PSI - Issue 14

Puneeth N et al. / Procedia Structural Integrity 14 (2019) 53–59 Author name / Structural Integrity Procedia 00 (2018) 000 – 000

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Figure 1 Typical optical micrographs of Hybrid MMC’s Observations for the following values were taken Wt.% for B1, B2, B3 was taken as 3% and for B4, B5, B6 was taken as 6%, B7, B8, B9 was 9%.Stir time for B1, B6, B8 was recorded as 8 min, for B2, B4, B9 it was 10 min and for B5, B3, B7 as 15 min.Stir speed for B1, B4, B7 was given as 150 rpm, for B2, B5, B8 as 200 rpm and for B3, B6, B9 as 250 rpm. The Fracture toughness- J integral test was carried out which was done on SENB specimen with width 25 mm and the thickness 12.5 mm. SENB specimen was done in two steps. The first step is fatigue pre-cracking up to a/w ratio is 0.45 and the second step is J Ic test of prepared specimen. Each SENB specimen was fatigue pre-cracked by machine to generate a sharp initial crack. SENB specimen was made to set up so that line of action of applied load passes midway between the support roll centers within ± % of the distance between centers. Measure the span length withn±0.5 % of the nominal length. When the load-line displacement measurement is referenced from loading jig there is a potential for introduction of error from two sources. They are elastic compression of fixture as load increases and indentation of specimen at loading points. For this type of three-point bend specimen test as load applied the corresponding displacement curve is plotted. And the area under the curve is found in square millimetres. Area under the curve is measured and is cross hatched. And this area is used in respective formula to evaluate J pl value. Finally Validation of J Q as J Ic checked using J Q = J Ic if, B> 25 and b 0 > 25 . Table 2: Fracture toughness values of 9 SENB specimens Here a/w ratio=0.45 and f (a/w) = 2.8 Specimen in MPa E in Mpa Peak load in N K i in MPa√m J Ic in MPa√m B1 126.61 2826.116 3180 17.4699 49.2802 B2 142.88 975.956 3600 19.7772 60.2645 B3 141.45 904.411 3180 17.46 72.3135 B4 145.24 905.486 3720 20.4365 61.1761 B5 175.89 1057.031 3480 19.118 83.7600 B6 140.99 1015.778 3240 17.799 59.8415 B7 149.08 991.223 4020 22.0846 61.5142 B8 148.72 1332.616 3660 20.1069 49.8499 B9 149.75 1192.277 3480 19.0967 60.9135