Voigt notation

Abstract: Preface by Jean Lemaitre Chapter 1 Introduction 1.1. Model construction 1.2. Applications to models Chapter 2 General concepts 2.1. Formulation of the constitutive equations 2.2. Principle of virtual power 2.3. Thermodyna~nicso f irreversible processes 2.4. Main class of constitutive equations 2.5. Yield criteria 2.6. Numerical methods for nonlinear equations 2.7. Numerical solution of differential equations 2.8. Finite element Chapter 3 Plasticity and 3D viscoplasticity 3.1. Generality 3.2. Formulation of the constitutive equations 3.3. Flow direction associated to the classical criteria 3.4. Expression of some particular constitutive equations in plasticity 3.5. Flow under prescribed strain rate 3.6. Non-associated plasticity 3.7. Nonlinear hardening 3.8. Some classical extensions 3.9. Hardening and recovery in viscoplasticity 3.10. Multimechanism models 3.1 1. Behaviour of porous materials Chapter 4 Introduction to damage mechanics 4.1. Introduction 4.2. Notions and general concepts 4.3. Damage variables and state laws 4.4. State and dissipative couplings 4.5. Damage deactivation 4.6. Damage evolution laws 4.7. Examples of damage models in brittle materials Chapter 5 Microstructural mechanics 5.1. Characteristic lengths and scales in microstructural mechanics 5.2. Some homogenization techniques 5.3. Application to linear elastic heterogeneous materials 5.4. Some examples. applications and extensions 5.5. Homogenization in thermoelasticity 5.6. Nonlinear homogenization 5.7. Computation of RVE 5.8. Homogenization of coarse grain structures Chapter 6 Finite deformations 6.1. Geometry and kinematics of continuum 6.2. Sthenics and statics of the continuum 6.3. Constitutive laws 6.4. Application: Simple glide 6.5. Finite deformations of generalized continua Chapter 7 Nonlinear structural analysis 7.1. The material object 7.2. Examples of implementations of particular models 7.3. Specificities related to finite elements Chapter 8 Strain localization 8.1. Bifurcation modes in elastoplasticity 8.2. Regularization methods Appendix Notation used A.1. Tensors A.2. Vectors, Matrices A.3. Voigt notation

Abstract: The relationships between the elastic moduli and compliances of transversely isotropic and orthotropic materials, which correspond to different appealing sets of linearly independent fourth-order base tensors used to cast the elastic moduli and compliances tensors, are derived by performing explicit inversions of the involved fourth-order tensors. The deduced sets of elastic constants are related to each other and to common engineering constants expressed in the Voigt notation with respect to the coordinate axes aligned along the directions orthogonal to the planes of material symmetry. The results are applied to a transversely isotropic monocrystalline zinc and an orthotropic human femural bone.

Abstract: In this work, a mathematical modeling of the elastic properties of cubic crystals with centrosymmetry at small scales by means of the Toupin–Mindlin anisotropic first strain gradient elasticity theory is presented. In this framework, two constitutive tensors are involved, a constitutive tensor of fourth-rank of the elastic constants and a constitutive tensor of sixth-rank of the gradient-elastic constants. First, $$3+11$$ material parameters (3 elastic and 11 gradient-elastic constants), 3 characteristic lengths and $$1+6$$ isotropy conditions are derived. The 11 gradient-elastic constants are given in terms of the 11 gradient-elastic constants in Voigt notation. Second, the numerical values of the obtained quantities are computed for four representative cubic materials, namely aluminum (Al), copper (Cu), iron (Fe) and tungsten (W) using an interatomic potential (MEAM). The positive definiteness of the strain energy density is examined leading to 3 necessary and sufficient conditions for the elastic constants and 7 ones for the gradient-elastic constants in Voigt notation. Moreover, 5 lattice relations as well as 8 generalized Cauchy relations for the gradient-elastic constants are derived. Furthermore, using the normalized Voigt notation, a tensor equivalent matrix representation of the two constitutive tensors is given. A generalization of the Voigt average toward the sixth-rank constitutive tensor of the gradient-elastic constants is given in order to determine isotropic gradient-elastic constants. In addition, Mindlin’s isotropic first strain gradient elasticity theory is also considered offering through comparisons a deeper understanding of the influence of the anisotropy in a crystal as well as the increased complexity of the mathematical modeling.

Abstract: We have developed an approximate method to calculate the P-wave phase and group velocities for orthorhombic media. Two forms of analytic approximations for P-wave velocities in orthorhombic media were built by analogy with the five-parameter moveout approximation and the four-parameter velocity approximation for transversely isotropic media, respectively. They are called the generalized moveout approximation (GMA)-type approximation and the Fomel approximation, respectively. We have developed approximations for elastic and acoustic orthorhombic media. We have characterized the elastic orthorhombic media in Voigt notation, and we can describe the acoustic orthorhombic media by introducing the modified Alkhalifah’s notation. Our numerical evaluations indicate that the GMA-type and Fomel approximations are accurate for elastic and acoustic orthorhombic media with strong anisotropy, and the GMA-type approximation is comparable with the approximation recently proposed by Sripanich and Fomel. Potential ...