To see the other types of publications on this topic, follow the link: Experimental mechanics.
Dissertations / Theses on the topic 'Experimental mechanics'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Experimental mechanics.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Wong, Chi-ming, and 黃志明. "Image processing in experimental mechanics." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1993. http://hub.hku.hk/bib/B31211951.
Full text
2
Wong, Chi-ming. "Image processing in experimental mechanics /." [Hong Kong : University of Hong Kong], 1993. http://sunzi.lib.hku.hk/hkuto/record.jsp?B13671595.
Full text
3
Alipour, Skandani Amir. "Computational and Experimental Nano Mechanics." Diss., Virginia Tech, 2014. http://hdl.handle.net/10919/64869.
Full textAbstract:
The many advances of nano technology extensively revolutionize mechanics. A tremendous need is growing to further bridge the gap between the classical mechanics and the nano scale for many applications at different engineering fields. For instance, the themes of interdisciplinary and multidisciplinary topics are getting more and more attention especially when the coherency is needed in diagnosing and treating terminal diseases or overcoming environmental threats. The fact that how mechanical, biomedical and electrical engineering can contribute to diagnosing and treating a tumor per se is both interesting and unveiling the necessity of further investments in these fields. This dissertation presents three different investigations in the area of nano mechanics and nano materials spanning from computational bioengineering to making mechanically more versatile composites.
The first part of this dissertation presents a numerical approach to study the effects of the carbon nano tubes (CNTs) on the human body in general and their absorbability into the lipid cell membranes in particular. Single wall carbon nano tubes (SWCNTs) are the elaborate examples of nano materials that departed from mere mechanical applications to the biomedical applications such as drug delivery vehicles. Recently, experimental biology provided detailed insights of the SWCNTs interaction with live organs. However, due to the instrumental and technical limitations, there are still numerous concerns yet to be addressed. In such situation, utilizing numerical simulation is a viable alternative to the experimental practices. From this perspective, this dissertation reports a molecular dynamics (MD) study to provide better insights on the effect of the carbon nano tubes chiralities and aspect ratios on their interaction with a lipid bilayer membrane as well as their reciprocal effects with surface functionalizing. Single walled carbon nano tubes can be utilized to diffuse selectively on the targeted cell via surface functionalizing. Many experimental attempts have smeared polyethylene glycol (PEG) as a biocompatible surfactant to carbon nano tubes. The simulation results indicated that SWCNTs have different time-evolving mechanisms to internalize within the lipid membrane. These mechanisms comprise both penetration and endocytosis. Also, this study revealed effects of length and chirality and surface functionalizing on the penetrability of different nano tubes.
The second part of the dissertation introduces a novel in situ method for qualitative and quantitative measurements of the negative stiffness of a single crystal utilizing nano mechanical characterization; nano indentation. The concept of negative stiffness was first introduced by metastable structures and later by materials with negative stiffness when embedded in a stiffer (positive stiffness) matrix. However, this is the first time a direct quantitative method is developed to measure the exact value of the negative stiffness for triglycine sulfate (TGS) crystals. With the advancements in the precise measuring devices and sensors, instrumented nano indentation became a reliable tool for measuring submicron properties of variety of materials ranging from single phase humongous materials to nano composites with heterogeneous microstructures. The developed approach in this chapter of the dissertation outlines how some modifications of the standard nano indentation tests can be utilized to measure the negative stiffness of a ferroelectric material at its Curie temperature.
Finally, the last two chapters outline the possible improvements in the mechanical properties of conventional carbon fiber composites by introducing 1D nano fillers to them. Particularly, their viscoelastic and viscoplastic behavior are studied extensively and different modeling techniques are utilized. Conventional structural materials are being replaced with the fiber-reinforced plastics (FRPs) in many different applications such as civil structures or aerospace and car industries. This is mainly due to their high strength to weight ratio and relatively easy fabrication methods. However, these composites did not reach their full potential due to durability limitations. The majorities of these limitations stem from the polymeric matrix or the interface between the matrix and fibers where poor adhesion fails to carry the desired mechanical loadings. Among such failures are the time-induced deformations or delayed failures that can cause fatal disasters if not taken care of properly. Many methodologies are offered so far to improve the FRPs' resistance to this category of time-induced deformations and delayed failures. Several researchers tried to modify the chemical formulation of polymers coming up with stiffer and less viscous matrices. Others tried to modify the adhesion of the fibers to the matrix by adding different chemically functional groups onto the fibers' surface. A third approach tried to modify the fiber to matrix adhesion and at the same time improve the viscous properties of the matrix itself. This can be achieved by growing 1D nano fillers on the fibers so that one side is bonded to the fiber and the other side embedded in the matrix enhancing the matrix with less viscous deformability. It is shown that resistance to creep deformation and stress relaxation of laminated composites improved considerably in the presence of the nano fillers such as multiwall carbon nano tubes (MWCNTs) and zinc oxide nano wires (ZnO- NWs). The constitutive behaviors of these hybrid composites were investigated further through the use of the time temperatures superposition (TTS) principle for the linear viscoelastic behavior and utilizing phenomenological models for the viscoplastic behavior.Ph. D.
4
Barry, Matthew M. "Analytical and experimental studies of thermoelectric devices and materials." Thesis, University of Pittsburgh, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10183683.
Full textAbstract:
Interest in thermoelectric devices (TEDs) for waste-heat recovery applications has recently increased due to a growing global environmental consciousness and the potential economic benefits of increasing cycle efficiency. Unlike conventional waste-heat recovery systems like the organic Rankine cycle, TEDs are steady-state, scalable apparatus that directly convert a temperature difference into electricity using the Seebeck effect. The benefits of TEDS, namely steady-state operation and scalability, are often outweighed by their low performance in terms of thermal conversion efficiency and power output. To address the issue of poor device performance, this dissertation takes a multi-faceted approach focusing on device modeling, analysis and design and material processing.
First, a complete one-dimensional thermal resistance network is developed to analytically model a TED, including heat exchangers, support structures and thermal and electrical contact resistances. The purpose of analytical modeling is twofold: to introduce an optimization algorithm of the thermoelectric material geometry based upon the realized temperature difference to maximize thermal conversion efficiency and power output; and to identify areas within the conventional TED that can be restructured to allow for a greater temperature difference across the junction and hence increased performance. Additionally, this model incorporates a component on the numerical resolution of radiation view factors within a TED cavity to properly model radiation heat transfer. Results indicate that geometric optimization increases performance upwards of 30% and the hot-side ceramic diminishes realized temperature difference. The resulting analytical model is validated with published numerical and comparable analytical models, and serves as a basis for experimental studies.
Second, an integrated thermoelectric device is presented. The integrated TED is a restructured TED that eliminates the hot-side ceramic and directly incorporates the hot-side heat exchanger into the hot-side interconnector, reducing the thermal resistance between source and hot-side junction. A single-state and multi-stage pin-fin integrated TED are developed and tested experimentally, and the performance characteristics are shown for a wide range of operating fluid temperatures and flow rates. Due to the eliminated to thermal restriction, the integrated TED shows unique performance characteristics in comparison to conventional TED, indicating increased performance.
Finally, a grain-boundary engineering approach to material processing of bulk bismuth telluride (Bi2Te3) is presented. Using uniaxial compaction and sintering techniques, the preferred crystallographic orientation (PCO) and coherency of grains, respectively, are controlled. The effect of sintering temperature on thermoelectric properties, specifically Seebeck coefficient, thermal conductivity and electrical resistivity, are determined for samples which exhibited the highest PCO. It is shown the performance of bulk Bi2Te3 produced by the presented method is comparable to that of nano-structured materials, with a maximum figure of merit of 0.40 attained at 383 K.
