1. A 0.25 inch thick wide Aluminum ( ksi ys 40 = σ

) tension panel has an edge crack a = 0.8 inch long. Based on fracture tests with a similar material for the same thickness, the fracture toughness has been measured as in ksiK IC 45 = .

(a) Calculate the plastic zone size (using Irwin's approach) for both plane stress and plane strain conditions at the critical loading. (4 point) (b) What is the magnitude of the largest remotely applied steady state stress that the panel in plane stress condition can support without failure? Use the effective crack length stress intensity factor equation: ( ) ( ) 12 .1, == effeffeffeff aYaaYK πσ . (3 point) (c) Derive ry θ =0( ) expression for plane stress condition using Tresca yield criteria and determine ry θ =0( ) at the critical loading and compare with (a). (6 point)