A flat leaf spring has fluctuating stress of max = 360 MPa and min = 160 MPa

A flat leaf spring has fluctuating stress of σmax = 360 MPa and σmin = 160 MPa applied for 8 (104) cycles. If the load changes to σmax = 320 MPa and σmin = −200 MPa, how many cycles should the spring survive? The material is AISI 1020 CD and has a fully corrected endurance strength of Se = 175 MPa. Assume that f = 0.9.
(a) Use Miner’s method.
(b) Use Manson’s method.