Summary

Abaqus contains an extensive library to model the behavior of various engineering materials. It includes models for metal plasticity and rubber elasticity.

The stress-strain data for the metal plasticity model must be defined in terms of true stress and true plastic strain. Nominal stress-strain data can be converted easily into true stress-strain data.

The metal plasticity model in Abaqus assumes incompressible plastic behavior.

For efficiency Abaqus/Explicit regularizes user-defined material curves by fitting them with curves composed of equally spaced points.

The hyperelastic material model in Abaqus/Standard allows true incompressibility. The hyperelastic material model in Abaqus/Explicit does not: the default Poisson's ratio for hyperelastic materials in Abaqus/Explicit is 0.475. Some analyses may require increasing Poisson's ratio to model incompressibility more accurately.

Polynomial, Ogden, Arruda-Boyce, Marlow, van der Waals, Mooney-Rivlin, neo-Hookean, reduced polynomial, and Yeoh strain energy functions are available for rubber elasticity (hyperelasticity). All models allow the material coefficients to be determined directly from experimental test data. The test data must be specified as nominal stress and nominal strain values.

The material evaluation capability in Abaqus/CAE can be used to verify the correlation between the behavior predicted by the hyperelastic material models and experimental test data.

Stability warnings may indicate that a hyperelastic material model is unsuitable for the strain ranges you wish to analyze.

The presence of symmetry can be used to reduce the size of a simulation since only part of the component needs to be modeled. The effect of the rest of the component is represented by applying appropriate boundary conditions.

Mesh design for large-distortion problems is more difficult than for small-displacement problems. The elements in the mesh must not become too distorted at any stage of the analysis.

Volumetric locking can be alleviated by permitting a small amount of compressibility. Care must be taken to ensure that the amount of compressibility introduced into the problem does not grossly affect the overall results.

The X–Y plotting capabilities in Abaqus/CAE allow data in curves to be manipulated to create new curves. Two curves or a curve and a constant can be added, subtracted, multiplied, or divided. Curves can also be differentiated, integrated, and combined.