Impact response and microstructural analysis of two glass/epoxy composite laminates
Pang, S.-S., Krishnappa, S., & Yang, C. (1995). Impact response and microstructural analysis of two glass/epoxy composite laminates. Paper presented at the American Society of Mechanical Engineers, Applied Mechanics Division, AMD,, 205, 467-480.
Low velocity impact tests were performed on two glass/epoxy (spring orientation and crossply) composite laminates. A weight drop tower tester was previously constructed to study the impact energy absorbed by a composite pipe using various impactors. In addition, this tester was used to predict the contact duration, force indentation and displacement of laminated composites due to impact with a hemispherical impactor. This study primarily focuses on the contact force of an impactor and on the response of the samples without consideration of the microscopic damage. The effect of impactor mass, two boundary conditions (clamp-free and clamped-clamped) and specimen dimension (length) on the impact response and microstructural damage were studied using the same experimental device. The resulting damaged specimens were sectioned and observed in an optical microscope. The energy levels in the two laminates were of similar magnitude but the delamination pattern and microstructural damage modes were quite different. The energy absorbed, peak force, and contact time increased with the increase in the impactor mass. The energy absorbed by similar specimens for the two boundary conditions were of similar magnitude, but the microstructural damage was different. The energy absorbed and the contact time increased with the increase in the specimen length. Conversely, the peak force and the visibility of the surface damage decreased with an increase in the specimen length. A correlation between the impact response and microstructural damage was provided. The observations were discussed in terms of rigidity of the specimen and potential damage sites.