Material Models

Numerous material models are available in NairnMPM and OSParticulas.

Define a Material

You create materials using a Material command block. Within that block all material properties are set using property commands. Refer to each material type to learn about its possible properties.

Linear Elastic Small Strain Materials

The materials in this section are all small-strain, linear elastic materials. They account for rotations by using a hypoelastic correction based on the Jaumann Derivative.

Name	ID	Description	Pσ	Pε	AS	3D
Isotropic	1	Linear elastic, isotropic	X	X	X	X
Transverse 1	2	Linear elastic, transversely isotropic with unique axis in the z direction	X	X	X	X
Transverse 2	3	Linear elastic, transversely isotropic with unique axis in the y direction	X	X	X	X
Orthotropic	4	Linear elastic, orthotopic material	X	X	X	X
Bistable	10	Elastic, isotropic material with two stable states having different properties	X	X	X

The table columns on the right indicate if each material can be used in plane stress (Pσ), plane strain (Pε), axisymmetric (AS), or 3D calculations.

Hyperelastic Materials

The materials in this section are all large-strain, elastic materials. They account for rotations based on a hyperelastic formulation.

Name	ID	Description	Pσ	Pε	AS	3D
Mooney	8	Elastic, isotropic and Ideal Rubber Elasticity	X	X	X	X
IdealGas	22	Ideal gas as hyperelastic material		X	X	X

The table columns on the right indicate if each material can be used in plane stress (Pσ), plane strain (Pε), axisymmetric (AS), or 3D calculations.

Elastic-Plastic Small Strain Materials

The materials in this section are all small-strain, elastic-plastic materials materials. They account for rotations by using a hypoelastic correction based on the Jaumann Derivative. They handle plasticity by combining one of these materials with any compatible hardening law.

Name	ID	Description	Pσ	Pε	AS	3D
IsoPlasticity	9	Small-strain, isotropic, elastic-plastic material	X	X	X	X
MGEOSMaterial	17	Small-strain, isotropic, elastic-plastic material using a Mie-Grüneisen equation of state.	X	X	X	X
HillPlastic	15	Anisotropic, elastic-plastic material.		X	X	X

The table columns on the right indicate if each material can be used in plane stress (Pσ), plane strain (Pε), axisymmetric (AS), or 3D calculations.

Hyperelastic-Plastic Materials

The materials in this section are designed to solve problems in finite strains; they are formulated within the framework of hyper elasticity formulation. They can handle plasticity by combining one of these materials with any compatible Hardening Laws.

Name	ID	Description	Pσ	Pε	AS	2M	3D
HEIsotropic	24	Isotropic, hyperelastic-plastic material		X	X		X
HEMGEOSMaterial	25	Isotropic, hyperelastic-plastic material using a Mie-Grüneisen equation of state.		X	X		X
HEAnisotropic	21	Anisotropic, hyperelastic material				X

The table columns on the right indicate if each material can be used in plane stress (Pσ), plane strain (Pε), axisymmetric (AS), 2D membrane, or 3D calculations.

Viscoelastic Materials

The materials in this section are viscoelastic materials materials.

Name	ID	Description	Pσ	Pε	AS	3D
Viscoelastic	6	Small-strain, linear viscoelastic material with sum of relaxation times	X	X	X	X

The table columns on the right indicate if each material can be used in plane stress (Pσ), plane strain (Pε), axisymmetric (AS), or 3D calculations.

Material Class Hierarchy

Materials are C++ classes. The following class hierarchy shows the orginzation of those C++ classes in NairnMPM and OSParticulas codes. A material in green is an abstract class that is never assigned to particles. All others are material classes (by their name and their ID in parentheses):

• MaterialBase
  • Elastic
    • Isotropic (1)
      • IsoPlasticity (9)
        • MGEOSMaterial (17)
      • Bistable (10)
    • Transverse 1 (2) (2.3)
      • Orthotropic (4)
        • AnisoPlasticity
          • HillPlastic (15)
            • WOODMATERIAL (19)
  • HyperElastic
    • Mooney (8)
    • HEIsotropic (24)
      • HEMGEOSMaterial (25)
    • HEAnisotropic (21)
    • IdealGas (22)
  • Viscoelastic (7)
  • RIGIDMATERIAL (11)