# Pin/Bolt Safety Check

You can determine if a bolt or a pin in an assembly can safely carry the applied loads, or if it will fail.

The software calculates the bolt strength factor of safety (SF) based on the combined load ratio a connector withstands and compares it with the user-defined factor of safety.

The pass/no-pass check for connectors is available for linear and nonlinear static studies. For nonlinear studies, the software displays the pass/no pass status of all pin and bolt connectors for each solution step.

Ra is the maximum of:
• SF * F / (At * S)
• Pre-load / (At * S)
 SF Bolt strength factor of safety calculated by the software. SF is the unknown of the combined load ratio equation.The factor of safety SF is calculated twice: SF1 is calculated based on the first bulleted value of the axial load ratio Ra and SF2 based on the second value of Ra.If (SF1 * F / (At * S)) > (Pre-load / (At * S)), then the first value of SF1 is considered for the pass/no pass criterion. If (Pre-load / (At * S)) > (SF1 * F / (At * S)), then the second value of SF2 is considered for the pass/no pass criterion. F Axial load calculated by the software At Tensile area Pre-load Bolt pre-load S Strength value of connector's material or grade (could be yield or ultimate tensile strength based on application). This is the user-defined value for Bolt Strength
Bending load ratio, Rb Rb = SF * D * M / (2 * S * I)
 SF Bolt strength factor of safety calculated by the software M Bending moment calculated by the software D Nominal shank diameter S Strength value of connector's material or grade (could be yield or ultimate tensile strength based on application). User-defined value for Bolt Strength.

I =0.25*π*r^4

Shear load ratio, Rs Rs = SF * V / (0.5 * At * S)
 SF Bolt strength factor of safety calculated by the software V Shear load calculated by the software At Tensile area S Strength value of connector's material or grade (could be yield or ultimate tensile strength based on application). User-defined value for Bolt Strength
The factor of 0.5 is applied to the material yield strength (or ultimate tensile strength) to account for the material shear strength. The calculation of the shear load ratio is more accurate when the yield strength of the material is considered. It is a conservative estimate, when the ultimate tensile strength of the material is considered.
Combined load ratio (Ra + Rb)^2 + Rs ^3 <=1

The equation is solved for the unknown bolt strength factor of safety SF.

Pass/ No Pass Safety Check

 Connector pass criterion Calculated bolt strength factor of safety SF > User-defined safety factor Connector no pass criterion Calculated bolt strength factor of safety SF < User-defined safety factor