Lecture24%20with%20slides

Lecture24%20with%20slides - Effects of elasticity,...

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1 1 Lecture 24 Creep 2 2 ε total = elastic + plastic + creep Effects of elasticity, plasticity & creep 3 Assume that an alloy with a modulus of 100 GPa exhibits steady-state power-law creep of the form s -1 , where Q = 160 kJ/mole, R = 8.31 J/mol.K, and is in MPa. An applied uniaxial stress of 30 MPa is applied. What is the strain after 10,000 hours at 600 ° C? () 10 5 7.4 10 exp / HH QR T εσ & % % Example ˜ σ H 4 Stress relaxation 5 Relaxation of bolts 6 Assume that an alloy with a modulus of 100 GPa exhibits steady-state power-law creep of the form s -1 , where Q = 160 kJ/mole, R = 8.31 J/mol.K, and is in MPa. Assume initial uniaxial stress is 100 MPa. Strain is held constant. What is the stress after 1,000 hours at 600 ° C? 10 5 7.4 10 exp / T & % % Example ˜ H
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2 7 δ, θ, etc. G ⇒η (shear viscosity) E 3 η ν⇒ 0.5 σ, P , Metc, stay the same d δ / dt ; d θ / dt Use of linear elastic analogue for linear creep problems N.B.: Use linear elasticity solutions for linear creep only 8 Empirical approaches to creep design 9 Empirical approaches to creep design 10 “Temperature-compensated time to failure” Larsen-Miller parameter: TC + log t r () [] C is in the range 18-22 (empirical) 11 Creep data for S-590 12 Larsen-Miller plot for S-590
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VK250 Lecture 24 1 C OMBINED MODELING OF CREEP ,
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This note was uploaded on 09/15/2010 for the course MATSCIE 250 taught by Professor Yalisove during the Fall '08 term at University of Michigan.

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Lecture24%20with%20slides - Effects of elasticity,...

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