1.7-3 A polyethylene bar with a diameterd = 70 mm is placed inside a steel tube with an inner diameter d, = 70.2 mm (see figure). The polyethylene bar is then compressed by an axial force P. At what value of the force P will the space between the polyethylene bar and the steel tube be closed? For polyethylene, assume E = 1.4 GPa and v = 0.4. Steel tube d, d2 Polyethylene- bar

Two round solid bars of different materials are connected in series against rigid supports as shown in Figure 4. Determine the stress in each bar and the support reactions if temperature is increased by 18° C. Bar A da, EA, A Bar B dв, Ев, ав LA LB Figure 4 Use the following information. Bar, B: Length, LB Diameter, dB Poisson's Ratio Young's Modulus EB = 210 kN/mm2 Coefficient of expansion aB = 12.4x106 °C- Bar, A: Length, LA Diameter, dA = 25mm =D40 mm = 10 mm 30 mm S. = 0.28 =D0.32 = 70 kN/mm² Coefficient of expansion aa = 16.5x10-6 °C-I Poisson's Ratio %3D Young's Modulus EA