B oris Spak

Abstract

The use of structural components in the aviation space places high demands on the safety under static and cyclic loading conditions during the total operating time. With immerging innovative developments in the production of thin-walled sheet metal components, savings in energy consumption and material are achievable by switching from metal-cutting production to forming operations. As the forming process has an impact the local material properties due to cold working, resulting residual stress state and surface finish, the fatigue life estimation requires the consideration of the forming history.

The structural component under consideration from aluminum alloy 7475 T761 is manufactured by automated, robot-assisted roll forming. Local changes in mechanical material properties are assessed trough hardness measurements and microscopic surface examination. Potentially existing residual stresses are determined via process simulation of the angled profile utilizing commercial finite element solver LS-Dyna. The process simulation is validated by comparison to the physical component. Local strains in the vicinity of the assumed failure location in cyclic loading regime are determined using full-field displacement measurements. A comparison to the results of a loading simulation with appropriate boundary conditions is carried out. The fatigue life assessment is performed using the Local Strain Approach.

The process-structure-property relationships are evaluated with respect to crack initiation for different tooling paths. The knowledge gained will be used to specifically control the roll forming process in the future in order to maximize the component performance of the lightweight structure.

Session