Academic literature on the topic 'Damage coefficient'

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Journal articles on the topic "Damage coefficient"

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Minhas, Zill-e. Hasnain, and Sun Qin. "Evolution of the Coefficient of Dynamic Viscosity with Growing Damage in Metals." Applied Mechanics and Materials 313-314 (March 2013): 72–76. http://dx.doi.org/10.4028/www.scientific.net/amm.313-314.72.

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Coefficient of dynamic viscosity (η) for uniaxial rectangular bar of steel is calculated using creep simulation in Ansys. Norton Secondary creep law with coefficients at 600 ᵒC is used. Steel bar is then inflicted with some damage elements in order to investigate the evolution of dynamic viscosity for varying degree of fatigued specimen at constant rate and temperature. Isotropic damage parameter (D) based on the volume fraction of damaged elements is used to formulate a linear relation between the coefficient of viscosity and D. It is found that with 0.001 increase is damage parameter (D), almost 0.6% decrease on the value of Coefficient of dynamic viscosity (η) is observed.
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Mei, Liu, Akira Mita, and Jin Zhou. "A Substructural Damage Identification Approach for Shear Structure Based on Changes in the First AR Model Coefficient Matrix." Journal of Structures 2015 (June 16, 2015): 1–16. http://dx.doi.org/10.1155/2015/976349.

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A substructural damage identification approach based on changes in the first AR model coefficient matrix is proposed in this paper to identify structural damage including its location and severity. Firstly, a substructure approach is adopted in the procedure to divide a complete structure into several substructures in order to significantly reduce the number of unknown parameters for each substructure so that damage identification processes can be independently conducted on each substructure. To establish a relation between changes in AR model coefficients and structural damage for each substructure, a theoretical derivation is presented. Thus the accelerations are fed into ARMAX models to determine the AR model coefficients for each substructure under undamaged and various damaged conditions, based on which changes in the first AR model coefficient matrix (CFAR) is obtained and adopted as the damage indicator for the proposed substructure damage identification approach. To better assess the performance of the proposed procedure, a numerical simulation and an experimental verification of the proposed approach are then carried out and the results show that the proposed procedure can successfully locate and quantify the damage in both simulation and laboratory experiment.
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Padzi, Mahfodzah M., S. Abdullah, and Mohd Zaki Nuawi. "Fatigue Damage Assessment Correlating with I-Kaz Coefficient." Applied Mechanics and Materials 471 (December 2013): 235–40. http://dx.doi.org/10.4028/www.scientific.net/amm.471.235.

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This paper describes the correlation between fatigue life with the I-kaz coefficients. Fatigue tests were performed according to the ASTM E466-96 standard with a strain gauge attached to the specimen being tested. AISI 1045 carbon steel was used as the material for this test due to its wide applications in the automotive and machinery industry. Fatigue tests were carried out at several constant loading stresses of 610 MPa, 650 MPa and 690 MPa at the sampling frequency of 8 Hz. A set of data acquisition system was used to collect the fatigue strain signals. The integrated Kurtosis-based algorithm for Z-filter (I-kaz) technique had been used to find the I-kaz coefficient. The I-kaz coefficient is found to have a good correlation with fatigue life, other than can represent fatigue damage.
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Bedrikovetsky, P., A. S. L. S. L. Vaz, C. Furtado, and A. L. S. L. S. de Souza. "Formation-Damage Evaluation From Nonlinear Skin Growth During Coreflooding." SPE Reservoir Evaluation & Engineering 14, no. 02 (March 24, 2011): 193–203. http://dx.doi.org/10.2118/112509-pa.

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Summary Injectivity decline of oilfield injection wells is a widespread phenomenon during seawater/produced-water injection. The decline may result in significant cost increase of the waterflooding project. Reliable modeling-based prediction of injectivity-index decrease is important for waterflood design as well as for the planning of preventive injected-water treatment. One of the reasons for well injectivity decline is permeability decrease caused by rock plugging by solid/liquid particles suspended in the injected water. The mathematical model for deep-bed filtration contains two empirical functions: the filtration coefficient and the formation-damage coefficient. These empirical coefficients must be determined from laboratory coreflood tests by forcing water with particles to flow through the core samples. A routine laboratory method determines the filtration coefficient from expensive and difficult particle-concentration measurements at the core effluent; then, the formation-damage coefficient is determined from inexpensive and simple pressure-drop measurements. An alternative three-point-pressure method uses pressure data at an intermediate point of the core, supplementing pressure measurements at the core inlet and outlet. The method provides unique and stable values for constant-filtration and formation-damage coefficients. In the current work, we consider a more complex case in which both coefficients are linear functions of retained-particle concentration. In this case, the model is fully determined by four constants. The three-point-pressure method furnishes unique values for the four model parameters. A new semianalytical model for axisymmetric suspension filtration was developed to predict well-injectivity decline from the linear coreflood data with pressure measurements in three core points.
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Qian, Yao, Ping Wang, Jiayin Chen, G. Bethel Lulu, Jingmang Xu, and Boyang An. "Numerical investigation of the influence of the creep curve on the wheel–rail contact damage in high-speed railway turnouts." Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit 233, no. 9 (December 26, 2018): 926–36. http://dx.doi.org/10.1177/0954409718819574.

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This paper studies the wheel–rail creep curve characteristics and dynamic behaviour in high-speed railway turnouts by considering different wheel–rail surfaces and simulating them using a dynamic functional vehicle–track model with different friction and Kalker’s weight coefficients. The dynamic performance and damage coefficient of CRH2 locomotive passing through the 18# turnout at a speed of 80 km/h are discussed under different friction and Kalker’s weight coefficients. The results show that the Kalker’s weight and friction coefficients have less influence on the wheel–rail dynamics and wear performance at low values. Vehicle operating stability is the highest when the high-speed wheels pass through the switching area and the Kalker’s weight coefficient is 0.1. In this case, both fatigue damage and wear are low. When the Kalker’s weight coefficient at the crossing area is 1 and the friction coefficient is 0.5, the dynamic wheel–rail performance is good, with reduced wear and good wheel–rail contact. When the Kalker’s weight coefficient is 0.1, the maximum wear number of the closure panel is closer to the lower limit of the second region of the damage function, and both fatigue damage and wear are very low. The results are useful for accurately describing the wheel–rail contact relationship in high-speed turnouts and for finding the most appropriate creep curve to decrease wear and to prolong the turnout service life.
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Dubey, Anurag, Vivien Denis, and Roger Serra. "A Novel VBSHM Strategy to Identify Geometrical Damage Properties Using Only Frequency Changes and Damage Library." Applied Sciences 10, no. 23 (December 5, 2020): 8717. http://dx.doi.org/10.3390/app10238717.

