In this blog, we will see how to define materials in Abaqus.
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.
Linear elastic behavior
A linear elastic material model:
- is valid for small elastic strains (normally less than 5%);
- can be isotropic, orthotropic, or fully anisotropic;
- can have properties that depend on temperature and/or other field variables; and
- can be defined with a distribution for solid continuum elements in Abaqus/Standard.
Defining linear elastic material behavior
The total stress is defined from the total elastic strain as
where is the total stress,
is the fourth-order elasticity tensor, and
is the total elastic strain (log strain in finite-strain problems). Do not use the linear elastic material definition when the elastic strains may become large; use a hyperelastic model instead. Even in finite-strain problems the elastic strains should still be small (less than 5%).
Hyperelastic behavior of rubberlike materials
The hyperelastic material model:
- is valid for materials that exhibit instantaneous elastic response up to large strains (such as rubber, solid propellant, or other elastomeric materials); and
- requires that geometric nonlinearity be accounted for during the analysis step, since it is intended for finite-strain applications.
Strain energy potentials
Hyperelastic materials are described in terms of a “strain energy potential,” , which defines the strain energy stored in the material per unit of reference volume (volume in the initial configuration) as a function of the strain at that point in the material. There are several forms of strain energy potentials available in Abaqus to model approximately incompressible isotropic elastomers: the Arruda-Boyce form, the Marlow form, the Mooney-Rivlin form, the neo-Hookean form, the Ogden form, the polynomial form, the reduced polynomial form, the Yeoh form, and the Van der Waals form.
Generally, when data from multiple experimental tests are available (typically, this requires at least uniaxial and equibiaxial test data), the Ogden and Van der Waals forms are more accurate in fitting experimental results. If limited test data are available for calibration, the Arruda-Boyce, Van der Waals, Yeoh, or reduced polynomial forms provide reasonable behavior. When only one set of test data (uniaxial, equibiaxial, or planar test data) is available, the Marlow form is recommended. In this case a strain energy potential is constructed that will reproduce the test data exactly and that will have reasonable behavior in other deformation modes.
📌 To understand more about Hyperelastic materials, please refer to User Assistance.
👉 Please check the below video to understand how to Create a Core Material in 3DEXPERIENCE:
👉 Please check the below video to understand how to Assign a Material in 3DEXPERIENCE:
