STP568: Impact Response of Graphite-Epoxy Flat Laminates Using Projectiles that Simulate Aircraft Engine Encounters

    Preston, JL
    Senior materials engineer and assistant project engineer, United Aircraft Corporation, Middletown, Conn.

    Cook, TS
    Senior materials engineer and assistant project engineer, United Aircraft Corporation, Middletown, Conn.

    Pages: 23    Published: Jan 1975


    Abstract

    An investigation of the response of a graphite-epoxy material to foreign object impact was made by impacting spherical projectiles of gelatin, ice, and steel normally on Modmor II/PR-286 flat panels. The observed damage was classified as transverse (stress wave delamination and cracking), penetrative, or structural (gross failure): the minimum, or threshold, velocity to cause each class of damage was established as a function of projectile characteristics. Steel projectiles had the lowest transverse damage threshold (30 m/s), followed by gelatin (170 m/s) and ice (215 m/s). Making use of the threshold velocities and assuming that the normal component of velocity produces the damage in non-normal impacts, a set of impact angles and velocities was established for each projectile material which would result in damage to composite fan blades. Analysis of the operating parameters of a typical turbine fan blade shows that small steel projectiles are most likely to cause delamination and penetration damage to unprotected graphite-epoxy composite fan blades.

    Keywords:

    graphite composites, epoxy resins, impact tests, composite materials, fiberglass reinforced plastics, fractures (materials), tests, damage, evaluation


    Paper ID: STP33150S

    Committee/Subcommittee: D30.02

    DOI: 10.1520/STP33150S


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