【作者】 黄睿；

【导师】 陶宝祺； 袁慎芳；

【作者基本信息】 南京航空航天大学 ， 测试计量技术及仪器， 2002， 博士

【摘要】 作为先进复合材料的一种，三维编织复合材料由于克服了层合复合材料层间脆弱的缺点，同时具有优异的整体性能和较高的强度、刚度、良好的抗冲击性能等优点，在航空航天等很多领域的应用日益广泛。但由于其编织工艺和固化成型工艺比较复杂，人们对它的认识还远远不够。目前对编织复合材料结构的健康状况、固化工艺的监测等相关研究还很少。 本文探索采用光纤传感技术对三维碳纤维/环氧编织复合材料性能和工艺进行了测试研究。主要研究内容如下： 1 对三维编织工艺进行了研究，提出光纤传感器编入编织复合材料的两种方法以及光纤的保护措施。采用四步法成功地将光纤传感器编入复合材料试件。随后研究了编织复合材料的固化成型工艺：树脂传递模塑(RTM)工艺。设计了含光纤编织试件的RTM固化成型系统，并成功地研制出编入光纤传感器的编织复合材料试件。 2 对编入材料的光纤与编织复合材料的相容性进行了研究。将光纤编入编织复合材料中，对光纤的截止波长、数值孔径、模场直径和串音进行了检测。实验结果表明这些光学性能参数在光纤编入编织复合材料试件后以及固化成型后变化较小。研究了光纤对编织复合材料性能的影响。对编入光纤试件和无光纤试件进行拉伸和压缩对比试验。结果表明光纤的编入对材料的拉伸弹性模量和压缩弹性模量影响也较小。当光纤及保护套管占的体积比约为1％时，拉伸弹性模量下降的幅度约为6％；压缩弹性模量下降的幅度约为6.7％。另外对光纤传感器的安装和引出设计也进行了研究。 3 研究了光纤传感技术在编织复合材料内部应变检测中的应用。用射线理论分析了光线在梯度光纤和阶跃光纤中的传播机理。并用模式理论讨论了光纤波导的标量分析和矢量分析。分析了偏振式、法布里-珀罗干涉型和微弯式光纤传感器的原理，并通过实验研究了它们在编织复合材料内部应变检测中的应用。实验结果表明编入编织复合材料的光纤传感器可以检测出材料内部的应变。这种方法对深入研究编织复合材料结构的性能、内部损伤的检测以及健康状况的监控具有重要价值。 4 研究了碳密封涂覆光纤在编织复合材料中的应用。碳密封涂覆光纤具有强度高、抗疲劳性能高等许多优点。从实验中也发现，在编织复合材料中使用碳密封涂覆光纤具有良好的传感效果。 5 研究了使用编入材料内部的光纤微弯传感器对编织复合材料RTM固化工艺进行监测。实验结果表明光纤微弯传感器可以监测树脂粘度的变化，并给出树脂粘度最低点以及固化结束点。内部微弯式光纤传感器可以对编织复合材料的RTM成型工艺 三维编织复合材料性能及工艺的光纤测试技术研究进行监测。 本文的主要创新点： l 首次提出光纤编入编织复合村料的方法，成功制作了编入光纤传感器的复合材料试件。 2首次对编入材料的光纤与编织复合村料的相容性进行了研究。 3首次采用偏振式、干涉型和微弯式光纤传感器对编织复合材料的内部应变进行了检测。 4首次采用微弯式光纤传感器对编织复合材料的 RTM艺进行了监测。 5首次研究了碳密封涂覆光纤在编织复合材料中的应用。更多还原

【Abstract】 As one kind of advanced materials, 3D braided composites are used widely in many fields, such as aeronautics & astronautics, because of their high strength, stiffness and good resistance to impact. However, due to their complicated braiding and cure processes, knowledge about them is far from enough. Research of health monitoring and cure monitoring about braided composite are quite little.In this dissertation, internal strain and cure process of braided composites are studied using optical fiber sensing technology. The contents are as follows:1. Based on study of 3D braiding process, two methods for optical fiber braiding and protecting are presented. Optical fibers are successfully braided into composite testpieces by four-step method. Cure process of braided composites is also studied. Resin Transfer Molding (RTM) cure system is designed. Testpieces with braided optical fibers are successfully fabricated.2. Compatibility of optical fiber and braided composites is studied. Cut-off wavelength, mode field diameter, numerical aperture and cross talk are chosen as test parameters of optical fibers. Research of those parameters shows that they change just a little before, after optical fiber’s being braided into the structures, and after the molding process. Contrast tests are also done to compare performances of testpiece with optical fiber with that of one without optical fiber. Tensional and compressive elastic moduli are researched. Results show that co-braided optical fibers have just a small quantity of effect on the elastic modulus of the braided composites. If volume ratio of optical fibers and their jackets to the braided testpiece is about one per cent, the tensional and compressive elastic moduli will decrease respectively by six and six point seven per cent. The fixing and lead-out design of optical fiber sensor are also studied.3. Optical fiber sensing technology is applied in internal strain measurement of braided composites. First, transmission mechanism of light wave in graded index fiber and stepindex fiber is analyzed using ray method. Scalar analysis and vector analysis are discussed using mode method. Mechanism of polarized, interferential and micobend optical fiber sensor is analyzed. Applications of these sensors in internal strain measurement of braided composites are experimentally studied. Results show that these sensors are effective for internal strain measurement. Method of internal parameter measurement based on co-braided optic fiber sensor is very valuable for further research to study structural features and monitor structural health condition.4. The RTM cure process of braided composites is monitored using microbend fiber optic sensor. Experimental results show the sensor is able to monitor variation of resin viscosity and to indicate time that resin viscosity is lowest and cure ends.5. Applications of optical fiber with carbon coating are also studied. This kind of optical fiber has advantages of high strength and antifatigue performance. Experimental results show that the optical fiber has good sensing features.The original researches done in this dissertation are as follows:1. The braiding and cure process for braided composites with monomode optical fiber are presented. Testpieces are successfully fabricated.2. The compatibility between optical fibers and braided composites is studied3. Internal strain of braided composites is measured by devising three kinds of optical fiber sensors. The sensors are polarimetric sensor, interferential sensor and microbend sensor.4. The RTM process is monitored using co-braided microbend fiber optic sensor.5. Applications of carbon hermetically coated optical fiber in braided composites are studied.更多还原