Development of Sysem for Three Dimensional Cracks and Damage

陶瓷复合材料的最终断裂是在载荷作用下微结构内部小裂纹的积累和损伤后发生的。本研究的目的是开发一种能够对这些微骨折进行三维检测和评估的设备。研究了Si-Ti-C-O陶瓷、C/C复合材料和颗粒弥散分布的PbO-B_2O_3-SiO_2玻璃复合材料的声发射特性和超声性能。声发射源分析表明，SiC/玻璃复合材料在2 OMum以下以剪切型微裂纹为主，并在断口附近产生内部微裂纹。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的关系。根据裂纹扩展的声发射分析结果，对纤维方向产生的声发射和内部损伤进行了评估。超声与声发射的集成系统可以弥补原位间歇损伤的缺陷。此外，还研制了激光声发射系统来检测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.