The MISSP (Manufacturing of Integral Stiffened Skin Panels) project aimed at proposing new manufacturing routes for metallic aircraft cargo doors. The main objectives of MISSP project were the following:
• To achieve further development, integration and validation of metallic technologies such as innovative light-weight alloys, environmentally friendly and low-cost manufacturing processes, and innovative recycling concepts at the end of the product life cycle. This objective was met in WP1 for roll-forming and HEHF manufacturing processes, in WP2 for creep-forming and in WP3 for HEHF. Nevertheless, during WP1 investigations, stretch forming was proven not to be a good candidate and validation of the process was not possible.
• To characterize and evaluate the properties of new light high-strength alloys such as Al-Mg-Sc alloys. This objective was achieved through an extensive preliminary testing campaign which contained (D2.2): Laser beam welding of AA5024 and AA5028 samples, Hybrid laser-GMAW welding of AA5024 and AA5028 samples, Friction stir welding of AlMgSc sheet and Laser beam welding with cold filler wire, and an additional testing campaign at the end of the project which contained (D2.6): LBW of AA5028 base material with AA5025 filler wire in butt-joint and T-joint configuration and investigations of these welds: Intergranular corrosion, tensile tests, liquid penetrant testing, radiography investigations, hardness measurements…
• To develop and combine advanced manufacturing processes such as High energy hydroforming, Creep Forming, Laser or Friction Stir Welding. This objective was met through the manufacturing of WP2 (creep-forming and LBW) and WP3 demonstrators (HEHF).
• To optimize and automate these advanced manufacturing processes through experiments and numerical modelling to increase their efficiency, repeatability and security. All used processes (roll-forming, creep-forming and HEHF) were optimized before and during the manufacturing of the demonstrators. Besides, numerical modelling was performed for stretch-forming. Creep forming and HEHF were numerically modelled leading the manufacturing tests to a successful result.
• To design and manufacture metallic structures applying the developed technologies. This objective was met through WP2 and WP3 parts that were within tolerances. Unfortunately, roll formed WP1 parts were slightly outside the given tolerances of 1mm. HEHF WP1 parts were almost not formed and this process would need improvement in order to get conform parts.
• To validate the properties of the parts and structures after application of the forming and welding processes. One WP1 part was mechanically tested. As expected, material properties were not degraded by this manufacturing process. AA5028 specimens representative of the demonstrators were tested and an additional welding campaign with T-joint specimens with the same geometry than the demonstrators was performed. At the beginning of the project 3DMF carried out a testing campaign on a smaller part representative of the demonstrator.
• To assess the use of these manufacturing processes and advanced alloys for the production of future metallic airframe structures. D4.1 D4.2 and D4.3 presented the cost of the manufacturing of related parts. Besides, the estimation of serial production cost was made when possible.
• To reduce the overall lead time and production costs for the manufacturing of cargo door structures by limiting the number of parts and assembly operations. WP4 shall evaluate possible cost savings and lead time reduction associated to each of the three design concepts proposed in this project. In particular, the reduction of assembly operations was achieved in WP3 with the integral cargo door. Cost savings and improvements are given through the WP4 deliverables.
