Creep Age Forming
The advantages of replacing conventional structures with lightweight alloys are many, however significant challenges in forming lightweight alloys, such as aluminium, remain. The focus of my research is new lightweight alloy forming processes such as the creep age forming (CAF) technique. In comparison with conventional metal forming processes, CAF can form structures with better mechanical properties and lower residual stresses at lower manufacturing costs. This technique, which is suitable for forming large integral panels with complex curvatures and abruptly changing thicknesses, is considered to be one of the most important metal forming techniques for next-generation aircraft.
CAF is a forming method combining forming and ageing heat treatment, in which the creep phenomenon takes place. In a CAF process, the alloy is elastically loaded onto a former and held at its artificial ageing temperature for a predetermined period of time. Under thermal exposure, material constituents of the metal precipitate and alter the microstructure and the mechanical properties of the alloy. While partial permanent deformation in the material is achieved through the synchronous occurrence of age-hardening and stress relaxation by creep. When the loading is released, the material sheet springs back to a shape somewhere between its original shape and the tool shape due to elastic recovery of stress. The key issues in this process are to control the change of the material properties and the springback of the formed alloy, which will be the central objectives of my work.
Dr Aaron C Lam
Ms Xia Huang