Design and analysis of aircraft sheet metal for spring back effect

Abstract

Since sheet metal forming industry has become one of the major manufacturing centers for automobile, aerospace and defense industries, the popularity of sheet metal products is attributable to their light weight, great interchangeability, good surface finish and low cost. There has been a growing interest during the past decade in using finite element method for spring back prediction following formation of arbitrary shapes. While it is apparently simple in concept, the prediction of spring back has proven challenging for a variety of reasons, including numerical sensitivity, physical sensitivity and poorly characterized material behavior under reverse loading and unloading conditions. Spring back of sheet metal parts after forming causes deviation from the designed target shape and produces downstream quality problems as well as assembly difficulties. It’s economic impact in terms of delayed production, tooling revision costs and rejection of unqualified parts is estimated to $50million/year in the U.S. automotive industry alone. It is obvious that controlling spring back is a vital concern in manufacturing.