this project started very open ended. Our professor allowed us to choose any component we wanted to analyze, within reason. Our team decided to simulate and analyze a few parts from a buggy, since they undergo extreme stress. Normally during competition there is little time to do a proper FEA study but this class was after the competition ended. We were able to apply things we learned from competing into the project. We were able to apply this to the next year’s competition as well.
We explored critical structural considerations of the suspension and analyzed on the viability of the components. Failure suspension will result in potentially hazardous situations to the operator of the vehicle as well as other competitors. We had to design a suspension that would not buckle during loading.
The A-Arm is a horizontal member that is attached at one end to the wheel hub assembly and to the frame at the other end. The damper is attached to the lower A-Arm, which provides the resistive motion upon the jounce of the suspension.
First, the loads and stresses are obtained using an analytical approach for a basis of Finite Element calculation. The A-arm is designed to withstand the loads seen by the vehicle in these dynamic situations. The stresses are analyzed statically at theoretical maximum value in order to analyze the element more thoroughly. The force on the system is calculated for a maximum loading situation. We decided the maximum was when the vehicle experiences a 3 foot drop.
For the mesh generation tetrahedral were used. Tetrahedral elements were chosen because of the accuracy gained in using triangular elements on a curved surface. Square elements are preferable in linear strain because the square elements are more closely approximate to square or rectangular stress/strain elements undergoing linear loading. Tetrahedral elements are better to approximate the dimensions of a curve, in this case, a cylindrical tube or beam. This added accuracy, which is important to the results obtained because the strain seen in the elements on a curve varies with position on that curve. Besides, small dimensions for the mesh are required to have more elements in order to be more accurate.
The red represents where most of the load is concentrated and how the stress is distributed along the member. The von Mises stress is much lower than the yield strength and has a safety factor of 2.86.
For part two the designed was refined slightly. The spring was moved closer to wheel. This would result in a better handling while turning
This resulted in a larger stress concentration at wheel connection which was not anticipated. It is still well within an acceptable range. This connection was simulated as a fixed connection when in reality it behaves like a pin connection.
Different loading conditions such as wheel travel were analyzed.
With this project we determined that the most critical condition for the suspension is when the car becomes airborne and lands on the ground.