To measure the in-plane deformation of a thin sheet of metal during a forming process, three small hardness indentations are placed on the sheet. Using a travelling microscope, the initial lengths of the sides of the right angle triangle (ABC) are shown in the picture below. After deformation, the sides have lengths 0.991 cm, 1.001 cm and 1.401 cm. A 1.401 cm B A 1.414 cm 90 1cm 1cm 0.991cm C Undeformed 1.001cm C Deformed (not to scale) a) Find the principal residual strains from the data supplied; [20 marks] what b) During this forming process plastic strains are much larger than elastic strains. It is also known that plastic strains generally do not cause volume changes. If the original thickness of the metal sheet is 6 mm, would be the thickness after the forming process? [10 marks]