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Material Response (material + response)
Selected AbstractsMATERIAL RESPONSE OF RAMAX-2 DURING HIGH-SPEED MACHINING USING QUICK-STOP DEVICEEXPERIMENTAL TECHNIQUES, Issue 2 2009M. Zeb First page of article [source] Hertzian Space: Material Response to Spatial PresenceARCHITECTURAL DESIGN, Issue 5 2007Mark Taylor Abstract Mark Taylor describes how an interest in the possibilities of generating spaces that fully respond to people's presence and their activities led him and Mark Burry to undertake a project with students at Victoria University Wellington, New Zealand, that spatialises the dynamics of a full body massage. Copyright © 2007 John Wiley & Sons, Ltd. [source] A Computational Framework for Patient-Specific Analysis of Articular Cartilage Incorporating Structural Information from DT-MRIGAMM - MITTEILUNGEN, Issue 2 2009David M. Pierce Abstract Accurate techniques for simulating sof t biological tissue deformation are an increasingly valuable tool in many areas of biomechanical analysis and medical image computing. To model the morphology and the material response of human articular cartilage a phenomenological and patient-specific simulation approach incorporating the collagen fibre fabric is proposed. We then demonstrate a unique combination of ultra-high field Diffusion Tensor Magnetic Resonance Imaging (17.6T DT-MRI) and a novel numerical approach incorporating the empirical data to predict the collagen fibre fabric deformation for an indentation experiment (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Probabilistic yielding and cyclic behavior of geomaterialsINTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 15 2010Kallol Sett Abstract In this paper, the novel concept of probabilistic yielding is used for 1-D cyclic simulation of the constitutive behavior of geomaterials. Fokker,Planck,Kolmogorov equation-based probabilistic elastic,plastic constitutive framework is applied for obtaining the complete probabilistic (probability density function) material response. Both perfectly plastic and hardening-type material models are considered. It is shown that when uncertainties in material parameters are taken into consideration, even the simple, elastic-perfectly plastic model captures some of the important features of geomaterial behavior, for example, modulus reduction with cyclic strain, which, deterministically, is only possible with more advanced constitutive models. Furthermore, it is also shown that the use of isotropic and kinematic hardening rules does not significantly improve the probabilistic material response. Copyright © 2010 John Wiley & Sons, Ltd. [source] Directional response of a reconstituted fine-grained soil,Part I: experimental investigationINTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 13 2006Daniele Costanzo Abstract This paper discusses the results of a large experimental program designed to investigate in a systematic manner the main features of the incremental response of fine-grained soils. The results are obtained from triaxial stress probing experiments carried out on a French silty clay (Beaucaire Marl). All the tests have been performed on reconstituted specimens, normally consolidated to an initial state which is either isotropic or anisotropic. In the interpretation of the experimental results, extensive use is made of the concept of strain response envelope. The response envelopes obtained for different stress increment magnitudes are remarkably consistent with each other and indicate an inelastic and irreversible material response, i.e. a strong dependence on the stress increment direction, also at relatively small strain levels. A companion paper (Int. J. Numer. Anal. Meth. Geomech., this issue, 2006) assesses the performance of some advanced constitutive models in reproducing the behaviour of reconstituted Beaucaire Marl as observed in this experimental program. Copyright © 2006 John Wiley & Sons, Ltd. [source] Visual framework for development and use of constitutive modelsINTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 15 2002Youssef M. A. Hashash Abstract Advanced constitutive relations are used in geotechnical engineering to capture measured soil and rock behaviour in the laboratory, and in numerical models to represent the material response. These constitutive relations have traditionally been difficult to use, understand, and develop except by a limited number of specialists. This paper describes a framework for transforming the representation of constitutive relations, as well as stress and strain quantities from a series of mathematical equations and matrix quantities to multidimensional geometric/visual objects in a dynamic interactive colour-rich display environment. The paper proposes a shift in current approaches to the development of