An aisi 1018 steel ball with 1-in diameter is used as a roller between a flat plate made from 2024 t3 aluminum and a flat table surface made from astm no. 30 gray cast iron. determine the maximum amount of weight that can be stacked on the aluminum plate without exceeding a maximum shear stress of 20 kpsi in any of the three pieces. assume a typical poisson's ratio of 0.3, is applicable to estimate the depth at which the maximum shear stress occurs for these materials. the plate plate can be treated as a ball with infinite diameter so that a 1/d term becomes equal to zero.