Static Analysis and Fatigue Life Prediction of Composite Leaf Springs of Automotive Suspension System

Abstract

Development of vehicles with the highest safety standards and lowest carbon emissions has been one of the primary goals of the automobile manufacturers. One of the methods of achieving higher fuel efficiency is by reducing vehicle weight by minimizing the unsprung weight without compromising strength and driver comfort. The study presents the behavior of the double-bolted-end joint semi-elliptical leaf spring that is generally used in the rear suspension of lightweight cars and commercial vehicles. 65si7 grade steel is conventionally used in the above leaf springs. The study evaluates the stress distribution, deflection and fatigue life assessment of leaf springs made up of glass epoxy (62% glass fiber), carbon epoxy (40% carbon fiber), and aluminum graphite (5% graphite). The results are compared with 65si7 steel leaf spring and analysed. The analysis performed showed a weight reduction of 76.4 %, 81.1%, 65.8% respectively. The first natural frequency was approximately 1.2 times greater than the road frequency. The simulated results for fatigue life cycles of leaf spring (10e5 cycles) was observed, whereas, for the conventional steel leaf spring (2e5 cycles) was observed. The results suggest the material aluminum graphite (5% graphite) will be the best replacement, considering the overall weight to strength ratio and cost.