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Vibration-based structural health monitoring is an efficient way to diagnose damage and structural integrity at the earliest stage. In this paper, a new strategy is developed for damage localization and estimation, as well as damage properties identification for a rectangular geometry damage using only eigenfrequencies of the healthy and damaged structure. This strategy is applied to a cantilever beam. In this framework, a damage library is built by correlating 2D and 3D finite element models. The correlation is done by minimizing a so-called frequency shift coefficient. The proposed strategy also uses the frequency shift coefficient to correlate a 2D damaged model with an unknown beam case. The 2D damage, represented by a bending stiffness reduction, is then associated to a 3D damage by employing the damage library. Numerical cases with single and double damage of varying position and severity are tested and used to validate the approach. Finally, experimental results are proposed that show the relevance of the strategy.
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Zhao, Xinze, Senming Xi, Meiyun Zhao, Wenyun PENG, Seng Tian, and Wei Li. "Fatigue Damage Analysis of Composite Insulator Cor Rod/sheath Interface." MATEC Web of Conferences 264 (2019): 01001. http://dx.doi.org/10.1051/matecconf/201926401001.

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A self-made fatigue testing machine was used to simulate the damage process of the insulator interface under working conditions and the damage degree is evaluated by the compressive shear test. The improved interface adhesion model reflects the interface debonding process under different fatigue loads by introducing the damage coefficient χ, migration coefficient α and the debonding coefficient μ. The relationship of fatigue loads and interface damage is established by the peeling force, the unit interface separation work and the peeling time. The test demonstrates that the interface damage near the bottom of the insulator is worse than that near the middle part. The result of this analysis will be beneficial in easily finding damaged places of the insulator, and so as to reduce the power breakdown.
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Le, Jie, Lingling Lu, Yabo Wang, Hongwei Song, Xiaodong Xing, and Chenguang Huang. "Damage identification of low-density material–filled sandwich panels with truss core based on vibration properties." Structural Health Monitoring 18, no. 5-6 (December 29, 2018): 1711–21. http://dx.doi.org/10.1177/1475921718820100.

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A damage-identification method based on flexibility matrix and Teager energy operator is proposed for low-density material–filled sandwich panels with truss core. In the proposed damage index, weight coefficient r is introduced to consider the effect of damages on both high-order and low-order modes. Numerical simulations and experiments are conducted to assess the performance of the proposed method. Effects of Young’s modulus of the filler material on the accuracy of the proposed method are also discussed. Results reveal that the method is reliable and effective for single-damage and multiple-damages identification of filled sandwich panels with truss core, and weight coefficient plays an important role, especially for cases with multiple damages or damages of small extent. Damage identification becomes more difficult as Young’s modulus of the filler increases, and there is a critical value, after which the damage could not be identified by the proposed method.
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Keyes, B. M., R. K. Ahrenkiel, G. J. Shaw, and G. P. Summers. "Minority-carrier lifetime damage coefficient of irradiated InP." Journal of Applied Physics 82, no. 5 (September 1997): 2156–63. http://dx.doi.org/10.1063/1.366023.

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Vellios, L., V. Kostopoulos, and S. A. Paipetis. "Fatigue Effect on the Dynamic Properties of Cfrp Composites." Advanced Composites Letters 3, no. 4 (July 1994): 096369359400300. http://dx.doi.org/10.1177/096369359400300405.

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Damage developing during fatigue of composite laminates affects both dynamic modulus of elasticity and damping coefficient of the material. It has been shown that the effect of fatigue on the damping coefficient is of particular importance. The damping variation could be used to characterise the damage state of the material, produced by fatigue. A model relating damage with damping was developed to correlate damage development to mechanical response. The damping coefficients of the composite of the fatigue test were measured at various stages, using the flexural free vibration of the test coupon hi cantilever configuration. The method was applied both in multidirectional and unidirectional laminates.
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Dissertations / Theses on the topic "Damage coefficient"

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Kassem, Emad Abdel-Rahman. "Measurements of moisture suction in hot mix asphalt mixes." Thesis, Texas A&M University, 2005. http://hdl.handle.net/1969.1/4259.

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The presence of moisture in hot mix asphalt (HMA) causes loss of strength and durability of the mix, which is referred to as moisture damage. This study deals with the development of experimental methods for measuring total suction in HMA, which can be defined as the free energy state of water in HMA mixes. The total suction is related to the ability of moisture to get into the mix under unsaturated conditions; it is also related to the ability of the mix to retain moisture. Soil suction has been studied extensively. However, suction in HMA as a porous material and its relationship to moisture damage have not been studied. The development of a procedure to measure the total suction in HMA mixes is the first objective of this research. The second objective is to relate suction measurements to physical and chemical properties of the mixtures. The objectives were achieved in two phases. In the first phase, the total suction was measured in HMA specimens with different types of aggregates (limestone and granite), and with different air void distributions and aggregate gradations. The results of this phase showed that the drying test using a 60 oC temperature-controlled room is the proper setup for measuring the total suction in HMA using thermocouple psychrometers. The characteristics of suction-moisture content curves were found to be related to the air void distribution in HMA. In the second phase, total suction was measured in sand asphalt specimens. These specimens had different combinations of aggregates and binders with different bond energies and exhibited different field performance in terms of resistance to moisture damage. The suction measurements in sand asphalt specimens were used to calculate the moisture diffusion coefficient. The results revealed that water diffused into sand asphalt specimens that are known to have poor resistance to moisture damage faster than those that are known to have good resistance to moisture damage
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Wong, Min Hao. "The development of scratch test methodology and characterization of surface damage of polypropylene." Texas A&M University, 2003. http://hdl.handle.net/1969.1/1194.

