Residual stresses due to roll bending of bi-layer Al-Cu sheet: Experimental and analytical investigations

Abstract

Applications of bi-layer sheets are developing in different industries. In many cases, manufacturers need to form bi-layer sheets to a desired curve by roll bending process. This process can induce considerable residual stresses. In this article, the residual stress distribution due to bending to specified curvature radius is measured in an Al-Cu sample. The sample is bent by three roll bending process to curvature radius of 350 mm. The slitting method is extended to measure induced residual stresses in bi-layer sheets. Also, an analytical solution has been proposed for prediction of residual stresses in bi-layer sheet. The analytical solution has been derived for material with elastic-power law hardening plastic behavior as the actual behavior of aluminum and copper is. Also in the analytical solution, the neutral axis movement due to different elastic moduli of aluminum and copper layer is considered. A maximum and minimum of measured residual stresses equal to 35 and 228 MPa, respectively, showing a remarkable magnitude in comparison with 51 and 36 MPa yield strength of copper and aluminum layer, respectively. Comparing the results show good agreement between analytical solution and experimental results.

Microstructure and mechanical properties characterization of architectured copper aluminum composites manufactured by cold-drawing

“…The coupled effect of this difference in elastic properties and yield strength results in residual stresses induced during the process [39,40,41]. Following the analytical computations by Bullough and Hartley [41] of residual stress in a 50%-Al CCA wire strained up to 4 (equivalent to a 1 mm-diameter CCA wire in this study), axial compressive stresses of about 80 MPa are expected in aluminum, whereas there would be around 70 MPa of tensile stress in copper.…”

Experimental study and finite element modelling of pure copper tube fabrication via the Parallel Tubular Channel Angular Pressing (PTCAP) Process

“…The increase in hardness homogeneity is because of the backpressure that decreases the changes that occur during the PTCAP process. Also, the variation of hardness is related to both the dominant mechanisms in the PTCAP process such as grain refinement and work hardening [33][34][35][36][37]…”

Residual Stress in Engineering Materials: A Review

“…In this formulation, the neutral axis movement due to different elastic moduli of the two layers was taken into account, and the results were in good agreement with those of slitting measurement. [ 146 ] In the work by Song and teammates, process‐induced residual stresses in the double‐ceramic‐layer thermal barrier coating systems were theoretically predicted using a new model. The influence of critical process parameters on the residual stresses was also investigated, and the model was successfully verified through comparisons with FE results.…”