5
Reggiani, Barbara <1976>. "Simulation models in biomechanics and experimental mechanics." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2007. http://amsdottorato.unibo.it/542/.
Full text
6
Saldner, Henrik O. "Electronic holography and shearography in experimental mechanics." Licentiate thesis, Luleå, 1994. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-26590.
Full text
7
Brown, Ainsmar Xavier. "Inflatable wing UAV experimental and analytical flight mechanics." Thesis, Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/39492.
Full textAbstract:
The field of man portable UASs (Unmanned Aerial Systems) is currently a key area in improving the fielded warrior's capabilities. Pressurized aerostructures that can perform with similar results of solid structures can potentially change how this objective may be accomplished now and in the future. Construction with high density polymers and other composites is currently part of active inflatable vehicle research. Many shape forming techniques have also been adapted from the airship and balloon manufacturing industry. Additional research includes modeling techniques so that these vehicles may be included in simulation packages.
A flight dynamics simulation with reduced-order aeroelastic effects derived with Lagrangian and Eulerian dynamics approaches were developed and optimized to predict the behavior of inflatable flexible structures in small UASs. The models are used to investigate the effects of significant structural deflections (warping) on aerodynamic surfaces. The model also includes compensation for large buoyancy ratios. Existing literature documents the similarity in structural dynamics of rigid beams and inflatable beams before wrinkling. Therefore, wing bending and torsional modes are approximated with the geometrically exact ntrinsic beam equations using NATASHA (Nonlinear Aeroelastic Trim And Stability for HALE Aircraft) code. An approach was also suggested for inclusion of unique phenomena such as wrinkling during flight. A simplified experimental setup will be designed to examine the most significant results observed from the simulation model. These methods may be suitable for specifying limits on flight maneuvers for inflatable UASs.
8
Lortie, Mireille. "Joint mechanics during movement : experimental and theoretical studies." Thesis, McGill University, 2001. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=38226.
Full textAbstract:
In the first of three manuscripts, we describe a study in which we measured the electromyographic (EMG) and mechanical responses to brief stretches of the ankle plantarflexors applied at various instants during an imposed movement of the ankle. The results demonstrate that afferent input resulting from movement of the ankle can both modulate and inhibit the reflex EMG activity. They also reveal a dissociation of reflex EMG activity and reflex torque during the movement that cannot be explained on the basis of results obtained under stationary conditions.In the second and third manuscripts, we describe two new techniques to identify time-varying systems from ensemble data. These are meant to serve as building blocks in the development of an algorithm to identify joint mechanics during movement. The first technique applies to linear time-varying systems while the second serves to identify time-varying Hammerstein systems. The techniques can be used when the system varies quickly and require no a priori knowledge of the structure of the linear element and of the form of the time variation. Furthermore, the inputs do not need to be white. Simulation results demonstrate that the new techniques perform well in the presence of significant output noise with a reasonable number of realizations. These techniques are thus capable of yielding good system models under realistic conditions.
9
Wang, Shuwen. "Experimental investigation of the mechanics of vibratory finishing." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0004/MQ46089.pdf.
Full text
10
Smith, Brian John. "Photon wave mechanics and experimental quantum state determination /." view abstract or download file of text, 2007. http://proquest.umi.com/pqdweb?did=1324388721&sid=1&Fmt=2&clientId=11238&RQT=309&VName=PQD.
Full textAbstract:
Thesis (Ph. D.)--University of Oregon, 2007.Typescript. Includes vita and abstract. Includes bibliographical references (leaves 231-242). Also available for download via the World Wide Web; free to University of Oregon users.
11
Swarén, Mikael. "Experimental test setups and simulations in skiing mechanics." Licentiate thesis, KTH, Strukturmekanik, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-144408.
Full textAbstract:
Product testing and development are essential parts in sports and for the athletes in their quest to reach the podium. Manufacturers of sports equipment often use basic test methods which do not test the equipment in a sports specific way. Much of the equipment used by world-class athletes is chosen based only on subjective tests and the athletes’ feelings. One short term aim was therefore to develop test methods for objective tests of sports equipment that also tested the equipment in a sports specific way. Another aim was to integrate mechanics and simulations to enhance the understanding of the test results. The more long term aims are to contribute to increased theoretical knowledge regarding test methods for sports equipment and to contribute to the development of test methods to create new and better sports equipment. Experimental tests combined with simulations can give valuable information to improve the performance and safety of sports equipment. Three studies dealt with the issue of objective yet sport specific test methods for sports equipment. The main methodological advancement is the modification of established test methods together with conventional mechanics calculations. New test devices and methodologies are proposed for alpine ski helmets and cross-country ski poles. Suggestions are given for improved test setups as well as theoretical simulation are introduced for glide tests of skis. The results show how sport specific test methodologies together with theoretical calculations can improve the objectiveness and relevance when testing sports equipment. However, the collected and used data require high precision to obtain high accuracy in the simulations. High data accuracy can be an issue in field measurements but also due to manufacturers not disclosing key material data. Still, the used methods and calculations in this thesis produce relevant and reliable results which can be implemented to accurate evaluations of different sports equipment. Even though it has not been a first priority aim in this work, the results from the alpine helmet study have been used by helmet manufacturers to design new helmets with increased safety properties. This further show how an objective and sport specific test approach together with theoretical simulation can improve sports equipment and in the longer perspective, also the athletes’ performances.QC 20140423
12
Jensen, Tori (Victoria M. ). "An experimental comparison of hitting mechanics in softball." Thesis, Massachusetts Institute of Technology, 2016. http://hdl.handle.net/1721.1/107866.
Full textAbstract:
Thesis: S.B., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2016.Page 37 blank. Cataloged from PDF version of thesis.
Includes bibliographical references (page 36).
To score points to win games, a softball team must be able to hit the ball with as the largest velocity as possible. In softball, there are two well-known hitting models, rotational and linear, yet little quantitative research has been done to determine which model produces the greatest ball velocity and if certain key inputs, such as weight shift and bat velocity, of the models contribute to that velocity. To determine these components, a high-speed EXLIM camera recorded the change in ball position to calculate the its exit velocity, a 70g accelerometer measured centripetal acceleration of the bat to determine bat velocity, while two force plates measured the transfer of weight as nine softball players swung a bat twenty times- ten times with a ball on the tee and ten times with a ball off of the tee. Although it was found that the two hitting models had statistically different weight shifts with 95% confidence, the average ball velocity for a linear model, 22.0 m/s ±1.9 m/s, was not different from the average ball velocity for a rotational model, 22.0 m/s ± 0.7 m/s, at 95% confidence. Since these values are not different with statistical significance, this research concludes that players that weight shift does not effect ball velocity and that players are encouraged to use whichever model feels most comfortable to them.
by Tori Jensen.
S.B.
13
Lindfors, Ulf. "Experimental study of the mechanics of rock joints." Licentiate thesis, Luleå tekniska universitet, 1996. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-25833.
Full text
14
Srinivasa, Prashanth. "Mechanics of Nanocellulose Foams : Experimental and Numerical Studies." Doctoral thesis, KTH, Hållfasthetslära (Avd.), 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-202590.
