Material Models

A wide collection of materials is encountered in stress analysis problems, and for any one of these materials a range of constitutive models is available to describe the material's behavior. For example, a component made from a standard structural steel can be modeled as an isotropic, linear elastic, material with no temperature dependence. This simple material model would probably suffice for routine design. However, if the component might be subjected to a severe overload, it is important to determine how it might deform under that load and if it has sufficient ductility to withstand the overload without catastrophic failure.

We can broadly classify the material behaviors of interest as follows:

• Materials that exhibit almost purely elastic response, possibly with some energy dissipation during rapid loading by viscoelastic response (such as rubber or solid propellant elastomers)
• Materials that yield and exhibit considerable ductility beyond yield (such as mild steel and other commonly used metals, ice at low strain rates, and clay)
• Materials that flow by rearrangement of particles that interact generally through some dominantly frictional mechanism (such as sand)
• Materials that break without any significant deformation and absorb little energy prior to fracture (such as rocks, concrete, ceramics, glass)