The basquin law for an alloy tested at r = −1 is n_f^b ((∆σ))/2= c
at a δσ of 300 mpa, nf is 105 cycles, and at a δσ of 200 mpa, nf is 107 cycles.
(a) determine the values of the constants b and c.
(b) what is nf for a stress range of 250 mpa?
(c) if a specimen is cycled at 250 mpa for 5 × 105 cycles, how many additional cycles based upon the miner-rule will the specimen be able to sustain at a stress range of 200 mpa?