Full textAbstract:
Nanofibrillär cellulosa (NFC) skum är en intressant klass av cellulära material med möjliga applikationer som sträcker sig från fordonsindustrin till biomedicin då det har unika och önskvärda mekaniska egenskaper. I ljuset av de senaste framstegen inom framställning av skum förutspås det tillämpas inom en rad olika områden, inklusive områden där dess mekaniska egenskaper är viktiga. Den makroskopiska responsen är oskiljbart kopplad till mikrostrukturen hos materialet. Det är därför nödvändigt att ha numeriska modeller som inte bara kan förutsäga makroskopisk respons utan också ge insikt vid anpassning av mikrostrukturen så att förbättrade makroskopiska egenskaper kan uppnås. I detta syfte studerar vi 2- och 3-dimensionella slumpmässiga cellulära modeller och karakteriserar genom experiment/simuleringar de makroskopiska och cellväggens materialegenskaper. I Artikel A utforskar vi lämpligheten av 2-dimensionella slumpmässiga strukturer för att representera skums makroskopiska respons i tryck. Även om den 2-dimensionella modellen inte kan beskriva det exakta beteendet, endast en storleksordning överensstämmelse uppnås, kartlägger vi effekten av inre kontakt på den makroskopiska responsen och studerar effekten av linjär storlek, väggtjocklek och cellväggens kurvatur. Slutsatsen som dras är att 2-dimensionella modeller är otillräckliga och att förbindelserna ut ur planet är icke-triviala. I Artikel B framställs NFC skum genom frystorkning och karakteriseras experimentellt vid enaxlig och bi-axiell belastning för att utvärdera materialets strukturella anisotropi. Skummet visas vara isotropiskt i planet. Vidare uppkommer stora icke-reversibla deformationer vid avlastning. En hyperelastisk kontinuum-modell anpassas till experimentell data. I Artikel C används tomografibaserade tvärsnittsbilder för att bestämma cellväggens materialegenskaper. Vi rekonstruerar en 3-dimensionell struktur baserad på tomografibilder och använder den i finita element-simuleringar för att bestämma elasticitetsmodulen och sträckgränsen för cellväggens material. Resultaten visar att den beräknade elasticitetsmodulen är jämförbar med den övre gränsen för NFC papper, medan sträckgränsen är jämförbar med uppskattningar från indirekta metoder. Simuleringarna bekräftar även skademekansimen att formering av plastiska gångjärn följs av kollaps, vilket också observerats i experimentella studier. I Artikel D använder vi de materialegenskaper som beräknats i det tomografibaserade arbetet i simuleringar av slumpmässigt genererade 3-dimensionella strukturer. Vi validerar de 3-dimensionella strukturerna mot strukturena som fångats med tomografi. Vi studerar därefter om de slumpmässiga strukturerna kan användas för att representera den makroskopiska responsen tillsammans med studierna av linjärstorlek och effekt av de delvis öppna/slutna cellerna. Vi beräknar även påverkan av cellytans kurvatur på elasticitetsmodulen och på platåspänningen. Vi visar att 3-dimensionella modeller är relativt representativa upp till medelhög töjningsgrad men att förtätningen inte fångas upp av med den representativa storlek som används.Nanofibrillar cellulose (NFC) foams are an interesting class of cellular materials that are being explored for a variety of applications, ranging from the automotive to the biomedical industries. The cellulose nanofibrils itself has unique and desirable mechanical properties. With recent advances in the preparation of these foams, it is anticipated that these foams will find applications in diverse areas, including those where the mechanical response is important. This macroscopic response is inextricably linked to the microstructure of the material. Thus, it is imperative to have numerical models that can not only predict the macroscopic response but can also provide insights towards tailoring the microstructure such that improved macroscopic properties can be sought. Towards this end, we study 2- and 3-D random cellular models along with characterising through experiments/simulations the macroscopic and cell wall material properties. In Paper A, we explore the suitability of two-dimensional random structures in representing the macroscopic compressive response of foams. Though the two-dimensional model fails to capture the exact response, only an order of magnitude agreement is found, we map the effect of internal contact on the macroscopic response and study the effect of linear size, wall thickness and non-straightness of the cell walls. It is concluded that 2-D models are inadequate and that the out of plane connectivity is non-trivial. In Paper B, NFC foams prepared from freeze-drying are experimentally characterised under uniaxial and biaxial loading conditions, with a view towards testing for structural anisotropy. It is found that the prepared foam is isotropic in the plane. The experiments also reveal that there are large irreversible deformations, when unloaded. A continuum hyperelastic model is fitted to the experimental data. In Paper C, tomography based scans of the NFC foams are used to arrive at the material properties of the cell walls. We reconstruct the three-dimensional structure from the tomography scans and use it in finite element simulations to determine the elastic modulus and yield strength of the cell wall material. It is seen that the estimated elastic modulus is comparable to the upper limit for NFC paper, while the yield strength is comparable to estimates from indirect methods. The simulations also corroborate the damage mechanism, i.e. by plastic hinge formations followed by the collapse of the inner structure, as observed by experimental studies. In Paper D, we utilise the material properties derived from the tomography-based work in simulating three-dimensional random structures. We validate the three-dimensional reconstruction method against the foam structures derived in microtomography. We then study the applicability of these random structures in representing the macroscopic response, together with studies on linear size and effect of partially open/closed cells. We also estimate the influence of cell face curvature on the elastic modulus and plateaus stress. It is concluded that 3-D models provide a reasonable representation of the response up to intermediate strain levels, but the densification regime is not captured by the considered representative size.
QC 20170301
15
García, Aragón Juan Antonio. "Experimental and analytical investigations of granular-fluid mixtures down inclines." Thesis, McGill University, 1993. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=41021.
Full textAbstract:
Granular-fluid mixtures flowing down an incline in the grain-inertia regime were studied experimentally and analytically. The equations of motion are based on the kinetic theory for granular flow. The boundary conditions are formulated following two methods. The first is a simple mechanical approach based on the energy exchange at the wall. The other is based on the kinetic theory for granular flow. Solutions for dry granular flow down a chute are studied in order to compare both methods. The extension of the kinetic theory presented here, includes drag forces resulting from the interstitial fluid that cushions interparticle collisions and particle-wall collisions. Frictional stresses, produced when long term contacts are present, and fluid turbulent fluctuations are introduced in the model.The results are compared with measurements from an experimental chute in which the inclination, the solids flow rate and fluid flow rate are all varied. The theory is found to give a good qualitative account of the observed behaviour. Finally an application of the model to the description of the mechanical behaviour of the Nevado del Ruiz 1985 debris flow is attempted.
16
Li, Dongli. "Computational and experimental study of shock wave interactions with cells." Thesis, University of Oxford, 2016. https://ora.ox.ac.uk/objects/uuid:38beffe8-06c9-4b49-89f8-f5318c527800.
Full textAbstract:
This thesis presents a combined numerical and experimental study on the response of kidney cells to shock waves. The motivation was to develop a mechanistic model of cell deformation in order to improve the clinical use of shock waves, by either enhancing their therapeutic action against target cells or minimising their impact on healthy cells. An ultra-high speed camera was used to visualise individual cells, embedded in tissue-mimicking gel, in order to measure their deformation when subject to a shock wave from a clinical shock wave source. Advanced image processing was employed to extract the contour of the cell from the images. The evolution of the observed cell contour revealed a relatively small deformation during the compressional phase and a much larger deformation during the tensile phases of a shock wave. The experimental observations were captured by a numerical model which describes the volumetric cell response with a bilinear Equation of State and the deviatoric cell response with a viscoelastic framework. Experiments using human kidney cancer cells (CAKI-2) and noncancerous kidney cells (HRE and HK-2) were compared to the model in order to determine their mechanical properties. The differences between cancerous and noncancerous cells were exploited to demonstrate a design process by which shock waves may be able to improve the specificity on targeted cancer cells while having minimal effect on normal cells. The cell response to shock waves was studied in a more biophysically realistic environment to include influence of cell size, shape and orientation, and the presence of neighbouring cells. The most significant difference was predicted when cells were in a cluster in which case the presence of neighbouring cells resulted in a four-fold increase on the von Mises stress and the membrane strain. Finally the numerical model was extended to capture the effect of cell damage using one of two paradigms. In the first paradigm the model captured microdamage during one shock wave but then assumed that the cell recovered by the time the next shock wave arrived. The second model allowed microdamage to accumulate with increasing number of shock waves. These models may be able to explain the strong effect that shock wave loading rate has on tissue damage. In conclusion a validated numerical model has been developed which provides a mechanistic understanding of how cells respond to shock waves. The model has application in suggesting improved strategies for current uses of shock waves, e.g., lithotripsy, as well as opening up new indications such as cancer treatment.
