Creep forming of Al-Li alloys

Research on Creep Forming Technology of AI-Li Alloy for double curvature skin with variable thickness

Investigators

COMAC supervisors and contact details:

Researchers at COMAC - TBA

Imperial supervisors and contact details:
Dr Zhusheng Shi

Professor Jianguo Lin

PhD student:
Mr Xi Wang

Project overview

Lightweight and high performance are the two key targets to improve payload, reduce exhaust emission and guarantee safety of commercial airplanes, and are being enhanced by new developments in both material and structure sides. In the material side, third-generation Al-Li alloys have been recently developed to achieve higher stiffness and corrosion behaviour with lower density than conventional aerospace aluminium alloys, such as 2000 series Al Cu Mg and 7000 series Al Zn Mg alloys. Meanwhile, skin panels with pre-designed varying thickness to achieve the required stiffness with the lowest weight of the structure become popular for aerospace products. Hence, manufacturing the advanced Al-Li alloy panels with varying thickness is of great significance to advance the development of commercial airplanes with higher quality, safety and energy efficiency.

Creep age forming (CAF) process has been well proven as a more efficient and accurate technology to manufacture large aerospace panels (such as wing skins) than conventional technologies, such as rolling, stamping and bumping. Many conventional aerospace aluminium alloys (Al Cu Mg and Al Zn Mg alloys) have been successfully formed by CAF process, and thus the process has the great potential and feasibility to manufacture panels with advanced Al-Li alloys. However, the complicated precipitation behaviour of Al-Li alloys during artificial ageing lead s to the asymmetric tension/compression creep ageing behaviour, which significantly raises the difficulty for CAF manufacture of Al-Li alloy panels with high accuracy. This project will enable the industrial application of CAF technology to advanced Al-Li alloy for aeronautical products.