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ETC 1250 Lesson 01b

# ETC 1250 Lesson 01b - Pounds A = Area Square inches Strain...

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Modulus of Elasticity: Steel (A36) = 30x10 6 psi = 30,000,000 psi Gray Cast Iron = 15x10 6 psi = 15,000,000 psi Concrete = 3x10 6 psi = 3,000,000 psi Other interesting Modulii: Rubber = 1,500 - 15,000 psi Nylon = 290,000 - 580,000 psi Oak wood (along grain) = 1,600,000 psi Pine wood (along grain) = 1,300,000 psi High-strength concrete = 4,350,000 psi Glass 11,200,000 psi Single carbon nanotube = 145,000,000 psi Diamond = 175,000,000 psi Useful Equations: Coefficient of thermal expansion = Equals increase in length per unit length per change in degree α = δ/(L ∙ ΔT) Where: α = Coefficient (/°F) or (/°C) Re-arranged δ = Deflection (Change in length) inches δ = αL(ΔT) L = Original length inches ΔT = Change in Temperature °F or °C Stress/Strength = Load acting on material s = P/A Where: s = Stress/Strength PSI (pounds per square inch) or Ksi (1000PSI) P = Load
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Unformatted text preview: Pounds A = Area Square inches Strain = total change in dimension divided by the original dimension ε = δ/L Where: ε = Strain in/in δ = Deflection (Change in length) inches L = Original length inches Modulus of Elasticity = the ratio where strain is proportional to stress E = s/ ε Where: E = Modulus of Elasticity PSI s = Stress/Strength PSI ε = Strain in/in Mike’s special equation: ε = s / E = δ / L 1. Circle the unknown (What are you solving for?) 2. Underline the knowns (What values can you extract from the problem statement?) 3. Use only two expressions (ex: ε = s/E, ε = δ/L, or s/E = δ/L) Safety Factor = failure stress divided by the allowable stress S.F. = s failure /s allowed Where: s failure = Stress that will cause failure PSI s allowed = Stress allowed in application PSI...
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ETC 1250 Lesson 01b - Pounds A = Area Square inches Strain...

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