Project Description: This five-person project was a half-semester assignment for a in-depth CAD course in Spring 2022. We were given a high-end RC car and tasked with reverse engineering it into a parametric 3D assembly that we were supposed to be able to freely scale via parametric models. We also had to conduct analyses such as reducing the weight of a part with topology optimization, do FEA, do CFD on the shell, and look at motion studies.
Software Used: Siemens NX, Star CCM+
My Role: I was responsible for the front and rear axle/suspension subassemblies. I did topology optimization on one of the suspension arms and compared the new and old strength-to-weight ratios using FEA. I simulated the suspension system going over bumps in the road to demonstrate that parts didn’t collide.
Other Roles: We divided up the components of the car. Someone modeled the wheels, another person took the front bumper, another person took the central chassis, and the final team member recreated the car shell by surface modelling.
Big Wins: This class taught me a ton about advanced CAD/CAE techniques and developed my skills substantially. I think the team overall produced a good-looking representation of our given RC car.
Challenges: We messed up the part links to our design skeleton that controlled parametric scaling, so the final scaling results were pretty wonky in the end.
Key Takeaways: Design skeletons are especially important for parametric assemblies. Collaborating on complex CAD assemblies without any form of PLM is a nightmare.
Here is the render of our team’s full car with and without the surface shell. We were trying to recreate an RC Corvette Stingray:
We were supposed to implement design skeletons to facilitate parts scaling parametrically. Since I had the full front and rear suspension subsystems, I had to make my own skeleton responsible for that level. I sketched over a picture of the real part to help plan the connection points and how I’d be constraining the joints in the skeleton. Below is an image of these points on our key reference planes. I did the same thing for the front suspension as well.
Here are my suspension subassemblies. The top images of the front were rendered by my teammate who also modeled the wheels. I am quite proud of the quality of these models, but creating them was only a part of the work required for this project…
Here is a slide pulled from our final presentation, showing some part analysis I did. I took the rear suspension arm and ran it through topology optimization to identify locations with unnecessary material for force experienced due to the weight of the car on the suspension. I then made a new version of the part to reduce weight by removing material around those areas. With my new FEA analysis, stress went up more than anticipated, but this appears to be due to sharp corners creating stress concentrations. If we compare my new part to the real part on the RC car, there are similar design choices, but they have some areas with material that I removed, likely since my topology optimization and FEA didn’t look at loads along the axis of the car.
Here’s FEA that I did on my subassembly, again to simulate force through the suspension due to the weight of the car resting on its wheels. The left shows a setup of grounded components, meshing, joining, and applied forces.
I created a rough car shell as an exercise in surface modeling and did minor CFD on the model. My teammate responsible for the real surface model of the RC car’s shell did more in depth CFD for our team presentation.