FIBER REINFORCED COMPOSITE SPAR FOR A ROTARY WING AIRCRAFT AND METHOD OF MANUFACTURE THEREOF

摘要

PCT No. PCT/US94/09967 Sec. 371 Date Aug. 31, 1994 Sec. 102(e) Date Aug. 31, 1994 PCT Filed Aug. 31, 1994 PCT Pub. No. WO96/06776 PCT Pub. Date Mar. 7, 1996A composite spar for a helicopter rotor blade includes upper and lower side-wall regions and forward and aft conic regions wherein the conic regions further define transition and closure subregions. Constant width crossplies and unidirectional plies are stacked and arranged to form crossply and unidirectional laminates. The crossply laminates form the upper and lower sidewall regions and end portions thereof extend into the forward and aft conic regions to form a staggered distribution of structural joints and slip plane interfaces therein. The crossply laminates are comprised of high modulus fibers which are oriented within a range of +/-42 DEG to about +/-38 DEG relative to the longitudinal axis of the composite spar. The unidirectional laminates form the upper and lower sidewall regions and have end portions extending into the transition subregions. The unidirectional laminates are interposed between the crossply laminates and comprised of a mix of high and low modulus fibers which are oriented substantially parallel to the longitudinal axis. Furthermore, plies of reinforce fabric having low modules fibers oriented above about 80 DEG relative to the longitudinal axis may be disposed between the unidirectional plies of the unidirectional laminate. The composite spar is manufactured in molds./!