5. A beam has a rectangular cross section. It is 10 mm deep and 25 mm...

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5. A beam has a rectangular cross section. It is 10 mm deep and 25 mm wide. It has a total length of 600 mm. It is made of three sections each 200 mm long, which are welded together. Failure occurs at the welds. The yield and tensile strengths of the welds are 450 MPa and 550 MPa, respectively. Fatigue of the two welds follow Basquin's Law of No=860 MPa The beam is simply supported (pin joints). It supports a constant point load of 1.0 kN located at 200 mm from one end of the beam (over one weld), and an oscillating point load located at 200 mm from the other one end (over the other weld) that varies between -600 N and +600 N. 1000 N 600 N to -600 N 200 mm 200 mm 200 mm 25 mm 10 mm a) b) Calculate the life-time of each of the two welds. (1.5 x 105, 3.7 x 104 cycles) After 2x104 cycles, the beam is removed from its supports, inspected and then replaced. However, when it is replaced, it may be rotated end-to-end (but not flipped up-side down). Estimate (i) the minimum and (ii) the maximum remaining life-time of the beam. (1.65 x 104, 3.2 x 104 cycles) 5. A beam has a rectangular cross section. It is 10 mm deep and 25 mm wide. It has a total length of 600 mm. It is made of three sections each 200 mm long, which are welded together. Failure occurs at the welds. The yield and tensile strengths of the welds are 450 MPa and 550 MPa, respectively. Fatigue of the two welds follow Basquin's Law of No=860 MPa The beam is simply supported (pin joints). It supports a constant point load of 1.0 kN located at 200 mm from one end of the beam (over one weld), and an oscillating point load located at 200 mm from the other one end (over the other weld) that varies between -600 N and +600 N. 1000 N 600 N to -600 N 200 mm 200 mm 200 mm 25 mm 10 mm a) b) Calculate the life-time of each of the two welds. (1.5 x 105, 3.7 x 104 cycles) After 2x104 cycles, the beam is removed from its supports, inspected and then replaced. However, when it is replaced, it may be rotated end-to-end (but not flipped up-side down). Estimate (i) the minimum and (ii) the maximum remaining life-time of the beam. (1.65 x 104, 3.2 x 104 cycles)