IT 329 hw2

# IT 329 hw2 - IT 329 Industrial Materials 2 Density The...

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IT 329 Industrial Materials 2. Density : The density is the weight per unit volume. We measure it today as Archimedes did: by weighing the material in air and in a fluid of known density. Units: Metric: Mg/m 3 ; Imperial: lb/in 3 Young’s Module : Young's modulus, E, is the slope of the initial, linear-elastic part of the stress-strain curve in tension or compression. For isotropic materials it is related to the bulk modulus K and to the shear modulus G by: E = 3(1-2v)K E= 2(1+v)G where ν is Poisson's ratio.Commonly ν ≈ 1/3, and hence E ≈ K, and E ≈ (8/3)G. Units: Metric: MPa; Imperial: 10 3 psi . Elastic Limit : The 'yield strength' σ y is one measure of the strength of a material; it is the stress at which it first suffers permanent (inelastic) deformation. It requires careful definition. For metals , the yield strength is defined as the 0.2% offset yield strength. This represents the stress at which the stress-strain curve for uniaxial tensile loading deviates by a strain of 0.2% from the linear-elastic line. It is the same in tension and compression. It is the stress at which dislocations move large distance through the crystals of the metal. Units: Metric: MPa; Imperial: 10 3 psi Tensile Strength : The tensile strength is the nominal stress at which a round bar

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## This note was uploaded on 04/07/2008 for the course IT 329 taught by Professor Djassemi during the Fall '07 term at Cal Poly.

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IT 329 hw2 - IT 329 Industrial Materials 2 Density The...

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