Question

8) A high strength bolt has fatigue defined by o = 220N where B=-0.089 (units of stress in ksi). The endurance limit occurs at N = 108 cycles. Find the stress oa at the endurance limit. Also, please plot ga vs Nrin a logarithmic scale for both quantities (using at least 4 data points) [10 points)

Answer 1

Sol. Griven: Aa= 220 N B = -0.089 No= 108 for endurance limit. at endurance limit, Stress na = 220x (108) -0.08 da = 42.699 Ksi i - log na = log 220 + Blog NF - bg da = 2.3424 - 0.089 lag Nf for Nf=1 logio a a= 2.3424 No= 100 legio na = 21644 NE= 104 16g,o na = 1.9864 narejena NE=108 Losio aa= 1.8084 legida 2.3429 2.1644- 1.9864 1.8084 4 8 bgio Na 02