Question

A preventive maintenance program has been conducted to replace a polymer gear with a required functional stress level of 20 MPa every two years. The polymer material was tested to have an initial stress of 36 MPa, which was dropped to 30 MPa after a year usage at a constant strain. Provide your engineering reasoning whether the maintenance program for the polymer gear with respect to reliability and cost is correct or not.

Answer 1

bata from the girco question 60 = 36mpa - 30 mpa t =1 (12 months we know year 4) GoC - 0 where 6 = stress impa) Go - Original stress impa) t = gelaration time Cin months) 1 - Oclaration constant (in months) 2016,+ values into ea?o substitute Then we get (-12) 30 = 36c (-1270) 30 36 In() = (-2) - In (0.8333) = -2 7) - 0:18232 = -1271 X = 66 months X calcu lating the initial stress required of only zompa for every 2 years (24 months) (-1/2) - G 2

(-24166) 20 - Gà C (-0.3636) 20 - 60 C 20 =GO - (-0.3636) e 20 0.695 28.77 :: Go = 28.79 mpa initial stress 93 still mainted above 20 mpa, for Hwo every gears, Hence, The maintaince program for the polymer failure gear prevents the >