reasonable boundaries. These assumptions are later validated regarding their influence on the final product.Figures and tables were used to present and compare the in- and out-of-plane E-Moduli, shear moduli and Poisson’s ratios of DuraPulp. The calculated in-plane E-Moduli were then compared to those obtained from an earlier study, where DuraPulp was tested in tension. The results showed that experimental and analytical values are very similar to each other.<br>Södra DuraPulp är en relativt ny eco-komposit, tillverkat av naturliga trä fibrer och polylactic syra som kommer från majsstärkelser. I dagsläget finns det få användningsområden för DuraPulp, huvudsakligen används det inom design. För att expandera användningsområdet behövs det mer kunskaper angående de mekaniska egenskaperna för materialet. Studien handlar om att karakterisera de mekaniska egenskaperna för DuraPulp på ett analytiskt sätt i form av mikro-mekanisk modellering och evaluering med hjälp av Matlab. De huvudsakliga mekaniska egenskaperna för PLA kunde hämtas från flera vetenskapliga källor, men de motsvarande mekaniska egenskaperna för fibrer kunde inte alla valideras. Delvis antogs dem i rimliga gränser och deras inverkan validerades med hjälp av en parameter studie.Figurer och tabeller användes för att presentera och jämföra in- och ut-plan E-Moduler, skjuvmoduler och tvärkontraktionstalen av DuraPulp. De beräknade in-plan E-modulerna för DuraPulp jämfördes med motsvarande E-moduler från en tidigare studie där DuraPulp genomgick dragtest. Resultatet visade att analytiska och experimentella värden överensstämmer bra med varandra.
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Halamová, Romana. "Problematika zjišťování statického modulu pružnosti betonu v konstrukcích." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2017. http://www.nusl.cz/ntk/nusl-265362.
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The thesis deals with the measurement of the elastic modulus of concrete in existing structures and possibilities of applicability of equations for the calculation of characteristic values of concrete compressive strength on the modulus of elasticity. The modulus of elasticity is determined by dynamic and static methods on specimens taken from the concrete blocks, whose composition varies by a water cement ratio and varying amounts of admixtures. In conclusion, the results of the measurements are compared and the characteristic values of the modulus of elasticity is determined.
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Eriksson, Anna, Viktoria Andersson, Katrin Berezniak, Markus Hall, Victor Håkanson, and Ida Biörs. "Reologi på gelberedningar." Thesis, Uppsala universitet, Institutionen för teknikvetenskaper, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-297837.
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Konsistensen på en gel bestående av tvärbunden hyaluronsyra beror av tre faktorer: total koncentration hyaluronsyra, gelningsgrad och tvärbindningsdensitet. För att utföra detta projekt erhölls tre olika geler med olika tvärbindningsdensitet. Dessa geler späddes dels med lösning av fri, icke tvärbunden, HA från 100 % gelningsgrad till 90 % och 80 %. De olika gelningsgraderna späddes också med natriumkloridlösning från den totala koncentrationen HA, 35 mg HA/g gel, till 25 mg/g och 15 mg/g. Projekts huvudfråga är att kartlägga gelens reologiska egenkaper då både total koncentration HA och gelningsgrad varieras. För att kunna kartlägga detta har en reometer brukats där följande tre tester körts: tidssvep, frekvenssvep och amplitudsvep. Från erhållen data har sedan två parametrar som representerar gelkompositionernas viskösa egenskaper (G'') och elastiska egenskaper (G') observerats. Även mätning av extruderingskraft har genomförts för att dra vidare paralleller och slutsatser mellan extruderingskraften och de reoligiska egenskaperna. Ur resultaten ses att förlusttangenten tenderar att sjunka när gelningsgraden ökar, d.v.s. gelerna blir då mer viskösa och mindre elastiska. Förlusttangenten sjunker även vid ökande total koncentration HA vilket betyder att G’ ökar mer än G’’ i vardera punkt som gör att förlusttangenten minskar.Det gick även att avläsa att de viskösa egenskaperna i gelen ökar då total koncentration hyaluronsyra minskar samt att de viskösa egenskaperna i gelerna minskar vid en sjunkande gelningsgrad. Mellan gelningsgrad 90-100 % och total koncentration HA 25-35 mg HA/g har analyserna som gjorts i detta projekt gett följande slutsatser. Konsistensen på gel A och C är mer påverkade av gelningsgraden än total koncentration HA. För gel B kan ingen dominerande parameter utläsas.<br>The softness of a gel made of crosslinked HA (HA = hyaluronic acid) depends onthree factors. One is the amount of free hyaluronic acid in the gel. Another is thedensity of the crosslinked network, which is the molecular entanglements in the gel.The third is the total concentration of HA. In this project a rheometer is used to measure the rheological properties by runningthe following tests: time sweep, frequency sweep and amplitude sweep. From theobtained data, parameters related to viscous properties (G’’) and elastic properties(G’) of the gels were observed. 27 different compositions of gels with three differentconcentrations (35 mg HA/g, 25 mg HA/g, 15 mg HA/g), three different gel contents(100%, 90%, 80%) and three different densities of crosslinked network (A, B, C) wereanalyzed. To draw further conclusions an analysis of extrusion force was performedas well. The results from the frequency sweeps show that the loss tangent for a gel increasedas the total concentration of HA was reduced and that the loss tangent for a gelincreased as the gel content was decreased. This indicates that the gels become moreviscous when either the concentration of HA or the gel content was decreased. Anincrease in concentration of HA results in an increase of G' and an increase of gelcontent also results in an increase of G'. The results from the amplitude sweeps showthat xG' (xG' = storage modulus at the crossover point between G' and G'') increasesas either the concentration of HA or the gel content is increased. For xStrain (xStrain= deformation of the gel at the crossover point) and xStress (xStress = the stressapplied to the gel at the crossover point) no clear trend can be seen regarding the gelcontent. But an increase in concentration of HA results in an increase of both xStrainand xStress. The results from the analysis of extrusion force show that an increase intotal concentration HA increases the force.
