Blank design for the stretch forming of aircraft skin

In this article, a new approach is proposed for the manufacture of aircraft skin. Based on the optimal designed flatten blank with pockets pre-machined, stretch forming process is employed to form the designed aircraft skin. This approach relatively increased the accuracy of pockets shapes and thickness value and reduced the machining difficulty on the curved surface compared with the traditional method that the pockets are machined after the blank deformed. To study the feasibility of this method, FEA software was used to conduct the numerical simulation to obtain CAD data of the deformed part. Then the profiles of the pockets were dispersed with numerous points and the correspondence relationships were set up among the designed pockets on flat blank, formed pockets and the target pockets. To improve the blank design, shape sensitive method was employed by evaluating the offset influence of two designed blanks on the formed pockets profiles. It could decrease the numbers of iteration in blank design and reduce the shapes deviations between the formed pockets profiles and the target pockets profiles.