Environmental Effects on Impact Damage Tolerance of Hybrid Composite Material
NAVAL ACADEMY ANNAPOLIS MD
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The behavior of an intraply hybrid composite material of polyethylene and graphite fibers in an epoxy matrix under the effects of environmental conditioning, impact damage, and fatigue loading was investigated. Although the ultimate tensile strength of the hybrid material was found to be lower than that of graphite material alone, the specific strengths of the materials were comparable. Dye-penetrant enhanced X-ray radiography and edge replication were used to evaluate the damage growth of the test material. Impact damage evaluations showed the initial crack tolerance of the hybrid materials was better than that of conventional graphite. Specimens of both materials were soaked in standard ocean water and their moisture absorption observed. The moisture absorption percentages for the hybrid and graphite materials were 2.91 percent and 1.47 percent by weight respectively. Both dry and wet hybrid material was subjected to impact and fatigue loading. During fatigue loading the hybrid material exhibited viscoelastic behavior characterized by a non-linear loading curve. The wet hybrid material experienced both a sharper reduction in stiffness, and a greater increase in damage area than the dry material.
- Laminates and Composite Materials
- Solid State Physics