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Economic Advanced Shaping Processes for Integral Structures


A higher degree of integration during aircraft structure needs to be developed, which will save weight and reduce manufacturing costs, for example a reduction in assembly cost (riveting process) by laser welding (e.g. fuselage) or integral machining (e.g. wing structures). For such new concepts, the current manufacturing chain has to be altered, unifying the forming steps and shifting this new step further towards the end of production. This enables more processing, such as machining, pocketing, welding, to be done in a flat condition to achieve the full cost reduction potential.

Project objectives

1. Forming stiffened structures to a single curvature of 1 250 to 3 000mm radii along stiffeners.

2. Forming bi-axially curved structures with an additional 10 000 mm radius across stiffeners.

3. Verification of estimated shell manufacturing cost reduction of 10% by more processing in a flat condition and a further 10% by avoidance of heavy and complex tooling.

4. Shell weight reduction of 10% using new alloys, which are less useful with conventional forming.

Description of the work

The objectives will be achieved by developing laser-forming methods to create 3D shapes from flat sheet material or even flat stiffened panels (Fig. 1 after conventional forming) using a controllable non-contact laser approach, eliminating expensive dies and forming tools. This requires the implementation of innovative techniques on a manufacturing scale and an understanding of the laser beam forming steps. To reach this goal, the project is organised into five technical Work Packages. The objective of Work Package 1 (Processes and materials basics) is to analyse basic influences of laser forming on the selected Al alloys. Work Package 2 (Process development and characterisation) is the central Work Package and includes process development and up-scaling, plus simulation implementation coming from Work Package 4. The objective of Work Package 3 (Biaxial curvature capability enhancement) is to cope with stiffened, bi-axially curved generic shapes. Work Package 4 (Simulation and verification) deals with process simulation. The main objective is to forecast the laser forming behaviour with a detailed 3D local model integrated in a ‘less’ detailed 2D global model, serving as a reference fast benchmark model to be used as an input to the control unit developed in Work Package 2. Work Package 5 (Economical evaluation and dissemination) has to verify the third main project objective by the economical evaluation of the laser-based forming processes developed during the project.

Expected results

The main aim is to develop laser-forming processes for integral fuselage and wing structures. Thus, relevant laser parameters with respect to minimum material degradation and maximum formable sheet thickness are evaluated. A simulation tool for the forming process is built up and integrated into a control system. The key to process control is to develop a predictive model to provide scanning strategies based on a required geometry. This system will include online 3D shape measurement to enable straight-line laser forming to the required final geometry

Process principle and fuselage panel after conventional forming and LBW of stringers
Process principle and fuselage panel after conventional forming and LBW of stringers