Continuous ultrasonic welding of thermoplastic composites. LCI Modelling for the Eco-Statement

Fraunhofer, Delft University of Technology (TUD) and University of Stuttgart - IABP are part of Clean Sky (CS), the largest European research programme for the development of the aeronautics industry. The programme focus on reducing aviation's environmental impacts, analyzing and quantifying the environmental footprint of air vehicles. Fraunhofer, the leader of Eco-Design Transversal Activity in Clean Sky, is responsible for the creation of the Clean Sky Environmental Database. This database aims at supporting the project partners in verifying whether the new technologies and demonstrators offer the expected environmental benefits. Life Cycle Inventories (LCI) from aircraft technologies have been developed together with CS partners such as the University of Stuttgart - IABP for the performance of the Life Cycle Assessments (or eco-statements). TUD has developed an innovative continuous ultrasonic welding process for thermoplastic composites, which is used for joining different thermoplastic parts, e.g. skin panels and omega stringers to produce stiffened fuselage panels. The main process parameters are force, amplitude of vibration and speed. Force and amplitude of vibration are responsible for the rate at which heat is generated during the welding process and, hence, define the range of welding speeds that result in high-strength welded joints. The process needs an additional similar thermoplastic material as an energy director to focus the ultrasonic energy on the welding zone. In the test case the parts have a thickness of approximately 1.85 mm. The expected technical and environmental improvements are increased efficiency, less waste, higher performance, increased recyclability and lower energy consumption compared to the reference technology. The LCI model for this process is ready to be considered in an LCA of a thermoplastic ultrasonic welded demonstrator. The model includes two life cycle phases: material and energy production; and manufacturing. End of life phase will be considered in the modelling at demonstrator level.