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Vicente, Fábio Bossoi [UNESP]. "Influência do oxigênio nas propriedades anelásticas e biocompatibilidade de ligas Ti-5Zr e Ti-10Zr." Universidade Estadual Paulista (UNESP), 2010. http://hdl.handle.net/11449/99694.
Full textAbstract:
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vicente_fb_me_bauru.pdf: 4080382 bytes, checksum: 373e375b5b088e5f1dc9657a337315a2 (MD5)<br>Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)<br>Atualmente, existe a necessidade de se encontrar materiais para o uso como biomateriais, principalmente em relação às suas propriedades mecânicas. Com isso, procura-se ligas com excelente biocompatibilidade, passividade química extrema e propriedades mecânicas para um bom comportamento do material a longo prazo. Amparado por excelentes propriedades, o titânio e suas ligas têm sido amplamente utilizados por várias décadas como materiais para implantes e dispositivos médicos em todo mundo. A liga Ti-6A1-4V ainda é a principal liga de titânio usada como biomaterial no Brasil, mas devido à preocupação sobre a toxidade do alumínio e do vanádio a longo prazo, têm sido desenvolvida novas ligas sem a presença destes elementos. Dentre as ligas binárias estudadas, a liga Ti-Zr apresenta propriedades vantajosas como boa resistência a tração, baixa densidade, boa biocompatibilidade. Neste trabalho amostras de Ti-5%p.Zr e Ti-10%p.Zr são submetidas a tratamentos térmicos de homogeneização e duas dopagens com oxigênio para verificar a influencia do processamento nas propriedades das ligas. As amostras foram caracterizadas através de medidas de densidades, microdureza, difração de raios X com análise de Rietveld, Análise Química, Análise de gases e ensaios de citotoxicidade. Ensaios no pêndulo de torção revelam o espectro anelástico das amostras e a resposta elástica do mesmo em função da temperatura. Através dos resultados pode-se obter uma relação entre a concentração de oxigênio e as propriedades mecânicas, estruturais e biocompatibilidade das ligas estudadas<br>Nowadays, there is a need to find reliable material for use as biomaterials, especially in relation to their mechanical properties. With this comes the search for alloys with excellent biocompatibility, extreme chemical passivity and mechanical properties in an effort to create a satisfactory long-term material. With the support of excellent properties, titanium and its alloys have benn widely used for several decades as materials for orthopedic and dental implants and medical devices worldwide. The Ti-6A1-4V alloy is still the main titanium alloy used as a biomaterials in Brazil, but due to concerns about the long-term toxicity of aluminum and vanadium, new alloys have benn developed without the presence of these elements. Among the binary alloys studied, Ti-ZR has advantageus properties such as good tensile strength, low density, good biocompatibility. In this work samples of Ti-5%p.Zr and Ti-10%p.Zr are subjected to heat treatment and homogenization of two doping with oxygen to check the influence of processing on the properties of alloys. The samples were characterized by density measurments, microhardness, X-ray diffraction with Rietveld analysis, Chemical Analysis, Analysis of gases and in vitro cytotoxicity tests. Torsion pendulum tests show the anelastic spectrum of samples and the same elastic response as a function of temperature. through the results we can obtain a relationship between oxygen concentration and mechanical properties, structural and biocompatibility of the alloys studied
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Almeida, Luciano Henrique de [UNESP]. "Efeito dos elementos intersticiais nas propriedades anelásticas da liga Ti-35Nb-7Zr-5Ta para aplicações biomédicas." Universidade Estadual Paulista (UNESP), 2008. http://hdl.handle.net/11449/100919.
Full textAbstract:
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almeida_lh_dr_bauru_prot.pdf: 5007545 bytes, checksum: 41716fcc83b2b706362664ae94c57d9b (MD5)<br>Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)<br>Desde a antiguidade o homem busca materiais que possam substituir parcial ou totalmente tecidos do corpo humano. Os materiais metálicos mais utilizados com essa finalidade se enquadram em três grupos: os aços inoxidáveis, as ligas a base de cobalto e as ligas a base de titânio, esta última com destaque em relação às outras duas. As ligas de titânio são classificadas de acordo com a fase estável à temperatura ambiente, podendo ser α, α + β e β. A liga comercialmente mais utilizada em implantes é a Ti-6A1-4V, uma liga tipo α + β, porém estudos mostraram que os elementos A1 e V apresentam alguns efeitos tóxicos. Visando contornar esse problema, tem sido desenvolvidas ligas sem a presença destes elementos e que apresentem propriedades adequadas para a sua utilização como biomaterial. Dentre os diferentes tipos de ligas de titânio, as ligas do tipo β têm um futuro promissor, pois são as ligas que apresentam menores valores de módulo de alasticidade. A liga Ti-35Nb-7Zr5Ta se destaca, pois tem o menor módulo de elasticidade dentre elas, 55 GPa. As propriedades mecânicas destes materiais são fortemente relacionadas com o seu processamento térmico e mecânico, bem como a presença de elementos intersticiais como H, O, N e C. Este trabalho teve como objetivo estudar a influência de elementos intersticiais em solução sólida nas propriedades físicas, mecânicas e biocompatibilidade da liga Ti-35Nb-7Zr-5Ta. Para isso foram realizadas medidas de difração de raios X, microscopia eletrônica de varredura e análises químicas, objetivando a caracterização das amostras. Foram realizados ensaios de citotoxicidade direta e indireta, espectroscopia mecânica e tratamentos térmicos, além de dopagem com oxigênio nas amostras, para verificar que influência os elementos intersticiais acarretariam nas propriedades físicas e biocompatibilidade desta liga...<br>Since the antiquity the man searches for materials that can substitute partially or totally tissues of the human body. The metallic materials more used with that purpose are in three groups: the stainless steels, the cobalt based alloys and the titanium based alloys, this last one with prominence in relation to the other ones two. The titanium alloys are classified in agreement with the stable phase to the room temperature, could be, α, α + β e β. The commercially more used alloy in implants it is Ti-6A1-4V, a α + β type alloy, even so studies showed that the elements A1 and V present some toxicant effects. Seeking to solve that problem, it has been development alloys without the presence of these elements and that present properties adapted for its use as biomaterial. Among the different types of titanium alloys, the β type have a promising future, because they are the alloys that present smaller values of elasticity modulus. The Ti-35Nb-7Zr-5Ta alloys stands out, therefore it has the smallest elasticity modulus among them 55 GPa. The mechanical properties of these materials are strongly related with its thermal and mechanical processing, as well as the presence of interstitial elements as H. O. N and C. This work had as objective to study the influence of interstitial elements (in solid solution) in the physical and mechanical properties, and biocompatibility of the Ti-35Nb-7Zr-5Ta alloy. For that, measures of X-ray diffaction X, scanning electron microscopy and chemical analyses were performed, objectifying the characterization of the samples. Tests of direct and indirect cytotoxicity, mechanical spectroscopy and heat treatments were made, besides of doping the samples with oxygen, to verify that influence the interstitial elements have in the physical properties and biocompatibility of this alloy. In the cytotoxicity tests the samples not presented toxic effect... (Complete abstract click electronic access below)
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Engström, Anders, and Toma Sumbasacu. "The length effect on Norway spruce boards : An investigation on indicating properties based on axial dynamic and edgewise bending MOEs." Thesis, Linnéuniversitetet, Institutionen för byggteknik (BY), 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-49099.
