To answer the question in the topic title, composite structures are not inherently harder than aluminum structures to repair. The process is quite different for obvious reasons and requires a different set of skills. This in of itself does not make it more difficult.
aluminum bends and can be relatively easily repaired.
Yes aluminum bends and can take a set without failing. That doesn't mean that the part can be bent back and remain servicable. Bent aluminum parts must be cut out and are then replaced by repair pieces spliced into the surrounding undamaged area. This is pretty straight forward but is by no means a quick process.
Composites on the other hand flex but don't take a set before failing. So you won't see bent composites. They will deflect under a load and return to their original shape unless loaded to the point of failure at which point they break, delaminate, or crack. The damaged area can then be removed and repair material bonded to the surrounding undamaged area. Sounds pretty similar to how aluminum is repaired? The major difference is how the repair material is joined to the existing structure. Aluminum mainly uses mechanical fasteners for the connection while composites use epoxy bonding for this. A third category, metal bonded structures, uses elements of both for accomplishment of the repairs.
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