Materials

General information

The definition of materials happens in the section MATERIALS. A material model defines its constitutive behavior, which may consist of several terms; however, there is always one material assigned to each element. This material can be an explicit material definition on its own, or a collection of behaviours consisting of a number of material models to be defined subsequently. The explicit definition of a material model is in general given by a single line of the form

MAT <id> <materialname> <parameters...>

One may also define a material by summation of several potentials.

A collection of material behaviors, on the other hand, looks like this:

MAT <id> <collectionname> NUMMAT <nmaterials> MATIDS <id_1> ... <id_nmaterials> <possibly further parameters>

Here, the terms of the <nmaterial> constitutive behaviors have to follow with their own number, which must correspond to <id_1> ... <id_nmaterials>.

Structural Material Models

A material model in structural mechanics defines the connection between deformation (usually strain) and stress. Many material models are available, including (hyper-)elastic, elasto-plastic, visco-elastic, visco-plastic, and even damage models. If you wish to implement a new material model, this is of course also possible, it is an in-house code after all. You’ll find more information on implementing material models in the material section of the developer guide.

Fluid Material Models

Other Material Models

Coupling Material Models for Various Physics on a Single Discretization

One may use a single (multiphysics) element type for a multiphysics simulation with matching discretizations. However, since each discretization belongs to a single physics representation and can thus only be connected to a single material, the other material has to be connected to the same discretization by cloning the discretization to the other physics.

In 4C, we use a material mapping section, which connects two material models to a single representation. One can see it here in for a simple Thermo-Structure-Interaction problem:

----------------------------------------------------------MATERIALS
MAT 1 MAT_Struct_ThermoStVenantK YOUNGNUM 1 YOUNG 2.1e08 NUE 0.3 DENS 7.85e-06 THEXPANS 1.1e-05 CAPA 6.445 CONDUCT 1031.2 INITTEMP 273.15
MAT 2 MAT_Fourier CONDUCT_PARA_NUM 1 CAPA 6.445 CONDUCT 1031.2
-----------------------------------------------CLONING MATERIAL MAP
SRC_FIELD structure SRC_MAT 1 TAR_FIELD thermo TAR_MAT 2
-------------------------------------------------STRUCTURE ELEMENTS
1 SOLIDSCALAR HEX8 1 2 3 4 5 6 7 8 MAT 1 KINEM nonlinear TECH fbar

Todo

Here we should have a list of the discretizations that can be coupled