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A new scratch test methodology is proposed. The new test methodology is developed based on the principles of materials science and solid mechanics, which include the consideration of material parameters, use of microscopy for image analysis and the finite element method (FEM). The consistency and reproducibility of test results are shown using a new scratch test device on two sets of neat and talcfilled polypropylene (PP) systems. Three different test conditions, i.e., linear load increase under constant rate, constant load under constant rate, and linear rate increase under constant load, have been conducted to determine the most effective, informative test conditions for evaluation of scratch resistance of polymers. Experimental observations and FEM results show a good qualitative correlation. The unique advantages of the new scratch test method for evaluating scratch resistance of polymers are discussed. A systematic study of surface damage effected by a progressive scratching load is performed on model polypropylene (PP) systems. Mar-scratch and stress -whitening transitions can be readily observed, and the corresponding critical loads determined. Distinctive scratch hardnesses and surface damage features are found for different material systems. Visibility of scratched surface is quantified using gray level analysis via a flatbed scanner and a commercial image analysis tool. It is found that the onset of scratch visibility can be determined accurately and reproducibly using the custom -built scratcher under progressive loading condition. Talc particles are found to be responsible for the increased light scattering, leading to greatly increased visibility. The observed scratch visibility is also found to be related to the measured frictional force profiles. Approaches for producing scratch resistant PP are discussed.
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Wong, Alvaro Yat Set. "´´Evaluación de la compatibilidad de tinciones no fluorescentes de Diffquik, Giemsa, Fastblast y de Feulgen con el Bioensayo Cometa en el ADN espermático humano´´." Bachelor's thesis, Universidad Ricardo Palma, 2016. http://cybertesis.urp.edu.pe/handle/urp/826.

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La fertilidad masculina puede ser medida mediante un espermatograma convencional, sin embargo este examen no incluye la valoración de la integridad del ADN espermático. Esta variable ha sido correlacionada con las tasas de fertilización, viabilidad y desarrollo del embrión, convirtiéndose en una herramienta de importancia clínica tanto para los programas de reproducción animal como los tratamientos de fertilidad asistida. El bioensayo Cometa es capaz de determinar de una manera exacta el valor de la integridad del ADN espermático, lamentablemente este examen no es de uso rutinario por su elevado costo de implementación ya que utiliza microscopia especializada y tinciones fluorescentes para evidenciar la migración del ADN. El objetivo de esta investigación fue evaluar la compatibilidad de las tinciones no fluorescentes Diffquik, Giemsa, de Feulgen y FastBlast en el bioensayo Cometa usando un método visual y automatizado. Se utilizaron 15 eyaculados previamente seleccionados de acuerdo al manual OMS 2010, para luego ser capacitados en búsqueda de homogeneidad adecuada para la experimentación. Cada muestra fue expuesta a una gradiente de Peróxido de hidrogeno (0, 10, 30,60 y 100 mM) por 1 hora a 4°C para luego evaluar el coeficiente de daño mediante el método visual y porcentaje de ADN en la cola mediante el método automatizado. Las pendientes de la regresión lineal en el método visual indican que los valores obtenidos por la tinción control SybrGreen (m=3,69) difieren con Giemsa (m=3,45) y Diffquik (m=2,57). En el método automatizado de igual manera SybrGreen (m=0.83), Giemsa (m=0,79) y Diffquik (m=0,77). Sin embargo SybrGreen es 1,06 veces más efectivo que Giemsa en el visual y 1,05 veces en el automatizado, sugiriendo una compatibilidad con el bioensayo cometa. De igual manera SybrGreen es 1,07 veces más efectivo que Diffquik en el visual y 1,44 veces en el automatizado, concluyendo una compatibilidad solo en el método visual.Male fertility can be measured by a conventional semen analysis, however, this examination does not include the assessment of sperm DNA integrity. This variable has been correlated with fertilization rates, embryo viability and development, becoming a tool of clinical importance for both animal breeding programs and assisted fertility treatments. Comet bioassay is able to determine an exact way the value of sperm DNA integrity, unfortunately this test is not routinely used because of its high cost of implementation because it uses specialized microscopy and fluorescent dyes to demonstrate DNA migration. The objective of this research was to evaluate the compatibility of non-fluorescent dyes Diffquik, Giemsa, Feulgen and Comet FastBlast in the bioassay using a visual and automated method. 15 ejaculates were used previously manually selected according to WHO 2010 and then be trained in finding adequate homogeneity for experimentation. Each sample was exposed to a hydrogen peroxide gradient (0, 10, 30,60 and 100 mM) for 1 hour at 4 ° C and then assess the damage coefficient by visual method and percentage of DNA in the tail by automated method. The slopes of the linear regressions on the visual method indicate that the values obtained by the SybrGreen Control staining (m = 3.69) differ with Giemsa (m = 3.45) and Diffquik (m = 2.57). In the same way automated method SybrGreen (m = 0.83), Giemsa (m = 0.79) and Diffquik (m = 0.77). However SybrGreen is 1.06 times more effective than Giemsa visual and 1.05 times in the automated, suggesting a comet support bioassay. Similarly SybrGreen is 1.07 times more effective than Diffquik visual and 1.44 times in the automated, concluding compatibility only in the visual method. Keywords:
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Bucevičius, Nerijus. "Ignalinos AE tikimybinio saugos vertinimo modelio neapibrėžtumo ir jautrumo analizė." Master's thesis, Lithuanian Academic Libraries Network (LABT), 2008. http://vddb.library.lt/obj/LT-eLABa-0001:E.02~2008~D_20080619_122205-88712.

