Research Article
Mechanical Properties Optimization of Friction Stir Welded Lap Joints in Aluminium Alloy
Table 9
Results of elongation analysis of variance (nugget zone).
| Estimated effects and coefficients for avg. El (coded units) | Term | | Effect | Coef. | SE coef. | T | | Constant | | — | 19.417 | 0.5612 | 34.60 | 0.018 | rpm | | −19.500 | −9.750 | 0.5612 | −17.37 | 0.037 | s/mm | | −3.500 | −1.750 | 0.5612 | −3.12 | 0.198 | rpm ∗ s/mm | | 0.833 | 0.417 | 0.5612 | 0.74 | 0.593 | Ct Pt | | — | 9.850 | 1.089 | 9.04 | 0.070 | | | S = 0.619324 | R2 = 99.82% | R2(adj) = 99.09% | | |
| Analysis of variance for avg. El (coded units) | Source | DF | Seq. SS | Adj. SS | Adj. MS | F | | Main effects | 2 | 179.25 | 149.80 | 74.90 | 195.26 | 0.051 | 2-Way interactions | 1 | 0.256 | 0.211 | 0.211 | 0.55 | 0.593 | Curvature | 1 | 31.37 | 31.37 | 31.37 | 81.80 | 0.070 | Residual error | 1 | 0.384 | 0.384 | 0.384 | — | — | Pure error | 1 | 0.384 | 0.384 | 0.84 | — | — | Total | 5 | 211.26 | — | — | — | — |
| Estimated coefficients for avg. El using data in uncoded units | Term | Coef. | | | | | | Constant | 71.56 | | | | | | rpm | −0.026 | | | | | | s/mm | −23.51 | | | | | | rpm ∗ s/mm | 0.0074 | | | | | | Ct Pt | 9.85 | | | | | |
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