Method for manufacture of a fiber reinforced composite spar for rotary

Abstract

A method for manufacture of a fiber reinforced composite spar for a helicopter rotor blade including upper and lower sidewall regions and forward and aft conic regions. Constant width crossplies and unidirectional plies are stacked and arranged to form crossply and unidirectional laminates. The composite spar is manufactured via a vacuum forming technique which includes forming the composite laminates directly over an inflatable mandrel assembly. Regarding the latter method, a spar forming apparatus is used to position and manipulate the mandrel assembly as composite laminates are laid. The spar forming apparatus includes first and second pedestal supports being suitably configured so as to facilitate formation of the butt joints in the conic regions of the composite spar. The pedestal supports are movable from a first orientation to facilitate lay-up of composite laminates over the mandrel assembly, to a second orientation to facilitate transfer of the mandrel assembly from one to the other of the pedestal supports. The spar forming apparatus further includes an electromagnetic coil system comprising at least one electrically activated coil and a controllable power source. The electrically activated coils are disposed in combination with each of the pedestal supports and the controllable power source selectively energizes the electrically activated coils to effect a magnetic clamping force between the mandrel assembly and one of the pedestal supports. Such electromagnetic coil system accurately positions the inflatable mandrel assembly during lay-up of the composite laminates and effects transfer of the mandrel assembly.