Finite Element Analysis of a Modular Pull-Up Bar
- Designed and modeled a custom modular pull-up bar using SolidWorks to perform FEA.
- Utilized various Bonded Conditions (surface, fixed, bonded) to properly simulate usage
-
Performed a Static Stress simulation that showed a Factor of Safety of 1.4 with little to no deformation under stress
- Performed Mesh Independency Analsyis to ensure simulation is accurate
- Utilized proper Loading Types (Zero-Based Loading) to simulate realistic repeated usage
- Performed Fatigue Analysis that showed longevity in design (26.8k cycles)
Boundary Conditions
The boundary conditions for this setup were as such:
-
The bolts attached to the wall were modeled as fixed, preventing any movement or rotation. This simulates a rigid connection between the support frame and the wall.
-
Welded parts were modeled using bonded contacts, representing rigid connections
-
All other non-welded components used frictional surface-to-surface contacts, allowing compression and limited sliding to simulate being removed from the wall
-
A distributed remote load was applied to the pull-up bar to represent a user's weight. The simulation used a load equivalent to a 250-pound person plus an additional 50 pounds to account for jerk. A remote distributed load provides a more realistic force distribution and reduces stress concentrations.
Mesh Independency Analysis
To ensure that the simulation can be trusted, a mesh independency analysis was performed. An initial curvature based mesh was created and then refined by reducing the element size and increasing the element count. Both meshes predicted the max von Mises stresses, which were then compared. As the deviation between the two was large, another iteration occured. This time the deviation was very small, indicating that the mesh is near or at convergence. Therefore, it can be trusted.
Static Stress Simulation
The final mesh from the independency analysis was used to conduct a static stress simulation. The highest stress concentrations were where load transfer and bending effects were greatest, along the joints and screws. The maximum displacement was 0.0237 inches but only at the ends of the bar which faces the most bending. Overall, this has good stiffness. The Factor of Safety was 1.449 which means it can handle more load than it needs to.
Fatigue Analysis
To test the longevity of the design, a fatigue analysis was conducted. It was set up via Zero Based Cyclic Loading which cycles between max loading and no loading. This is to simulate the forces the pull-up bar might experience during usage. Results showed 26.8k cycles which means that the pull-up bar will last a while, even under the heavy loads it faces.