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Neapibrėžtumo analizė techninių sistemų modeliavimo rezultatams yra ypač aktuali, kai modeliuojamas pavojingų sistemų darbas, saugą užtikrinančių sistemų funkcionavimas, nagrinėjami avarijų scenarijai ar kiti, su rizika susiję klausimai. Tokiais atvejais, ypatingai reaktorių saugos analizės srityje, yra labai svarbu, kad gauti modeliavimo rezultatais būtų robastiški. Šiame darbe yra atliekama Ignalinos AE tikimybinio saugos vertinimo modelio neapibrėžtumo ir jautrumo analizė. Neapibrėžtumo ir jautrumo analizė atlikta naudojantis skirtingais statistinio vertinimo metodais, taikant programų paketą SUSA. Gauti rezultatai palyginti su tikimybinio modeliavimo sistemos Risk Spectrum PSA tyrimo rezultatais. Palyginimas parodė, jog skirtingais metodais ir programiniais paketais parametrų reikšmingumas įvertintas vienodai. Statistinė neapibrėžtumo ir jautrumo analizė, taikant Monte Karlo modeliavimo metodą, leido nustatyti parametrus turėjusius didžiausią įtaką modelio rezultatui.
The uncertainty estimation is the part of full analysis for modelling of safety system functioning in case of the accident, for risk estimation and for making the risk-based decision. In this paper the uncertainty and sensitivity analysis of Ignalina NPP probabilistic safety assessment model was performed using SUSA software package. The results were compared with the results, performed using software package Risk Spectrumm PSA. Statistical analysis of uncertainty and sensitivity allows to estimate the influence of parameters on the calculation results and find those modelling parameters that have the largest impact on the result. Conclusions about for importance of a parameters and sensitivity of the result are obtained using a linear approximation of the model under analysis.
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Kharrat, Mohamed. "Design and development of a torsional guided-waves inspection system for the detection and sizing of defects in pipes." Thesis, Ecully, Ecole centrale de Lyon, 2012. http://www.theses.fr/2012ECDL0016/document.

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Plusieurs industries manipulent des substances liquides et gazeuses qui circulent souvent dans de longues canalisations. La technique d'ondes guidées est couramment utilisée dans ce domaine. Cette technique est en progrès continu. Dans cette thèse, un système d'inspection a été conçu et développé. Il est basé sur des transducteurs piézoélectriques qui génèrent des ondes guidées de torsion pouvant se propager le long du tube testé. Les signaux réfléchis des défauts et singularités rencontrés sont détectés aussi par des capteurs piézoélectriques. Des simulations numériques utilisantpar la méthode d'éléments finis standard et la méthode Wave Finite Element(WFEM) ont été effectuées afin de vérifier et de visualiser le phénomène de propagation des ondes dans des tubes intacts et endommagés. Un ensemble de tests a été mis en place sur des tubes droits et courbés avec deux matériaux différents: PVC et acier. L'interaction entre les ondes générées et les défauts usinés a été prouvée.Les résultats numériques et expérimentaux confirment certaines caractéristiques spécifiques concernant le coefficient de réflexion de l'onde. Par la suite, un pipeline industriel d'environ soixante mètres de long et contenant plusieurs défauts et singularités a été testé par le système d'inspection. Les signaux enregistrés ont soumis certains traitements numériques afin de les rendre exploitables. Les signaux traités sont analysés afin d'identifier et de distinguer les réflexions des défauts de celles des singularités structurés. La méthode WFEM a été employée pour construire une base de données numérique des coefficients de réflexion en variant la profondeur et les extensions axiale et circonférentielle du défaut modélisé. Le calcul a été établi en fonction de la fréquence. La corrélation des tailles des défauts est effectuée en balayant la base de données numérique pour trouver la combinaison appropriée de dimensions pour un défaut donné. Les réflexions à partir des singularités structurées (coudes, blocs de béton, colliers, et les soudures) sont traitées ainsi en comparant des coefficients de réflexion obtenus par WFEM à ceux évalués expérimentalement. Enfin, on a étudié numériquement l'effet de la position angulaire d'un défaut sur les coefficients de réflexion et de transmission tout en excitant à différents types d'ondes. La méthode WFE est aussi utilisée pour effectuer le calcul. Cette étude donne un guide à la localisation circonférentielle des défauts dans les tubes
Long pipelines are widely used in several industries transporting liquid or gas. The guided wave technique is commonly used in this field and it is under continuing progress. In this thesis, an inspection system has been designed and developed. Piezoelectric transducers are employed to generate torsional guided waves that could propagate along the tested pipe; and receive reflected signals from encountered features and damages. Numerical simulations using standard FE and Wave Finite Element methods have been carried out in order to verify and visualize the wave propagation phenomenon in both intact and damaged pipes. A set of tests has been performed on straight and curved pipes with two different materials: PVC and steel. The interaction between generated waves and machined defects has been proven. Numerical and experimental results confirm some specific features in the wave reflection coefficient. Thereafter, an industrial pipeline of about sixty meters long and containing several features has been tested by the inspection system.Recorded signals had submitted some numerical treatments in order to make them interpretable. Processed signals are analyzed to identify defects reflections from structured singularities echoes. The Wave Finite Element Method (WFEM) has been used to construct a numerical database of reflection coefficients from modelled defects by varying thickness, axial and circumferential extents. Calculation was made depending on frequency. The approximation of defect sizes is carried out by sweeping the numerical database to find the suitable combination of dimensions fora given defect. Reflections from structural singularities (elbows, concrete blocks,clamps, and welds) are treated as well by comparing reflection coefficients obtained by WFEM to those evaluated experimentally. Finally, a numerical investigation deals with the effect of defect angular-position on reflection and transmission coefficients while exciting by different types of waves. The spectral method Wave Finite Element has been used to carry out calculation. This study gives guidance to circumferential localization of defects in pipes
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Singh, Jaskirat. "Wind Speed Profiles and Pressure Coefficients Obtained in the Wind Induced Damage Simulator for Silsoe Cube Model." Thesis, Université d'Ottawa / University of Ottawa, 2020. http://hdl.handle.net/10393/41094.

