Materials
Use the tool to view, add, and edit the material properties that are used for NLFE bodies.
Create and Edit Materials

From the Model menu, select from the dropdown menu.
The Material Properties dialog opens.
 Select an elasticity type from the leftmost dropdown menu.

Select a material from the Material list and review its properties.
CAUTION: For your convenience, a set of materials are provided by default. The values of the properties provided are generic in nature, and might not be appropriate for the actual problem or material you intend to use with it. It is advised these materials be used with caution and that you obtain more accurate material properties.
 Optional:
Edit the material's elastic strain limit by entering a value in the
corresponding field.
Note: For NLFE bodies, MotionSolve will provide warning whenever the strain in the body crosses this specified limit. You can also disable a material's elastic strain limit but deactivating the check box next to the field.

Add a new material property.
 Select the desired elasticity type.
 Click the Add button to bring up the Add a Material Property dialog.
 Specify a label for the material property.
 Specify a variable name for the material property.
 Select a preexisting material to use as a source for the new material's values or select New.
Tip: Delete any material property that was added by selecting that property and clicking Delete. 
Edit the material property.
 Click Close to exit the dialog.
Hyper Elastic Materials Overview
For hyper elastic materials, different constitutive material models are supported, such as: NeoHookean (both compressible and incompressible), MooneyRivlin, and Yeoh models that are used to model a hyper elastic NLFE Body.
Hyper elastic materials can undergo large deformations with a nonlinear stress strain relationship.
The constitutive models for hyper elastic materials are characterized using the strain energy density function.
Type  Equation  Description 

NeoHookean Compressible  $U=\frac{\mu}{2}({I}_{1}3)\mu \mathrm{ln}J+\frac{\lambda}{2}{(\mathrm{ln}J)}^{2}$  U  Strain Energy density function μ  Shear modulus ${I}_{1}{r}_{x}^{T}{r}_{x}+{r}_{y}^{T}{r}_{y}+{r}_{z}^{T}r{}_{z}$  rx, ry, and rz are the gradients of NLFE grids $\lambda =\frac{2\mu v}{12v}$ , is called the 2nd Lame's constant, v is the Poisson's ratio $J=\mathrm{det}(J)={r}_{x}^{T}({r}_{y}\times {r}_{z})$ 
NeoHookean Incompressible  $U=\frac{\mu}{2}({\overline{I}}_{1}3)+\frac{k}{2}{(J1)}^{2}$ 
${\overline{I}}_{1}={J}^{\frac{2}{3}}{I}_{1}$
$k=\frac{2\mu (1+v)}{3(12v)}$ , bulk modulus 
MooneyRivlin  $U={\mu}_{10}(\overline{I}{}_{1}3)+{\mu}_{01}({\overline{I}}_{2}3)+\frac{k}{2}{(J1)}^{2}$  μ_{01} and μ_{10} are material constants ${\overline{I}}_{2}={J}^{\frac{4}{3}}{I}_{2}$ ${\overline{I}}_{2}=\frac{1}{2}\left({\left(tr\left(C\right)\right)}^{2}\left(tr\left({C}^{2}\right)\right)\right)$ , where C is the CauchyGreen deformation tensor $C={J}^{T}J$ $J=\left[{r}_{x}{r}_{y}{r}_{z}\right]$ ${r}_{x}{r}_{y}{r}_{z}$ are the gradient vectors 
Yeoh  $U={C}_{10}({\overline{I}}_{1}3)+{C}_{20}{({\overline{I}}_{1}3)}^{2}+{C}_{30}{({\overline{I}}_{1}3)}^{3}+\frac{k}{2}{(J1)}^{2}$  C_{10}, C_{20}, and C_{30} are material constants 
The material constants for these models have to be derived through testing, such as: uniaxial, bending, and shear tests.