Prediction of longitudinal residual stress distribution in cold-formed square hollow sections

Considering the characteristics of roll-forming, springback and microstructure changes during the welding process, the longitudinal residual stresses (LRS) of cold-formed square hollow sections (CFSHS) in the roll-forming and high-energy welding processes was simulated with finite element method. It is concluded that LRS of CFSHS at the outer and inner surfaces are basically equal in value and opposite in direction, the LRS maximum did not appear at the inner or outer surfaces, the corner LRS maximum is greater than the flat maximum, and its distribution along the thickness direction is similar to "sin" curve distribution. Although the high-energy welding process shall make the LRS of CFSHS significantly improved near the weld, but the effect is limited for the whole section.