Accession Number : ADA304582

Title :   Fabrication and Testing of Prestressed Composite Rotor Blade Spar Specimens.

Descriptive Note : Final rept. Jun 72-Oct 74,

Corporate Author : ARDE INC MAHWAH NJ

Personal Author(s) : Gleich, David

PDF Url : ADA304582

Report Date : OCT 1974

Pagination or Media Count : 118

Abstract : Prestressed composite spar specimens were fabricated and evaluated by crack propogation and ballistic penetration tests. The crack propogation tests on flawed specimens showed that the prestressed composite spar construction significantly suppresses crack growth. This provides a 'fail-safe'1 feature leading to increased safe operational life and improved survivability. Damage from three (3) high velocity 30 caliber projectile hits was confined to three small holes in the ballistic test specimen. No fragmentation or crack propogation was observed indicating good ballistic damage resistance. Rotor attachment approaches and improved structural performance configurations were identified. Design theory was verified by tests. The prestressed composite spar configuration consisted of a compressively prestressed high strength ARDEFORM 301 stainless steel liner overwrapped with pretensioned S-994 fiberglass. The prestresses, imparted during cryogenic stretchforming fabrication, are chosen to maintain compression in the metal liner under operating loads. This prestressed composite material construction presents considerable crack propogation and fatigue property improvements leading to increased structural performance.

Descriptors :   *COMPOSITE STRUCTURES, *CRACK PROPAGATION, *ROTOR BLADES, STRESSES, METALS, SURVIVABILITY, FRAGMENTATION, PERFORMANCE(ENGINEERING), STRUCTURAL PROPERTIES, COMPOSITE MATERIALS, RESISTANCE, LININGS, PENETRATION, CONSTRUCTION, HIGH STRENGTH, HOLES(OPENINGS), CONFIGURATIONS, FATIGUE, ATTACHMENT, ROTORS, BALLISTICS, PRESTRESSING, AMMUNITION DAMAGE, SPARS.

Subject Categories : Laminates and Composite Materials
      Structural Engineering and Building Technology
      Jet and Gas Turbine Engines

Distribution Statement : APPROVED FOR PUBLIC RELEASE