This task gives you detailed formulas of failure criteria you can visualize as postprocessing results using the Generate Image command: 

Failure Criteria for Composite Properties 


If you are in a composite context and the material you refer to is orthotropic (Orthotropic material 2D, Orthotropic material 3D and Fiber material), you can compute failure criteria and visualize them as postprocessing results. Those failure criteria are TsaiHill, TsaiWu, Maximum Failure and Hoffman. You can define the characteristics of orthotropic materials in the Analysis tab of the Properties dialog box. To know more about this dialog box, refer to Modifying Material Physical Properties.
TsaiHill CriterionFor each lamina the TsaiHill failure criterion requires that:
where:
TsaiWu CriterionFor each lamina the TsaiWu failure criterion requires that:
Maximum Failure CriterionThe maximum failure criterion is defined as follows:
Hoffman CriterionThe Hoffman criterion requires that:


If one of the shear stress values (Shear Stress Limit in XY Plane, Shear Stress Limit in YZ Plane
or Shear Stress Limit in XZ Plane) is not defined in the
Properties dialog box, the associated term is neglected in the formula (S_{12}, S_{23}
and S_{13} cannot be null in the formula).
This means that the shear stresses in the XYplane are
neglected. The formula are different depending on the:


Failure Criteria for Isotropic Materials 


If you work with an isotropic material, you can compute failure criteria and visualize them as postprocessing results. Those criteria are Tresca, Tresca Stress and Von Mises. Tresca Stress CriterionThe Tresca stress criterion is defined as follows:
where are the principal stresses. Tresca CriterionThe Tresca criterion requires that:
where Re is the linear elastic limit. Von Mises CriterionThe Von Mises criterion requires that:
where Re is the linear elastic limit. 

