A steel wire AB is stretched between rigid supports (see figure). The initial prestress in the wire is 42 MPa when the temperature is 20°C. (a) What is the stress o in the wire when the tem - perature drops to 0°C? (b) At what temperature T will the stress in the wire become zero? (Assume a = 14 x10-6/°C and E=200 GPa.) Steel wire

4(a) A solid circular bar is experiencing axial load F=3 kN as in Figure 4(a). Find the strain energy in the bar, E=200GPa. F= 3 kN F= 3 kN Solid circular bar 6 = 40 mm Figure 4(a) 4(b) A simple ABCD structure is being loaded built in at D and loaded with load P at A, as in Figure 4b. The structure is made of steel solid round cross section with 100mm diameter with E= 200GPA, o, = 250 MPa. AB = Im, BC= 1.5m, CD= 2.5m Neglect the energy from the shear and axial load, find the ; i) Vertical deflection of point A i) Horizontal deflection of point A iii) Slope of point C D Figure 4b A в P=10N

Example:- A three 1in *3in wood board is connected together by bolt (d=0.5in) as shown in the figure. The washer dimensions are (Do-2in, Di-0.5in). The nut is a 0.5in (Zinc Finish, grade A Finished Hex. Nut). Analyze the stress developed in the wood and the bolt in the following two cases :- Case I:-An External force of (P=1400lb) that is applied on the wood board on the right is transmitted through the bolt to left wood board. - Case II: There is no external force but the nut is tightened so that internal stress of o=2700psi is developed in the bolt. 돌 - P/2 -F P/2 NT NT

A rigid bar ACE is supported by three vertical wires and is initially horizontal, as shown in the figure. Then, a force P is applied at the center of the bar. All wires are made from the same material with modulus of elasticity E = 200 GPa and have the same cross-sectional area, A = 10 mm². You may assume that the deformations are small and that the stresses are within the elastic range for this problem. 1.5 m A D F 1.0 m 1.0 m H C E P A 2.0 m Figure 3.1: Rigid bar supported by three vertical wires a) Find the normal stresses and the axial displacements in the wires if P = 15 kN. b) Knowing that AB is the critical wire, and its yield stress is oy maximum P that can be applied. = 1500 MPa, find the

A copper bar AB with a length 25 in. anddiameter 2 in. is placed in position at room temperaturewith a gap of 0.008 in. between end A anda rigid restraint (see figure). The bar is supportedat end B by an elastic spring with a spring constantk =1.2 x106 lb/in.(a) Calculate the axial compressive stress sc inthe bar if the temperature of the bar only rises508F. (For copper, use α = 9.6 x10 6 /°F  andE =16 x106 psi.)(b) What is the force in the spring? (Neglect gravityeffects.)(c) Repeat part (a) if k ->∞ .

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