Advanced composite strength and damage models are available in the Explicit Dynamics solver. The Orthotropic Strength Model forms part of this capability and is usually used in combination with an orthotropic equation of state.
For orthotropic materials, the yield surface is defined by the following function:
 | (11–3) |
There are constraints on the values of Aij to ensure a valid yield surface is defined. To express these constraints, the matrices E and e are defined as follows:
 | (11–4) |
Then the constraints expressed in terms of the Aij coefficients and e and E are:
> 0Det E < 0
Non-zero eigenvalues of e must all have the same sign
The constraints for valid yield surface definition are automatically checked upon definition of the yield function.
Full details of the model are found here in the Autodyn Composite Modeling Guide. This provides further information on the available modeling techniques and how to obtain/fit material data to the models.
For full details of the original model development and characterization work, see this reference: 12.
The list of input parameters is summarized below:
| Parameter | Description |
|---|---|
| STRENGTH MODEL : Orthotropic Strength | |
 | Plasticity parameter |
 | Plasticity parameter |
 | Plasticity parameter |
 | Plasticity parameter |
 | Plasticity parameter |
 | Plasticity parameter |
 | Plasticity parameter |
 | Plasticity parameter |
 | Plasticity parameter |
| Eff. Stress #1 | Master curve definition |
| Eff. Stress #2 | Master curve definition |
| Eff. Stress #3 | Master curve definition |
| Eff. Stress #4 | Master curve definition |
| Eff. Stress #5 | Master curve definition |
| Eff. Stress #6 | Master curve definition |
| Eff. Stress #7 | Master curve definition |
| Eff. Stress #8 | Master curve definition |
| Eff. Stress #9 | Master curve definition |
| Eff. Stress #10 | Master curve definition |
| Eff. Plastic Strain #1 | Master curve definition |
| Eff. Plastic Strain #2 | Master curve definition |
| Eff. Plastic Strain #3 | Master curve definition |
| Eff. Plastic Strain #4 | Master curve definition |
| Eff. Plastic Strain #5 | Master curve definition |
| Eff. Plastic Strain #6 | Master curve definition |
| Eff. Plastic Strain #7 | Master curve definition |
| Eff. Plastic Strain #8 | Master curve definition |
| Eff. Plastic Strain #9 | Master curve definition |
| Eff. Plastic Strain #10 | Master curve definition |