Development of Expert System for Autoclave Molding of Advanced Composite Materials Using Optical Fiber Sensor

本研究项目的目的是利用光纤传感器构建先进复合材料高压罐成型工艺的专家系统。1.利用本课题开发的专家系统，构建了基于光纤传感器的结构内部应变在线监测系统。该系统对控制成型工艺条件是有效的。该系统有效地应用于单向复合材料层合板内部应变的实时监测。建立了由专家系统建立造型所必需的数据库的基本测量技术。具体结果如下：(1)通过介电常数监测得到的树脂的固化度与光学传感器测量的内部应变之间的关系。(2)超声波在固化层板中的传播速度可以很好地反映复合材料的固化度。这表明，不仅可以通过光纤的现场监测，还可以通过超声方法对已固化材料的固化条件进行评估。(3)结合成型压力估算了断裂韧性，建立了断裂韧性与固化压力之间的关系。(4)研究了光纤注入对复合材料压缩强度的影响。这为测量光纤内部应变的最佳埋入光纤方法提供了基础数据。

The objective of this research project is to construct an expert system for the autoclave molding process of advanced composite materials by using optical fiber sensors. The following results were obtained ; 1. Using the expert system developed in this project, a system for in-situ monitoring of the internal strain by optical fiber sensors was constructed. This system is available and effective for controlling the molding conditions. The system is effectively applied to real-time monitoring of the internal strain of uni-directional composite laminates.2. Basic measuring techniques for construction of date base indispensable for molding by expert system could be established. The specific results are as follows ;(1) Relation between degree of cure of the resin obtained by dielectric constant monitoring and the internal strain measured by optycal sensors was specified.(2) It was shown that ultrasonic wave velocities propagating in cured laminates could be a good indicator of the degree of cure of composites. This shows that the optimum cure conditions can be estimated not only by in-situ monitoring with optical fibers but also by ultrasonic way applied to already cured materials.(3) The fracture toughness was estimated in conjunction with the molding pressure, by which the relation between the fracture toughness and the curing pressure was established.(4) The effects of implantation of optical fibers into composite materials on the compressive strength were investigated. This gave basic data for optimum method of embedding the optical fibers by which the internal strain is measured.