112 M.D. Olson et al. 0 10 20 30 40 50 60 70 80 −800 −600 −400 −200 0 200 400 600 x (mm) Stress (MPa) s1 s2 s3 s4 s5 s6 Mean±Std 0 10 20 30 40 50 60 70 −800 −600 −400 −200 0 200 400 600 y (mm) Stress (MPa) s1 s2 s3 s4 s5 s6 Mean±Std a b Fig. 16.16 Line plots of individual measurements (dashed) and the mean and repeatability standard (solid black) for the nickel disk samples along the (a) x-direction at y D3.18 mm and (b) along the y-direction at x D40.52mm 60 80 100 120 140 160 180 200 220 0 10 20 30 40 50 60 E (GPa) Repeatability Std (MPa) Al T−section Ti plate Ni disk SS forging SS DM plate median mean 75th percentile 95th percentile Fig. 16.17 Repeatability standard deviation versus elastic modulus (E) 16.5 Summary/Conclusions Five repeatability studies were performed using an aluminum T-section, a stainless steel plate with a dissimilar metal slotfilled weld, a stainless steel forging, a titanium plate with an electron beam slot-filled weld, and a nickel disk forging. Each repeatability study included five to ten contour method measurements and determined the repeatability standard deviation. The results of the repeatability studies show consistent levels of repeatability over most of the specimen interior and localized regions of higher variability (typically along the part perimeter). The mean repeatability standard deviation ranged from 5 MPa for the aluminum T-section to 35 MPa for the stainless steel forging, which represent the minimum and maximum values of the population. Similarly, the value of the 95th percentile repeatability standard deviation ranged from 15 MPa for the aluminum T-section to 85 MPa for the stainless steel forging.
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