Rigid bar ABC is supported by two identical solid bronze [σY = 331 MPa; E = 105 GPa; α = 22.0 × 10−6/°C] rods and a single solid steel [σY = 250 MPa; E = 200 GPa; α = 11.7×10−6/°C] rod. Bronze rods (1) each have diameters of d1 = 26 mm and lengths of L1 = 3.3 m. Steel rod (2) has a length of L2 = 4.4 m. (a) Calculate the diameter d2 required for steel rod (2) so that the deflection of joint B is zero for any change in temperature. (b) Using the value of d2 determined in part (a), determine the maximum temperature decrease that is allowable for this assembly if a factor of safety of 2.4 is specified for the normal stress in each rod. Since the temperature is decreasing, the answer should be negative.
Rigid bar ABC is supported by two identical solid bronze [σY = 331 MPa; E = 105 GPa; α = 22.0 × 10−6/°C] rods and a single solid steel [σY = 250 MPa; E = 200 GPa; α = 11.7×10−6/°C] rod. Bronze rods (1) each have diameters of d1 = 26 mm and lengths of L1 = 3.3 m. Steel rod (2) has a length of L2 = 4.4 m.
(a) Calculate the diameter d2 required for steel rod (2) so that the deflection of joint B is zero for any change in temperature.
(b) Using the value of d2 determined in part (a), determine the maximum temperature decrease that is allowable for this assembly if a factor of safety of 2.4 is specified for the normal stress in each rod. Since the temperature is decreasing, the answer should be negative.
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