A new method for inferencing initial residual stress distribution in structural titanium alloy components incorporating prior knowledge of machining-induced residual stress

The initial residual stress (IRS) remained in the stock material of titanium alloy is resulted by various material forming and preparation processes, which is a main cause of machining deformation of structural components. Modeling IRS across a stock material is essential for accurate prediction and control of machining deformation. This paper reports a new method for inferring the distribution of IRS, that is, initial residual stress field (IRSF) based on monitored deformation force during machining, incorporating a prior knowledge of machining-induced residual stress (MRS) distribution. The main problem to be resolved is the difficult-to-measure and high residual stress induced during the machining process which significantly affects the determination of IRSF. This research first established the mechanical relationship between respective IRSF, MRS and deformation force of a component, and developed a cutting simulation model for predicting MRS. The predicted MRS was treated as a prior, which was integrated into the mechanical relationship, to infer IRSF across the component based on the deformation force. The method was validated by both simulation and real experiments on an aviation titanium alloy structural component. The simulation results shown that under the two sets of simulation data, the inference accuracy was improved by 81% and 53%, respectively, compared with the method without considering the prior knowledge of MRS. The experimental results shown that the root mean square error between the predicted deformation and the actual deformation was 0.078 mm, based on the obtained IRSF, which proved the effectiveness of the proposed method and demonstrated that the method provided reliable support for controlling the machining accuracy of titanium alloy components.