constitutive equations and their use in numerical simulations by taking advantage of rapid advancements in information technology and computer graphics. A novel interactive visualization development and learning environment for material constitutive relations referred to as VizCoRe is presented. Visualization examples of two constitutive relations, the linear elastic with von Mises failure criteria and the Modified Cam Clay (MCC) are shown. These include two- and three-dimensional renderings of stress states and paths and yield and failure surfaces. In addition, the environment allows for the visualization of the implicit integration algorithm used for the numerical integration of both constitutive models. Copyright © 2002 John Wiley & Sons, Ltd. [source] Enrichment of enhanced assumed strain approximations for representing strong discontinuities: addressing volumetric incompressibility and the discontinuous patch testINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 1 2004J. E. Dolbow Abstract We present a geometrically non-linear assumed strain method that allows for the presence of arbitrary, intra-finite element discontinuities in the deformation map. Special attention is placed on the coarse-mesh accuracy of these methods and their ability to avoid mesh locking in the incompressible limit. Given an underlying mesh and an arbitrary failure surface, we first construct an enriched approximation for the deformation map with the non-linear analogue of the extended finite element method (X-FEM). With regard to the richer space of functions spanned by the gradient of the enriched approximation, we then adopt a broader interpretation of variational consistency for the construction of the enhanced strain. In particular, in those elements intersected by the failure surface, we construct enhanced strain approximations which are orthogonal to piecewise-constant stress fields. Contrast is drawn with existing strong discontinuity approaches where the enhanced strain variations in localized elements were constructed to be orthogonal to constant nominal stress fields. Importantly, the present formulation gives rise to a symmetric tangent stiffness matrix, even in localized elements. The present modification also allows for the satisfaction of a discontinuous patch test, wherein two different constant stress fields (on each side of the failure surface) lie in the solution space. We demonstrate how the proposed modifications eliminate spurious stress oscillations along the failure surface, particularly for nearly incompressible material response. Additional numerical examples are provided to illustrate the efficacy of the modified method for problems in hyperelastic fracture mechanics. Copyright © 2003 John Wiley & Sons, Ltd. [source] A numerical model for the cyclic deterioration of railway tracksINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 4 2003Akke S. J. Suiker Abstract An elasto-plastic material model is proposed that can be used to simulate the cyclic deterioration of railway tracks. The model describes the envelope of the irreversible, plastic material response generated during a cyclic loading process, thereby distinguishing the mechanisms of frictional sliding and volumetric compaction. The reversible response is represented by a pressure-dependent, hypo-elastic material law. After the numerical integration of the model is specified, the model is calibrated on laboratory experiments and employed in a finite-element case study of the long-term settlement behaviour of a railway track. The main features of the model are illustrated by comparing the computed response with the response obtained by in situ track measurements. Copyright © 2003 John Wiley & Sons, Ltd. [source] Hertzian Ring Crack Initiation in Hot-Pressed Silicon CarbidesJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 8 2009Andrew A. Wereszczak The use of Hertzian indentation to measure ring crack initiation force (RCIF) distributions in four hot-pressed silicon carbide (SiC) ceramics is described. Three diamond indenter diameters were used with each SiC; the RCIF in each test was identified with the aid of an acoustic emission system; and two-parameter Weibull RCIF distributions were determined for all 12 combinations. RCIF testing was found to be an effective discriminator of contact damage initiation and response. It consistently produced the same ranking of RCIF between the four SiCs, with all three different indenter diameters, which is noteworthy because Knoop hardness and fracture toughness measurements were only subtly different or equivalent for the four SiCs. However, because RCIF, like hardness, is a characteristic response of a target material to an applied indentation condition (e.g., a function of indenter diameter) and not a material property, the implications and possible