Notched Strength and Fractures Behavior of Chopped Glass Mat Reinforced Unsaturated Piastics

摘要

Glass chopped fiber mats have been used as traditional reinforcements for fiber reinforced plastics. However, the literature is found limited even it has a long history. However short fiber mats is considered to be suitable reinforcement configuration for natural fiber or filled composites because the natural fiber is inherently short fiber. Various fiber textile technologies are available to be used to -fabricate the fiber mats structure, for example needle punching process. Therefore the relation between different textile manufacturing techniques (the fiber mat structure) and the composites properties is considered necessary to be should be fully understood. Chopped glass mat reinforced composite was used as experimental materials and the fracture behavior of the specimens with drill-hole was investigated. Acoustic emission (AE) measurement was carried out by using Dual AE measurement system with both 140 KHz and 1 MHz sensors to understand the fiber and matrix fracture behaviors simultaneously. Also the characteristic distance was calculated experimentally and was compared theoretically with the values obtained from finite element stress analysis. It is found that the notched strength decrease by drilling a hole in the center. While regarding to the effect of w/d ratio i.e. the ratio of width to the diameter of the drill-hole, w/d of 3 specimens seems to have relative higher notched strength as compared to 2 or 5 w/d specimens. During the tensile test AE signals which detected by both 140 kHz and 1MHz are found to be generated almost at the same time. Additionally, the white area before the final broken seems to relative to the characteristic distance calculated by finite element stress analysis.