ANSYS120官方培训教程 Explicit_Dynamics_Chapter 9_Material_Models.pptVIP

Material Behavior Under Dynamic Loading In general, materials have a complex response to dynamic loading The following phenomena may need to be modelled Non-linear pressure response Strain hardening Strain rate hardening Thermal softening Compaction (porous materials) Orthotropic behavior (e.g. composites) Crushing damage (e.g. ceramics, glass, geological materials, concrete) Chemical energy deposition (e.g. explosives) Tensile failure Phase changes (solid-liquid-gas) No single material model incorporates all of these effects Engineering Data offers a selection of models from which you can choose based on the material(s) present in your simulation Modeling Provided By Engineering Data Material Deformation Material deformation can be split into two independent parts Volumetric Response - changes in volume (pressure) Equation of state (EOS) Deviatoric Response - changes in shape Strength model Also, it is often necessary to specify a Failure model as materials can only sustain limited amount of stress / deformation before they break / crack / cavitate (fluids). Principal Stresses A stress state in 3D can be described by a tensor with six stress components Components depend on the orientation of the coordinate system used. The stress tensor itself is a physical quantity Independent of the coordinate system used When the coordinate system is chosen to coincide with the eigenvectors of the stress tensor, the stress tensor is represented by a diagonal matrix where σ1, σ2 , and σ3, are the principal stresses (eigenvalues). The principal stresses may be combined to form the first, second and third stress invariants, respectively. Because of its simplicity, working and thinking in the principal coordinate system is often used in the formulation of material models. Elastic Response Non-linear Response Models Available for Explicit Dynamics Elastic Constants Physical and Thermal Properties Density All material must have a valid density defined for Expli