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DEVELOPMENT OF DYNAMIC FRACTURE TOUGHNESS TESTING APPARATUS

动态断裂韧性测试仪的研制

基本信息

批准号：
59850019
负责人：
YAGAWA Genki
金额：
$ 12.54万
依托单位：
University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Developmental Scientific Research
财政年份：
1984
资助国家：
日本
起止时间：
1984 至 1986
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-59850019/
关键词：
Dynamic Fracture Test Toughness Fracture Mechanics Visco-plasticity Picture Processing J積分電磁力

项目摘要

In this year, using the dynamic fracture toughness testing system developed so far, the dynamic toughness values of a nuclear pressure vessel steel A508 class 3 were evaluated in a broad temperature range from lower self to upper shelf, and compared with the static values obtained from the three point bending test in literature. It was shown that the dynamic toughness data seemed about 30 to 50% smaller than the static ones, and that the transition temperature shifted by 40 to 50 deg to the higher temperature range. In the upper shelf temperature range, the dynamic toughness data were also a little reduced compared with the static data. The toughness data obtained from the surface force loading test were well coincident with those from the body force ones although the number of surface force loading data was very small. It is expected from the result that the influences of the Joule heating at the vicinity of the crack tip on the fracture toughness data are almost negligible in practic … More e.Also, it seems that the high-strain-rate dependent plasticity as well as inertia forces must be taken into account simultaneously in order to describe accurately the dynamic ductile fracture phenomena. Then we depeloped the finite element analysis program based on an implicit visco-plastic formulation as well as a dynamic and nonlinear fracture mechanics, which was utilized to re-evaluate the dynamic toughness data. The results showed that the dynamic toughness data in upper shelf temperature range increased by about 5% in consideration of strain-rate effects for the fracture parameter calculation. However, the modified dynamic data were still smaller than the static data.The dynamic strain measurement system based on the computer picture processing technique was applied to experimentally evaluate fracture mechanics parameter such as the J-integral. In this method, basing on the deformation theory of plasticity, one calculates the stress distribution for the strain distribution measered by the picture processing technique. Then the J integral can calculated according to the usual path integration scheme. The obtained values of the J-integral had the good path independence and the coincidence with the J integral value from the COD method. The present method can be applied to calculate the J-integral of any shaped two-dimensional cracked specimen since it utilizes the strain-stress data very close a crack tip. Less

本文利用自行研制的动态断裂韧性测试系统，对核压力容器用A508 3级钢在自下而上的宽温度范围内的动态断裂韧性进行了测试，并与文献中的静态三点弯曲试验结果进行了比较。结果表明，动态韧性数据似乎比静态数据小30 - 50%，转变温度向高温区移动了40 - 50 ℃。在上架温度范围内，动态韧性数据与静态数据相比也略有降低。表面力加载试验所得的韧性数据与体积力加载试验所得的韧性数据吻合较好，尽管表面力加载试验的数据很少。结果表明，裂纹尖端焦耳热对断裂韧性的影响在实际应用中几乎可以忽略不计。 ...更多信息此外，看来，高应变率相关的塑性以及惯性力必须同时考虑，以准确地描述动态韧性断裂现象。然后，我们开发了基于隐式粘塑性公式以及动态和非线性断裂力学的有限元分析程序，用于重新评估动态韧性数据。结果表明，在断裂参数计算中考虑应变率效应后，上架温度范围内的动态韧性数据提高了约5%。采用基于计算机图像处理技术的动态应变测量系统对断裂力学参数J积分进行了实验研究。该方法以塑性变形理论为基础，利用图象处理技术测得的应变分布计算应力分布。然后根据通常的路径积分方案计算J积分。所得J积分值具有良好的路径无关性，且与COD法所得J积分值吻合较好。由于本方法利用了裂纹尖端附近的应变-应力数据，因此可用于计算任意形状二维裂纹试样的J积分。少