A COMPUTATIONAL APPROACH FOR EVALUATING HELICAL COMPRESSION SPRINGS
Helical compression springs are generally synthesized and evaluated by determining the maximum torsional stress, fatigue life, natural frequency, and/or load loss due to stress relaxation. To this end, researchers have developed finite element analysis (FEA) modeling methods to simulate the design performance of helical compression springs. The intent of this paper was to make a useful contribution to the published works for evaluating round wire helical compression springs. Specifically, commercially available FEA software was used to construct a structural model of a helical compression spring to simulate its full range of compression. The proposed FEA modeling methodology considers coil-to-coil contact and the end coils were modeled as rigid surfaces. With 9 mm of compression, the predicted spring rate correlated with the analytically calculated value to within 5%.
Failure analysis of a helical compression spring for a heavy vehicle's suspension system
This paper analyzed why a compression coil spring fractured at the transition position from the bearing coil to the first active coil in service, while the nominal stress here should always be much less than that at the inside coil position of a fully active coil. Visual observations indicated that a wear scar was formed on the first active coil and the fracture surface showed radiating ridges emanating from the wear scar. Scanning electron microscopy examination showed crescent shaped region and beach marks, typical of fatigue failure. ZnCaph phosphate layer and painting around the contact zone were worn out due to contact and friction and resulted in corrosion and corrosion pits induced local stress concentration. Stress analysis indicated severe stress singularities at the edges of the contact zone, which facilitated cycle slip and fatigue crack nucleation. Recommendations were also made for improving the fatigue performance of the suspension springs.
Static analysis and fatigue life prediction of steel and composite leaf spring for light passenger vehicles
This paper describes static and fatigue analysis of steel leaf spring and composite multi leaf spring made of glass fibre reinforced polymer. Primary objective is to compare the load carrying capacity, stiffness and weight savings of composite leaf spring with that of steel leaf spring. The design constraints are stresses and deflections. Finite element analysis with full bump load on 3-D model of composite multi leaf spring was done using ANSYS 7.1 and analytical results were compared with experimental results. Composite leaf spring had 67.35% lesser stress, 64.95% higher stiffness and 126.98% higher natural frequency than that of existing steel leaf spring. A weight reduction of 68.15 % was also achieved by using composite leaf spring. Fatigue life of composite leaf spring (10, 00,000 cycles) was more than that of conventional steel leaf spring (2, 00,000 cycles).