Design and Fabrication a Lightweight Spring Made of Natural Rubber for a Motorcycle’s Shock Absorber

Abstract

This research aims to design and fabricate a spring made of natural rubber for a lightweight motorcycle’s shock absorber. This study is carried out in four main steps. First, a stiffness property of a steel coil spring and a damping property of a commercial shock absorber were tested using an Instron® material testing machine and a test rig. Second, six different types of rubber compounds (A-1, A-2, A-3, B-1, B-2, and B-3) were formulated and the best compound was selected to use for a rubber spring. Third, the rubber spring was designed and analyzed using the finite element method to investigate the best model. Finally, a prototype of the rubber spring was fabricated and tested. The steel coil spring was replaced by the rubber spring and tested for its damping property within a real shock absorber. The results of the prototype testing showed that the weight of the rubber spring was lower than the steel coil spring about 48%. The stiffness property of the rubber spring was higher than the steel coil spring around 43% and the damping property of the shock absorber using rubber spring was higher than the damping property of the shock absorber using steel coil spring about 6%.  The rubber spring provided more advantages than the steel coil spring for its good corrosion resistance, lightweight, and ease of maintenance. However, the implementation of the rubber spring in the real motorcycle and its fatigue life should be studied in the next future.