Bonded repair technology is now a widely accepted alternative to mechanically fastened repairs to secondary and tertiary aircraft structure. This paper presents an analytical method to optimise the profile of the scarf joint between dissimilar modulus adherends so that adhesive stresses are approximately uniform along the joint. The optimised scarf repair is expected to enhance joint strength and reduce the amount of material removal. Finite element analyses have been performed to both validate the optimal solution and to evaluate the use of low stiffness patch to repair carbon epoxy composites. In particular, the influence of patch lay-up on adhesive stresses has been investigated. The use of interleaved adhesive layers in the repair laminate served to raise the stress concentration in the adhesive adjacent to load oriented plies connected to the interleaved adhesive on both halves of the scarf joint. The use of a linearly varying scarf angle raised the magnitude of the stress peak on the side of the joint where the local scarf angle was a maximum. The use of a more complex taper profile to minimise ply induced stress concentrations in the adhesive may be possible, but would be very difficult to manufacture.
Improved design methods for scarf repairs to highly strained composite aircraft structure
Verbesserte Designmethoden für Schrägstoßreparaturen an hochgradig gedehnten Verbundwerkstoff-Flugzeugstrukturen
2006
13 Seiten, 19 Bilder, 2 Tabellen, 7 Quellen
Conference paper
English
Schrägstoß , Flugzeugbau , Verbundwerkstoff , Reparatur , mechanische Befestigung , Entwurf , theoretisches Modell , numerische Analyse , Verbinden nichtartgleicher Werkstoffe , Elastizitätsmodul , Klebverbindung , Kleben (Verbinden) , Klebstoff , Haftfestigkeit , Finite-Elemente-Methode , Scherspannung , Steifigkeit , Zwischenschicht , Spannungskonzentration , Laminat , Verdrehung , Poisson-Zahl , Empfindlichkeitsanalyse
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