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When using timber for construction purposes it is important to know its strength. One way to do this is by sorting the boards into strength classes that are defined by European standards. A commonly used method for strength grading is based on dynamic excitation in the longitudinal direction of the board to obtain an average dynamic longitudinal modulus of elasticity (MOE). This in turn correlates with the bending strength of the board in such a way that it can be used as an indicating property (IP) to bending strength. The use of MOE as an IP has proven to give the highest coefficient of determination (R2) to both bending and tensile strength in boards. Through the research described in this thesis, one might find that both reducing the length of a board to half its initial length and by removing the part containing the lowest local MOE in edgewise bending provided similar results, the axial dynamic MOE remaining within a 1% tolerance whereas the lowest IP based on local MOE in edgewise bending increased by 6–7%.
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Michelena, Isis. "Influência da porosidade no módulo de elasticidade de um material compósito com foco na indústria de materiais de fricção." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2013. http://hdl.handle.net/10183/150645.
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O presente trabalho propõe uma modelagem matemática simplificada que tem como foco o cálculo do módulo de elasticidade em matérias de fricção levando em consideração a porosidade. A modelagem proposta foi desenvolvida tendo como base a Lei das Misturas Modificada e os equacionamentos propostos por Spriggs e Kingery. Para simplificação do modelo, foi analisado um compósito com um aglomerante e um elemento de reforço. A escolha das matérias-primas levou em consideração os elementos mais utilizados em um material de fricção, desta forma o aglomerante utilizado foi uma resina fenólica e os agentes de reforço foram fibras de vidro e aramida. O equacionamento foi verificado utilizando dados empíricos. Para tanto, foram utilizados dois grupos de compósitos, um com resina fenólica e fibra de vidro e o outro com resina fenólica e fibra aramida. A verificação da influência das fibras no compósito foi feita variando o percentual de fibra, de 5% a 30% em peso, com um aumento de 5% entre as amostras. Os materiais foram confeccionados segundo o método de cura a quente sob pressão, seguido de tratamento térmico. Para a verificação das propriedades mecânicas foi realizado o teste de flexão a 3-pontos, segundo a norma ASTM D790,07. Em uma primeira análise, foi verificado o teor mínimo para que a fibra comece a atuar como reforço estrutural, e este para os dois grupos investigados foi de aproximadamente 2%, ou seja em todas as amostras as fibras estão atuando como elemento de reforço. O ensaio de porosidade seguiu a norma Volkswagen PV 3005 Por esse, foi possível verificar que para o compósito com fibra de vidro, quanto maior o teor de fibra, menor a porosidade apresentada pelo compósito. Para o compósito com aramida, a porosidade só diminui até 15%, após mantém-se constante. Este resultado pôde ser explicado pelo fato da aramida se apresentar na forma de polpa, dificultando a molhabilidade da resina. Como não há correlação linear entre porosidade e módulo de elasticidade para o compósito com fibra aramida, é proposto um modelo que seja apto à avaliação dos dois compósitos em questão. A utilização deste modelo visou a redução expressiva no tempo despendido e esforços de desenvolvimento de produtos, colaborando para a redução dos custos de projeto e aumento da competitividade destes produtos. A modelagem matemática simplificada proposta permitiu obter uma correlação entre o módulo de elasticidade e a porosidade. Os dados calculados através do modelo proposto concordam de forma satisfatória com os resultados experimentais.<br>The present work shows a simplified mathematical modeling focused on the modulus of elasticity in a friction material considering the inherent porosity of this material. The suggested model was developed based on the modified Law of Mixtures and equations proposed by Spriggs and Kingery. To obtain a simplified model a composite constituted of a binder and a reinforcement element was analyzed. Raw materials used in these tests were chosen based on raw materials most used in a friction industry, the binder used is a phenolic resin and reinforcing components are glass fiber and aramid fiber. The proposed model was verified based on the empirical data, analyzing two groups of composite material, one with a phenolic resin and fiber glass and another one with phenolic resin and aramid fiber. To understand the influence of the reinforcing components in the composite, the percentage of fibers was varied from 5% to 30%, the difference between samples is 5%. The materials were manufactured using the process typically used for friction materials, heat curing under pressure followed by heat treatment. The samples were tested under 3-points bending test procedure, according to ASTM D790-07 standard. In a preliminary analysis the minimum fraction of fiber that works as a reinforcing component is 2%, according to critical volume equation. Then in all the samples analyzed the fibers are acting as reinforcement elements. The porosity test was made according to VW PV 3005 standard Using this method, it was possible to verify that increasing the percentage of glass fiber the percentage of porosity decrease. For the aramid composite the percentage of porosity decreases up to 15% of fiber, from this point the value is kept constant. This result can be explained if we consider the fact that the aramid fiber is used in the pulp form, hindering the wettability of the resin. Since there is no linear correlation between porosity and elastic modulus for the composite with aramid fiber, it is proposed a model that is able to appraisal the two composites in question. The use of this model aims a significant reduction in time spent and resources on development, helping to reduce the project cost and increasing the product competitiveness. The simplified mathematical model proposed supported a correlation between modulus of elasticity and porosity. Data calculated by the proposed model agrees satisfactorily with the experimental results.
