Factor of Safety

The Factor of Safety PropertyManager allows you to assess the safety of solid and shell models (sheet metals and surfaces) based on a failure criterion.

Factor of Safety - Step 1 of 3

• Component . For assemblies and multibody parts, select All, or select a component or body from the menu.

• Criterion . Failure criteria:

• • Maximum von Mises stress

  • Maximum shear stress (Tresca)

  • Mohr-Coulomb stress

  • Maximum Normal stress

  • Automatic. Automatically selects the most appropriate failure criterion across all element types. The software applies the following 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.

• What does this mean. Displays the mathematical relation used by the Criterion.

Composite Options

Failure criteria for composites. (Available for models with composite shells only)

Property

• Include title text. Lets you type a custom title for the plot.

• Associate plot with name view orientation. Associates a predefined view orientation with the active plot.

• Next . Goes to the next step.

Factor of Safety - Step 2 of 3

• Units . Sets the stress units.

• Set stress limit. Sets the property used for determining the stress limit:

• • to Yield strength. Sets the stress limit to yield strength.

  • to Ultimate strength. Sets the stress limit to ultimate strength.

  • to User defined. Sets the stress limit to a user-specified value.

If you selected Mohr-Coulomb stress criterion from the previous step, you must set the tensile and compressive stress limits.

• Multiplication factor. Allows you to enter a multiplication factor for calculating the selected stress limit. For example, if you apply a factor of 0.5 to a yield strength stress limit of 2000 psi, Factor of Safety uses 0.5 x 2000 = 1000 psi for the stress limit.

• Beam Results

• Shell Results . Available for shells only. Select the shell face for which you want to perform the Factor of Safety:

• • Top

  • Bottom

  • Minimum

  • Maximum

You should run two checks: one for the top face, and the other for the bottom face.

• Material involved. Displays the material names and properties related to the stress limits used by Factor of Safety.

Composite Options

Available for models with composite shells only.

• Worst-case across all plies. Envelope plot for minimum FOS across all plies (including top and bottom faces of every ply).

• Ply number. Allows you to select the ply number for the factor of safety output. This option is not available when Worst-case across all plies is selected. You can select the top or bottom face for the selected ply number.

• Prev . Returns to the previous step.

• Next . Goes to the next step.

Factor of Safety - Step 3 of 3

• Factor of safety distribution. Plots the distribution of the factor of safety.

• Areas below factor of safety. Plots the regions below the specified factor of safety (displayed in red color). Regions above the specified factor of safety are displayed in blue color.

• Safety result. Lists the minimum factor of safety based on the selected criterion.

• Prev . Returns to the previous step.

Related Topics

To use Factor of Safety