Development of Sysem for Three Dimensional Cracks and Damage

陶瓷复合材料的最终断裂发生在加载条件下微结构内部的小裂纹和损伤的累积之后。本研究的目的是开发一种能够对这些微裂缝进行三维检测和评价的设备。本文研究了Si-Ti-C-O陶瓷、C/C复合材料和SiC颗粒分散的PbO-B_2 O_3-SiO_2玻璃复合材料的声发射特性和超声特性。本文提出了考虑纤维取向引起的力学各向异性的三维声发射定位算法，并研究了裂纹扩展与声发射定位之间的关系。通过这些裂纹扩展的AE分析结果，评价了沿纤维方向沿着产生的AE和内部损伤。超声与声发射的集成系统可以检测原位间隔损伤。同时，还开发了激光声发射系统，用于评价涂层材料和碳纤维复合材料中的微裂纹。

Final fractures in ceramic composites occur after the accumulation of small cracks and damage inside of microstructure under loading. The objective of this research is to develop the equipment which can detect and evaluate these microfractures in three-dimensionally. We investigated the Si-Ti-C-O ceramics, C/C composites and SiC particle dispersed Pbo-B_2O_3-SiO_2 glass composites and measured AE characteristics and ultrasonic properties, AE source analysis of SiC/glass composites demonstrated that shear type micro cracks under 2Omum were dominant and internal microcracks were generated near final fracture. We developed thc three dimensional AE location algorithm including mechanical anisotropy due to fiber alignment and investigated the relationship between crack propagation and AE location. AE generated along the fiber direction and internal damage was evaluated by these results of AE analysis with crack propagation. The integrated system of ultrasonic and AE could defect the in-situ interval damage. Also laser AE system was developed to evaluate the microcracks in coating materials and CFRP.