Effects of pre-stresses on impact-induced damage of CFRP laminates

The objective of this study is to experimentally evaluate the effects of the impact-induced damages of Carbon Fiber Reinforced Plastic (CFRP) laminated composites under no stress and pre-stress conditions such as (1) no loading, (2) compressive loading, and (3) tensile loading. The symmetrical 4-points bending apparatus was designed and manufactured for making the pre-stressed conditions. Four kinds of test specimens having laminate configurations of (012/θ20/012) were employed, wherein their ply angles (denoted as "θ") were 30°, 45°, 60°, and 90°. The test specimens were impacted with an air-gun type of impact apparatus. First, a strain change caused by the impact was measured. Second, a mechanical scanning acoustic reflection microscope (SAM: pulse-wave mode) was used to detect an interior damage (e.g., delamination) of the impact-induced specimens.

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