A specimen in the shape of a cube 20 mm on each side is being compressed without friction in a die cavity, as shown in Fig. 2.35d, where the width of the groove is 15 mm. Assume that the linearly strain-hardening material has the true stress-true strain curve given by σ = 70 + 30ε MPa. Calculate the compressive force required when the height of the specimen is at 3 mm, according to both yield criteria.