17
Kelly, David. "Computational mechanics in practice : mathematical adaptions and experimental applications." Thesis, University of Bristol, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.570852.
Full textAbstract:
The definition and quantification of complexity is a source of debate. A promising answer, from Crutch field, Shalizi and co-workers, identifies complexity with the amount of information required to optimally predict the future of a process. Computational mechanics computes this quantity for discrete time series; quantifying the complexity and generating minimal, optimally predictive models. Here we adapt and apply these methods to two very different problems. First, we extend computational mechanics to continuous data which cluster around discrete values. This is applied to the analysis of single molecule experimental data; allowing us to infer hidden Markov models without the necessity of assuming model architecture and allowing for the inference of degenerate states, giving advantages over previous analysis methods. The new analysis methods are demonstrated to perform well on both simulated data, in high noise and sparse data conditions; and experimental data, namely fluorescence resonance energy transfer spectra of Holliday junction conformational dynamics. Secondly, we apply computational mechanics to investigations of the HP model of protein folding. Computational mechanics was used to investigate the properties of the sequence sets folding to the highly designable structures. A hypothesised correlation between structures' designability and the statistical complexity of its sequence set was unsupported. However, methods were developed to succinctly encapsulate the non-local statistical regularities of sequence sets and used to accurately predict the structure of designing and randomly generated sequences. Finally, limitations of the standard algorithm for reconstructing predictive models are addressed. The algorithm can fail due to pair-wise comparisons of conditional distributions. A clustering method, considering all distributions simultaneously has been developed. This also makes clear when the algorithm may be effectively employed. A second issue concerns a class of processes for which computational mechanics cannot infer the correct, optimally predictive models. Adaptions to allow the inference of these processes have been devised.
18
Ward, Paul. "A computational and experimental study on respiratory oscillation mechanics for the control of mechanical ventilation." Thesis, King's College London (University of London), 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.435804.
Full text
19
Sattarzadeh, Shirvan Sohrab. "Experimental study of complex pipe flow." Thesis, KTH, Processteknisk strömningsmekanik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-36074.
Full text
20
Yatnalkar, Ravi Shriram. "Experimental Investigation of Plastic Deformation of Ti-6Al-4V under Various Loading Conditions." The Ohio State University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=osu1282067894.
Full text
21
Gardner, Kevin Alexander. "Experimental Study of Air Blast and Water Shock Loading on Automotive Body Panels." The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1468938824.
Full text
22
Wang, Ruoya. "Novel theoretical and experimental frameworks for multiscale quantification of arterial mechanics." Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/47718.
Full textAbstract:
The mechanical behavior of the arterial wall is determined by the composition and structure of its internal constituents as well as the applied traction-forces, such as pressure and axial stretch. The purpose of this work is to develop new theoretical frameworks and experimental methodologies to further the understanding of arterial mechanics and role of the various intrinsic and extrinsic mechanically motivating factors. Specifically, residual deformation, matrix organization, and perivascular support are investigated in the context of their effects on the overall and local mechanical behavior of the artery. We propose new kinematic frameworks to determine the displacement field due to residual deformations previously unknown, which include longitudinal and shearing residual deformations. This allows for improved predictions of the local, intramural stresses of the artery. We found distinct microstructural differences between the femoral and carotid arteries from non-human primates. These arteries are functionally and mechanically different, but are geometrically and compositionally similar, thereby suggesting differences in their microstructural alignments, particularly of their collagen fibers. Finally, we quantified the mechanical constraint of perivascular support on the coronary artery by mechanically testing the artery in-situ before and after surgical exposure.
23
Jones, Claire Frances. "Cerebrospinal fluid mechanics during and after experimental spinal cord injury." Thesis, University of British Columbia, 2011. http://hdl.handle.net/2429/35757.
Full textAbstract:
Despite concentrated research efforts there is currently no treatment for spinal cord injury (SCI). Several researchers have identified that cerebrospinal fluid (CSF) may have a role in the biomechanics of the injury event and in the secondary physiologic response, but this has not been closely examined. The aim of this thesis was to develop a large animal model and a benchtop model of human SCI, and to use these to characterise (1) the pressure response of the CSF during the SCI event, (2) the effect of CSF thickness on mechanical indicators of injury severity, and (3) the pressure differentials and cord morphology associated with thecal occlusion and decompression.
Study 1 presented the large animal model and provided preliminary CSF pressure transient data that indicated further investigation was warranted. In Study 2, the CSF pressure transients from medium and high severity human-like SCIs were characterised. The peak pressures at 30 mm from the impact were within the range associated with experimental traumatic brain injury, but the wave was damped to peak pressures associated with noninjurious everyday fluctuations by 100 mm. In Study 3, results from the bench-top model demonstrated that the thickness of the CSF layer is directly proportional to the resultant peak CSF pressure, cord compression and impact load.
In Study 4, the cranial-caudal CSF pressure differential increased gradually over eight hours of thecal occlusion. Decompression eliminated or reduced the differential, after which it did not change significantly. These results indicate that lumbar CSF pressure measured prior to decompression may not be representative of CSF pressure cranial to an injury. In Study 5, the change in spinal cord and thecal sac morphology after surgical decompression was assessed with ultrasound. Moderate SCI was associated with a residual cord deformation and then gradual swelling, while high severity SCIs exhibited immediate swelling which occluded the thecal sac within five hours.
The different aspects of CSF response to SCI demonstrated in this thesis can potentially be used to assess and validate current and future models of SCI, and to guide future studies of clinical management strategies such as CSF drainage and early decompression.
24
Teomete, Egemen. "Mechanics of wire saw machining process experimental analyses and modeling /." [Ames, Iowa : Iowa State University], 2008.
Find full text
25
Biglino, Giovanni. "Experimental study of the mechanics of the intra-aortic balloon." Thesis, Brunel University, 2010. http://bura.brunel.ac.uk/handle/2438/4510.
Full textAbstract:
This thesis deals with the mechanics of the Intra-Aortic Balloon Pump (IABP), the most widely used temporary cardiac assist device, whose beneficial action is based on the principle of counterpulsation. The investigation is carried out in vitro in increasingly more realistic setups, including a mock circulatory system with physiological distribution of peripheral resistance and compliance in which IABP counterpulsation was simulated. Pressure and flow measurements show the effect of variables such as intra-luminal pressure, angle and aortic compliance on balloon hemodynamics. These data are complemented by results on the duration of balloon inflation and deflation obtained by means of high-speed camera visualisation. Furthermore, wave intensity analysis is carried out and it is identified as a possible alternative method for the assessment of IABP performance. This work includes two prototypes of intra-aortic balloons of novel shape with the balloon chamber tapering both from and toward the balloon tip. In clinical terms, with reference to the semi-recumbent position in which patients assisted with the IABP are nursed in the intensive care unit, the results presented in this thesis indicate that operating the balloon at an angle compromises the benefit of counterpulsation when assessed in vitro.
