Uncertainty Assessment for Bulk Residual Stress Characterization Using Layer Removal Method

Background The appearance of part distortion after machining is a recurring issue when manufacturing aerospace parts. Despite the development of distortion calculation and avoidance tools, this issue remains unsolved due to the difficulties in measuring accurately and economically the residual stresses of the machining blanks. In the last years, the on-machine layer removal method has shown its potential for automation and industrial implementation, offering the possibility to obtain the final component from blanks with measured residual stresses. However, the accuracy of this method remains unexplored. Objective Develop an uncertainty assessment procedure for the on-machine Layer Removal method in ribbed geometries and provide guidelines regarding data treatment. Methods A procedure to quantify the error associated with different uncertainty sources is presented and used. Once the main uncertainty source is determined, with Monte Carlo simulations the procedure is evaluated on aluminum alloy 7050-T7451 test-pieces under different data treatment alternatives. Results On-machine probing measurements are the main uncertainty source for the on-machine Layer Removal method for bulk residual-stress characterization. For the studied case, applying symmetry and data filtering reduces the uncertainty range which, is quantified for the different data treatment alternatives. Experimental results agree with simulations. Conclusions The present work demonstrates that the procedure to quantify uncertainty enables a rapid assessment of the bulk residual-stress measurement accuracy in relation to machining distortion.

Automated summary

This study developed an uncertainty assessment procedure for the on-machine Layer Removal method and provided guidelines for data treatment. The main uncertainty source was found to be the on-machine probing measurements. Applying symmetry and data filtering reduced the uncertainty range.