In a project for the aircraft industry, ALE has optimised the fatigue life of finger doubler repairs. External repair doublers are used to repair damaged aircraft skin panels. For the particular case of fibre-metal laminate skin, fatigue cracks occur in the skin underneath the repair doubler. This leads to inspection problems, which can be avoided if finger doubler repairs are used.
Finite Element (FE) analysis was used to evaluate peak stress for a given design. The FE model is set-up parametrically, such that the pre-processing, analysis and post-processing is fully automated, based on only the design parameters.
From the optimization, a finger doubler design was found, not only avoiding the inspection problems of the reference design, but also having an improved fatigue life and reduced mass.