2 lecture 4 - Failure Predictors and Safety Factors - slide

Small 3d element small 2d planar element mohrs circle

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Unformatted text preview: al laboratory real world Mechanical Design An aside – Mohr’s stress circle It is expected that you are confidant with this concept as 436-303 Mechanics and Materials is a pre-requisite for this subject. Small 3D element Small 2D planar element Mohr’s circle finds σ1, σ2, σ3 and τMAX and ϕ from σx, σy, σz ,τxy etc. Mechanical Design Failure Predictors Failure of a component will occur when the value of some function of stresses, X(σ1, σ2, σ3) anywhere in the component reaches that value of the stress function attained in a uniaxial test specimen that is at the point of failure: Xfail = X(S, 0, 0) S = Strength of the material Sy = Yield Strength of the material (component and test specimen) Mechanical Design Failure Predictors Maximum principal stress failure predictor Failure of a component will occur when the value of maximum principal stress, σ1 = σMAX anywhere in the component reaches the value of (σ1, σ2, σ3) = (SU, 0, 0) in a uniaxial test specimen. σ1 = σMAX = SU SU = Ultimate Tensile (fracture) Strength of the material (component and test specimen) Mech...
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This note was uploaded on 04/09/2012 for the course MECHANICAL 101 taught by Professor Kent during the Three '11 term at University of Melbourne.

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