3-19. The two bars are made of polystyrene, which has the stress-strain diagram shown. If the cross-sectional area of bar AB is 1.5 in and BC is 4 in, determine the largest force P that can be supported before any member ruptures: Assume that buckling does not occur. 4 ft. P 3 ft B 3-22. The stress-strain diagram for a polyester resin is given in the figure. If the rigid beam is supported by a strut AB and post CD made from this material, determine the largest load P that can be applied to the beam before it ruptures. The diameter of the strut is 12 mm and the diameter of the post is 40 mm. 3-30. The elastic portion of the stress-strain diagram for a steel alloy is shown in the figure. The specimen from which it was obtained had an original diameter of 13 mm and a gauge length of 50 mm. If a load of P 20 kN is applied to the specimen, determine its diameter and gauge length. | Take v = 0.4. (MPa) = 2 m P C 0.5 m 0.75 m '0.75 m D 400 0.002 (mm/mm) 3-31. The shear stress-strain diagram for a steel alloy is shown in the figure. If a bolt having a diameter of 0.25 in. is made of this material and used in the lap joint, determine the modulus of elasticity E and the force P required to cause the material to yield. Take >> = = 0.3.