Airframe life extension by optimised shape reworking - Overview of DSTO developments

Abstract

The Defence Science and Technology Organisation Australia (DSTO) has developed a unique life extension approach, where optimised rework shapes are designed and implemented at critical airframe features. These shapes are used to remove local cracking, and also to minimise the peak stresses. The free-form optimal shapes are obtained using an iterative gradientless finite-element method, which is based on an analogy with biological growth. This paper covers the robust design approach, lessons learned from practical applications, fatigue trends, and improved and efficient in situ manufacturing methods. An important aspect of the this work has been the transition from theory and generic developments to practical applications. It is shown that large increases in fatigue lives and inspection intervals can be achieved with appropriate design. © Commonwealth of Australia 2009.