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 afluctuating loading condition of maximum and minimum stresses of420 MPa and 140 MPa respectively for a total of 50,000 cycles. Theloading condition of the spring then changes to maximum and minimumstresses of 350 MPa and -200 MPa respectively. Estimate theremaining life of the spring under the new loading condition usingPalmgren-Miner cumulative damage theory. Assume that thefully-corrected endurance limit is 200 MPa and Sn is 90% ofSut.
