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January 2025
Key Facts at One Glance:
- Innovative Suspension System: AMZ Racing’s electric race car, Dufour, featured a novel suspension design combining mechanical and hydraulic elements to enhance stability and traction, with two heave spring-dampers enabling better control and stiffness.
- Customized Bump-Stop Solution: Angst+Pfister engineered a customized rubber bump-stop that met non-linear stiffness requirements, fit into the limited space of the suspension, and protected the car from ground impacts without compromising performance.
- Successful Industry-Academia Partnership: The collaboration between Angst+Pfister and AMZ Racing bridged academic innovation with industrial expertise, resulting in a high-performing car that excelled in Formula Student competitions and advanced engineering excellence.
Formula Student competitions provide an unparalleled opportunity for engineering students to showcase their design, technical, and racing skills. For the Academic Motorsports Club Zurich (AMZ Racing), pushing the boundaries of innovation is nothing new. Each season, they strive to design and build faster, more efficient electric race cars. For their 2024 car, Dufour, the team aimed to develop a novel suspension system that required precision-engineered parts. In this ambitious project, Angst+Pfister played a pivotal role in supporting AMZ Racing by providing a custom-designed rubber bump-stop, which improved the car’s driving performance and responsiveness, while protecting it from ground impact on uneven tracks.
Read all about the challenges faced by AMZ Racing, the innovative solution proposed by Angst+Pfister, and how this partnership bridged academia and industry in the pursuit of engineering excellence.
The Engineering Challenge: Novel Heave Spring-Damper System
AMZ Racing's 2024 car, Dufour, featured an innovative susension design that combined mechanical and hydraulic elements to provide superior platform stability and traction. The system included two heave spring-dampers – one in the front and one in the rear. This setup allowed more individual control of suspension properties while maintaining high stiffness, making it ideal for navigating the competitive race circuits of Formula Student.
The challenge AMZ faced was ensuring the suspension system could be tuned for maximum performance and had adequate protection. The car was designed to sit as close to the ground as possible to maximize downforce and traction but increasing the likelihood of ground impact. They needed a rubber bump-stop within the heave spring-dampers to absorb sudden shock loads and avoid hard metal-to-metal contact that could occur especially on uneven tracks. Without this component, the car risked losing traction or suffering sudden driving instabilities or hardware failures that could cost them the race.
A high-quality bump-stop was essential to protect the car from ground collisions that could potentially end the race prematurely. However, sourcing a part that fit within the limited space of the suspension assembly while fulfilling strict non-linear stiffness requirements proved to be a complex challenge.
The Specific Needs
AMZ Racing needed a partner with both the technical expertise and manufacturing capabilities to design a custom rubber bump-stop that would:
- Deliver the non-linear stiffness needed to allow the car to sit as close to the ground as possible, ensure precise control for the driver, while protecting against ground impact.
- Fit into the confined space within the suspension system.
- Be delivered in time for testing and performance tuning, critical to the success of the car before the competition season.
Angst+Pfister’s Solution: Custom-Designed Bump Stops
Having supported AMZ Racing in previous projects, Angst+Pfister was a trusted partner that the team turned to for a solution. The engineering experts at Angst+Pfister collaborated closely with AMZ to understand the specific requirements of the new suspension system. They proposed a custom-designed bump-stop that would fit in their assembly and meet the stiffness curve required by AMZ, providing a tailored solution for the unique demands of Dufour.
Angst+Pfister offered the following:
- Custom Rubber Design: The bump stop was engineered with a simple yet cost-efficient design that could be quickly prototyped and tested. It was crafted to fit the specific dimensions required by the suspension system, with a maximum height of 15 to 20mm and a diameter of 30mm.
- Non-linear Stiffness: The bump stop was designed to offer progressive stiffness. After 5mm of linear travel at a low stiffness (50 N/mm), the part would engage in a progressively stiffer response, reaching a peak force of several kilonewtons to absorb significant impacts and prevent ground collisions.
- Multiple Prototypes: To ensure the ideal performance, Angst+Pfister provided three bump stops with varying hardness levels, allowing AMZ to test and select the best option during prototype trials. This flexibility allowed the team to fine-tune the car's performance and suspension behavior.
- Precision Manufacturing and Timely Delivery: Angst+Pfister used its network of manufacturing partners to deliver the bump stops within two months, ensuring they were ready in time for integration into the car’s production schedule and testing phase.
Collaboration and engineering excellence
The successful development of the bump stop was the result of close collaboration between Angst+Pfister and AMZ Racing. Angst+Pfister's in-depth knowledge of elastomer design and expertise in vibration-damping components were key to developing a solution that met AMZ's exacting standards.
The process included:
- Early-stage consultation: Angst+Pfister engineers met with the AMZ team at the Innovation Park Zurich (IPZ) to discuss requirements, view cars from previous race seasons in the workshop and provide insights into rubber behaviour for optimal component performance.
- Virtual design and simulation: Angst+Pfister used advanced design tools to simulate the performance of the end buffer, ensuring that the product met AMZ's stiffness requirements before production.
- Fine-tuning: To maximise flexibility, Angst+Pfister supplied three different hardness buffers. The engagement point of the pads was also adjustable with shims, allowing AMZ to change the starting point of the bumper and further adjust stiffness.
Real-World Performance and Results
The custom bump stops from Angst+Pfister proved crucial during the racing season. According to AMZ Racing’s CEO, Samuel Vonder Mühll, the bump stops not only protected the car from ground impacts but also enhanced the vehicle's driving dynamics. They allowed AMZ to maintain a low ride height without compromising safety, even on the notoriously bumpy Formula Student Germany (FSG) track, where vertical forces of up to 7g frequently caused hardware failures for other teams.
Vonder Mühll emphasized the success of the bump stops:
"The performance of the bump stops completely fulfilled what I had wished for during the design phase, both in terms of enhancing tunability of the driving behavior and hardware protection. Thanks to the bump stops, our car survived every impact easily."
Conclusion: A Partnership for Innovation
Angst+Pfister’s support of AMZ Racing in developing the custom rubber bump-stop demonstrates the value of industry-academia partnerships in advancing engineering innovation. By offering their engineering expertise, design capabilities, and manufacturing resources, Angst+Pfister enabled AMZ Racing to build a cutting-edge suspension system that enhanced the performance and durability of their 2024 car, Dufour.
This collaboration not only contributed to AMZ Racing’s success on the track but also highlights Angst+Pfister’s commitment to supporting the next generation of engineers. By fostering close connections with student projects at Innovation Park Zurich, Angst+Pfister continues to demonstrate its role as an ideal partner for both engineering and education.
For engineers, the key takeaway from this collaboration is the importance of precision engineering, customized solutions, and the power of partnerships in tackling complex challenges, driving innovation, and achieving excellence in high-performance applications like Formula Student racing.
Source of images: Image courtesy of AMZ Racing (www.amzracing.ch). All rights reserved.
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