Modeling, analysis and testing of the steering system in a Formula Student car FS_UIS2013

Abstract

The University of Stavanger (UiS ) is competing in a Formula Student competition at Silverstone in spring 2013 with a Formula Student racing car. This Master Thesis aims to design, analyze and test the steering system of the racing car. The car is built during the process of writing the thesis. A manual steering system was preferred as the weight of the car is low and to reduce the risk of spillage due to the hydraulic pump that would be necessary with a power-assisted steering system. With an electrical driven system, additional weight would be added with an extra or heavier battery. The car was designed for optimal performance in the skid-pad event with a reversed-Ackermann design. The Ackermann angle of the offset arm was set to 39.3 degrees giving the outer wheel an angle of 13 degrees and the inner wheel an angle of 11 degrees in a turn with a radius of 7583 mm. The steering rack was placed in a far-front position to avoid big buildups of momentum during driving. The tie rods were angled at a same angle as the lower a-arm to reduce the bump steer. The biggest lateral force occurred during cornering and this was used for the design of the tie rods. During the analysis of the system, a bigger force occurred on the tie rod during braking, and the system was rechecked and approved for this force. MSC Adams was used in the design and analysis phase to consider the functionality and behavior of the steering system. Due to limitations in the budget, the team used the same Hoosier tires as last year. The 2014 team should pay to get access to the Milliken Research Associates, which is a tire test consortium, to obtain tire test data and make a decision if another brand of tire would fit the project better. The budget for the steering system should also be raised to be able to buy a lighter steering rack to lower the total weight of the steering system. The total weight of the 2013 steering system is 3957.8 grams. The 2013 budget for the steering system was set to 5500 NOK. A new quick release mechanism had to be bought which raised the total amount for the system to 6228.56 NOK. It should be possible to use the same quick release mechanism next year.