26
Tran, Hai Thanh. "Experimental and Computational Study on Fracture Mechanics of Multilayered Structures." Scholar Commons, 2016. http://scholarcommons.usf.edu/etd/6595.
Full textAbstract:
Many devices in electronics are in the form of multilayered structures. These structures can fail catastrophically if they contain defects or cracks. Enhancing their fracture properties is therefore critical to improve the reliability of the systems. The interface-dominated fracture mechanics of multilayered structure was studied using experiments and finite element (FE) modeling by considering two examples: thin films on polymer substrates in flexible electronics and Cu leadframe/epoxy molding compound (EMC) in micro-electronics packaging.
In the first example, aluminum-manganese (Al-Mn) thin films with Mn concentration up to 20.5 at.% were deposited on polyimide (PI) substrates. A variety of phases, including supersaturated fcc (5.2 at.% Mn), duplex fcc and amorphous (11.5 at.% Mn), and completely amorphous phase (20.5 at.% Mn) were obtained by adjusting alloying concentration in the film. In comparison with crystalline and dual phase counterparts, the amorphous thin film exhibits the highest fracture stress and fracture toughness, but limited elongation. Based on a fracture mechanism model, a multilayer scheme was adopted to optimize the ductility and the fracture properties of the amorphous film/PI system. Tensile deformation and subsequent fracture of strained Al-Mn films on PI were investigated experimentally and by FE simulations. It was found that by sandwiching the amorphous film (20.5 at.% Mn) between two ductile copper (Cu) layers, the elongation can be improved by more than ten times, and the interfacial fracture toughness by twenty four times with a limited sacrifice of the film's fracture toughness (less than 18%). This design provides important guidelines to obtain optimized mechanical properties of future flexible electronics devices.
The reliability of amorphous brittle Al-Mn (20.5 at.% Mn) thin films deposited on PI substrates is strongly influenced by the film/substrate interface adhesion. Some strategies to improve the adhesion of the interface were conducted, including roughening the surface of the PI substrate, adding a buffer layer and then tuning its thickness. Tensile testing and FE analysis of amorphous Al-Mn thin films with and without buffer layers coated on intact and plasma etched rough PI were investigated. It was found that by adding a chromium buffer layer of 75 nm on a rough PI substrate, the interface adhesion of the film/substrate can increase by almost twenty times. The obtained results would thus shed light on the interfacial engineering strategies for improving interface adhesion for flexible electronics.
In the second example, a systematic investigation and characterization of the interfacial fracture toughness of the bimaterial Cu leadframe/EMC was carried out. Experiments and FE simulations were used to investigate delamination and interfacial fracture toughness of the biomaterial system. Two dimensional simulations using computational fracture mechanics tools, such as virtual crack closure technique, virtual crack extension and J-integral proved to be computationally cheap and accurate to find the interfacial fracture toughness of the bimaterial structures. The effects of temperature, moisture diffusion and mode-mixity on the interfacial fracture toughness were investigated. Testing temperature and moisture exposure significantly reduce the interfacial fracture toughness, and its relationship with the mode-mixity was achieved by fitting the results with an analytic formula.
27
Al-Riffai, Mahmoud. "Experimental Study of Breach Mechanics in Overtopped Noncohesive Earthen Embankments." Thesis, Université d'Ottawa / University of Ottawa, 2014. http://hdl.handle.net/10393/31505.
Full textAbstract:
A comprehensive experimental program dealing with three-dimensional overtopping and breach development as well as two-dimensional overtopping physical tests of noncohesive earth embankments has been conducted on scale models in the Hydraulic Laboratory at the Department of Civil Engineering at the University of Ottawa. The experimental program which consisted of three phases focused on geotechnical and hydraulic aspects of the embankment breach mechanism. The first two phases focused on two test series for the three-dimensional breach overtopping tests: drainage and compaction. The test series were designed to determine the embankment breach characteristics using test parameters which have not been adequately identified or controlled in past noncohesive physical models: initial soil-water state and optimum dry unit weight. Both parameters were controlled in laboratory tests by means of compaction effort and seepage through the embankment body, respectively. The dynamic compaction technique employed in the preliminary experimental phase was refined to represent a more realistic method. A novel method was thus designed to simulate the construction of a real-size prototype embankment, where a vibratory and static load was used to apply and control, respectively, the compaction effort. The hydraulic aspects of the embankment breach mechanism were also investigated. For the first time, scale series tests have been used to assess the Froude criterion using tilted and quasi-exact geometric scales under very low inflow within the scope of three-dimensional breach overtopping. Data measurements included a time-history of water surface levels and video footage captured from three locations: upstream, downstream and above the embankment models. The analysis for the spatial breach overtopping tests involved measurement of the breach outflow hydrograph and breach channel evolution at the upstream slope, using hydrologic routing and a developed photogrammetric technique using the video footage, respectively. An expression which estimates the breach outflow based on this apparent upstream control section was therefore derived. The relationship between the measured and estimated breach outflow was expressed in terms of breach discharge efficiency. The third phase of the experimental program was comprised of two-dimensional overtopping tests to investigate the erodibility of a steep slope in overtopped noncohesive embankment models. A novel experimental two-dimensional configuration used to measure the pore-water-pressures within the embankment model body was developed using micro and standard tensiometer-transducer-probe assemblies, designed, assembled and tested at the Geotechnical Engineering Laboratory. A transient flownet analysis was developed using ArcGIS and the time-history of the pore-water-pressure measurements. All flow parameters were computed using the free water surface and bed profiles captured using a photogrammetric technique and the developed hydrologic routing method. Using the one-dimensional Saint-Venant equations, an analytical expression for the bed shear stress was derived to take into account the effects of unsteady flow, boundary seepage and steep slopes. Using the measured erosion rates and the sediment continuity principle, the bed mobility relationship expressed by the Shields and transport parameters was revisited to account for the effects of unsteady and supercritical flow on a downstream steep slope in the presence of boundary seepage. This novel transient flownet approach will lead to the development of new sediment mobility relationships for breach flows, instead of the classical sediment transport-capacity formulations which are based on steady, subcritical and normal flow conditions.
28
Jadrnak, Sharon Marie. "Experimental studies of bimodal granular material flows." Thesis, Georgia Institute of Technology, 1989. http://hdl.handle.net/1853/16107.
Full text
29
Li, Hong. "Experimental micromechanics of composite buckling strength." Thesis, Georgia Institute of Technology, 1988. http://hdl.handle.net/1853/11719.
Full text
30
Cheng, Huojin. "Model based experimental investigation on Powered Gait Orthosis (PGO) /." Available online. Click here, 2005. http://sunshine.lib.mtu.edu/ETD/DISS/chengh/PGO.pdf.
Full text
31
Turcott, Rios Eduardo Enrique. "Experimental study of the compressional behaviour of two-phase media." Thesis, McGill University, 1991. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=70342.
