Stress analysis on the tube space frame chassis was conducted in detail with the MSC Nastran program. The accuracy of the simulation was a major improvement over previous attempts to accurately simulate chassis stiffness in a given development time frame. This software allowed for detailed analysis of weldment nodes, taking into account the bending stresses that occur due to the nature of welding tubes to a common node. Options for boundary conditions and element types are plentiful in the program, allowing for detailed yet organized analysis of several structures for several loading types. The Stress Error Estimator allowed users to check their work and identify areas of concern for calculation accuracy. The final result was a chassis that is stiffer and lighter than all previous chassis.
MSC Adams was utilized for various vehicle dynamics simulations. Suspension hard-points were created in Adams/view from previous models and tested for variations in wheel angles for various motions with Adam/solver and Adams/PPT. A vehicle model was created and tested in the constant radius cornering analysis. The motion of the vehicle as well as loads at the tires during the simulation event provided valuable insight into spring selection and damper settings during the physical testing phase of production. Simulated values resulted in a clear direction of vehicle behavior with a given spring selection that lead to correct spring and anti-roll bar selection for steady-state cornering. Spring selection was verified to provide proper grip balance to the vehicle in the testing phase.
MSC Adams has revealed large potential for improvement of the CPP FSAE simulation program. Adams/view has allowed for high speed construction of the vehicle suspension model. Adams/view proved intuitive enough to utilize modeling skills acquired in other programs. Adams/solver has allowed modeling to move beyond geometry for kinematic and dynamic analysis of the suspension and chassis system, allowing for integrated analysis among behavior previously unavailable.
Future potential simulations include: force-based roll and pitch center analysis of SLA suspension, tire data analysis, steady state and transient roll event analysis. Long term goals will focus on full vehicle model with the addition of tire behavior and model response in specified maneuvering events. Coupled with the current test regimen, theoretical results can be verified with physical testing, following the scientific method.
MSC software has provided the CPP FSAE team with unprecedented opportunity to develop a more refined and reliable vehicle through virtual simulation without increasing finance needed for vehicle development. In previous years, chassis and suspension design has been limited to Solidworks Motion Simulation and stress analysis through the Cosmos add-in. MSC software has greatly improved accuracy for deflection and stress values, reduced design time in suspension kinematics and chassis development and has increased integration between the chassis and suspension systems. This has allowed more time to be focused on manufacturing, and on-track testing.
Cal Poly Pomona FSAE, Christopher Rossi