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Hazardous winds, such as tornadoes and hurricanes, have a great impact on civil engineering structures and cause significant social and economic disturbances. The wind speed and pressure tested in the conventional wind tunnel experiments are much smaller than the actual wind speed and pressure measured in the field. Therefore, the Wind-induced Damage Simulator (WDS) was constructed at the University of Ottawa to overcome the wind speed limitations of wind tunnels and to simulate different types of wind speed profiles. WDS is an isolated cubic box with dimensions 3.65m x3.65 m and 3.0 m height, with multiple inlets on the side faces of the testing chamber and an outlet on the top side. This unique equipment creates a controlled environment for studying wind speed profiles in a confined space, by regulating the air flow with the aid of an attached industrial blower. To measure the simulated wind velocities inside the WDS and to obtain the wind speed profile in the testing chamber, Aeroprobe (12- Hole Probe) sensor was used for different combinations of opened inlets and at four different locations. The data collected from the Aeroprobe was processed by the use of the Aeroflow 2.7.5.7346 software, to get the velocity of wind in three different directions (u, v and w) and the mean velocity at a single point. After determining the mean velocity at different heights and RPM values at all four positions, Matlab software was used to determine the wind profile and the spectra of the turbulence intensities and these were compared for different heights at the four investigated locations and for various rotations per minute (RPM) values (400 to 800 RPM) for controlling the blower. Once the flow characterization was completed, the wind-induced pressure for three models of the Silsoe Cube were measured as a part of the second phase of the test. The current experiment employed 3 different scales of Silsoe cube: 1:40, 1:30 and 1:20, while the pressure coefficients were determined at 16 different points along a vertical line crossing the faces of the cube. A pressure taps system with 16 channels and a Scanivale pressure scanner were used to measure the pressure at 16 different positions on the cube. Matlab software was used to determine the pressure coefficients from the data measured by pressure taps. The pressure coefficienst for the Silsoe Cube were plotted and compared for the three different scales. Also, for determining the best scale to be used in future experiments. The pressure coefficients of the 3 different scaled model of Silsoe Cubes was compared with full-scale data reported in the literature for the same structure. Based on the results obtained from the experiments, recommendations for the best location in the testing chamber for the future experiments employing the WDS were formulated.
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Yano, Marcus Omori. "Extrapolation of autoregressive model for damage progression analysis /." Ilha Solteira, 2019. http://hdl.handle.net/11449/182287.

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Orientador: Samuel da Silva
Resumo: O principal objetivo deste trabalho é usar métodos de extrapolação em coeficientes de modelos autorregressivos (AR), para fornecer informações futuras de condições de estruturas na existência de mecanismo de danos pré-definidos. Os modelos AR são estimados considerando a predição de um passo à frente, verificados e validados a partir de dados de vibração de uma estrutura na condição não danificada. Os erros de predição são usados para extrair um indicador para classificar a condição do sistema. Então, um novo modelo é identificado se qualquer variação de índices de dano ocorrer, e seus coeficientes são comparados com os do modelo de referência. A extrapolação dos coeficientes de AR é realizada através das splines cúbicas por partes que evitam possíveis instabilidades e alterações indesejáveis dos polinômios, obtendo aproximações adequadas através de polinômios de baixa ordem. Uma curva de tendência para o indicador capaz de predizer o comportamento futuro pode ser obtida a partir da extrapolação direta dos coeficientes. Uma estrutura de três andares com um para-choque e uma coluna de alumínio colocada no centro do último andar são analisados com diferentes cenários de dano para ilustrar a abordagem. Os resultados indicam a possibilidade de estimar a condição futura do sistema a partir dos dados de vibração nas condições de danos iniciais.
Abstract: The main purpose of this work is to apply extrapolation methods upon coefficients of autoregressive models (AR), to provide future condition information of structures in the existence of predefined damage mechanism. The AR models are estimated considering one-step-ahead prediction, verified and validated from vibration data of a structure in the undamaged condition. The prediction errors are used to extract an indicator to classify the system state condition. Then, a new model is identified if any variation of damage indices occurs, and its coefficients are compared to the ones from the reference model. The extrapolation of the AR coefficients is performed through the piecewise cubic splines that avoid possible instabilities and undesirable changes of the polynomials, obtaining suitable approximations through low-order polynomials. A trending curve for the indicator capable of predicting future behavior can be obtained from direct coefficient extrapolation. A benchmark of a three-story building structure with a bumper and an aluminum column placed on the center of the top floor is analyzed with different damage scenarios to illustrate the approach. The results indicate the feasibility of estimating the future system state from the vibration data in the initial damage conditions.
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Serhal, Jamil. "Étude de la vulnérabilité des bâtiments en maçonnerie soumis à des mouvements de terrains et élaboration de critères d’évolution de leur rigidité." Thesis, Université de Lorraine, 2016. http://www.theses.fr/2016LORR0024/document.

