3. A sheet of material is subjected to a two-dimensional stress system in the xy plane. At a given point, an element with its sides parallel to x and y axes is found to have a shear strain of 1x10-4, while an element at 30 to the first has a shear strain of 4x10-4. (a) Find the maximum shear strain at this point. (b) If the shear modulus of the material is 80 GPa find the difference between the two principal stresses 4. The displacements, in meters, at an arbitrary point (x,y,z) in a given body are: u(x, y, z) = (x + y) 12) 10-4 v(x,y,z)=(2xy+2)x10-4 w(x,y,z)=0 (a) Determine the strains in x-y-z coordinates at any point. (b) Is the body in plane strain? Explain why or why not. (c) Determine by a calculation whether or not compatibility holds for this strain field. (d) From (a) what is the strain tensor at the point (2,1,1)?