Full textAbstract:
This thesis is concerned with the experimental evaluation of the volumetric deformation of a two-phase medium at the microscopic level. The basic definitions of the significant parameters involved in the mechanical response behaviour of the structured medium are based on the concepts of Probabilistic Micromechanics. A simple phenomenological model and the leading structural parameter $ theta sb{s}$ (Solid phase volume fraction) are discussed briefly. The experimental work makes use of a series of macroscopic tests to attain different states of deformation so that the evolution of the internal microstructural changes can be analyzed. The combined use of ultramicrotomy techniques and the Scanning Electron Microscopy operating in the Backscattered Electron mode allowed the quantification of the microstructural changes at large magnifications. The concepts of practical Stereology were adopted for the quantification of a large number of observation areas representative of the complete phenomenon to determine the leading structural parameter $ theta sb{s}.$ A semi-automatic system was developed for the determination of $ theta sb{s}$ corresponding to each observation area. A fully-automatic image analyzer also was used for the evaluation of the first state of deformation. The experimental procedure employed in this investigation is described in detail and its application is illustrated by the evaluation of $ theta sb{s}$ and its evolution at the microscopic level. The evaluations of the distributions of this parameter also are shown. In the conclusion of this thesis, the obtained results for the Al-Quetol are discussed and general remarks concerning the experimental technique and its application to other structured media are indicated.
32
Kurian, Thomas. "An experimental investigation of disturbance growth in boundary layer flows." Doctoral thesis, KTH, Mekanik, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-12949.
Full textAbstract:
This thesis deals with the early stages of transition to turbulence in two different baseflows, namely the Falkner-Skan-Cooke boundary layer (FSC) and the asymptotic suction boundary layer (ASBL). Grid-generated turbulence is studied in order to characterise the isotropy levels, free-stream turbulence levels and characteristic length scales that will be present in the receptivity study. By varying the grids and their location it is possible to control the turbulence intensity level, Tu, and the integral length scale independently. Comparisons with other studies show that for increasing Re_M the isotropy levels and the rate of kinetic energy decay asymptotically approach the theoretical values. The FSC describes a a 3D boundary layer subjected to a pressure gradient. The FSC is stable to TS-waves, but becomes susceptible to both travelling and stationary crossflow disturbances. In the experiments the travelling modes were triggered using free-stream turbulence (FST) and the stationary modes were triggered using an array of cylindrical roughness elements. The receptivity phase to FST was linear as well as the initial growth. For high enough $Tu$ inside the boundary layer, nonlinear behaviour was observed further downstream. The stationary mode could only be triggered using tall roughness elements, with low heights resulting in no noticeable disturbances. The receptivity is found to be nonlinear for the roughness heights tested and the growth of the disturbances is exponential. For low levels of FST, Tu < 0.25%, the travelling mode as well as the stationary mode grew. The ASBL is formed when uniform suction is applied to the surface of a porous plate with a flow over it. This baseflow is very stable to TS-waves, and was used to study the transient growth. For the ASBL, stationary disturbances were triggered using a spanwise array or cylindrical roughness elements. The velocity signals were decomposed using a spatial Fourier transform to study the growth of individual modes. The fundamental mode as well as some harmonics were seen to undergo transient growth, before finally decaying exponentially. Comparisons were made to the experimental data using optimal perturbation theory. The global optimals did not describe the transient growth effects well. The calculations were redone for suboptimal times and showed agreement with the experimental data, showing that optimal perturbation theory can describe transient growth if the initial disturbance state is known.QC20100702
33
Wolff, Paul. "Experimental investigation of an actively controlled mechanical seal." Diss., Georgia Institute of Technology, 1993. http://hdl.handle.net/1853/17228.
Full text
34
Li, Zongze. "Design and Testing of Experimental Langmuir Turbulence Facilities." Scholar Commons, 2019. https://scholarcommons.usf.edu/etd/7845.
Full textAbstract:
Langmuir Circulation is a common phenomenon driven by wind in oceans and lakes and was first studied by Langmuir in 1927. According to various ocean observations, this kind of phenomenon plays an important role in many phenomena such as the aggregation of bubbles, the distribution of plankton as well as the mixing of spilled oil and sediment in the ocean. To study this, an experimental facility has been developed in the lab which creates a small scale version of Langmuir Circulation.
This thesis is about the design and testing of this tank and surrounding aluminum frame, as well as the design and construction of the illumination equipment (the Green Lantern 2.0) needed for Particle Image Velocimetry measurements within the tank. ANSYS will be used to show whether the tank is structurally strong enough to support the fluid. An enhancement is found that prevents a frontward bend of tank wall, which is analyzed by ANSYS to find an optimized construction to minimize tank deformation. Then, the Light-Emitting Diode (LED) and collimating lens selection for the Green Lantern 2.0 will also be shown in this paper. Besides, this thesis also presents preliminary flow measurement data acquired using the illumination equipment (the Green Lantern).
35
Rådmark, Magnus. "Photonic quantum information and experimental tests of foundations of quantum mechanics." Doctoral thesis, Stockholms universitet, Fysikum, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-37464.
Full textAbstract:
Entanglement is a key resource in many quantum information schemes and in the last years the research on multi-qubit entanglement has drawn lots of attention. In this thesis the experimental generation and characterisation of multi-qubit entanglement is presented. Specifically we have prepared entangled states of up to six qubits. The qubits were implemented in the polarisation degree of freedom of single photons. We emphasise that one type of states that we produce are rotationally invariant states, remaining unchanged under simultaneous identical unitary transformations of all their individual constituents. Such states can be applied to e.g. decoherence-free encoding, quantum communication without sharing a common reference frame, quantum telecloning, secret sharing and remote state preparation schemes. They also have properties which are interesting in studies of foundations of quantum mechanics. In the experimental implementation we use a single source of entangled photon pairs, based on parametric down-conversion, and extract the first, second and third order events. Our experimental setup is completely free from interferometric overlaps, making it robust and contributing to a high fidelity of the generated states. To our knowledge, the achieved fidelity is the highest that has been observed for six-qubit entangled states and our measurement results are in very good agreement with predictions of quantum theory. We have also performed another novel test of the foundations of quantum mechanics. It is based on an inequality that is fulfilled by any non-contextual hidden variable theory, but can be violated by quantum mechanics. This test is similar to Bell inequality tests, which rule out local hidden variable theories as possible completions of quantum mechanics. Here, however, we show that non-contextual hidden variable theories cannot explain certain experimental results, which are consistent with quantum mechanics. Hence, neither of these theories can be used to make quantum mechanics complete.
36
MacKenzie, P. M. "Developments in Moire interferometry and its application in experimental fracture mechanics." Thesis, University of Strathclyde, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.382405.
Full text
37
Hu, Shiqiong. "Mechanics and Dynamics of Cell Adhesion : Experimental Study of the Osteoclasts." Lyon, Ecole normale supérieure, 2010. http://www.theses.fr/2010ENSL0594.
