The use of these materials is starting to penetrate aircraft secondary structures. Reducing the material thickness and modulus will negatively affect the vibration response and stiffness of the structure. This is a disadvantage for drivability and comfort. Improved methodologies are needed to combine new materials and processing into structural solutions with optimised vehicle features. Due to the stochastic nature of the structural loads during service, the dominating fracture mode is fatigue.
Cracks develop preferentially at joints such as spot welds, where the local stress is high.
Methodologies to predict and avoid crack initiation need to be developed further. Improved analysis methods are also required to handle reduced margins in optimised designs. Th development of production process parameters to facilitate optimisation of the structural properties in the new materials is a major task. A large number of joining and forming techniques, such as pressing, hydroforming, spot welding, laser welding, friction stir welding, clinching, bonding and combinations of these technologies, are being used or evaluated within the automotive industry. A better understanding of the mechanisms governing these processes is needed.