Solidworks FEA under various loading conditions
Wooden Squat Rack
- Structural and FEA of a wooden squat rack with real world testing
Loading Analysis
How much weight?
The first critical step involved establishing realistic loading conditions that the squat rack would experience during use. Dynamic loading was calculated using the fundamental relationship F = m*v/Δt, where rapid movements during exercises can generate forces 4-5 times body weight. For a 220-pound user, this translates to potential loads of 880-1100 pounds during dynamic movements such as kipping pull-ups or explosive exercises.
Multiple loading scenarios were systematically analyzed including static hanging (1x body weight at 220 lbs), controlled pull-ups (2x body weight at 440 lbs), dynamic movements (3x body weight at 660 lbs), and extreme gymnastic-level movements (4x body weight at 880 lbs). Additionally, front rack loading was evaluated with 800 pounds distributed across the rack (400 pounds per side), representing heavy barbell storage or squatting scenarios.
The analysis also considered uneven ground conditions to model real-world installation scenarios where the rack might not be perfectly level. This required modeling the additional stresses that would occur from uneven fixture mounting and angular loading conditions, ensuring the design would perform safely even under less-than-ideal installation circumstances.
Design Process and Methods
Hardware Creation
Hardware Creation
Hardware Creation
Prefab hardware was carefully modeled in SolidWorks to ensure accurate dimensions and materials. Simpson Strong Ties, Brackets, screws, nuts and bolts were all researched and modeled to industry standards.
Part Creation
Hardware Creation
Hardware Creation
Lumber, Nuts and Bolts, Simpson Strong Ties, Screws, and brackets were created as Separate parts in SolidWorks. Additionally, the uneven ground that would serve as foundation was modeled.
Assembly
Hardware Creation
Initial Load Analysis
All the parts were mated, and a static simulation was created. The area below the hardpack ground created a fixed restraint, as did the preexisting structure. Bolts and nuts were preloaded with torque, and connections between fasteners was established. Contact points were assigned anywhere two parts met. A Curvature based mesh was created
Initial Load Analysis
Initial Load Analysis
Initial Load Analysis
The initial loading was a static 220 lb person hanging from the steel bar. The bolts and nuts attaching the new build to the preexisting build were experiencing stress and deformation that was unacceptable and seemed unnatural.
Adding Washers
Initial Load Analysis
Adding Washers
The moment of the load transferred to the bolts seemed to be the cause. Large washers were created to spread the stress out. Additionally, the mesh was refined around the bolts to prevent unnatural spikes. Bolt tension was re researched and a more appropriate tension was preloaded. Between these steps we got to the correct and acceptable amount of stress on these bolts.
Steel Bar
Initial Load Analysis
Adding Washers
At 220lbs the 3/4 " steel pull up bar was already showing signs that it would fail under fatigue. With the dynamic load of a moving person we would quickly surpass the 1020 steel's yield strength of 350 MPa. A 1 1/4" bar and a 1 1/2 " bar were ran thru the simulations. The best result was with the 1 1/2" bar which would give us a FOS of 8.95 at 440lb (dynamic load of 2x BW) and a FOS of 1.19 at 660 lb's (heavy dynamic load at 3x BW). Since this was built for me, knowing the limitations I could put on the bar this was an acceptable FOS.
Loading Test Cases
Loading Test Cases
Loading Test Cases
A loading case manager ran thru multiple different loading scenarios. The structure was able to hold 800 lbs front loading with ease and the pull up bar could support dynamic bodyweight movements within an acceptable FOS
BOM and sourcing
Loading Test Cases
Loading Test Cases
All parts were established in a BOM. Lumber was sourced and cut and drilled. Fasteners were bought prefabricated. All Parts were installed to specification
Installation
Loading Test Cases
Installation
The Squat Rack and Pull Up station were successfully attached to the existing structure. The have operated normally under many different loading conditions and hardware shows no signs of plastic or major elastic deformation
Results and Performance Analysis
FEA, static and dynamic analysis were a success
Following the successful completion of the FEA analysis, the squat rack was constructed according to the validated design specifications. The final structure incorporated all recommended design changes, including the upgraded 1.5-inch pull-up bar and proper connection hardware with large washers for force distribution.
The construction process validated many of the analysis assumptions, particularly regarding the importance of proper bolt installation and preload. The completed rack has performed as predicted by the analysis, with no signs of excessive deflection or stress concentration under normal use conditions.
Reflection and Lessons Learned
Future uses of computer aided design optimization
This project provided valuable insights into the complexities of structural finite element analysis beyond basic SolidWorks operation. The importance of accurate loading condition determination became evident, as the difference between static and dynamic forces significantly impacts design requirements. Real-world exercise movements can generate forces several times greater than static body weight, requiring careful consideration in safety factor calculations and highlighting the need for comprehensive loading analysis.
The analysis highlighted the critical importance of proper boundary condition modeling and constraint application. Initial simulations with incorrect bolt preload conditions produced misleading results, demonstrating that software proficiency must be combined with engineering judgment and understanding of real-world connection behavior. This experience reinforced the principle that FEA is only as accurate as the assumptions and boundary conditions applied.
Curvature-based mesh refinement in SolidWorks proved crucial for accurate stress prediction, with small changes in mesh density around critical areas producing significant variations in calculated stress levels. This reinforced the importance of convergence studies and conservative analysis approaches when safety is paramount, particularly in areas of geometric complexity such as bolt holes and connection details.
The project also emphasized the value of iterative design improvement, as the initial bar sizing proved inadequate and required upgrading based on analysis results. This demonstrates the cost-effectiveness of thorough analysis before construction, as design modifications are far less expensive than post-construction failures or retrofits. The ability to quickly evaluate design alternatives in SolidWorks enabled rapid optimization of the design.
Perhaps most importantly, the analysis reinforced the distinction between personal use and general public applications in terms of acceptable risk levels and safety factors. While the final design is suitable for informed personal use with understood limitations, commercial applications would require additional safety margins and more conservative design approaches. This project successfully demonstrated how FEA can be used to establish safe operating parameters and design limits for custom engineering applications.