Finite element and experimental studies of springback in sheet metal forming

grantor: University of TorontoThe ultimate goal of the metal forming industry is to form components made of a specific material into a required shape without experiencing wrinkling, bifurcation and springback. Of the aforementioned difficulties, attention in this thesis is devoted to springback resulting from unloading following stretch forming. In spite of the exhaustive application of the process to form many engineering components, the design and selection of sheet materials and tooling geometry to minimize springback still rely on the elusive trial and error approach. It is thus the objective of this thesis to avoid the ad hoc approach by analyzing the process using the finite element method. Three aspects of the current problem are accordingly investigated. The first is concerned with the development of a finite element model of the stretch forming process accounting for material and geometric nonlinearities, and interface conditions using ANSYS software. The second aspect of the work is concerned with the springback experienced by the deformed sheet following the punch release stroke. In the third, attention was focused to the validation of the invite element models. Two alternative test rig designs were developed to test the axisymmetric and the plane strain models. However, in view of cost and time limitations, only the plane strain stretch forming rig was built to test the corresponding FE model. The technique was then applied to a case study concerning the stretch forming of a rear bulkhead for an aircraft. (Abstract shortened by UMI.)M.A.Sc