FBG监测复合材料层合板固化工艺及低速冲击损伤研究

发布时间：2018-05-23 08:48

本文选题：玻璃纤维复合材料 + FBG　；参考：《东华大学》2015年硕士论文

【摘要】：复合材料因其优异的性能在航空航天、海军舰艇、民用基础设施制造上得到了广泛的应用。为了保证使用安全，需要对这些结构进行长期的在线监测，分析结构在外界载荷和损伤，特别是冲击损伤情况下的即时应变响应。光栅传感器以其优良的应变和温度传感性能被大量应用于纤维增强复合材料构件的结构监测中。布拉格光纤光栅传感器（FBG）结构简单、质轻、径细、高灵敏度、不产生磁场干扰，正逐渐成为材料内部结构监测的主要手段。将布拉格光纤光栅集成在复合材料结构件中，对结构的损伤、疲劳、冲击等情况进行实时监测，及时发现结构中的损伤，维修或替换损坏结构件,对保证结构安全具有十分重要的意义。本文首先探讨了光栅传感器的温度和应变传感机理，，测定了光栅的温度和应变灵敏系数。采用真空辅助成型工艺（VARI）制作了玻璃纤维增强层合板，测定结果表明光栅对于温度和应变有准确的传感性，光栅波长信号在高温时也有很好的稳定性。其次，利用光栅对层合板的固化过程进行了监测，并分析了不同铺层顺序对层合板残余应力的影响。监测结果表明，光栅可以准确监测到层合板固化的四个阶段，从波长变化曲线可以得到凝胶时间，波长差值反应固化前后的残余应力，0°铺层多的层合板残余应力偏小，为改善固化工艺提供参考。为了使用FBG研究层合板在低速冲击作用下的破坏情况，文中分析了层合板在冲击作用下的破坏机理。通过对层合板进行2J能量的反复冲击及5J,10J,15J和20J的单次冲击监测，分析了光栅在层合板厚度方向不同位置的应变响应情况及波长偏移量与冲击能量之间的关系，结合目视检测和超声C扫检测结果表明，光栅可以有效监测到低速冲击下层合板内部的应变响应，波长差值可以反映层合板内部损伤的大小。最后，本文通过准静态压缩实验测定了光栅在静态压缩下的波长响应，结果表明层合板在准静态压缩下的波长变化趋势与冲击变化趋势相似。本论文利用光栅对复合材料的成型过程及低速冲击损伤机理进行了研究和分析，为改善复合材料成型工艺提高复合材料性能提供了依据，也为利用光栅监测复合材料结构件的健康状态提供了理论基础。
[Abstract]:Composite materials have been widely used in aerospace, naval vessels and civil infrastructure because of their excellent properties. In order to ensure the safety of the structures, it is necessary to carry out long-term on-line monitoring to analyze the immediate strain response of the structures under external loads and damage, especially in the case of impact damage. Grating sensors are widely used in the structural monitoring of fiber reinforced composite components due to their excellent strain and temperature sensing properties. Fiber Bragg grating sensors (FBGs) have simple structure, light weight, fine diameter, high sensitivity and no magnetic field interference. FBGs are gradually becoming the main means of material internal structure monitoring. The fiber Bragg grating is integrated into the composite structure to monitor the damage, fatigue and impact of the structure in real time to detect the damage, repair or replace the damaged structure in time. It is of great significance to ensure structural safety. In this paper, the temperature and strain sensing mechanism of the grating sensor is discussed, and the temperature and strain sensitivity coefficient of the grating is measured. Glass fiber reinforced laminates were fabricated by vacuum assisted molding process (VARI). The measurement results show that the grating has an accurate sensitivity to temperature and strain, and the grating wavelength signal has good stability at high temperature. Secondly, the solidification process of laminates is monitored by grating, and the influence of different layering order on the residual stress of laminated plates is analyzed. The monitoring results show that the grating can accurately detect the four stages of laminate solidification, the gelation time can be obtained from the wavelength variation curve, and the residual stress of the laminated plate with more than 0 掳layering before and after curing by wavelength difference reaction is small. It provides reference for improving curing process. In order to study the failure of laminated plates under low speed impact by using FBG, the failure mechanism of laminated plates under impact is analyzed in this paper. By repeated impact of 2J energy and single impact monitoring of 5J / 10J / 15J and 20J, the strain response of the grating at different positions of the laminated plate thickness and the relationship between the wavelength offset and the impact energy are analyzed. The results of visual inspection and ultrasonic C-scan show that the grating can effectively detect the strain response of the lower laminates with low speed impact, and the wavelength difference can reflect the internal damage of the laminated plates. Finally, the wavelength response of grating under static compression is measured by quasi-static compression experiment. The results show that the wavelength variation trend of laminated plate under quasi-static compression is similar to that of impact. In this paper, the molding process and low speed impact damage mechanism of composites are studied and analyzed by grating, which provides a basis for improving the properties of composites. It also provides a theoretical basis for using gratings to monitor the health state of composite structures.
【学位授予单位】：东华大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TS102.42;TB33

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