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Tichý, Aleš. "Vliv velikosti a tvaru zkušebního tělesa na modul pružnosti lehkých betonů." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2019. http://www.nusl.cz/ntk/nusl-391974.
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The diploma thesis deals with the determination of the influence of size, shape and type of test specimen on values of modulus of elasticity of light-weight concrete. A lot of different specimens were prepared from two concrete’s mixtures for the experiment. Tests for measurement of static modulus of elasticity and dynamic modulus of elasticity by ultrasonic impulse velocity method were made. The results were assessed and summarized in tabular and graphical form.
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Sjögren, Torsten. "Influences of the Graphite Phase on Elastic and Plastic Deformation Behaviour of Cast Irons." Doctoral thesis, Linköpings universitet, Konstruktionsmaterial, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-8776.
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The amount and morphology of the graphite phase largely controls the resulting properties of cast iron. For instance, in flake graphite cast irons the mechanical properties are low while the thermal conductivity is high. This is in contrast with spheroidal graphite cast irons where the mechanical properties are high and the thermal conductivity is low. These differences are due to the different graphite morphologies and must be accounted for in the design work and material selection of cast iron components. In this work the influence of the graphite phase on the elastic and plastic deformation behaviour of cast irons has been studied. The material grades studied originate from castings for marine diesel engine piston rings with different chemical analyses. Two groups of pearlitic cast iron materials were studied; one with differences in graphite morphology and one with grey irons that differed in graphite content. For these different material grades the mechanical properties were correlated to microstructural parameters. In addition to standard uniaxial tensile tests, acoustic emission measurements were used for the study of deformation. When studying the modulus of elasticity of the cast iron it was found that the modulus of elasticity of the inherent graphite phase depends on the roundness of the graphite particles and is due to the strong anisotropy of the graphite phase. A linear correlation between nodularity and the modulus of elasticity of the graphite phase was derived. This correlation made it possible to account for the anisotropy of the graphite phase in the model used. By applying the linear function when modelling the effective modulus of elasticity, a high accuracy between experimental and theoretical values was achieved. Another factor affecting the elastic response when subjecting a cast iron component to tensile load was found to be the plastic deformation that actually occurs at very low strains for all of the studied cast iron grades. It was observed that the plastic deformation in the low strain elastic region, quantified by using acoustic emission measurements, increased linearly with decreasing modulus of elasticity. These measurements showed that the amount of plastic deformation in the elastic region was largely controlled by the graphite morphology. It was concluded that as the roundness of the graphite particles increases, the plastic deformation activity in the elastic region decreases. The plastic deformation activity continued linearly into the pronounced plastic region of the tensile tests. A decrease in roundness or increase in graphite fraction resulted in an increase of the amount of plastic deformation and the strain hardening exponent. A dependence between strength coefficient and graphite fraction was observed. Models for the flow curves for pearlitic cast irons were developed and shown to accurately reproduce the observed experimental curves. The surveys performed and conclusions from this thesis will be helpful in the design of new cast iron materials.
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Valentová, Renata. "Zjišťování dynamických modulů cihelného střepu." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2012. http://www.nusl.cz/ntk/nusl-225668.
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This master’s thesis deals with the determination of dynamic modulus of elasticity non-destructive methods of brick body. The test samples were laboratory-made from two types of brick earth and further were used cotouts from the full brick types clinker. For measuring were used ultrasonic impulse and resonant-impact method.
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Montija, Fernando Celotto. "Aspectos da variabilidade experimental do ensaio de módulo de deformação do concreto." Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/3/3146/tde-01042009-135948/.
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Esta dissertação insere-se nas áreas de qualidade laboratorial e de ensaios de controle de concreto, especificamente quanto à propriedade módulo estático de deformação ou módulo de Young. A motivação do trabalho é a elevada variabilidade de resultados experimentais observada pelo meio técnico nacional em ensaios interlaboratoriais, cujos resultados indicam desvios-padrão totais da ordem de 3,5 GPa, valor significativo para o controle tecnológico de obras de construção civil. Os objetivos buscados foram a identificação das parcelas da variabilidade oriundas da produção e do ensaio, com especial atenção àquela originada na instrumentação para medida das deformações durante o ensaio, e a discussão da aplicabilidade do conceito semiprobabilístico normativo à propriedade módulo de deformação do concreto. Além disso, a própria discussão da aplicabilidade da sistemática de pesquisa e análise sobre este tipo de ensaio e de material constou como um objetivo do trabalho. Para tal, desenvolveu-se um programa experimental em duas etapas: a primeira foi destinada às avaliações de acurácia (precisão e exatidão) do método de ensaio. As avaliações se deram segundo roteiros da área metrológica para validação de métodos e sistemas de medida. De quatro instrumentações para medida das deformações testadas, uma se mostrou mais precisa (identificada como clip gages) e outra se mostrou a mais suscetível a erros sistemáticos e aleatórios entre as testadas (identificada como compressômetro com dois relógios comparadores). Recomendou-se a ampliação do programa experimental para o âmbito interlaboratorial, pois, a rigor, o método de ensaio vigente não poderia ser considerado validado em termos de acurácia baseando-se unicamente nos resultados deste programa experimental. Porém, concluiu-se pela possibilidade de aceitação prática do método independentemente da utilização de três de um total de quatro tipos de instrumentação para medida das deformações testados em ensaio, sem que houvesse prejuízo para a produção ou o controle tecnológico usual desta propriedade. Na segunda etapa, obteve-se um Diagrama de Dosagem e estudou-se um cenário de fornecimento de concreto sob critérios estatísticos diferentes de atendimento à especificação de módulo de deformação: utilização do valor característico e do valor médio, com diferença de 4 GPa entre eles. Estimou-se um aumento da ordem de 9% no deslocamento vertical de uma viga simples bi-apoiada quando executada com o concreto de menor módulo em relação à execução com o de maior módulo. Por sua vez, o concreto de maior módulo exigiria um aumento no consumo de cimento da ordem de até 200 kg/m3, se conservados todos os insumos materiais e os demais parâmetros tecnológicos contidos nos traços. Concluiu-se pela aplicabilidade do uso da sistemática empregada na avaliação da acurácia do método de ensaio e do uso do conceito semiprobabilístico para esta propriedade.