A theory of porous media and harmonic wave propagation in poroelastic body

2020 ◽  
Vol 85 (1) ◽  
pp. 1-26
Author(s):  
Romulo Brito da Silva ◽  
I-Shih Liu ◽  
Mauro Antonio Rincon
Keyword(s):  
Soil Mechanics ◽  
Harmonic Wave ◽  
Mixture Theory ◽  
Material Model ◽  
Nonlinear Material ◽  
Inertial Effect ◽  
Attenuation Coefficients ◽  
Poroelastic Media ◽  
Solid Constituent ◽  
Constituent Phase

Abstract The present work is based on a mixture theory of poroelastic media which is consistent with the classical Darcy’s law and uplift force in soil mechanics. In addition, it also results in having an inertial effect on the motion of solid constituent as commonly expected, in contrast to Biot’s theory, where relative acceleration is introduced as an interactive force between solid and fluid constituents to account for the apparent inertial effect. The propagation of plane harmonic waves in homogeneously deformed region is considered. For different poroelastic models with either incompressible solid or incompressible fluid constituent, phase speeds and attenuation coefficients are analysed and numerically determined with convenient data from a nonlinear material model for comparison with some available results in the literature.

On Identification of Material Models When Nonrepeatability of Test Data is Present: Application to Textile Composites

2004 ◽  
Vol 126 (4) ◽  
pp. 443-449 ◽  
Author(s):  
Abbas S. Milani ◽  
James A. Nemes
Keyword(s):  
Test Data ◽  
Standard Form ◽  
Model Identification ◽  
Material Model ◽  
Textile Composites ◽  
Nonlinear Material ◽  
Standard Material ◽  
Identification Process ◽  
Qualitative And Quantitative ◽  
Space Transformation

Engineering test data occasionally violate assumptions underlying standard material model identification. Consequently, one has to apply appropriate remedies with respect to each violation to enhance the reliability of identified material parameters. This paper generalizes the use of the signal-to-noise weighting scheme when heteroscedasticity of test data are suspected. Different mathematical and practical aspects of the approach are discussed. Additionally, the ensuing weighted identification process is simplified to an equivalent standard form by means of a space transformation. Finally, the approach is applied to the identification of a nonlinear material model for textile composites, on both qualitative and quantitative levels.

A Finite-Element and Experimental Analysis of Stress Distribution in Various Shear Tests for Solder Joints

1998 ◽  
Vol 120 (1) ◽  
pp. 106-113 ◽  
Author(s):  
T. Reinikainen ◽  
M. Poech ◽  
M. Krumm ◽  
J. Kivilahti
Keyword(s):  
Finite Element ◽  
Stress Distribution ◽  
Low Cycle Fatigue ◽  
Material Model ◽  
Lap Joints ◽  
Optical Measurements ◽  
Nonlinear Material ◽  
Lap Joint ◽  
The Finite Element Method ◽  
Shear Tests

Solder alloys are commonly tested with shear tests to study their mechanical properties or low-cycle fatigue performance. In this work, the suitability of various shear tests for quantitative solder-joint testing is investigated by means of the finite element method. The stress state and stress distribution in the following well known geometries are studied: the double-lap test, the ring and plug test, the losipescu test, and two single-lap tests. A new test geometry, the grooved-lap test, is introduced and compared to the conventional tests. The results of simulations with an elastic material model in plane-strain indicate that considerable differences in the purity of the state of shear (rε = −ε1/ε3) as well as in the stress distribution in the joint exist among the shear tests. However, simulations with a nonlinear material model show that stress inhomogenities are smoothed by the plastic and creep deformation occurring in the joint. Optical measurements of the deformation of real single-lap and grooved-lap joints show that the single-lap joint rotates slightly during creep, whereas in the grooved-lap joint no rotation can be detected. This confirms the simulation results that in the single-lap test the initially nonuniform stress distribution changes during creep, and in the grooved-lap test the uniform stress distribution remains constant through the test.