limitations should be acknowledged when using RCIF to discriminate the target material response. [source] Nanostructure and Micromechanical Properties of Silica/Silicon Oxycarbide Porous CompositesJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 11 2004Araceli Flores The microhardness,nanostructure correlation of a series of silica/silicon oxycarbide porous composites has been investigated, as a function of pyrolysis temperature, Tp. The pyrolyzed products have been studied by means of scanning electron microscopy, mercury porosimetry, chemical analysis, solid-state 29Si-NMR, X-ray diffraction, Raman spectroscopy, and microindentation hardness. Two distinct regimes are found for the microhardness behavior with Tp. In the low-temperature regime (1000°C ,Tp < 1300°C), the material response to indentation seems to be dominated by the large amount of pores present in the samples. In this Tp range, low microhardness values, H, are found (<110 MPa). Above Tp= 1300°C, a conspicuous H increase is observed. In this high-temperature regime (Tp= 1300,1500°C), microhardness values are shown to notably increase with increasing pyrolysis temperature. The H behavior at Tp= 1300,1500°C is discussed in terms of (i) the volume fraction of pores and the average pore size, (ii) the bond density of the oxycarbide network, and (iii) the occurrence of a nanocrystalline SiC phase. [source] Friction evaluation of elastomers in lubricated contactLUBRICATION SCIENCE, Issue 10 2009Gregory F. Simmons Abstract Friction testing of elastomers in lubricated contact is discussed with a focus on developing experimental arrangements that can produce worthwhile results. Practical issues unique to elastomers are covered as well as their solutions, including contact mechanics, material response to loading, contact edges, oil absorption, cleaning and specimen geometry. A critique of reciprocating laboratory testing machines, including high-frequency short stroke and low-frequency long stroke friction and wear machines, is conducted for their usefulness, as is critical analysis of a wide variety of specimen configurations with the aim of helping the laboratory experimenter to overcome many of the pitfalls associated with testing of elastomers in lubricated conditions. Results from experiments using various testing arrangements are analysed, and it is found that the synthetic ester and mineral oil used produced similar results. Copyright © 2009 John Wiley & Sons, Ltd. [source] The minimum free energy for incompressible viscoelastic fluidsMATHEMATICAL METHODS IN THE APPLIED SCIENCES, Issue 18 2006Giovambattista Amendola Abstract A general closed expression is given in the frequency domain for the isothermal minimum free energy of an incompressible viscoelastic fluid, whose constitutive equation is expressed by a linear functional of the history of strain. Another equivalent form of the minimum free energy is also derived and used to study the particular case of a discrete model material response. Copyright © 2006 John Wiley & Sons, Ltd. [source] Classes of Anisotropic Finite Plasticity Models and their Implementation in a Brick-Type Shell ElementPROCEEDINGS IN APPLIED MATHEMATICS & MECHANICS, Issue 1 2003N. Apel We discuss two constitutive models formulated in terms of logarithmic strains suitable for the description of elastoplastic material response. We consider two different approaches to the definition of the plastic deformation. The first is based on the introduction of a plastic map yielding a multiplicative decomposition of the deformation gradient into an elastic and plastic part. The second one uses an additive decomposition of the current metric. A quantitative analysis of both approaches by means of numerical examples of sheet metal forming processes are presented. [source] A non-reflecting layer method for non-linear wave-type equations on unbounded domains with applications to shape memory alloy rodsINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 15 2005M. Newman Abstract In this paper a new technique is introduced and applied in solving one-dimensional linear and non-linear wave-type equations on an unbounded spatial domain. This new technique referred to as the non-reflecting layer method (NRLM) extends the computational domain with an artificial layer on which a one-way wave equation is solved. The method will be applied to compute stress waves in long rods consisting of NiTi shape memory alloy material subjected to impact loading and undergoing detwinning and pseudo-elastic material responses. The NRLM has been tested on model problems and it has been found that the computed solutions agree well with the exact solutions, i.e. normalized error levels are in ranges acceptable for engineering computations. Copyright © 2005 John Wiley & Sons, Ltd. [source] | |||||||||||||||||||||||||