Clemson FSAE - 2019-2020 Architecture and Frame
During my time at Clemson University, I had the opportunity to lead the development of the vehicle architecture, frame, and human interface devices (HID). Shown below are highlights from the 2019-2020 vehicle’s architecture and frame development.
As Lead Chassis Engineer, I led the development of the architecture following through to the design and manufacturing of the frame and HID ergonomic components. These projects allowed me to apply my engineering knowledge in a collaborative environment, to hands-on design projects from ideation to completion.
This project allowed me to work closely and train incoming team members for the role of Lead Chassis Engineer as I moved on to finish my Master’s Thesis. Through these experiences I was able to grow as a team member, leader, and engineer.
Clemson FSAE - Chassis Tolerance Study
This design project aimed to address the largest bottleneck in the vehicle’s production, in the manufacturing the frame. Unnecessarily tight tolerances greatly increased manufacturing time without adequate validation for their selection. Additionally, bending through the control arm links in both models and physical testing was identified leading to an investigation of the chassis tolerances as a package. Quantification of tolerancing was approached in the following aspects:
Tolerance stack-up and its affects on packaging and rules compliance
Tolerance affects on loading through the suspension and frame
Tolerance affects on kinematic performance (in progress)
The first approach used spreadsheets to identify sub-system interactions and tolerance stacking through the frame and suspension. This following spreadsheets highlight some of the approaches to quantification while doubling as a BoM and cutlist for the space frame and suspension links.
The second approach implemented optimization to identify which tolerances had the largest impact on loading through the chassis. This was approached by optimizing the chassis for tolerance errors that results in a ‘worst-case’ scenario for loading and stress in the chassis. This allows us to identify the sensitivity of the chassis nodes for tolerance error (direction and magnitude). We can then select tolerances for the most sensitive nodes that keep the structure within allowable loading specifications.
First, a parametric CAD model of a quarter car was developed with variables for the X,Y,Z coordinates of all chassis / suspension nodes. These were allowed to vary up to +/- 0.100” in each axis by the optimizer. The Tcl/Tk FEA script used in the frame development was then updated for the quarter-car model. Each of the suspension’s joints were modeled in full degrees of freedom with 1D infinitely rigid elements modeling suspension rocker and fastener hardware. Peak stress and displacement of the suspension link nodes was outputted by the FEA script for optimization. A post-processing Matlab node was used to then calculate suspension link bending using the outputted control arm node and midpoint displacements.
Finally, the process was automated through modeFRONTIER, post-processing results through modeFRONTIER and excel for analysis. This optimization maximized both peak stress and suspension link bending displacement using modeFORNTIER’s MOGA-II genetic algorithm. This allowed us to identify ‘worst-case’ tolerance scenarios, specify appropriate tolerances accordingly, and propose solutions to poor loading conditions identified (control arm bending, etc.).
Clemson FSAE - Front Wing Mounting
This design project highlights many of the practical aspects of FSAE, from problem solving to physical validation. In this design project, I lead the re-design and validation of a front wing mounting solution to meet crashworthiness targets in conjunction with the front impact foam / crash structure as well as reliability targets. This project allowed the implementation of topology optimization, energy absorption calculations, physical testing of energy absorption, and validation of models for composite components.
Crashworthiness in frontal collisions and reliability were the driving design requirements for the project. Energy absorption targets set by the front impact structure require only the mounting bolts to fail within a range of allowable forces. Reliability of the surrounding components then must exceed these loading and operating conditions while remaining light weight. Lastly, simple shear, tube-buckling, and mass calculations were used to meet the design targets. This presented a challenging engineering exercise for the chassis and aerodynamic teams to overcome together.
