Figure 2. 290 20 1196 NiCrMoV Bend Bars . 474 by. 394 by 2.16 200F Energy per Unit Thickness at a Given Deflection, in. lbs./in. 80 7723 160 8-.025 8 = .020 120 6 = .015 8 - .010 40 .10 1 .15 .20 .25 .30 .35 Crack Length, inches Energy per unit thickness vs crack length data for a rotor steel bend specimen for various deflections determined by Begley and Landes. 1. Begley and Landes determined the J Integral for a Ni-Cr-Mo-V Rotor Steel by evaluating the load (P) versus deflection (8) curves in 3 point bending as a function of the crack length. The specimen geometry is shown in the drawing below. The load and the deflection are measured at the loading point for samples with various crack lengths that are tested to failure. The energy required to produce a given deflection is shown in the attached figure as a function of crack length. (a) Using this information, calculate the J Integral for each of the deflections shown for a crack length of 0.25 in. (b) For this crack length, fracture occurs at a deflection of about 0.024 in. Estimate the J Integral value at which fracture occurs and from that estimate the plane strain fracture toughness of this steel. P P 2 W a W = 0.474 in. B = 0.394 in. B P 2