Fastener and Hole Constraints

Inspire provides the ability to constrain the load in fasteners and cylindrical hole supports to achieve improved load distribution in a structure.

Evenly distributing or limiting the maximum force in all bolts, screws, cylindrical hole supports, and other connections in a structure is a common aim of good design practice. When structures become complex in shape or loading, it can be difficult to achieve this objective. One approach is to use topology optimization to redistribute material away from direct load paths so that underutilized fasteners carry more of the applied load. This can be done by setting optimization properties in the Property Editor.

Figure 1. Optimization Properties

Optimization Properties

Following is a list of fastener optimization properties and the types of objects to which they apply (indicated in parentheses). Press F3 to open the Property Editor.

Enable (fasteners, cylindrical hole supports)
Select to enable optimization of the selected fasteners or cylindrical hole supports.
Autocalculate Allowable Forces (fasteners, cylindrical hole supports)
Deselect this value to manually enter the allowable axial and shear forces.
Allowable Axial Force (fasteners, cylindrical hole supports)

Based on the yield stress and the area of the hole Inspire automatically determines the maximum stress allowed for the fastener or cylindrical hole support. Deselect Autocalculate Allowable Forces to enable manually entry of the Allowable Axial Force.

Allowable Shear Forces (fasteners, cylindrical hole supports)

Inspire automatically determines the maximum force allowed for the fastener or cylindrical hole support. Deselect Autocalculate Allowable Forces to enable manual entry of the Allowable Shear Force.

  • In many structures, loads are not uniformly applied and geometry is often non-symmetric. This can lead to large variations in the forces that the fasteners and connection points carry.
  • Changing the topology of the structure will change the amount of load in each fastener.
  • By limiting the maximum load in a fastener or set of fasteners, the topology generated by Inspire can be more evenly distribute the resultant forces, reducing the maximum stresses and a helping torque retention.