<br>This work is developed into the areas of laboratorial quality and concrete control tests, specifically focusing on the static modulus of elasticity or Young´s modulus. The motivation of this work is the high variability of experimental results observed by national technicians in interlaboratorial tests. These results show total standard deviations of around 3.5 GPa, a significant value for the technological control for civil construction. The main objectives are the identification of the variability fragments derived from the production and test, specially the ones related to the instrumentation for measuring deformations during the test, and the discussion of the semi-probabilistic concept applicability on the concrete Young´s modulus control. Moreover, the discussion of the applicability of the procedure used in this work and its analysis are also objective pursued here. The experimental program was developed in two steps: the first step covered the accuracy assessments (precision and exactness) of test method. The assessments were carried out according to instructions from Metrology concepts for the validation of the methods and the measure systems. One out of four instrumentations for measuring the tested deformations proved to be more precise (identified as clip gages) and another one proved to be more susceptible to systematic and random errors (identified as a compressometer with two dial indicators). The extension of the experimental program to an interlaboratorial scope is recommended because the current test method could not be considered valid based only on the results of this experimental program. However, it was shown that the practical acceptance of the test method for three among the four kinds of instrumentations analyzed, without damaging the production or the usual technological control of this property, is possible. On the second step, a mix design diagram was obtained and a case of supply of concrete under different statistical criteria (fulfillment the modulus of elasticity specification): the use of the characteristic value and the average value, with difference of 4 GPa between them. An increase of 9% on the vertical transference of a simple dual supported beam was observed when using a lower modulus concrete, when compared to another one with a higher modulus. On the other hand, the modulus increase would require an increment in the cement consumption up to 200 kg per cubic meter, if all the material inputs and further technological parameters is maintained. The final conclusion was that the procedure used on the assessment of the test method accuracy and the semi-probabilistic concept on this material property is applicable.
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Bizet, Laurent. "Caractérisation et modélisation du comportement thermomécanique des matériaux métalliques : vers la prise en compte des hétérogénéités micro-structurales intrinsèques." Thesis, Université Grenoble Alpes (ComUE), 2016. http://www.theses.fr/2016GREAA001/document.
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La prédiction de la géométrie d'une pièce mise en forme par déformation plastique grâce à un logiciel de calcul par éléments finis (EF) s'effectue en suivant séquentiellement différentes étapes : la caractérisation thermo-mécanique du matériau, la modélisation de son comportement et son intégration dans un logiciel EF, puis la mise en données et la simulation de l'opération de formage. La phase de modélisation consiste entre autre à identifier quel type de modèle de comportement est le plus approprié pour prédire les réactions du matériau lors de l'opération de formage. Ces modèles sont essentiellement développés dans le cadre de la mécanique des milieux continus (MMC). L'hypothèse forte, si ce n'est centrale, de la MMC consiste à considérer que les variables qui servent à déterminer le comportement du matériau sont continues et dérivables. Cependant, les connaissances les plus élémentaires de métallurgie indiquent que les grandeurs locales dans les matériaux métalliques sont discontinues. La majorité des modèles de comportement mécanique des matériaux métalliques repose sur la définition d'un volume élémentaire représentatif dont la taille est assez grande pour permettre une homogénéisation de la description du comportement en gommant l'influence des hétérogénéités localesL'objet de ces travaux est de montrer que la prise en compte des hétérogénéités locales dans la modélisation du comportement des matériaux métalliques est pertinente et contribue à l'amélioration de la prédiction des simulations d'opérations de mise en forme en élargissant le potentiel prédictif des modèles ainsi construits. Un modèle élasto-plastique prenant en compte les hétérogénéités locales est alors proposé<br>To obtain a relevant shape of a formed part during its finite element simulation, several steps are needed: thermo-mechanical caracterization of the material, definition of the most relevant model and integration of this model in the FE software and finally after data converting and computing processes. The modelling step include, among other things, the identification of the most appropriate model to fit the experimental material behaviour. Those models are essentially developped within the framework of continuum mechanics (CM). A strong, if not the main assumption of the CM consists in considering that mechanical description variables are continuous and differentiable. However, the basic knowledge of metallurgy indicates that local data in metallic materials are discontinuous. For metallic materials, the majority of constitutive models are based on the definition of a representative elementary volume (REV). This REV is supposed to be large enough to erase the incidence of local heterogeneities. Then those constitutive models are assumed to be homogeneous.The aim of this work is to show that introducing local heterogeneities in the description of constitutive models is relevant and contribute to improve the simulation accuracy. Those models also provide an enlargement of the simulation predictive potential. Then an elasto-plastic model, based on local heterogeneities description, is proposed
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Persson, Anna, and Martin Strand. "Stabilisering av betongstommar : Beräkning av en ekvivalent beräkningsmodul med hänsyn till samverkande kort- och långtidslast." Thesis, KTH, Byggteknik och design, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-125745.
