ANSYS STRUCTURAL: U-Bracket Static Simulation

ANSYS Static Structural: U-Bracket Analysis under Bolt Pretension Load and Fixed Support

Description

In this project, we present a structural simulation of a U-bracket in ANSYS Static Structural.

A bracket is considered a supporting element utilized to connect, mount, or reinforce two separate pieces. Brackets have many applications, widely used in shelving, piping supports, wall mounting, automotive and aerospace structures, and other general mechanical assemblies.

The Brackets are manufactured in several types, such as L-brackets, T-brackets, gusset brackets, and others. For this study, a U-shaped bracket is modeled. The U-bracket is a common type that has high stiffness and is used to straddle or clamp another component between its two arms.

Note that, using bolts and nuts, the two sides of the U-bracket are bolted together. Therefore, the goal of this study is to evaluate the structural response of the U-bracket under the pretension load. In other words, it studies how a bolted clamp behaves when the fastener is tightened.

Methodology

First, we modeled the geometry of the bracket with Design Modeler software. The computational domain corresponds to a single U-bracket. It is constructed from five square faces; each side contains one hole at the center. A horizontal face sits in the middle at the top; from its sides, two vertical faces fold downward; and from the bottom, two horizontal faces extend outward. Also, through the hole in the right-hand vertical face, a cylindrical bolt becomes bolted to the hole in the opposing left-hand vertical face, clamping the two arms together.

Second, we meshed the domain; an unstructured mesh was created, generating about 12,000 elements. Finally, we completed the simulation and calculations with ANSYS Static Structural software.

We considered that the cylindrical bolt is assigned a bolt pretension condition along its axis from the right face toward the left face. It means that the pretension is the clamping preload created when the bolt is tightened, so that it pulls the two vertical arms toward each other. On the other hand, the bottom surfaces of the two outer horizontal faces are defined as fixed supports, representing the bracket being constrained onto a rigid base with no degrees of freedom.

Conclusion

After the calculations, we obtained the contours of total deformation, equivalent strain, and equivalent (von Mises) stress over the bracket. The results are fully consistent with the behavior of a U-bracket under a bolt pretension load.

The total deformation distribution shows that the maximum deflection occurs on the two vertical arms, where these faces are drawn inward toward each other. Also, the top horizontal face between these two arms is also affected by their deformation. Since the two outer faces remain fixed to the base, the bolt pretension load pulls the vertical faces together, and the central top face bends slightly.

The stress distribution shows that the highest stress appears adjacent to the bolt holes in the two vertical faces. This is due to the clamping force being transferred through the holes.