Numerical Simulation of the Twist Deformation for the Stiffened Panel with Laser Forming

In the laser forming process of the panel with crossed reinforcing bars (PWCRB), a kind of stiffened panel, twisting of the panel occurred when it was formed under the integral continuous scanning strategy (ICSS). The twisting was restrained obviously when the middle stiffener was heated. In order to reveal the twisting mechanism, a FE model was established and corresponding simulations were conducted. Furthermore, an equivalent model of the sectional structure was established, and a model of the buckling critical load of the stiffener was established based on principle of minimum potential energy. It revealed that the buckling critical load of the middle stiffener was smaller than that of the marginal stiffener. The simulation results showed that the stiffeners suffered from pressure and bending moment during the forming process, which tended to induce the buckling of the stiffeners. Besides, the residual stress of the middle stiffener was larger than that of the marginal stiffener. The bending angle of the middle stiffener increased when it was heated. Besides, the lateral-torsional deformation of the middle stiffener decreased and the twisting of the panel was restrained. It demonstrated that the twisting phenomenon of the PWCRB was caused by the middle stiffener, which suffered from lateral-torsional buckling when the panel was formed with the ICSS.