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Unformatted text preview: a) What is the relaxation time? (Ans. about 60.5 days) b) What stress will be exerted by the elastomer in the same stretched position after 90 days? (Ans. 2.5 MPa) c) Will the stress approach the design stress of 0 MPa after 1 year? (Engineering judgement is required to solve this problem. (Ans. Yes it will.) Explain your answer. d) Tests at 25 o C show that the relaxation time is 50 days. What is the activation energy for stress relaxation for this elastomer. Express your answer in cal/mole. (Ans. Q is about 6613 cal/mole) e) The engineer is informed that the actual service temperature will be 30 o C. What is the relaxation time at this temperature? (Ans. About 42 days.) f) Will the stress approach 0 MPa in 1 year at this temperature? (Ans. It is not likely.) M. McDill AERO3700...
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- Spring '11