MATS 3011 Lecture : Lecture 2262014.pdf
Document Summary
Recap mechanical properties this is engineering stress/strain curve engineering b/c more practical to measure, also smaller usually than true stress/strain. If stretch past yield strength and then stop applying force, then permanent deformationdoesn"t come back to original thing has residual strain curve deviates after yield strength (0. 002 fracture slope = modulus of electricity. =e where e = modulus of elasticity, sigma = elastic region. Connection between e and bonding ro = eqbm distance, also = bond length the slope = stiffness. Stronger bonds --> higher stiffness --> higher e ex: diamond, steel, ceramics (stiffer --> higher e) Polymers --> less stiff --> low e1; (b/c mostly van der waals bonds) Material 1 b/c smaller ro, steeper slope, larger second derivative. Shear stress & strain this force is perpendicular to the normal nbar to area a0. Shear strain = a/h = tan( ) = (gamma)