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L’objectif principal de cette recherche est l’étude du dommage des bâtiments en maçonnerie subissant des tassements différentiels. Cette contribution, en s’appuyant sur la modélisation numérique, les méthodes analytiques et sur l’expérimentation, vise à une meilleure compréhension du comportement des structures en maçonnerie. Ce problème trouve diverses applications en ingénierie avec par exemple les maisons situées dans des zones de creusement de tunnels, ou des zones subissant des affaissements de terrains. L’étude bibliographique met en évidence la diversité des méthodes permettant de catégoriser le dommage des bâtiments subissant des tassements. La cohérence de ces méthodes est étudiée. En particulier, le travail porte sur l’étude de l’influence des propriétés mécaniques des bâtiments sur les valeurs seuils proposées pour catégoriser le dommage. Une étude de sensibilité est mise en œuvre afin de proposer des intervalles de seuils dépendant des propriétés des bâtiments. Cette incertitude est alors formalisée par le développement de courbes de fragilité permettant de quantifier en terme de probabilité la sévérité du dommage pour différents types de bâtiments. En addition, la rigidité des bâtiments subissant des mouvements de terrains est un paramètre important pour étudier les phénomènes d’interaction sol-structure et évaluer les tassements différentiels transmis par le terrain aux structures. L’évolution de cette rigidité en fonction du dommage associé aux tassements n’est pas étudiée dans la littérature. Une méthodologie d’étude de la variation de la rigidité des bâtiments en maçonnerie en fonction du tassement transmis a été développée au moyen de modélisations numérique (logiciel UDEC). Des formulations analytiques sont alors proposées pour relier la réduction de la rigidité des bâtiments en fonction du tassement subis et de leurs propriétés. Une procédure expérimentale est mise en place afin de valider la méthodologique numérique. En conclusion, les deux principales contributions de cette thèse sont 1) une amélioration de l’évaluation du dommage des bâtiments en fonction de leurs propriétés, au moyen des courbes de fragilité et 2) le développement d’une méthodologie numérique permettant d’évaluer l’évolution de la rigidité des bâtiments en maçonnerie en fonction du tassement qu’ils subissent et en fonction de leurs propriétés
The main purpose of this research is the assessment of the damage of masonry buildings undergoing differential settlements. This contribution, which is based on numerical modeling, analytical methods and experimentation, aims for a better understanding of the behavior of masonry structures. The treated issue may be applied in different engineering fields, as for example the case of buildings located in tunneling areas or in areas suffering land subsidence. The bibliography survey presents a diversity of methods to categorize the damage of buildings undergoing settlement. This variety of methods, parameters and thresholds used to qualify the severity of the damage, prompted us to study the consistency of these methods, and the effect of the properties of masonry buildings - undergoing ground movements - on proposed threshold values. A sensitivity analysis on building properties is implemented in order to propose thresholds values intervals that depend on buildings properties. This uncertainty is then taken into account with the development of fragility curves that aim quantifying the damage in terms of probability according to a typology of buildings. In addition, the stiffness of buildings undergoing ground movements plays a very important role in studying the phenomenon of soil-structure interaction. However, the evolution of the stiffness of the damaged building due to settlements is not investigated in the literature. Numerical modeling (UDEC) is used to develop a methodology for the study of the stiffness variation of masonry buildings in relation to he settlement suffered by the structure. Analytical formulations are proposed to relate the reduction of the stiffness of the buildings with regard to the suffered settlement, and depending on the buildings properties. Some experimental tests are performed to validate the numerical methodology. Finally, the two mains results are 1) improvement in the assessment of buildings damage with the drawn of fragility curves and 2) the numerical methodology to formulate the changes in the stiffness of masonry buildings according to the suffered settlement, and according to their properties
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Newberry, James. "A Damage Assessment and Wind Loading Analysis of Residential Structures Built Post-1996 in Punta Gorda in the Wake of Hurricane Charley." Scholar Commons, 2006. http://scholarcommons.usf.edu/etd/3749.

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One of the communities in the path of Hurricane Charley as it came ashore August 13, 2004, was Punta Gorda, recording gusts up to 145 mph. This project utilizes aerial photos taken approximately 10 days after the storm battered the area, using a digital photography program. Focusing on the one-story residential structures (houses) of the Punta Gorda area, a damage assessment could be made of the area’s homes, and how they stood up to the storm. This study focused further on homes built after major changes to the local/state building codes went into effect (starting in 1996) after the devastation left in south Florida by Hurricane Andrew in 1992. After selecting approximately 20 damaged houses, damaged from wind loading only, an analysis of these houses (or types of houses) could then be undertaken complying with the most current building/wind codes used at the time of Charley’s landfall. Furthermore, by looking at the pictures, and using reports outlining the types of damage seen from the storm, the building/wind codes could then be checked for their effectiveness. After performing a wind loading analysis on houses similar to those seen in the selected pictures, and using the wind code provisions of ASCE 7-98, calculations show a substantial increase in local wind pressure to various zones of the roof. High pressure zones of the roof included the ridges of the gable and hipped style roofs, as well as the corners and the edges. More emphasis needs to be placed on the installation of the clay tiles (mandated by certain deed-restricted subdivisions of Punta Gorda). If the tiles are ripped off from the wind, then the roof sheathing becomes exposed to the environment, and if this becomes damaged, rain leaking down into the interior of the house would cause additional damage.
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Yango, Takwe. "Characterization of Filter Cake Buildup and Cleanup under Dynamic Fluid Loss Conditions." Thesis, 2011. http://hdl.handle.net/1969.1/ETD-TAMU-2011-08-10076.

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Hydraulic fracturing is a popular stimulation method in tight gas and shale gas reservoirs that uses a viscous fluid to fracture the reservoir rock and uniformly transport proppant to create a highly conductive path that is kept open by the proppant after fracturing. This method is used to improve the productivity of the otherwise low permeability reservoirs. Hydraulic fracturing, though in general beneficial, is a complex process that has a number of challenges in fracturing design and execution. This research focuses on studying the damage caused by the fracturing fluid (gel) to the fracture and the conditions to remove the damage. Guar gum and its derivatives have been the most commonly used polymers to increase the viscosity of fracturing fluids. The fracturing fluid gets dehydrated under pressure leaving behind a highly concentrated unbroken residue called filter cake which causes permeability impairment in the proppant pack, resulting in low fracture conductivity and decreased effective fracture length. This study seeks to characterize filter cakes. By measuring its thickness and with the leak off volume, the concentration and yield stress of the filter cake can be estimated. The thickness of the filter cake was measured with a precise laser profilometer. Correlations are proposed to estimate filter cake properties (thickness, concentration and yield stress) based on pumping conditions (pump rate, time and net pressure) and rock properties. With these properties known, a required flow back rate of the reservoir fluid can be estimated to clean up the filter cake modeled as a non-newtonian fluid exhibiting a yield stress. Typical field conditions were referenced and scaled down in the lab to closely represent the field conditions. Recommendations are provided on gel damage based on the observation of the study.
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Books on the topic "Damage coefficient"

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Roshanak, Hakimzadeh, and United States. National Aeronautics and Space Administration., eds. Diffusion length damage coefficient and annealing studies in proton-irradiated InP. [Washington, DC]: National Aeronautics and Space Administration, 1993.

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Roshanak, Hakimzadeh, and United States. National Aeronautics and Space Administration., eds. Diffusion length damage coefficient and annealing studies in proton-irradiated InP. [Washington, DC]: National Aeronautics and Space Administration, 1993.

