Influence of anisotropy of sheets from aluminum-lithium alloy 1441 on the springback after stretch-wrap forming

Computer simulation of the stretch forming process with different anisotropy of properties in the software package PAM-STAMP 2G was implemented in the work. The design of the multivariate experiment was made to analyze the effect of the anisotropy of the mechanical properties on the springback of the skin after stretch forming. The optimal combination of anisotropy coefficients, ultimate strength, yield strength and uniform elongation that minimizes springback of the finished skin was established. After modeling of all variants of a covering the regression analysis of results is carried out and the mathematical model of dependence of a spring on anisotropy of properties is made. It was found that to minimize the springback variation of the skin blank must be property oriented relative to the press table: the stretch forming direction must coincide with the direction of maximum anisotropy coefficients, and the transverse direction of the stretch forming must coincide with the minimum of anisotropy coefficients. Using known methods of finding the global minimum of the function it defined was the optimal anisotropy of mechanical properties, providing the minimum springback for the considering scheme of stretch forming of skins from aluminium-lithium alloy 1441. To whole, it is recommended to enterprises to provide an input control not only on mechanical properties, but also on the coefficients of lateral strain, i.e. anisotropy, as they have the greatest impact on obtaining the required shape of the product.