The square rubber block is subjected to a shear strain yxy = XXXXXXXXXXtimes XXXXXXXXXXy, where x and y are in mm. This deformation is in the shape shown by the dashed lines, where all the lines...

The square rubber block is subjected to a shear strain yxy = 40(10-6) times + 20(10-6) y, where x and y are in mm. This deformation is in the shape shown by the dashed lines, where all the lines parallel to the y axis remain vertical after the deformation. Determine the normal strain along edge BC.