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提出了激光扫描法辨识热环境下纤维/树脂基复合材料损耗因子。首先,以该类型复合材料薄板试件为例,基于复模量法对其在热环境下的振动响应进行了理论求解;然后,建立了复合材料薄板的激光扫描框架模型,并在分别通过激光扫描法和复模量法获得其振动响应的基础上,利用最小二乘法构造响应相对误差函数,进而辨识获得热环境下纤维/树脂基复合材料在纤维各个方向的损耗因子。接着,在明确了热环境下复合材料损耗因子辨识原理的基础上,总结并概括出一套合理、规范的辨识流程。最后,搭建了基于激光扫描热环境下复合材料薄板振动测试系统,并以TC500碳纤维/树脂基薄板为研究对象,在常温到300℃的高温环境下对其前4阶共振响应进行了实际测试,并通过第1阶共振响应数据对损耗因子进行辨识。结果表明,在温度从常温上升到300℃时,纤维/树脂基复合材料的损耗因子呈现不断增大的趋势。另外,还将辨识出的100℃下对应的材料损耗因子代入到理论模型中,计算得到了复合材料薄板试件在该温度下的第2、第3、第4阶共振响应的理论结果,通过与相同温度下实验测试获得的第2、第3、第4阶共振响应进行对比可知,两者的偏差在1.4%~13.8%之间,进而验证了所提出的辨识方法的有效性和实用性。
A laser scanning method is proposed to identify the fiber / resin matrix composite loss factor in thermal environment. Firstly, taking this kind of composite thin-plate specimen as an example, the vibration response of the composite thin-plate specimen is solved theoretically based on the complex modulus method. Then, the laser scanning frame model of the composite material sheet is established. Scanning method and complex modulus method to obtain the vibration response, the least squares method was used to construct the response relative error function, and then the loss factor of the fiber / resin matrix composites in various directions of the fiber under the thermal environment was obtained. Then, based on the principle of identifying the loss factor of composite materials in thermal environment, a set of reasonable and standard identification process is summarized and summarized. Finally, a vibration test system of composite thin plate based on laser scanning thermal environment was set up. The TC500 carbon fiber / resin based thin plate was taken as the research object, and the first 4 orders of resonance responses were tested under high temperature from room temperature to 300 ℃. The first-order resonance response data is used to identify the loss factor. The results show that the loss factor of fiber / resin matrix composites shows an increasing trend when the temperature rises from room temperature to 300 ℃. In addition, the corresponding material loss factor at 100 ℃ was also substituted into the theoretical model, and the theoretical results of the second, the third and the fourth resonance responses of the composite thin plate specimen at the temperature were calculated. Compared with the second, third and fourth order resonance responses obtained from the experiment at the same temperature, the deviation between the two is between 1.4% and 13.8%, which verifies the validity and practicability of the proposed method .