Research on machining distortion due to residual stresses of large monolithic beam

Machining-induced distortion of large monolithic parts with thin walled structures creates problems in aircraft manufacturing industry. Typical monolithic beams of airframe are machined by NC machine and machining distortions are recorded. Thin walled structures are prone to distortions and dimensional instabilities due to internal stresses; therefore, stress-relieved vibration method is applied to reduce the internal stresses in blank material and results in better machining performance and dimension stability. But vibration stress-relief method doesn't work always due to unknown reasons. Machining simulations in ANSYS are performed to predict the residual stress-induced machining distortion and simulation result is compared with the machining measurements to validate the simulation process. Cutting simulations have been executed by the element deactivation technique after developing the initial residual stresses via sequential coupled field analysis. The possibility of residual stress being relieved more reasonably and less distortion by optimized machining sequence through simulation is discussed.