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MER200: Theory of Elasticity Lecture 6. TWO DIMENSIONAL PROBLEMS Plane Stress Problems Stress Functions. Equilibrium. Strain-Displacement. Compatibility. Isotropic Stress-Strain Relations. Plane Strain Condition. Thin Plate Load uniformly distributed over thickness
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MER200: Theory of Elasticity Lecture 6 TWO DIMENSIONAL PROBLEMS Plane Stress Problems Stress Functions MER200: Theory of Elasticity
Equilibrium MER200: Theory of Elasticity
Strain-Displacement MER200: Theory of Elasticity
Compatibility MER200: Theory of Elasticity
Isotropic Stress-Strain Relations MER200: Theory of Elasticity
Plane Strain Condition • Thin Plate • Load uniformly distributed over thickness • Load parallel to the plane of the plate • Normal and Shearing stresses on the faces of the plate are zero • σz=τxz= τxz=0 • Stresses with z components through the thickness closely approximated by 0. • Fz=0 • Fx=Fx(x,y), Fy=Fy(x,y) MER200: Theory of Elasticity
Equations of Elasticity forPlane Stress MER200: Theory of Elasticity
Reducing Governing EquationsFrom Eight to Three • Starting with Compatibility MER200: Theory of Elasticity
Constitutive Equations forPlane Strain MER200: Theory of Elasticity
Three Equations • Compatibility in terms of Stress • Equilibrium MER200: Theory of Elasticity
Stress Functions • Plane Stress Compatibility • Plane Strain Compatibility MER200: Theory of Elasticity
Body Force is Conservative • Potential Function V exists • V causes compatibility equations to reduce to one equation with one dependent variable MER200: Theory of Elasticity
Airy’s Stress Function φ • Definitions • Φ implies that equilibrium equations are identically satisfied MER200: Theory of Elasticity
Compatibility equations can now be written • For Plane Stress • Biharmonic operator • Biharmonic equation MER200: Theory of Elasticity