A sheet of material is subjected to a two-dimensional stress system in the x-y plane. At a given point, an element with its sides parallel to x and y axes is found to have a shear strain of 1x10, while an element at 45° to the first has a shear strain of 4x10 (Fig. 2). a) Calçulate the maximum shear strain at this point. b) If the shear modulus 100 MPa, find the difference between the two principal stresses. y y =4x104 ソ=104 \ 45 °

2.6 The truss ABC shown in the figure supports a horizontal load P₁ = 9 kN and a vertical load P₂ = 18 kN. Both bars have cross-sectional area A = 1,290 mm² and are made of steel with E= 210 GPa. a) Determine the strain energy U₁ of the truss when the load P₁ acts alone (P₂ = 0). b) Determine the strain energy U₂ when the load P2 acts alone (P₁ = 0). c) Determine the strain energy U when both loads act simultaneously. 813 mm 1524 mm P₁ = 9 kN P₂ = 18 kN

The principle planes are two planes which are separated by 90° where the principle stresses occur. Under which condition do the principle stresses and associated principle planes occur? O O O O When the shear stress is not zero When the normal stress in the y-direction is zero Don't Know When the normal stress in x-direction is zero When the shear stress is zero

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