Impact Attenuator Design and Manufacture

Introduction

This is an individual final year project dissertation. The project is focused on the crash worthiness of a racing vehicle, including the design of deformable crash structure, known as frontal impact attenuator, which is a structural safety feature used for the 2020 University of Brighton Formula Student vehicle. The task required in order to achieve this includes developing a detailed design, stress calculations for safety critical features, impact test at the Cranfield Impact Test Centre, and the production of manufacturing drawings. The design must be compliant accordingly with the 2020 IMechE Formula Student competition rules.

Glossary

Impact Attenuator - a deformable structure, used for absorbing the energy generated during an impact at a certain velocity. This component is a major in the vehicle because it decelerates the velocity impact of the vehicles begging it to a gradually to a stop preventing any intrusion into the footwell area of the vehicle chassis that might cause any injuries to the driver.

Anti-Intrusion Plate – metal plate welded into the vehicle front bulkhead chassis, secured to the impact attenuator located at the frontal part of the vehicle intended to prevent any objects from reaching the driver’s feet during an impact.

CAD – Computer Aided Design.

Chassis [noun] – base frame of a motor vehicle.

Crash Structure – one of the most crucial components of the vehicle. This single structure located in the frontal part of the vehicle attached to the frontal main body chassis which is designed to absorb the colliding vehicle’s kinetic energy, bringing the vehicle gradually to a stop.

Front Bulkhead – one of the structural partition compartments, where the engine, radiator, and others are located. This compartment is also crucial because, located in the frontal part of the vehicle, hence affecting the aerodynamics which will influence the vehicle performance.

Structural Safety – the probability that failure will not occur or that a specified criterion will not be exceeded.

"The Comet" University of Brighton 2020

Impact Attenuator Rules

According to the IMechE Formula Student Competition 2020 Rules each vehicle must be equipped with an Impact attenuator.

Impact Attenuator must be:

▪ Installed forward of the front bulkhead;

▪ Total mass of the vehicle 300kg (including the attenuator);

▪ Velocity of Impact: 7 m/s;

▪ Decelerate the vehicle at rate of 20g and 40g peak;

▪ Energy Absorbed meet or exceed 7350J;

▪ Minimum dimensions 200mm x 200mm x 100mm;

▪ All teams must submit an Impact Attenuator data report using the template provided by the IMechE;

▪ Not able to penetrate the front bulkhead in the event of impact;

▪ Must be attached securely and directly to the Anti Intrusion Plate;

▪ Not part of the non-structural bodywork;

▪ Designed with a closed front section;

▪ Must not be wider or higher than the Anti Intrusion Plate;

▪ On all vehicles, a 1.5mm solid steel or 4.0mm solid aluminum Anti Intrusion Plate must be integrated into the Impact Attenuator.

During the Impact Attenuator test:

▪ Impact Attenuator must be attached to the Anti Intrusion Plate using the intended vehicle attachment method;

▪ Must be at least 50mm clearance rearwards of the Anti-Intrusion Plate to the test fixture;

▪ The parts of the Anti-Intrusion Plate may not deflect more than 25mm from the initial position.

Tools and Technologies

Knowledge and Experience: CAD, Mechanical design, force and stress calculations.

Manufacturing Skills: Prototype manufacture, machining, fabrication, laser cutting.

Software Skills: Solidworks, Excel, MatLab

Impact Attenuator Designs

To design the final three impact attenuators, Microsoft Excel and Solid works (CAD) are the software used for developing, designing and predicting the structural behavior and results.

Images of the final design (IA – Charlie) and assembled of the impact attenuator assemble on the “The Comet” Brighton University 2020.

All final three design have passed the test and the requirements of the rules.

Design1: Alpha