Nonlinear Material Model in Part Variation Simulations of Sheet Metals

2019 ◽  
Vol 19 (2) ◽  
Author(s):  
Soner Camuz ◽  
Samuel Lorin ◽  
Kristina Wärmefjord ◽  
Rikard Söderberg
Keyword(s):  
Material Model ◽  
Nonlinear Material ◽  
Isotropic Hardening ◽  
Elastoplastic Material ◽  
Processing Unit ◽  
Central Processing ◽  
Physical Experiments ◽  
Linear Relationships ◽  
Influence Coefficients ◽  
Variation Simulation

Current methodologies for variation simulation of compliant sheet metal assemblies and parts are simplified by assuming linear relationships. From the observed physical experiments, it is evident that plastic strains are a source of error that is not captured in the conventional variational simulation methods. This paper presents an adaptation toward an elastoplastic material model with isotropic hardening in the method of influence coefficients (MIC) methodology for variation simulations. The results are presented in two case studies using a benchmark case involving a two-dimensional (2D) quarter symmetric plate with a centered hole, subjected to both uniaxial and biaxial displacement. The adaptation shows a great reduction in central processing unit time with limited effect on the accuracy of the results compared to direct Monte Carlo simulations.

Experiment and Elastic-Plastic Modelling of the IPN160 Beam

2015 ◽  
Vol 769 ◽  
pp. 331-335
Author(s):  
Jakub Vasek ◽  
Oldrich Sucharda
Keyword(s):  
Computational Models ◽  
Plastic Material ◽  
Numerical Models ◽  
Steel Structure ◽  
Material Model ◽  
Nonlinear Material ◽  
Software Application ◽  
Elastic Plastic ◽  
Elastic Plastic Material ◽  
Isoparametric Finite Elements

The paper compares the numerical models of and experiments with a beam. The purpose is to evaluate the nonlinear material model of a steel structure. The steel is modelled as an ideal elastic-plastic material. The FEM and eight-node isoparametric finite elements are considered in the analysis. The 3D calculations use different material constants and several approaches are being tested in order to create the computational models. The calculations are performed in the software application developed by our university.

Nonlinear Behaviour of Concrete Foundation Slab

2016 ◽  
Vol 821 ◽  
pp. 495-502
Author(s):  
Josef Fiedler ◽  
Tomáš Koudelka
Keyword(s):  
Finite Element Method ◽  
Concrete Slab ◽  
Material Model ◽  
Nonlinear Material ◽  
Nonlinear Behaviour ◽  
Plastic Yielding ◽  
The Finite Element Method ◽  
Foundation Slab ◽  
Subsoil Model ◽  
Concrete Computation

A layered model is used for nonlinear analysis of a foundation concrete slab. Calculation is performed using interaction with elastic Winkler-Pasternak subsoil model and considering plastic yielding of slab layers. Two Drucker-Prager yield criterions define a nonlinear material model for concrete. Computation is done by the SIFEL solver using the Finite Element Method.

Analysis of Buffering Properties of Honeycomb Material

2012 ◽  
Vol 482-484 ◽  
pp. 1146-1149
Author(s):  
Ming Bo Yang ◽  
Jin Bao Chen ◽  
Fei Deng ◽  
Meng Chen
Keyword(s):  
Theoretical Analysis ◽  
Material Properties ◽  
Orthotropic Material ◽  
Soil Mechanics ◽  
Material Model ◽  
Lunar Soil ◽  
Equivalent Material ◽  
User Material Model ◽  
Honeycomb Material ◽  
Equivalent Material Properties

The buffering properties of honeycomb material are analyzed in the presented work. Theoretical analysis based on energy method is first presented, the buffering process of honeycomb material can be divided into three phases, honeycomb material can be equivalent to orthotropic material and the equivalent material properties are given. Being good at soil mechanics, Abaqus can simulate lunar soil very well. Using a constitutive model for honeycomb material, which is a built-in user material model, the presented work developed a honeycomb material simulation model and verified with a practical example. Now we can analysis the entire landing buffer process in Abaqus, which is a complement to existing analysis processes.

