What is the best material for using in collapsible mandrel for filamnet winding? Cheers.
Steel. At least the 10+ meter diameter mandrels my clients use, are steel… They can be increased in diameter with large bolts.
PVC pipe. Cut it open lengthwise, and force it open a bit.
I have seem angle iron and turnbuckle style bolts used as square mandrel. Wrapped in plastic (or mylar tape?), and then wound. I would think the same way can be done with a steel tube, cut once. Weld nuts to the inside with bolts…tighten the bolt, pulls the steel gap together, and composite pulls off.