Development of AE system for detecting sub-surface crack due to very high cycle fatigue at reduced temperature

开发 AE 系统，用于检测由于低温下非常高的循环疲劳而导致的次表面裂纹

基本信息

批准号：
18560085
负责人：
OGAWA Takeshi
金额：
$ 2.34万
依托单位：
Aoyama Gakuin University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2006
资助国家：
日本
起止时间：
2006 至 2007
项目状态：
已结题

项目摘要

Aging problems are becoming serious for many of the large scale steel structures constructed in the 20th century. In the 21st century, it is required to use these old structures as long as possible based on high quality maintenance. In order to evaluate the integrity of structures and devices with respect to safety and fitness for service, metal fatigue is a critical subject. Especially, phenomenon of very high cycle fatigue has been clarified in this decade, and thus more research activities are required for fracture mechanisms and prevention techniques.The objectives of this project are the establishment of ultrasonic fatigue testing method available for a wide range of materials using our originally developed fatigue testing machine, which is applicable for low temperature regime, as well as the development of detecting method for sub-surface crack during very high cycle fatigue tests using acoustic emission (AE). For the former, ultrasonic fatigue testing machine had been ready and the results were obtained for austenitic stainless steel. It is a future projects to evaluate very high cycle fatigue characteristics for wide variety of materials. Since the latter is a very difficult task, detecting technology of sub-surface crack has not been achieved yet. However, the AE detecting technology using optical fiber sensor was applied for various subjects except the sub-surface crack detection. The optical fiber AE technique was very effective for water blockage of water pipes of power generation plant. Besides these research works, fatigue crack monitoring technique from the crack initiation to final fracture was investigated, because it is important to complete the original objectives of the project.

对于20世纪建造的许多大型钢结构，衰老问题变得越来越严重。在21世纪，需要根据高质量维护，尽可能长时间地使用这些旧结构。为了评估结构和设备在服务的安全性和适应性方面的完整性，金属疲劳是关键的主题。特别是，在这十年中已经阐明了非常高循环疲劳的现象，因此，裂缝机制和预防技术需要更多的研究活动。该项目的目标是建立用于使用多种材料的超声疲劳测试方法的建立我们最初开发的疲劳测试机，适用于低温状态，以及使用声发射（AE）在非常高的循环疲劳测试中开发地下裂纹的检测方法。对于前者，已经准备好了超声波疲劳测试机，并获得了奥氏体不锈钢的结果。这是一个未来的项目，可以评估各种材料的非常高的循环疲劳特征。由于后者是一项非常艰巨的任务，因此尚未实现地下裂纹的检测技术。但是，除了地下表面裂纹检测外，使用光纤传感器的AE检测技术用于各种受试者。光纤AE技术对于发电厂的水管的水阻滞非常有效。除了这些研究工作外，还研究了从裂纹启动到最终断裂的疲劳裂纹监测技术，因为完成项目的原始目标很重要。