Investigation of through thickness residual stress distribution and springback in bent AL plate by slotting method

Residual stresses generated during the manufacturing process have direct effects on product life cycle and properties. Thus, it is essential to understand the effects of processing on residual stress distribution. In this paper, a technique for through thickness residual stress measurement was developed and tested experimentally. In this technique, a bent plate slotted in the middle of the concave surface leads to springback of the plate. The residual stress distribution and springback induced by local material removal are theoretically analyzed. This "slotting method" is more convenient than other relaxation methods because it is determined directly from the data and does not require tedious inversion; additionally, it allows the determination of a springback map through thickness residual stress distribution. Here, the research object was a 30-mm-thick aluminum alloy plate that had remaining thickness residual stress induced by bending, and the slotting processes were carried out with FE simulation and experiment, respectively. The simulation results on the residual stress distribution shows consistence with the analytical results. Furthermore, the slotting processes with different groove depths and locations were also investigated. The measured springback data shows minor deviation from the numerical analysis, which verifies that the technique provides a reasonable assessment of the through thickness residual stress distribution and springback.