1. A flat plate 1.0 m wide and 50 mm thick contains a through-thickness central crack of length 100 mm. The plate is subjected to a uniaxial tensile load P perpendicular to the crack plane. Given: . Treating the plate to be in plane strain state,
   1. Calculate the elastic and plastic components and therefore total J in terms of P.
   2. Plot Jel, Jpland J Vs. P on the same graph.
   3. Keeping the crack size constant (100 mm), determine the critical load at failure if the material has a JIC= 500 kJ/m2.