# Modeled Bolt Preloads in SOLIDWORKS Simulation

Article by Ryan Dark on May 18, 2015

SOLIDWORKS Simulation is capable of applying theoretical bolt connectors to holes of a model for an FEA analysis. Simulation is also capable of simulating modeled bolts with applied preloads as well. In this article, I show an example of using modeled bolt preloads in SOLIDWORKS Simulation.

## Setup

In this setup, two plates are modeled along with a bolt body and a nut body placed into the position shown in Figure 1. No loads are being used in this example except for loads that will represent the internal forces of the bolt/nut system at their threaded interface.

Figure 1: Cross sectional view of a two plate system with modeled bolt and nut.

## Fixtures

A “Fixed” fixture definition is placed on the edge of the bottom plate far from the bolt hole itself to facilitate observing how the stress distribution propagates through the plates due to the bolt preload as shown in Figure 2.

Figure 2: Fixture placement shown to be on the outside edge face of the bottom plate.

The bolt has a downward axial force applied to it of 10 lbs (an arbitrary axial preload force value). This force is applied specifically to a split line face that partitions off the shank of the bolt that is contacting the nut and where internal forces of a preload would generate.

Figure 3: Bolt force applied to split line face.

The nut, likewise, has a force applied in the upward axial direction on the hole shank face (shown in Figure 4). This force is also 10 lbs. In this way, the bolt and nut both experience a force that will cause a clamping action to plates placed between them.

Figure 4: Nut force applied to hole shank face.

## Contacts

In this example, as all bodies have been modeled with contacting faces, a global contact definition of “No Penetration” is applied in the analysis. This will allow all bodies to slide against one another as the solver converges to the equilibrium. Notably, it will allow the nut to slide down the shank of the bolt to the location of the preload equilibrium.

## Results

Once the analysis has been solved the resulting stress plot (shown in Figure 5) will reflect the internal stresses of a bolt/nut system preloaded to 10 lbs. Additionally, the stress distribution of the plates themselves around the hole will be less susceptible to form stress concentrations.

Figure 5: Stress plot showing internal stresses of a modeled bolt due to preload.

## More SOLIDWORKS Simulation Tips & Tricks

A Guide for Using Bearing Connectors in SOLIDWORKS Simulation