New Technologies for Shot and Laser Peen Forming of Wing Skins

Abstract:  Aircraft wing panels have a complex shape that are subjected to cycling loads in service.  Wing panels are often machined from thick aluminum plate, then shot peen formed.  In addition to providing the required contour, the compressive residual stress from shot peen forming a flat panel provides resistance to high cycle fatigue.  In the past, the development of a shot peening scheme was an iterative process developed over many shipsets.  Now, that is no longer the case. With recently developed proprietary software, it is now possible to create a shot peening map modelling peening intensities across the surface of the skin.  Also, the flat pattern required for machining the skin can be calculated from the computer model of the finished part so the details such as access holes, lands and pockets are correctly located.  In addition to wing skin panels, structural components that have distorted due to residual stresses from machining or heat treating can be made acceptable by corrective shot peen forming.  This modelling approach to development of corrective shot peening allows a more accurate approach.  This paper will also cover the greater depths of residual stress and increased accuracy of laser peening when compared with conventional shot peening allowing for application to thicker components.