Post-Damage Compressive Strength of Woven Hybrid Composites Impacted with Various Energy Levels

Abstract

The low velocity impact damages, such as delamination, fiber breakage, and matrix cracking, may be accidental and might go unnoticed. There are many instances where laminates are used in structures where impact is likely. Furthermore, due to the mechanisms of strength reduction, it may be expected that impact damage would have significant effect on the behavior of the laminates. The work described here consists of experimental measurement of the post-impact compressive strength of hybrid composite laminates. An investigation of damage initiation and experimentation on a woven glass/satin epoxy composite material was performed for different impact velocities and impactor masses. Impacted laminates were loaded in compression and the final failure was typically due to fiber breakage occurring through the center of the impacted area of the laminate. Plain weave Glass/Textile Satin Epoxy laminate was the candidate material with [0/90]s orientation. Possible differences in the impact response and measurable differences in the sizes of the impact damage area were recorded. The behavior of post-impact compressive strength of laminate was found to be dependent on percentage of glass content, impactor mass, and impactor velocity. The failure loads for the impact damage laminates are shown to be comparable with those for laminates containing central open holes, and found that compression after impact (CAI) strength is more than open hole compression (OHC) strength. In addition, numerical modeling of impacted and open hole laminates is carried to explain the region of stress concentration and its severity.