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Book chapters on the topic "Damage coefficient"

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Wei, Llide, Cong Xin Chen, and Chun He Yang. "Study on Constitutive Relation and Permeable Coefficient Tensor of Rocks under Tensile Stress Loading with Micromechanics." In Fracture and Damage Mechanics V, 899–902. Stafa: Trans Tech Publications Ltd., 2006. http://dx.doi.org/10.4028/0-87849-413-8.899.

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Kim, Tae Soo, Han Seung Lee, Sung Ho Tae, and Sung Ok Oh. "Friction Coefficient in High Tension Bolt Joints Using a Zn/Al Metal Spray Corrosion Resistance Method." In Advances in Fracture and Damage Mechanics VI, 465–68. Stafa: Trans Tech Publications Ltd., 2007. http://dx.doi.org/10.4028/0-87849-448-0.465.

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Kang, In Seok, Han Seung Lee, Jae Deog Kim, Jae Ho Jang, and Jing Yeong Seong. "An Experimental Study on the Performance Evaluation of RC Beams to Calculate the Partial Reduction Coefficient of High Strength Glass Fiber Transparent Composite Panels." In Advances in Fracture and Damage Mechanics VI, 777–80. Stafa: Trans Tech Publications Ltd., 2007. http://dx.doi.org/10.4028/0-87849-448-0.777.

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Frolova, Ksenia P., and Elena N. Vilchevskaya. "Effective Diffusion Coefficient of a Porous Material Applied to the Problem of Hydrogen Damage." In Advanced Structured Materials, 113–30. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-66948-5_7.

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Shone, Simon P., Brian R. Mace, and Tim P. Waters. "Damage Assessment of Beams Using Flexural Wave Reflection Coefficients." In Damage Assessment of Structures VII, 193–98. Stafa: Trans Tech Publications Ltd., 2007. http://dx.doi.org/10.4028/0-87849-444-8.193.

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Morassi, Antonino. "Generalized Fourier Coefficients and Applications to Damage Detection in Rods." In Damage Assessment of Structures VII, 83–88. Stafa: Trans Tech Publications Ltd., 2007. http://dx.doi.org/10.4028/0-87849-444-8.83.

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Sparks, M. H., and T. M. Flanders. "Effects of Spectral Perturbation on Calculated Damage Coefficients." In Proceedings of the Seventh ASTM-Euratom Symposium on Reactor Dosimetry, 583–90. Dordrecht: Springer Netherlands, 1992. http://dx.doi.org/10.1007/978-94-011-2781-3_67.

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Zhang, Y., C. C. de Visser, Q. P. Chu, and E. J. van Kampen. "Aircraft Damage Pattern Recognition Using Aerodynamic Coefficients and Fuzzy Logic." In Advances in Aerospace Guidance, Navigation and Control, 335–48. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-65283-2_18.

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Akeh, Ugbah Paul, Steve Woolnough, and Olumide A. Olaniyan. "ECMWF Subseasonal to Seasonal Precipitation Forecast for Use as a Climate Adaptation Tool Over Nigeria." In African Handbook of Climate Change Adaptation, 1613–30. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-45106-6_97.

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AbstractFarmers in most parts of Africa and Asia still practice subsistence farming which relies minly on seasonal rainfall for Agricultural production. A timely and accurate prediction of the rainfall onset, cessation, expected rainfall amount, and its intra-seasonal variability is very likely to reduce losses and risk of extreme weather as well as maximize agricultural output to ensure food security.Based on this, a study was carried out to evaluate the performance of the European Centre for Medium-range Weather Forecast (ECMWF) numerical Weather Prediction Model and its Subseasonal to Seasonal (S2S) precipitation forecast to ascertain its usefulness as a climate change adaptation tool over Nigeria. Observed daily and monthly CHIRPS reanalysis precipitation amount and the ECMWF subseasonal weekly precipitation forecast data for the period 1995–2015 was used. The forecast and observed precipitation were analyzed from May to September while El Nino and La Nina years were identified using the Oceanic Nino Index. Skill of the forecast was determined from standard metrics: Bias, Root Mean Square Error (RMSE), and Anomaly Correlation Coefficient (ACC).The Bias, RMSE, and ACC scores reveal that the ECMWF model is capable of predicting precipitation over Southern Nigeria, with the best skill at one week lead time and poorest skills at lead time of 4 weeks. Results also show that the model is more reliable during El Nino years than La-Nina. However, some improvement in the model by ECMWF can give better results and make this tool a more dependable tool for disaster risk preparedness, reduction and prevention of possible damages and losses from extreme rainfall during the wet season, thus enhancing climate change adaptation.
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Tee, Kong Fah. "Optimization of Condensed Stiffness Matrices for Structural Health Monitoring." In Optimization of Design for Better Structural Capacity, 150–85. IGI Global, 2019. http://dx.doi.org/10.4018/978-1-5225-7059-2.ch006.

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This chapter aims to develop a system identification methodology for determining structural parameters of linear dynamic systems, taking into consideration practical constraints such as insufficient sensors. Based on numerical analysis of measured responses (output) due to known excitations (input), structural parameters such as stiffness values are identified. If the values at the damaged state are compared with the identified values at the undamaged state, damage detection and quantification can be carried out. To retrieve second-order parameters from the identified state space model, various methodologies developed thus far impose different restrictions on the number of sensors and actuators employed. The restrictions are relaxed in this study by a proposed method called the condensed model identification and recovery (CMIR) method. To estimate individual stiffness coefficient from the condensed stiffness matrices, the genetic algorithms approach is presented to accomplish the required optimization problem.
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Conference papers on the topic "Damage coefficient"

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Wennberg, K. E., and M. M. Sharma. "Determination of the Filtration Coefficient and the Transition Time for Water Injection Wells." In SPE European Formation Damage Conference. Society of Petroleum Engineers, 1997. http://dx.doi.org/10.2118/38181-ms.

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Qiu, Xiangdong, Muhammad Ali Khalid, and Abullah Sultan. "How to Determine True Acid Diffusion Coefficient to Optimize Formation Damage Treatment?" In SPE European Formation Damage Conference and Exhibition. Society of Petroleum Engineers, 2015. http://dx.doi.org/10.2118/174241-ms.