Full textAbstract:
Osteoclasts are large, multinucleated cells, which resorb mineralized bone. When an osteoclast encounters a substrate, dot-like actin-rich structures, the podosomes, appear and assemble into clusters, rings or a belt. We experimentally investigate, from a cell population to a single podosome, their function and dynamics. Over a cell population, kinetic measurements show that the cell surface area A scales as A ~ K2, where K is the number of nuclei, indicating a flat morphology. By defining quantities that account for the spatial distribution of the actin within the cell, we demonstrate that the podosomes organization only depends on the time after differentiation, and not on K. In a single osteoclast, the observation of a strong coupling between cell spreading and podosomes formation lead us to propose that podosomes play an important role in osteoclast motility. Analysis of osteoclast migration, and the forces it applies on the substrate, demonstrates that the internal dynamics of the actin within the cell does not only correlate with cell migration, but drives it. Finally, in order to understand the internal dynamics of a single podosome, we improved the model of Biben et al. (2005) by considering on the one hand, actin polymerization, and on the other hand, diffusion and attachment kinetics of the gelsolin, an actin severing protein. We find that podosomes are mainly governed by the actin dynamics, regardless of gelsolin concentrationLes ostéoclastes sont des cellules multinucléées, responsables de la résorption osseuse. Quand ils sont déposés sur un substrat, des structures ponctuelles riches en actine, les podosomes, apparaissent et s'assemblent en clusters, anneaux ou ceinture. Nous avons étudié expérimentalement leur fonction et leur dynamique, depuis une population entière jusqu'à l'échelle d'un unique podosome. Sur une population de cellules, des mesures cinétiques montrent que la surface de la cellule A varie comme A ~ K2, où K est le nombre de noyaux ; ce résultat indique une forme aplatie. Par ailleurs, la mesure de quantités qui prennent en compte l'organisation spatiale de l'actine dans la cellule montre que l'organisation des podosomes ne dépend que du temps écoulé après différentiation, et non de K. Dans un seul ostéoclaste, l'observation d'un fort couplage entre l'étalement d'une cellule et la formation des podosomes nous a conduit a suggérer que les podosomes jouent un rôle important dans la mobilité des ostéoclastes. L'analyse de la migration d'ostéoclastes, ainsi que des forces appliquées sur le substrat, montre que la dynamique interne de l'actine dans la cellule est non seulement corrélée avec la migration cellulaire, mais la gouverne. Enfin, afin de comprendre la dynamique interne d'un podosome, nous avons amélioré le modèle de Biben et al. (2005), en prenant en compte d'une part, la polymérisation de l'actine, et d'autre part, la diffusion et la cinétique d'attachement de la gelsoline, une protéine responsable de la coupe des filaments d'actine. Nous montrons que les podosomes sont principalement gouvernés par la dynamique de l'actine, indépendamment de la concentration en gelsoline
38
Andreasson, Eskil. "Realistic Package Opening Simulations : An Experimental Mechanics and Physics Based Approach." Licentiate thesis, Blekinge Tekniska Högskola, Institutionen för maskinteknik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-00610.
Full textAbstract:
A finite element modeling strategy targeting package opening simulations is the final goal with this work. The developed simulation model will be used to proactively predict the opening compatibility early in the development process of a new opening device and/or a new packaging material. To be able to create such a model, the focus is to develop a combined and integrated physical/virtual test procedure for mechanical characterization and calibration of thin packaging materials. Furthermore, the governing mechanical properties of the materials involved in the opening performance needs to be identified and quantified with experiments. Different experimental techniques complemented with video recording equipment were refined and utilized during the course of work. An automatic or semi-automatic material model parameter identification process involving video capturing of the deformation process and inverse modeling is proposed for the different packaging material layers. Both an accurate continuum model and a damage material model, used in the simulation model, were translated and extracted from the experimental test results. The results presented show that it is possible to select constitutive material models in conjunction with continuum material damage models, adequately predicting the mechanical behavior of intended failure in thin laminated packaging materials. A thorough material mechanics understanding of individual material layers evolution of microstructure and the micro mechanisms involved in the deformation process is essential for appropriate selection of numerical material models. Finally, with a slight modification of already available techniques and functionalities in the commercial finite element software AbaqusTM it was possible to build the suitable simulation model. To build a realistic simulation model an accurate description of the geometrical features is important. Therefore, advancements within the experimental visualization techniques utilizing a combination of video recording, photoelasticity and Scanning Electron Microscopy (SEM) of the micro structure have enabled extraction of geometries and additional information from ordinary standard experimental tests. Finally, a comparison of the experimental opening and the virtual opening, showed a good correlation with the developed finite element modeling technique. The advantage with the developed modeling approach is that it is possible to modify the material composition of the laminate. Individual material layers can be altered and the mechanical properties, thickness or geometrical shape can be changed. Furthermore, the model is flexible and a new opening device i.e. geometry and load case can easily be adopted in the simulation model. Therefore, this type of simulation model is a useful tool and can be used for decision support early in the concept selection of development projects.
39
Morrison, D. J. "Experimental and computational modelling of the flows in service reservoirs." Thesis, Cranfield University, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.323928.
Full text
40
Seidt, Jeremy Daniel. "Plastic Deformation and Ductile Fracture of 2024-T351 Aluminum under Various Loading Conditions." The Ohio State University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=osu1268148067.
Full text
41
Alam, Syed Yasir. "EXPERIMENTAL STUDY AND NUMERICAL ANALYSIS OF CRACK OPENING IN CONCRETE." Phd thesis, Ecole centrale de nantes - ECN, 2011. http://tel.archives-ouvertes.fr/tel-00669877.
Full textAbstract:
Il est communément admis l'existence d'un effet d'échelle sur les résistances nominales des matériaux quasi-fragiles tels que les matériaux cimentaires. Cet effet doit être pris en compte dans le dimensionnement vis-à-vis du comportement ultime des structures en béton afin de limiter les dommages et les ouvertures de fissures. Celles-ci sont de plus en plus utilisées pour étudier le comportement du béton et caractériser la durabilité des structures. Différentes théories existent dans la littérature pour décrire l'effet d'échelle. Parmi celles-ci on trouve la théorie déterministe de Bazant où l'énergie de fissuration est considérée comme indépendante de la taille et il est supposé qu'à charge maximale, la longueur de fissure est proportionnelle à la taille de l'échantillon. Dans le cadre de ce travail, on s'est attaché à étudier expérimentalement et numériquement les relations entre la longueur de fissure et la taille des éprouvettes. Sur le plan expérimental, l'effet d'échelle est caractérisé par des essais de flexion trois points sur des poutres de béton entaillées de tailles géométriquement similaires. L'influence de la taille des agrégats sur le comportement à la rupture a aussi été étudiée. La technique de Corrélation d'Images Numériques (DIC) est adoptée dans cette étude pour déterminer à la fois la longueur et l'ouverture de la fissure à différentes étapes de chargement. Cette méthode s'est révélée comme un outil robuste et de haute précision pour la mesure des paramètres caractérisant les fissures. Les résultats ont montré un effet de taille significatif sur le processus de propagation des fissures. En outre, l'effet d'échelle diminue lorsque la taille des agrégats augmente. Une étude sur poutres en béton armé est aussi réalisée pour étudier l'effet d'échelle sur l'ouverture et l'espacement des fissures. De point de vue réglementaire, il a été observé que l'Eurocode 2 sous estime les ouvertures de fissures. Sur le plan numérique, le comportement à la rupture des poutres en béton est simulé en utilisant un modèle d'endommagement non local. La longueur interne et d'autres paramètres du modèle sont calibrés par une technique de calibration inverse qui utilise une procédure automatique. Les profils d'ouverture de fissures sont déterminés par des procédures de post-traitement. L'analyse du comportement mécanique et de la propagation des fissures indiquent un effet d'échelle similaire à celui détecté par les résultats expérimentaux.
42
Schultze, John Francis. "Evaluation of analytical and experimental methods to predict constrained layer damping behavior." Thesis, This resource online, 1992. http://scholar.lib.vt.edu/theses/available/etd-09122009-040317/.
Full text
43
Wåhlin, Fredrik. "Experimental Investigation of Impinging Diesel Sprays for HCCI Combustion." Doctoral thesis, KTH, Maskinkonstruktion (Avd.), 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4276.
