A NEW INTEGRATED APPROACH TO THE DESIGN OF A RACE CAR SUSPENSION

An innovative approach has been used to design the front suspension of the Formula SAE race car of the Università degli Studi di Firenze. The critical review of the 2005 car showed that it's necessary to improve suspension reliability, reduce Time to Market and costs. DFSS is the only design methodology that allows to resolve these criticities integrating in an organized and structured way several design tools. An Identify - Design - Optimize - Verify (IDOV) approach has been used and through Qualica QFD® has been possible to manage every project phase and the used methodologies like Quality Function Deployment (QFD), Value Analysis and Design Failure Mode Effects Analysis (DFMEA). In the Identify phase, QFD has been used in order to correlate the Voice of Customer (VOC) with the Critical To Quality characteristics (CTQs) and to calculate their importance. In the Design phase the Functional Surfaces methodology has allowed to characterize Functional Requirements (FR) which has been then correlated with CTQs through QFD. Then the Value Analysis has allowed to determine the Design Parameters (DPs) which need to be improved. The suspension Short Long Arm (SLA) is the most important DP, so a new DFSS project has been created to study it. In the new Design phase, Value Analysis has been repeated, Rod Ends and their mounts has proved to be the DP which needed to be improved. These DPs have been re- design, using a Design for Manufacturability (DfM) approach, replacing the spherical Rod End with groved one. DfM has allowed to plan manufacturing processes and to estimate costs with a Bill of Material. In the new Optimize phase, the failure modes of the suspension SLA have been foreseen through a DFMEA. During this phase, a procedure to measure groving force and one to measure Rod End's friction coefficent have been identify, in order to improve the SLA reliability. The created model has been used to study the innovation impact on costs and customers satisfaction. It will be used to design the rear suspension too because it has similar functional and structural requirements of the front one.