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Zhong, Shuncong, and S. Olutunde Oyadiji. "Wavelet-Based Structural Damage Detection." In ASME 2007 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/detc2007-35632.

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In this paper, a new wavelet-based approach for crack identification in beam-like structures is presented and applied to simply-supported beams with single or multiple cracks. A novel damage index, based on finding the difference between two sets of detail coefficients obtained by the use of the Stationary Wavelet Transform (SWT) of two reconstructed sets of modal displacement data of the cracked beam-like structure, is proposed for single crack detection or multiple crack detection. These two sets of mode shape data represent the left half and the modified right half of the modal data of the structure. Currently, SWT is widely used in the field of image processing for image noise reduction and image quality improvement. However, because it can provide an accurate estimate of the variances at each scale and facilitate the identification of salient features in a signal, SWT has great potential in the field of structural damage detection. In this paper, the modal responses of the damaged simply supported beams used are computed using the finite element method (FEM). The modal data generate is decomposed by SWT into a smooth curve, called approximation coefficient, and detail coefficient. It is shown that the detail coefficient includes crack information that is useful for structural damage detection. Therefore, a novel damage index, the difference of the SWT detail coefficients of two reconstructed sets of modal displacement data, is proposed and employed. The numerical simulation results show that the proposed wavelet-based method has a good anti-noise ability and it does not require the modal parameters of an intact structure as a baseline for crack detection. Therefore, it can be recommended for real applications in structural health monitoring and damage detection.
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Abdolahipour, Soheila, Mahmoud Mani, and Ghazaleh M. Ahmadi Dehaghi. "Numerical and Experimental Study of the Influence of Damage on the Aerodynamic Characteristics of a Finite Wing." In ASME-JSME-KSME 2011 Joint Fluids Engineering Conference. ASMEDC, 2011. http://dx.doi.org/10.1115/ajk2011-03055.

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In this paper the flow on a finite wing with star shape damage is numerically and experimentally investigated to understand the influences of damage on the aerodynamic characteristics of wing. To study the effects of different span positions, the damage was considered in tip, middle and root position of the wing span. The aerodynamic coefficients and their increments due to damage were extracted and the results were compared to each other and also to the results of experimental. Then flow visualizations were practiced to make evident the flow structure on the model and to help to understand the influences of each position of damage on the aerodynamic coefficients. There was the flow through the damage which was driven by the pressure difference between the upper and lower wing surfaces. The flow could take two forms dependent on the angle of attack. The first form was a “weak-jet” which formed an attached wake and resulted in small changes in force and moment coefficients. The second form resulted from increased incidence. This was the “strong-jet” where through flow penetrated into the free stream flow with large separated wake and reverse flow. The effect on the force and moment coefficients was significant in this case. Generally comparing to an undamaged model, increasing incidence for a damaged model resulted increase loss of lift coefficient, increased drag coefficient and more negative pitching moment coefficient.
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Guo, Yajing, Shunxing Tang, Hongchao Hui, Yuyu Wang, Qing Tang, Baoqiang Zhu, and Zunqi Lin. "Transverse stimulated Raman scattering gain coefficient measurement in KDP crystal." In SPIE/SIOM Pacific Rim Laser Damage: Optical Materials for High-Power Lasers, edited by Jianda Shao, Takahisa Jitsuno, and Wolfgang Rudolph. SPIE, 2013. http://dx.doi.org/10.1117/12.2020127.

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Chen, Pengju, Hui Wang, and Mei Ding. "Cluster Analysis with Grey Comprehensive Correlation Coefficient for Prediction of Bridge Damage." In 20th COTA International Conference of Transportation Professionals. Reston, VA: American Society of Civil Engineers, 2020. http://dx.doi.org/10.1061/9780784483053.095.

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DE OLIVEIRA, MARIO A., NELCILENO V. S. ARAUJO, DANIEL J. INMAN, and JOZUE VIEIRA FILHO. "A New Strategy for Damage Identification in SHM Systems by Exploring Kappa Coefficient." In Structural Health Monitoring 2017. Lancaster, PA: DEStech Publications, Inc., 2017. http://dx.doi.org/10.12783/shm2017/13947.

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Rizzo, Piervincenzo, and Francesco Lanza di Scalea. "Wavelet coefficient analysis for the quantitative determination of damage in tendons and cables." In Smart Structures and Materials, edited by Masayoshi Tomizuka. SPIE, 2005. http://dx.doi.org/10.1117/12.598304.

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Passano, Elizabeth, Carl M. Larsen, and Jie Wu. "On the Prediction of Fatigue Damage From VIV." In ASME 2014 33rd International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/omae2014-24217.

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Empirical methods for calculation of response from vortex shedding are based on a set of coefficients that determines response frequencies, excitation force and damping, but also how competing frequencies will appear in time and along a structure. It is easy to formulate a mathematical model for Vortex Induced Vibrations (VIV), but the key challenges are to find the necessary hydrodynamic coefficients and a model for how the active frequencies appear in time and space. Since the original version of VIVANA was released more than ten years ago, new information has been become available through new test techniques, as well as from new methods for analysis of old tests. In this study, recent re-examination of the results of the NDP 38 m tests is presented. The observed response behavior is compared to predicted VIV response and fatigue. The consequences of assuming that response frequencies will be active concurrently or consecutively are investigated and predicted response and fatigue are compared to results based on the measurements. Another method that has provided valuable information has been inverse analysis, by which forces on a flexible beam are estimated from measured strains and/or accelerations. When forces are known, the underlying coefficients can be calculated from the standard equations. Inverse analysis has been carried out from a set of experiments, and a new set of coefficients has been estimated for use in coefficient based programs such as VIVANA. Initial comparisons between measured and predicted response show that the new coefficients give an improved agreement with regard to amplitudes and frequency composition.
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Zhang, Jing, and Liang-yan Cheng. "Investigation of combination characteristic of damage location and intensity in arch using wavelet coefficient." In 2011 Second International Conference on Mechanic Automation and Control Engineering (MACE). IEEE, 2011. http://dx.doi.org/10.1109/mace.2011.5986936.

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