Blog #3 - Progress Update

        Between the dates of January 13 and January 31, the team had to make some modifications to the suspension system design to clear up issues that arose. For example, the rear bellcrank/damper system was positioned in a way that put too much stress on the chassis tubes and a high risk of interference during motion. The team decided to build a damper bridge to alleviate the stresses the chassis will be subjected to and find an optimum location for attaching the dampers. Moreover, the rear bell cranks needed to be redesigned for clearance issues and to ensure they can handle the forces acting on them from the dampers, pushrods, and the anti-roll bar (Figure 1).  Another issue the team encountered involved the design of the anti-roll bar system. The system required the team to purchase a steering coupler and steering shaft to ensure tolerance issues would not be a problem since the company selling them gave rough estimates of the dimensions. The team decided to purchase the steering coupler and the shaft to measure and compare the dimensions to what was originally used, and made some slight remodifications to the anti-roll bar system based on the steering coupler and shaft dimensions (Figure 2). The anti-roll bar will be used to reduce roll stiffness of the vehicle to enhance the stability of the vehicle when cornering. The anti-roll bar system is mounted onto the chassis and is connected to the bell crank through the drop link. 

Figure 1. The following figure shows the damper bridge inserted in the rear chassis which is also connected to the bell crank system.

Figure 2. The front anti-roll bar system is displayed above. The system contains the anti-roll bar, lever arms, and the drop links connecting the arms to the bell cranks. From the figure, a large portion of the steering shaft is inside the steering coupler and flange sleeve.

         The rear uprights required some modifications after careful analysis of FEA was completed. Material was added in the upper section of the upright to ensure upright strength was being met. Also, the tabs that are to be welded onto the chassis were weak when it came to handling suspension link forces with the extra forces coming from the pushrods. As a result, the team modified the design of the tabs and ensured that the new thickness of the tabs was enough to handle the loads. Also, the steering rack plate that constraints the steering rack required modifications to ensure that all the forces from the chassis and the suspension links will be resolved. After performing FEA on it, the design showed that the safety factor was too low and could possibly bend when subjected to steering forces. This took several iterations to validate the sufficiency of steering rack to take forces, resolve them by its geometry, and achieve the goal of supporting the steering column. Also, the team has already started and finished multiple drawings required to send to vendors for part fabrication. DXF files for tabs and bell cranks are finalized, and the finalization of the uprights’ DXF files are coming up soon. Finally, the jigs for the suspension tabs were sent for fabrication and they are already cut out (Figure 3). The jigs will be used to help with the placement of suspension tabs when welding them onto the race car.

Figure 3a. The image shows some of the jigs assembled Figure 3b. The image shows a closeup view of the jigs

      From January 31 through February 14, the team will be welding the jigs to help stabilize them onto the chassis before welding the tabs onto the chassis. The team will also finalize the damper bridge design by then. Next, the suspension team will be compiling other necessary drawings to send to vendors for part fabrication and send them. The team is also planning on  fabricating multiple parts (e.g. suspension links) in the FSAE workshop and print 3D prototypes for the uprights. The biggest challenge that will come across is time. It is important for us to be able to keep up with deadlines while managing other tasks (e.g. academics).