Fatigue Properties of AS4/PEEK APC-2 Composite Laminates at Elevated Temperature

• Main Authors: Peng Shen Sheng, 彭聖森
• Other Authors: Jen Ming Hwa
• Format: Others
• Language: zh-TW
• Published: 1999
• Online Access: http://ndltd.ncl.edu.tw/handle/17879046007234749098

碩士 === 國立中山大學 === 機械工程學系 === 87 === The thesis is aimed to investigate the mechanism and mechanical properties of thermoplastic AS-4 / PEEK composite laminates subjected to tension-tension fatigue at elevated temperature. We adopt diaphragm forming method by controlling temperature, pressure, vacuum and time condition according to the obtained best curing process to form composite laminates of low crystallinity, trans- crystallinity and good fiber / matrix interfaces. We use the common type of laminates of cross-ply [0 / 90] and quasi-isotropic [0 / 45 / 90 / -45] . Static tension test is performed to measure the elastic modulus and ultimate strength at four different temperatures, such as 25C, 75C, 125C, 175C. And the tension-tension fatigue test is conducted to yield fatigue strength and the S-N curves. Then, we use the degradation of stiffness to explain the fatigue properties at elevated temperature. At last, we observe the failure cross section of composite laminates and understand the failure initiation and mechanism through Scanning Electron Microscope (SEM). The result of experiments can be concluded as follows. The ultimate strength of cross-ply composite laminates is larger than that of quasi-isotropic at room and elevated temperature. Also the fatigue strength of cross-ply composite laminates is larger than that of quasi-isotropic at room temperature. However, the degradation of the fatigue strength of cross-ply composite laminates is less than that of quasi-isotropic when the temperature is raising smoothly. As for the failure mechanism, we obviously observe that the ductile and brittle failure of matrix occur at room and elevated temperature.