| Summary: | 碩士 === 逢甲大學 === 紡織工程學系 === 87 === This paper describes an experimental program undertaken to investigate a non-penetrating impact damage in three different structure composites, which were made with multiaxial warp knitted glass fabric (MMWK), nonwoven glass fiber mat (N), and M/N/M structure reinforced unsaturated polyester laminates. Laminates were subjected to falling-weight at the normalized impact energy of 16 J/layer. After impact, sectioning of specimens was carried out for fractographic studies with a camera and a metallographic microscope. All of N laminates were penetrated in this condition. Impact induced delamination characterized by a butterfly shape was observed on both MMWK and M/N/M laminates. The radial matrix crack, fiber breaking, debonding, and delamination were observed on both MMWK and M/N/M laminates. However, a conical region beneath centrally depressed region does not found delamination or fiber breaking. No significant shear failure and energy rebounding appeared in all of N laminates, but they are found in both MMWK and M/N/M laminates. Moreover, there are two main peaks in the load time trace of M/N/N laminate. In experiments, energy absorption ratios of MMWK, N and M/N/M laminates approach 85﹪, 40﹪and 80﹪, respectively. M/N/M laminate has the best residual compression strength in all of three structures, and N laminate is the worse one. After impact test, the structure of N laminate remains the highest residual compression strength ratio, and both MMWK and M/N/M laminates have larger loss of compression strength since their higher energy absorption.
|
|---|
