The effect caused by testing conditions on the mechanical properties of composite laminates

• Main Authors: ZHENG-TING ZHONG, 鍾政庭
• Other Authors: TSUNG-HAN HSIEH
• Format: Others
• Language: zh-TW
• Published: 2019
• Online Access: http://ndltd.ncl.edu.tw/handle/gdv995

碩士 === 國立高雄科技大學 === 模具工程系 === 107 === Composite materials have been widely used in industries related to automobiles, ships and aerospace due to their outstanding material properties. The process of the composite product will be based on the design requirements of different products to optimize fiber orientation of the composite laminates. However, the error of the fiber orientation during laying up the laminas results in the decrease in the structure performance of the composite products. This may cause the material damage and the user’s life. The aim of this study is to investigate the influence of the testing conditions of composite materials on the testing results. The effect caused by the testing speeds and conditions of sample preparations on the mechanical properties was investigated by using tensile, compression and three-point bending tests. From the experimental results, the optimal test speed of the UD (uni-directional) CFRP (carbon fiber reinforced polymer) is 3mm/min, and is 3mm/min for woven CFRP laminates. For the polymer bulk sample, there is no effect on the testing speed of the tensile performance. As for the fiber orientation error, UD carbon composite laminates are extremely sensitive to the fiber angle. The error of 0° UD CFRP in tensile and compression test can be allowed to be less than 1° and 3°, respectively. The allowable error fiber angle of 90° UD CFRP in tensile and compression tests should be less than 87° and 80°. The allowable error angle of woven CFRP laminates in both tensile and compression tests should be less than 5°. In the three-point bending test, the error angle of the fiber orientation of the UD CFRP composite laminates and woven laminates due to the cutting process in the sample preparation should be less than 5°, the influence of the different span rations on the flexural properties was examined by the experiment. The results show that the best span ration to the thickness of the specimens of the UD and woven CFRP laminates are 1:40 in the three-point bending test.