Contour Method Residual Stress Measurement Uncertainty in a Quenched Aluminum Bar and a Stainless Steel Welded Plate

This paper describes a newly developed uncertainty estimate for contour method residual stress measurements and presents results from two experiments where the uncertainty estimate was applied. The uncertainty estimate includes contributions from random error sources including the error arising from noise in displacement measurements and the smoothing of the displacement surfaces. The output is a two-dimensional, spatially varying uncertainty estimate such that every point on the cross-section where residual stress is determined has a corresponding uncertainty value. The current paper describes the use of the newly developed uncertainty estimate in a quenched aluminum bar with a cross section of 51 × 76 mm and a stainless steel weld plate with a cross-section of 25.4 × 152.4 mm, with a 6.35 mm deep groove, filled with a multi-pass weld. The estimated uncertainty in the quenched aluminum bar is approximately 5 MPa over the majority of the cross-section, with localized areas of higher uncertainty, up to 10 MPa. The estimated uncertainty in the welded stainless steel plate is approximately 22 MPa over the majority of the cross-section, with localized areas of higher uncertainty, over 50 MPa.