16.1.1 Material library: overview

This chapter describes how to define materials in ABAQUS and contains brief descriptions of each of the material behaviors provided. Further details of the more advanced behaviors are provided in the ABAQUS Theory Manual.

Defining materials

Materials are defined by:

selecting material behaviors and defining them (“Material data definition,” Section 16.1.2); and
combining complementary material behaviors such as elasticity and plasticity (“Combining material behaviors,” Section 16.1.3).

A local coordinate system can be used for material calculations (“Orientations,” Section 2.2.5). Any anisotropic properties must be given in this local system.

Available material behaviors

The material library in ABAQUS is intended to provide comprehensive coverage of both linear and nonlinear, isotropic and anisotropic material behaviors. The use of numerical integration in the elements, including numerical integration across the cross-sections of shells and beams, provides the flexibility to analyze the most complex composite structures.

Material behaviors fall into the following general categories:

general properties (material damping, density, thermal expansion);
elastic mechanical properties;
inelastic mechanical properties;
thermal properties;
acoustic properties;
hydrostatic fluid properties;
equations of state;
mass diffusion properties;
electrical properties; and
pore fluid flow properties.

Some of the mechanical behaviors offered are mutually exclusive: such behaviors cannot appear together in a single material definition. Some behaviors require the presence of other behaviors; for example, plasticity requires linear elasticity. Such requirements are discussed at the end of each material behavior description, as well as in “Combining material behaviors,” Section 16.1.3.

Using material behaviors with various element types

There are no general restrictions on the use of particular material behaviors with solid, shell, and beam elements. Any combination that makes sense is acceptable. The few restrictions that do exist are mentioned when that particular behavior is described in the pages that follow. A section on the elements available for use with a material behavior appears at the end of each material behavior description.

Using complete material definitions

A material definition can include behaviors that are not meaningful for the elements or analysis in which the material is being used. Such behaviors will be ignored. For example, a material definition can include heat transfer properties (conductivity, specific heat) as well as stress-strain properties (elastic moduli, yield stress, etc). When this material definition is used with uncoupled stress/displacement elements, the heat transfer properties are ignored by ABAQUS; when it is used with heat transfer elements, the mechanical strength properties are ignored. This capability allows you to develop complete material definitions and use them in any analysis.