1. Using a single edge notched bend specimen of nodular cast iron, a Jic test is performed based on the unloading compliance technique. In figure la the measured load P is plotted as a function of the load displacement v. From these data the slope of the P-v curve during the different unloading-loading cycles are found as follows: no. slope [N/mm] 123 45 19200 18800 17600 15800 13300 (no crack growth yet) 6 11000 For specimens with this geometry and made of this material the relative crack length a/W is plotted in figure 1b as a function of the compliance C. Other data are: Material: Young's modulus E = 200 000 MPa yield strength Sys = 350 MPa ultimate tensile strength Suts - 450 MPa Specimen: thickness B = 7 mm height W=4B a) Roughly indicate the positions of the J-Aa points in figure 1c, as they follow from the experimental results. Be sure to add numerical values to the vertical axis. J may be calculated without making a distinction between elastic and plastic displacements. b) Explain how crack tip blunting is quantified for a Jic test. Indicate this in figure 1c. The critical J value according to ASTM E 813 is defined as the value after 0.2 mm of stable crack growth. c). d) In figure 1c, draw the line that represents this stable crack growth. Roughly show in figure 1c how the critical J-value, Jie, is obtained. 3000 2500 2000 1500 1000 500 0 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Figure la v [mm] 14 1.1 1.2 1.3 J [N/mm] a/W[-] 0.80 0.75 0.70 0.65 0.60 0.55 0.50 30 30 Figure 1b 40 40 50 60 70 80 90 100 110 120 130 140 C 1E6 [mm/N] 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 2.2 2.4 2.6 Aa [mm] Figure 1c