Simulating residual stresses formed in the technological sequence of shot-impact treatment–flap-wheel trimming

The paper aims to study the stress-strain state of the surface layer in a VT95 aluminum alloy part during its shot-impact treatment in the sequence of “shot-impact treatment–flap-wheel trimming” operations. The research objects included large parts, such as panels and cladding of complex shapes used in aircraft, missile, and shipbuilding industries. Computer simulation in the Ansys Workbench 19.0 software package was used to develop a methodology for determining residual stresses. As a result of simulating the studied treatment sequence, a visual representation of the residual stress formation pattern, as well as physical values and distribution curves of residual stresses, were obtained. The distribution pattern of residual stresses after performing two types of treatment was established to be similar. The maximum value of residual stresses, obtained as a result of performing a shot-impact treatment of the part surface with a shot of 3.0 mm in diameter at a shot-impact rate of 25 m/s, reaches about 600 MPa at a depth of 1.0 mm. Following the shot-impact treatment, flap-wheel trimming is performed in the finite element simulation as a set of abrasive grains at a rate of 18.316 m/s. The removal of the 25-, 50-, and 75-μm layer from the surface of the plate during trimming contributes to the shearing of the upper part in the residual stress diagram and, as a result, to a decrease in the values of residual stresses in the shot-impact treatment–flap-wheel trimming sequence to 400 MPa. In addition, along with an increase in the thickness of the layer removed from the surface during trimming, the value of residual stresses decreases more slowly. In this case, the thickness of the removed layer causes no effect on the depth of residual compression stresses (about 0.7 mm). The developed finite element model makes it possible to predict and control the level and magnitude of residual stresses in an aluminum alloy sample at the stage of its preparation for both a shot-impact treatment operation and the combination of shotimpact treatment and flap-wheel trimming.