Full textAbstract:
Engine research and development is to a large extent driven by the quest of lowering exhaust emissions and fuel consumption. The combination of low emissions and low fuel consumption is not the simultaneous characteristic of the world’s primary engine concepts, the diesel and the spark-ignited (SI) engine. However, such a concept do exist, it is commonly called Homogeneous Charge Compression Ignition (HCCI). The HCCI combustion concept is when a premixed air and fuel mixture is ignited by the heat of compression. The operation is unthrottled, like the diesel engine, which is advantageous for its efficiency. The premixed air / fuel mixture preclude soot formation, like the SI engine. An exclusive feature of HCCI combustion is extremely low NOX production due to low-temperature combustion. The mixture preparation of the typical gasoline HCCI engine is similar to the SI engine, via port-injection, which results in a well homogenized mixture. Port injection of diesel fuel is however very difficult since the environment is too cold for the fuel to vaporise. A better alternative is therefore direct-injection. However, injection must occur in a way where a homogeneous mixture is formed, while contact of the liquid fuel with cold walls is avoided. There are many approaches to direct-injected mixture formation. This thesis focuses on exploring the concept of impinging sprays; its characteristics and its impact on combustion and emissions. The work comprises unique information regarding impinging sprays, as well as results regarding engine performance. It is concluded that impinging sprays are well suited for early direct-injection.QC 20100824
44
Bellani, Gabriele. "Experimental Studies of Complex Flows through Image-Based Techniques." Doctoral thesis, KTH, Strömningsfysik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-33821.
Full textAbstract:
This thesis deals with the development of experimental techniques for the study of complex flows inspired to a large extent by the papermaking process. In particular one part of this thesis is devoted to the development of laboratory experiments based on index-of-refraction matching and imaging techniques to study the behavior of dilute and concentrated suspension of elongated particles. Another part is aimed at exploring the potential of the synergy between experiments and numerical simulations to access quantities otherwise not-measurable in complex flows. Highspeedimaging experiments have been specifically designed for this purpose. The first of the Refractive IndexMatching (RIM) experiment was aimed at studying the flow generated during the filtration of a fiber suspension using Particle Image Velocimetry (PIV) and pressure drop measurements. The experiments were performed in a vertical laboratory filtration device. Index of refraction matching of fibers and fluids allowed measurements to be performed in the proximity and, to some extent, in the forming network during filtration. The area over which the forming network induces velocity gradients has been measured and have been found to be independent of the Reynolds number but dependent on the fiber length and the structure of the network. Analysis of the flow scales in the proximity of the network showed that the signature of the mesh used to filter the suspension is never completely suppressed as the network thickness increases. Also, pressure drop measurements over a static fiber network have been performed. A linear dependence of the pressure drop with the basis weight (mass of fibers in the network per unit area) and a non-dimensional filtration resistance independent of filtration velocity and network thickness (if network compressibility is accounted for) was found. These findings can help explain characteristics that are observed on paper sheets and help improvede watering efficiency. The second RIM experiment was aimed at measuring the interactions of Taylorscale elongated particles with turbulence. RIM particles with embedded tracers and Stereoscopic PIV were combined to simultaneously measure fluid phase and particle velocity. The novelty of this technique is that it allows to measure the three-dimensional angular velocity vector of arbitrarily shaped particles. This technique was applied to study the interaction of neutrally buoyant ellipsoidal particles with stationary homogeneous isotropic turbulence. The results were compared to the case of spherical particles. The main result is that both spherical and ellipsoidal particles provide enhancement of the small scales and reduction of the large scales at volume concentrations as low as 0.1%. However, the reduction of the large scales was much more evident for spherical particles. These results highlight the fact that particle elongation introduces different mechanisms of turbulent modulation as compared to the spherical particles. The first of the high-speed imaging experiments was to provide a database for test and validation of a CFD-based flow observer for complex flows. For this purpose time resolved measurements of a turbulent confined jet have been performed with high-speed PIV. The measurements have been used both as a feedback signal and as a reference for the evaluation of a CFD-based estimator for complex flows. Furthermore, based on the measurements Kalman filters have been designed and implemented in the observer. The experimental data have also been used to compare two modal decompositions, namely Proper Orthogonal Decomposition and Dynamical Modal Decomposition and evaluate their ability to describe the global behavior of complex flow. The second of the high-speed imaging experiment was applied to study spreading of a droplet on a solid surface. These experiments have been performed with extremely high time-resolution (140000 fps), over a range of parameters (in terms of droplet viscosity, equilibrium contact angle and droplet size) larger than any other experiment reported in the literature in a single work. By combining the experiments and direct numerical simulations a dissipative mechanisms arising from the contact line movement has been identified and the corresponding macroscopic coefficient has been measured.iQC 20110519
45
Ingram, Gregory O. "Experimental characterization of the effect of inertia on ductility." Thesis, Georgia Institute of Technology, 2003. http://hdl.handle.net/1853/16087.
Full text
46
Lundell, Fredrik. "Experimental studies of bypass transition and its control." Doctoral thesis, KTH, Mekanik, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3480.
Full textAbstract:
Bypass transition, i.e. transition of a boundary layer at subcritical Reynolds numbers, has been studied. Fundamental studies of the phenomenon as such have been performed side by side with experiments aimed at controlling, i.e. delaying, transition. The experiments have been performed in three different flow facilities, two with air as the working fluid (a plane channel flow and a wind-tunnel) and one with water (a water channel). From the water channel data the well known low-speed streaks appearing in a boundary layer under a turbulent free stream are found to be correlated with upward motion in the boundary layer. The streaks are found to scale in proportion to the boundary-layer thickness in both the streamwise and wall-normal directions. The streamwise length is around hundred boundary-layer thicknesses. It is found that the secondary instability of the streaks grows slower for disturbances consisting of less than four wavelengths, as compared to continuous wavetrains. Elongated low-speed structures are controlled, first in the plane channel flow and then by a reactive system in the wind-tunnel. In the channel, the breakdown of generated streaks is delayed by applying localized suction under the regions of low velocity. Measurements of the disturbance environment withand without control applied show that both the growth of the secondary instability and its spreading in the spanwise direction are reduced when applying the control. In order to be successful, the control has to be applied to a narrow region (about 1/10th of a streak width) around the position of minimum velocity. The reactive system in the windtunnel, comprising four upstream sensors and four suction ports downstream, inhibits the growth of the amplitude of the streaks for a certain distance downstream of the suction ports. After the inhibited growth the disturbances start to grow again and far downstream the streak amplitude returns to close to the uncontrolled values.QC 20100527
47
Hardie, Staffan. "Drag Estimations on Experimental Aircraft Using CFD." Thesis, Mälardalen University, Department of Mathematics and Physics, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-334.
Full textAbstract:
The drag approximations done in the initial design phase needed to be verified. A model of the aircraft has been analyzed with CFD and results examined to see how accurate the estimations were. A step by step analysis was made and then a simulation was run. The drag results of the CFD analysis did not meet the goal of the initial design study. Several reasons for this are discussed. The analysis shows that the aircraft design works well aerodynamically but also shows a few areas where the design can be improved.
Det approximerade värdet på luftmotståndet som gjordes I den preliminära designfasen behövde verifieras. En flygplansmodell har analyserats med CFD och resultaten har undersökts för att se hur exakta antagandena var. En analys gjordes steg för steg och slutligen har en simulering utförts. Det uppmätta luftmotståndet motsvarade inte målet i den preliminära designfasen. Flera olika anledningar till detta diskuteras. Analysen visar att denna flygplansdesign fungerar bra aerodynamiskt men identifierar också en del punkter på vilken den kan förbättras.
48
Krebs, Derek J. "Correlation of finite element and experimental eigenvectors /." Online version of thesis, 1990. http://hdl.handle.net/1850/10591.
Full text
49
Holder, Alexander Joseph. "Experimental studies of complex fluids in complex flows." Thesis, Swansea University, 2014. https://cronfa.swan.ac.uk/Record/cronfa42995.
Full text
50
Roth, Ronald B. "An experimental investigation and optimization of a variable reluctance spherical motor." Diss., Georgia Institute of Technology, 1992. http://hdl.handle.net/1853/18913.
Full text