ENGR 220 Homework Problems: Week 5 - Chapter 6 1. A specimen of aluminum having a rectangular cross section 10 mm × 12.7 mm (0.4 in. × 0.5 in.) is pulled in tension with 35,500 N (8000 lbs) force, producing only elastic deformation. Calculate the resulting strain. 2. A cylindrical rod of copper (E = 110 GPa, 16 x 106 psi) having a yield strength of 240 MPa (35,000 psi) is to be subjected to a load of 6660 N (1500 lbf). If the length of the rod is 380 mm (15.0 in.), what must be the diameter to allow an elongation of 0.50 mm (0.020 in.)? 3. A cylindrical specimen of a hypothetical metal alloy is stressed in compression. If its original and final diameters are 20.000 and 20.025 mm, respectively, and its final length is 74.96 mm, compute its original length if the deformation is totally elastic. The elastic and shear moduli for this alloy are 105 GPa and 39.7 GPa, respectively. 4. A cylindrical specimen of aluminum having a diameter of 12.8 mm and a gauge length of 50.800 mm is pulled in tension. Use the load-elongation characteristics tabulated below to complete parts (a) through (e). Load N 0 7330 15,100 23,100 30,400 51.003 34,400 51.054 38,400 41,300 44,800 52.832 46,200 53.848 47,300 54.864 47,500 55.880 46,100 56.896 44,800 57.658 42,600 58.420 36,400 59.182 Length mm 50.800 50.851 50.902 50.952 51.308 51.816 Fracture (a) Plot the data as engineering stress versus engineering strain using a computer program (such as Excel). (b) Compute the modulus of elasticity. (c) Determine the yield strength at a strain offset of 0.002. (d) Determine the tensile strength of this alloy. (e) What is the approximate ductility, in percent elongation? 1