材料期刊网

在研究多层媒介中的微波信号传播与反射机理的基础上,利用微波网络分析仪对3层复合材料中间层的纤维方向进行了检测研究.首先,根据N5225A网络分析仪记录的反射系数相位计算出反射系数相位差;然后,建立反射系数相位差与表示中间层纤维方向的β建立对应关系;最后,利用反射系数相位差表征纤维方向的变化.实验结果表明,矩形波导相对于复合材料纤维方向的角度(α)会对检测结果有一定的影响,反射系数相位差随工作频率的变化规律不同,并且对中间层的纤维方向的变化敏感范围也不同,波导口长边平行于第一层的纤维时,即α为0°时,对β为15~45°较敏感,波导口长边垂直于第一层的纤维时,即α为90°时,对β为45~75°较敏感;复合材料末端加一反射板可以增强检测效果,检测工作频率为33 GHz,中间层纤维方向变化30°时,有反射板的反射系数相位差变化10°,而没有反射板的变化5°.

Based on the transmission and reflection mechanism of the microwave signal in the multilayer medium, a network analyzer was used to detect the carbon fiber direction in the middle layer of the composite materials.Firstly, the reflection phase difference is calculated according to the reflection phase recorded by N5225A network analyzer.Secondly, the relationship is established between phase difference vs.β.Finally, the reflection phase difference characterization is used to characterize the fiber direction changes.The results show that the angle (α) of the long sides of the rectangular waveguide and the carbon fiber can impact on the test results.The reflection plate in the end of the composite can enhance detection effect.When the angle (α) is different, the relationship between phase difference vs.frequency is different, and the sensitive range to the fiber direction is different as well.When α is 0°, the sensitive range of β is 15~45°.When α is 90°, the sensitive range of β is 45~75°.When the frequency is 33 GHz, and the change of β is 30°,the change of reflection phase difference detected the composite with the reflection plate is 10°, but 5° detected the composite without the reflection plate.