| 摘要 |
<p>A composite spar for a helicopter rotor blade includes upper and lower sidewall regions (40, 42) and forward and aft conic regions (45, 47) wherein the conic regions further define transition and closure subregions (50, 52). Constant width crossplies (62) and unidirectional plies (72) are stacked and arranged to form crossply and unidirectional laminates (60, 70). The crossply laminates (60) form the upper and lower sidewall regions (40, 42) and end portions thereof extend into the forward and aft conic regions (45, 47) to form a staggered distribution of structural joints (68) and slip plane interfaces (66) therein. The crossply laminates are comprised of high modulus fibers which are oriented within a range of +/- 42° to about +/- 38 ° relative to the longitudinal axis (25) of the composite spar (10). The unidirectional laminates (70) form the upper and lower sidewall regions (40, 42) and have end portions (72e) extending into the transition subregions (50). The unidirectional laminates (70) are interposed between the crossply laminates (60) and comprised of a mix of high and low modulus fibers which are oriented substantially parallel to the longitudinal axis (25). Furthermore, plies of reinforcing fabric (80) having low modulus fibers oriented above about 80° relative to the longitudinal axis (25) may be disposed between the unidirectional plies (72) of the unidirectional laminate (70). The composite spar is manufactured in molds.</p> |