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Vid stabilisering av betongstommar är det komplicerat att välja en korrekt elasticitetsmodul. Detta då stommens laster verkar under både kort och lång tid. I detta examensarbete utförs en noggrann kryptalsberäkning för varje plans vertikala element, där hänsyn tas till den varierande byggtiden. Utifrån det analyseras kort- och långtidslaster med respektive elasticitetsmodul för att erhålla en ekvivalent elasticitetsmodul som tar hänsyn till de olika belastningstiderna. Denna elasticitetsmodul bestäms efter förhållandet mellan stommens knäcksäkerhet, snedställning och den vindlast som verkar på byggnaden. Den ekvivalenta elasticitetsmodulen ligger till grund för mer noggrann indata än tidigare vid stabilitetsberäkningar och redovisas i diagram som sedan kan användas i det praktiska ingenjörsarbetet. Där inget annat anges utförs beräkningar enligt Eurokod 2.Där inget annat anges är figurerna ritade av författarna.<br>When considering stabilization of concrete structures it is difficult to assign a correct modulus of elasticity to the structure. This is due to the presence of both short- and long-term loads. In this thesis a detailed calculation of each vertical elements creep coefficient is performed, which takes into account the varying construction time. Furthermore short and long term loads with respective modulus of elasticity are analyzed to obtain an equivalent modulus of elasticity corresponding to the two previously mentioned. The equivalent modulus of elasticity is determined by the relationship between the buckling resistance of the structure, initial imperfections and the wind load acting on the building. The equivalent modulus of elasticity is the basis for a more accurate input for stability calculations and is presented in graphs that can be used in the practice of engineering. Unless otherwise stated, calculations are performed according to Eurocode 2.Unless otherwise stated, the figures are drawn by the authors.
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Marchi, Renata D\'Agostino De. "Estudo sobre a variabilidade do módulo de deformação do concreto associada a fatores intrínsecos à produção do material." Universidade de São Paulo, 2011. http://www.teses.usp.br/teses/disponiveis/3/3146/tde-23032012-102942/.
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Em função da especificação do módulo de elasticidade ou módulo de deformação do concreto ser cada vez mais frequente, se faz necessário o conhecimento da variabilidade desta propriedade, relacionada ao processo de produção, de modo a tornar mais confiável sua avaliação e que possibilite melhores condições no controle de produção para o atendimento aos requisitos associados a esta propriedade. Várias pesquisas têm comprovado que a variabilidade das propriedades mecânicas dos materiais de construção obedece a processos aleatórios. Portanto, os métodos de segurança no projeto estrutural devem estar fundamentados no conceito da teoria das probabilidades e não em métodos deterministas. Isso já acontece para a determinação da resistência à compressão, conforme estabelecido pela ABNT NBR 12655 (2006). A presente dissertação tem como objetivo principal estudar o controle experimental do módulo estático de deformação do concreto, mostrando a influência da variação dos materiais constituintes do concreto, dentro da realidade de uma Central de Concreto. Também objetiva apresentar uma discussão da aplicabilidade do conceito semiprobabilístico das normas nacionais de projeto, dosagem e controle tecnológico à propriedade módulo de deformação do concreto. A metodologia da pesquisa envolveu a escolha de uma central dosadora de concreto localizada na cidade de São Paulo, com a avaliação em dois concretos de resistências características (f ck ) de 25 e 30 MPa, que são comumente solicitados no mercado em que se insere. Para cada f ck foram realizados ensaios para determinação do módulo de deformação secante, E cs, três vezes por semana por um período de nove meses. Em função da precisão observada em pesquisa recente, foi utilizada a instrumentação clip gage para avaliação da propriedade módulo de deformação. Foram realizados ensaios sob o plano de carregamento secante, previsto na ABNT NBR 8522 (2008). Concluiu-se que, pelo fato do módulo de deformação do concreto ser influenciado pela resistência à compressão, que obedece a uma distribuição probabilística, não se pode atribuir à propriedade uma característica determinística, incorrendo no risco de não atendimento da propriedade. Recomendou-se o estabelecimento de tolerâncias para a especificação do módulo de deformação, uma vez que é uma variável com distribuição de probabilidade de rejeição. Sugeriu-se a discussão de mudança de enfoque no controle do módulo de deformação do concreto, com o controle por valor característico, tal qual ocorre para a resistência à compressão, atribuindo-se um estimador que atribua valores inferiores ao módulo de deformação, considerando-se uma rejeição aceitável. Também pode-se atribuir uma faixa de variação aceitável do valor em torno da média, uma vez que a responsabilidade estrutural do parâmetro módulo de deformação é menor do que o da resistência à compressão.<br>The modulus of elasticity requirements for concrete structures is becoming even more frequent. So, the knowledge of the variables involved in the experimental results became more important in order to make more reliable its assessment and enabling better conditions for specifications requirements attendance in relation to this property. Several studies have shown that the variability of mechanical properties of construction materials is subjected to random processes. Therefore, the security methods in the structural design must be based in the probability theory concept rather than deterministic methods. The randomness of the, compressive strength of concrete is already take in account in the quality control process according to the Brazilian Standard ABNT NBR 12655 (2006). The present work aims to study the experimental control of static modulus of elasticity of concrete, showing the influence of the constituent materials used in a Concrete Ready Mix Plant. It also intends to present a discussion on the applicability of the semi-probabilistic concept of national design standards in the mix design and production control of concrete in order to attend the elastic modulus requirements. The research methodology had two main steps: the first one, developed at a Concrete Ready Mix Plant located in São Paulo City, was based on the assessment of two characteristic compressive strength (f ck ) of 25 MPa and 30 MPa, which are commonly demanded in this market. For each strength class, tests were done to evaluate the variability of static modulus of elasticity of concrete, E cs, three times per week, during a period of nine months. On the second step, an analysis of elastic modules of concretes provided at six different sites, where the characteristic strength was 30 MPa, which was made using the same materials used in the first step. It has been used the clip gage instrumentation for measuring deformation to the assessment of static modulus of elasticity of concrete. It was used due to the precision that has been observed in recent research. The evaluation has been done according to the Brazilian Standard ABNT NBR 8522 (2008). It was possible to conclude that the modulus of elasticity of concrete is influenced by the compressive strength, so it follows a probabilistic distribution and cannot be associated to a deterministic model of quality control, due to the risk of non-compliance of the requirement. It was recommended the establishment of tolerances for the measured modulus of elasticity results, taking in account its random characteristic. The possibility of changing the focus on modulus of elasticity quality control was proposed, turning the deterministic criterion as occurs for the compressive strength, giving an estimator that assigns lower values to the modulus of elasticity, considering an acceptable rejection. It can be also based in a method that allows the acceptance of a concrete that lies within a predetermined tolerance around the average value, because the structural responsibility of modulus of elasticity is lower than the compressive strength.
