Nowadays, the manufacturing of aerospace composite structures is done in a high-tech production environment using robotic equipment for processing and assembling aerospace (sub) structures. The certification according stringent airworthiness requirements is done based on these automated and controlled manufacturing processes. But in case of damages to the composite structures, repair can only be done by manual repair processes. Compared to the automated and controlled manufacturing processes these manual repair processes are less reproducible.
The challenge is to develop automated repair methods and processes with a reproducibility compared to the manufacturing processes. To reach this target a lot of fundamental and industrial research work has to be done. Shortening the repair time is necessary because the time that an aircraft can stand on the ground for repair is limited. Automation is necessary to shorten the repair time and enables you to work with very accurate lasers, allowing for a customised replacement of the material.
Innovation Track 6: Automating the repair process
The aim of this project is the automation of the abrasion process. So that in the repair process, the automated removal of the damaged composite material including coating will be many times faster than manual removal. Three methods will be selected and evaluated in the project: laser abrasion, milling and water jet abrasion. All three methods are used to remove composite material and to create a scarfed pocket around the damaged area. The repair will take place by adhesive bonding of a cured or prepreg patch into the pocket.
For this purpose the available laser equipment will be further developed by Fokker Services to demonstrate the automated laser abrasion on double curved surfaces. As almost all aircraft parts are double curved this is essential for applications on an aircraft. Besides a full depth repair also shallow repairs used for (stone) impact damages will be investigated. NLR will investigate the automation of the milling process by evaluating the available milling robot (MobileBlock from DMGMORI) and water jet equipment (from AWJ).
Runtime: 1st of March – end of February 2020
The laser abrasion technology is developed and thoroughly investigated showing that it is possible to create a very accurate cut-out with a clean surface, that can be used for adhesive bonding without further surface treatment. The water jet abrasion and milling processes show similar results.