Answer Happy

We perform a fracture mechanics test on a non-standard notched specimen made of a 35Cr-4Mo steel. During the test, the evolution of the load P in N) is acquired as a function of the crack opening displacement d (in mm) as shown in Figure 2. 80000 70000 60000 PA 50000 Applied load P (in N) +0000 30000 d. 20000 10000 P b 0 0 0.1 0.2 0.5 0.6 0.7 0.3 0.4 Displacement d (in mm) Figure 2: Fracture mechanics experiment on 35Cr-4Mo steel. Plan The stress intensity factor for this specimen is given by K, Ра b.e = a with f © - 29-1835•(9) * 43.74(89) -2,017-()*6386 (9) ' 29.6-185.5x +655.7 x x + e= specimen thickness = 20 mm b = specimen width = 40 mm a = crack length = 7 mm Questions: a) Using the above graph, find the value of fracture toughness Kic for 35Cr-4Mo steel material. You must show all steps in your solution, including all construction lines on the graph. b) A pressurized pipe in 35Cr-4Mo steel with interior radius c = 1.0 m and wall thickness e = 60 mm is subjected to an internal pressure variation between zero and AP = 19 MPa. Such pressures result in a cyclic (hoop) stress do in the wall of the cylinder given by: ДРxc Δσ = e Calculate the critical crack length af at which the cylinder would abruptly fail. Assume AK = AOV Ta for cylinders containing a small radial crack of length a.