Performing a Factor of Safety Check

Use the Factor of Safety Wizard to assess the safety of your design.

1. In Step 1 of 3:
   1. Select All, a component or a body in Component.
      When you select All, the stress limit of each component is considered. Factor of Safety is not calculated for components that have no stress limit defined. Such components are grayed out in the Factor of Safety plots.
   2. In Criterion , select a failure criterion from the list or Automatic.
      See Failure Criteria for more information.
      When you select Automatic, the software applies these conditions:

      • The default Failure Criterion assigned in the Material dialog box for each material.
      • If you have not assigned a default failure criterion in the Material dialog box, the software assigns the Mohr-Coulomb stress criterion.
      • If you selected Max von Mises or Max shear (Tresca) criterion for a beam material, the software uses the yield strength as allowable stress.
      • If you selected Max normal or Mohr-Coulomb criterion for a beam material, the software uses the tensile strength as the allowable stress.
      • For composite shells, the Tsai-Hill failure criterion is applied when Automatic is selected.
      The What does this mean area shows the mathematical statement of the criterion you select.
   3. Under Property, type a custom title for the plot in Include title text.
      You can select predefined view orientation to associate with the active plot in Associate plot with name view orientation.
2. In Step 2 of 3:
   • For the Max shear stress (Tresca), Max von Mises stress, Max normal stress criteria, and Mohr-Coulomb criteria:
     • Select stress Units.
     • Under Set stress limit to, select one of the following options:

       Option	Description
       Yield strength	Sets the limit stress to the yield strength of the material.
       Ultimate strength	Sets the limit stress to the ultimate strength of the material.
       User defined	Type a value for the limit stress.

       For the Mohr-Coulomb stress criterion only, you need to set both tensile and compressive stress limits.
     • Under Multiplication factor, enter the factor to multiply the stress limit with. Default value is 1.0.

     The Material involved box shows the material of the selected component and the associated yield and ultimate strengths. The Max stress in the model box shows the maximum stress in the model.

   • For Composite Options select one of the following:

     Option	Description
     Worst-case across all plies	For an envelope plot of factor of safety (lowest value across top and bottom faces of all plies).
     Ply number, and select Top or Bottom face for that ply number.

3. In Step 3 of 3, select one of the following:

   Option	Description
   Factor of Safety distribution	To plot the distribution of the factor of safety. Areas of the FOS plot with values larger than 100 are shown with the color of the 100 value. If the maximum FOS value is less than 100, then the chart is scaled from the minimum to the maximum FOS value.
   Areas below factor of safety	To view the areas of the model with factor of safety less than the specified value. When selecting Areas below factor of safety, the software displays regions of the model with factors of safety less than the specified value in red (unsafe regions) and regions with higher factors of safety in blue (safe regions).

   The Safety result box shows the minimum factor of safety based on the selected criterion.
4. Click .