GATE Mechanical Engineering (ME) 2016 Shift 1 Solved Paper

A hypothetical engineering stress-strain curve shown in the figure has three straight lines PQ, QR, RS with coordinates P(0, 0), Q(0.2, 100), R(0.6, 140) and S(0.8, 130). ‘Q’ is the yield point. ‘R’ is the UTS point and ‘S’ the fracture point

The toughness of the material (in MJ/m³) is ______