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Ferreira, Renata Prata. "Estudo do efeito da força, do módulo de elasticidade e do envelhecimento termomecânico no desgaste abrasivo da borracha de polibutadieno baixo cis." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/3/3151/tde-19072016-115907/.
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Esta Dissertação de Mestrado tem como Objetivo estudar a influência da tangente delta, envelhecimento termomecânico e força no comportamento de uma borracha de polibutadieno baixo cis perante o desgaste abrasivo através de experimentos em roda de borracha, utilizando planejamento fatorial completo em dois níveis (DOE 2k). A literatura possui muitas informações em relação à força indicando uma relação exponencial com a taxa de desgaste, todavia em relação à tangente delta e ao envelhecimento termomecânico quase não há dados. Ao final do trabalho foi possível verificar que todos os fatores estudados são significativos com relação ao desgaste da borracha, sendo a força a variável com maior influência, seguida pelo envelhecimento. A histerese medida pela tangente delta, apesar de ser um fator importante, só exerce influência no desgaste quando a borracha se encontra no estado envelhecido. Além disto, este trabalho também apresenta informações complementares sobre propriedades que são características da borracha e pouco difundidos, como o smearing, características de ondas de abrasão (abrasion pattern), comprimento de onda (Schallamach wavelength) e ondas de destacamento (waves of detachment).<br>This goal of this Master thesis is the study the influence of loss factor, thermomechanical aging and applied load to the abrasion behavior of low cis polibutadiene rubber through rubber wheel testing machine experiments using 2k factorial experiment design in two levels (DOE 2k). The literature has many information involving action of force showing exponential relationship between wear rate with applied load, almost no data related to the influence of loss factor and the thermomechanical aging. It was observed that all the studied factors are significant to the wear of rubber, the force being the variable with the greatest influence, followed by aging. The loss factor, despite being an important factor, only influences the wear behavior of aged rubber. In addition, this work presents some information regarding to the typical properties only for rubber and rubber products, such as smearing, abrasion pattern and Schallamach wavelength.
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Vicente, Fábio Bossoi. "Influência do oxigênio nas propriedades anelásticas e biocompatibilidade de ligas Ti-5Zr e Ti-10Zr /." Bauru : [s.n.], 2010. http://hdl.handle.net/11449/99694.
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Orientador: Carlos Roberto Grandini<br>Banca: Ana Paulo Rosifini Alves Claro<br>Banca: Paulo Sergio da Silva Junior<br>O Programa de Pós-Graduação em Ciência e Tecnologia de Materiais, PosMat, tem caráter institucional e integra as atividades de pesquisa em materiais de diversos campi da Unesp<br>Resumo: Atualmente, existe a necessidade de se encontrar materiais para o uso como biomateriais, principalmente em relação às suas propriedades mecânicas. Com isso, procura-se ligas com excelente biocompatibilidade, passividade química extrema e propriedades mecânicas para um bom comportamento do material a longo prazo. Amparado por excelentes propriedades, o titânio e suas ligas têm sido amplamente utilizados por várias décadas como materiais para implantes e dispositivos médicos em todo mundo. A liga Ti-6A1-4V ainda é a principal liga de titânio usada como biomaterial no Brasil, mas devido à preocupação sobre a toxidade do alumínio e do vanádio a longo prazo, têm sido desenvolvida novas ligas sem a presença destes elementos. Dentre as ligas binárias estudadas, a liga Ti-Zr apresenta propriedades vantajosas como boa resistência a tração, baixa densidade, boa biocompatibilidade. Neste trabalho amostras de Ti-5%p.Zr e Ti-10%p.Zr são submetidas a tratamentos térmicos de homogeneização e duas dopagens com oxigênio para verificar a influencia do processamento nas propriedades das ligas. As amostras foram caracterizadas através de medidas de densidades, microdureza, difração de raios X com análise de Rietveld, Análise Química, Análise de gases e ensaios de citotoxicidade. Ensaios no pêndulo de torção revelam o espectro anelástico das amostras e a resposta elástica do mesmo em função da temperatura. Através dos resultados pode-se obter uma relação entre a concentração de oxigênio e as propriedades mecânicas, estruturais e biocompatibilidade das ligas estudadas<br>Abstract: Nowadays, there is a need to find reliable material for use as biomaterials, especially in relation to their mechanical properties. With this comes the search for alloys with excellent biocompatibility, extreme chemical passivity and mechanical properties in an effort to create a satisfactory long-term material. With the support of excellent properties, titanium and its alloys have benn widely used for several decades as materials for orthopedic and dental implants and medical devices worldwide. The Ti-6A1-4V alloy is still the main titanium alloy used as a biomaterials in Brazil, but due to concerns about the long-term toxicity of aluminum and vanadium, new alloys have benn developed without the presence of these elements. Among the binary alloys studied, Ti-ZR has advantageus properties such as good tensile strength, low density, good biocompatibility. In this work samples of Ti-5%p.Zr and Ti-10%p.Zr are subjected to heat treatment and homogenization of two doping with oxygen to check the influence of processing on the properties of alloys. The samples were characterized by density measurments, microhardness, X-ray diffraction with Rietveld analysis, Chemical Analysis, Analysis of gases and in vitro cytotoxicity tests. Torsion pendulum tests show the anelastic spectrum of samples and the same elastic response as a function of temperature. through the results we can obtain a relationship between oxygen concentration and mechanical properties, structural and biocompatibility of the alloys studied<br>Mestre
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Johnson, Eleda. "The Elastic Behavior of Plagioclase Feldspar at High Pressure." Thesis, Virginia Tech, 2007. http://hdl.handle.net/10919/36450.