Buckling of Rectangular Cross-Ply Laminated Plates With Nonlinear Stress-Strain Behavior

1979 ◽  
Vol 46 (3) ◽  
pp. 637-643 ◽  
Author(s):  
Harold S. Morgan ◽  
Robert M. Jones
Keyword(s):  
Strain Curve ◽  
Material Model ◽  
Laminated Plates ◽  
Nonlinear Material ◽  
Stress Strain ◽  
Buckling Loads ◽  
Strain Behavior ◽  
Reinforced Composite ◽  
Nonlinear Stress ◽  
Behavior Characteristic

The Jones-Nelson-Morgan nonlinear material model is used in the derivation of a buckling criterion for laminated plates with nonlinear stress-strain behavior characteristic of many fiber-reinforced composite materials. A search procedure is developed to solve this buckling criterion which is transcendental because of interdependence of the buckling load and the coefficients relating the variations in laminate forces and moments to the variations in strains and curvatures. The effect of stress-strain curve nonlinearities on laminate buckling loads is illustrated by comparing solutions of the buckling criterion to buckling loads for laminates with linear stress-strain behavior.

scholarly journals Elastography Method for Reconstruction of Nonlinear Breast Tissue Properties

2009 ◽  
Vol 2009 ◽  
pp. 1-9 ◽  
Author(s):  
Z. G. Wang ◽  
Y. Liu ◽  
G. Wang ◽  
L. Z. Sun
Keyword(s):  
Breast Tissue ◽  
Three Dimensional ◽  
Material Model ◽  
Nonlinear Material ◽  
Fatty Tissue ◽  
Nonlinear Method ◽  
Tissue Properties ◽  
Breast Cancer Study ◽  
Breast Phantom ◽  
The Difference

Elastography is developed as a quantitative approach to imaging linear elastic properties of tissues to detect suspicious tumors. In this paper a nonlinear elastography method is introduced for reconstruction of complex breast tissue properties. The elastic parameters are estimated by optimally minimizing the difference between the computed forces and experimental measures. A nonlinear adjoint method is derived to calculate the gradient of the objective function, which significantly enhances the numerical efficiency and stability. Simulations are conducted on a three-dimensional heterogeneous breast phantom extracting from real imaging including fatty tissue, glandular tissue, and tumors. An exponential-form of nonlinear material model is applied. The effect of noise is taken into account. Results demonstrate that the proposed nonlinear method opens the door toward nonlinear elastography and provides guidelines for future development and clinical application in breast cancer study.

scholarly journals Nonlinear Material Model for Quasi-Unidirectional Woven Composite Accounting for Viscoelastic, Viscous Deformation, and Stiffness Reduction

Polymers ◽  
2018 ◽  
Vol 10 (8) ◽  
pp. 903 ◽  
Author(s):  
Zhanyu Zhai ◽  
Bingyan Jiang ◽  
Dietmar Drummer
Keyword(s):  
Material Model ◽  
Tensile Tests ◽  
Experimental Results ◽  
Nonlinear Material ◽  
Weibull Function ◽  
Viscous Deformation ◽  
Stiffness Reduction ◽  
Viscoelastic Strain ◽  
Proposed Model ◽  
The Individual

To clarify the individual contribution of viscoelastic and viscous deformation to the global nonlinear response of composites, multilevel cyclic loading-unloading recovery tensile tests were carried out. The experimental results show that there is a linear relationship between the viscous strain and viscoelastic strain of composites, regardless of the off-axis angle or loading stress level. On the basis of experimental results, a coupled damage-plasticity constitutive model was proposed. In this model, the plasticity theory was adopted to assess the evolution of viscous strains. The viscoelastic strain was represented as a linear function of viscous strains. Moreover, the Weibull function of the effective stress was introduced to evaluate the damage variables in terms of stiffness reduction. The tensile stress-strain curves, predicted by the proposed model, showed a good agreement with experimental results.

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