Investigation of residual stress distribution in single point incremental forming of aluminum parts by X-ray diffraction technique

Abstract

Knowledge of the residual stress magnitudes induced during the manufacturing process is of interest since these could affect the structural integrity of manufactured parts depending on whether these are in tension or compression. It is also well known that in a wide variety of aerospace components subjected to external loads during work service, only the compressive residual stresses are acceptable. Therefore, the aim of this work focuses on determining residual stresses and their effects created along aluminum parts manufactured by single point incremental sheet forming (SPIF) process. Experimentally, the residual stresses induced during the SPIF process of the formed parts are estimated by using the X-ray diffraction technique on the inner and outer surfaces. It was found that the recorded residual stresses were changing from tensile to compressive ones along the formed part which is an indication of bending effects. Analytical evaluation of these effects reveals that the magnitude of the bending stress distribution is significant when compared to the material yield stress. Furthermore, the variation of sheet thickness was recorded in the same regions at which the XRD measurements were recorded. Experimental data show that there is a correlation between the residual and bending stress distributions with respect to the variation of the sheet thickness that affects the microstructural evolution of the aluminum parts.