Full textAbstract:
Feldspars are one of the archetypical families of framework silicates. They not only comprise around 60% volumetrically of the Earthâ s crust, but are among some of the most structurally complicated minerals. Investigation into the structural behavior of various intermediate plagioclases at pressure has been undertaken with the intent of categorizing the elastic behavior with pressure across the solid solution series and establishing a conceptual model to characterize feldspar compression.
Complex behavior has been observed in the Equation of State for plagioclase feldspars in excess of 3 GPa, including an anomalous softening of ordered albite in excess of 8.4 GPa (Benusa et al 2005: Am Min 90:1115-1120). This softening was not observed in the EoS for the more intermediate plagioclase compositions containing between 20 and 40 mol% of end-member anorthite. The calculated elastic compliance tensor sums at room pressure show a general stiffening with increasing anorthite component, small elastic changes at the C-1 to I-1 transition, and a dominantly first-order response at the P-1 to I-1 transition near end-member anorthite.
The crystal structure of An37 plagioclase was determined by single-crystal X-ray diffraction. The compression mechanisms in An37 are similar to those in albite at lower pressures. The softening in albite at higher pressures is therefore attributed to the structural shearing in albite that is absent in An37 plagioclase up to 9.5 GPa.<br>Master of Science
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You, Therese. "Negative energy elasticity and a model for the behavior of the residual strain in doubly cross-linked gels fabricated by shear strain." Thesis, Uppsala universitet, Polymerkemi, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-420125.
Full textAbstract:
Doubly cross-linked gels were fabricated based on tetra-poly(ethylene glycol) (Tetra-PEG) by shear strain. These are gels with two network structures present in the same polymeric network. The second network structure is introduced by applying a mechanical field to the first natural network structure. These doubly cross-linked gels indicated a negative energy elasticity supporting earlier findings where the energy elasticity was found significantly negative for Tetra-PEG gel. Acquired results indicate implications for past research on the elasticity of polymer gels where the energy contribution was approximated to zero. Obtained results also indicated that the modulus of rigidity for the doubly cross-linked gels is constant regardless of applied shear strain during fabrication. This would indicate that the same second network structure is formed for the interval of 25-800% applied shear strain. The residual strain for the fabricated gels can be well-described using an exponential fitting of the apparent shear modulus of the first network structure and an expression derived from the two-network theory and classic rubber theory. These theories also seem to predict the experimental residual strains for lower strain regions (<100%) quite well. However for larger strain regions (>100%) non-linear effects seem to affect the results causing a deviation. A slight increased modulus of rigidity was noted for the doubly cross-linked gels compared to the regular Tetra-PEG gel. However as the reproducibility of the concluded measurements could not be confirmed during this thesis the results are not conclusive and only indicate the conclusions mentioned above.
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Ors, Kerime. "An Investigation On Compatibility Properties Of Exterior Finish Coats For Insulated Walls In Terms Of Water Vapour Pemeability And Modulus Ofelasticity." Master's thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/12607741/index.pdf.
Full textAbstract:
The compatibility properties of some contemporary finish coats together with their complementary layers used in insulated exterior walls were examined in terms of water vapour permeability and modulus of elasticity.
Basic physical and mechanical properties of some synthetic-, cement- and polymer-based external finish coats were analyzed in laboratory. Some additional samples, complementing the wall section, were also examined for their water vapour permeability.
Results showed that the finish coats were high vapour permeable although they had high resistance to water vapour permeation, which was achieved by their application in thin layers. Cement-based undercoats were found to be medium permeable. The application of primer and/or paint was found to decrease the permeability of finish coats in different ranges. Thermal insulation layer was found to interrupt water vapour flow considerably. Among polystyrene- and mineral-wool-based thermal insulation boards, rockwool was recommended as the insulation layer due to its medium vapour permeability. In conclusion, walls insulated externally with rockwool boards and plastered with polymer-based finish coat, FC8ACB or synthetic-based finish coat FC3SB were found to be the most proper combination in terms of breathing and thermal resistance capabilities. All finish coats seemed to have sufficient strength and except the synthetic-based finish coat, FC2SB, they seemed to be compatible with each other and with the masonry in terms of their Emod values. Further studies were recommended on some other compatibility properties of finishing systems, such as thermal and moisture dilatation properties, and on the relation between the resistance to water vapour permeation and water permeability.
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Dogan, Ibrahim Onur. "Structural Vibration Analysis Of Single Walled Carbon Nanotubes With Atom-vacancies." Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/3/12611550/index.pdf.
Full textAbstract:
Recent investigations in nanotechnology show that carbon nanotubes (CNT) have one of the most significant mechanical, electrical and optical properties. Interactions
between those areas like electrical, optical and mechanical properties are also very promising in both research and industrial fields. Those unique characteristics are
built by mainly the atomistic structure of the carbon nanotubes.
In this thesis, the effects of vacant atoms on single walled carbon nanotubes (SWCNT) are investigated using matrix stiffness method. In order to use this
technique a linkage between structural mechanics and molecular mechanics is established. A code has been developed to construct the SWCNT with the desired
chirality, extracting the vacant atoms with the corresponding atomic bonds between the neighbor nodes and calculating the effect of those vacancies on its vibrational
properties. A finite element software is also utilized for validation of the code and results.
In order to investigate the convergence of the effect of those vacant nodes a numerous number of analyses have been carried out with randomly positioned vacant
atoms. Also consecutive vacant nodes have been positioned in order to investigate the effect on the structural properties through the length of a CNT. In addition to those, as a case study, the reduction in Young'<br>s modulus property
because of the vacancies has also been investigated and the effects are tabulated in
the report.
It is concluded in this study that the any amount of vacant atoms have substantial effect on modal frequencies and Young'<br>s modulus. Chirality and the position of the
vacancies are the main parameters determining the structural properties of a CNT.