The University of Western Australia Motorsport team has competed in Formula SAE Australasia since 2001. With the help of ANSYS pervasive engineering simulation solutions, our team has won the event twice, taken the trophy for engineering design four times and collected more than 30 trophies for individual events. As of 2017, we are now partnering with Edith Cowan University Racing, another Western Australian team, in a collaboration known as Australian Formula Collective (AFC).
AFC pursues innovative, lightweight parts in order to reduce both real-world and cost event expenses. These parts, however, can become quite complex, often requiring a mix of solid and shell elements for efficient and accurate simulation. They often contain a multitude of joints and connection types, further complicating simulation. So we have turned to ANSYS’ powerful and rapid finite element analysis (FEA) and computational fluid dynamics (CFD) solutions for the design and analysis of automotive parts.
To design a brake pedalbox for the 2017 AFC Formula SAE internal combustion car, we required a solution that could be manufactured rapidly at minimal expense, while still meeting safety and weight requirements. Sheet metal fabrication from laser-cut 4130 chromoly sheet, along with off-the-shelf Tilton master cylinders, were selected with a focus on performance. Given a worst case loading scenario in excess of 2 kN applied at the pedal face, along with a mixture of joints, bearings, materials and jointing techniques, the team required a robust simulation package that would provide not only rapid, but most importantly, reliable results for the safety-critical braking system.
Because the pedalbox is a mix of thin sheet metal components and thicker machined or cast elements, computation with only solid elements would be impractical (and likely less accurate). Fortunately, ANSYS provides user-friendly support for a mixture of elements within the same simulation.
Our team decided to set up the pedalbox and brake pedal separately. We used ANSYS mesh connections to rapidly model joints within the fabricated (shell element) section of the pedalbox, and modeled the joints between the fabricated pedalbox and the floor/master cylinders with frictional contacts. It was important to model these connections accurately as the master cylinders are intended to be braced together in practice, and contribute significantly to the strength of the finished component. ANSYS provides a means to rapidly model bolted connections by splitting a simplified bolt model based on user input, a facility not afforded so conveniently by competing suites.
Initially, we applied bolt pretensions to the model to generate contact stresses at the interfaces between the components. After these contacts were established the bolted connections were locked with built-in functionality (to reduce computation expense). The worst case loading scenario was then applied, and post-processed into easy-to-interpret plots and illustrations.
The simulation results provided useful insight into the pedalbox design, quickly identifying areas that may be prone to fatigue or failure, this helped us to take preventative measures, such as reinforcement or more thorough post-weld inspection. The absolute worst case loads are considered to be realistic, and at the limit of what a 95th percentile male could produce, and comply with the requirements of the competition brief.
Using ANSYS’ powerful engineering simulation tools, our AFC team is confident that we have produced a part that delivers the best compromise between weight and performance, while meeting or exceeding safety requirements imposed by SAE.