Question

Leaf springs are commonly used in low-cost or high-stiffness vehicle suspensions, e.g. golf cars, light-truck rear axle. Consider a cold-drawn AISI 1040 flat leaf spring subjected to a fluctuating loading condition of maximum and minimum stresses of 420 MPa and 140 MPa respectively for a total of 50,000 cycles. The loading condition of the spring then changes to maximum and minimum stresses of 350 MPa and -200 MPa respectively. Estimate the remaining life of the spring under the new loading condition using Palmgren-Miner cumulative damage theory. Assume that the fully-corrected endurance limit is 200 MPa and Sn is 90% of Sut.

Answer 1