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Analyses of Time Dependent Behavior of Fracture Process Zone in Concrete and Constitution of Its Numerical Model

混凝土断裂过程区时变行为分析及其数值模型的构建

基本信息

批准号：
09650516
负责人：
MASAJI Yamanouchi
金额：
$ 0.26万
依托单位：
Fukushima National College of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1998
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-09650516/
关键词：
Concrete Fracture Process Zone Tension Softening Process Time Dependence 3-D AE Source Location AE Energy Fractal Dimension energy of crack formation 引張軟化則アコースティックエミッションアコースティック・エミッション

项目摘要

The fracture parameters such as fracture energy and brittleness are deeply concerned with the cumulative process of micro cracking in the fracture process zone. The purpose of this research is to obtain the time dependent behavior of micro cracking in the fracture process zone of notched concrete beam under constant loadings, using three dimensional AE source location method.The velocity of the crack mouth opening displacement changes from steady to accelerative state beyond a certain critical point. AE source locations distribute widely in the steady state, and in a line at the front of the fracture process zone after the critical point. This means that the process of accelerative micro craking is connected with the initial state of tension softening.To research on the critical point, the tension softening diagram is evaluated by means of poly-linear inverse analysis method. On the basis of comparison between AE source locations and the crack type distributions in the fractured cross section, meso-scopic fracture mechanism in tension softening process is considered. It makes clear that the cumulative AE energy is increasing with the same manner of the energy of crack formation. This result suggests that the proposed AE energy represents quantitatively micro cracking in fracture process zone.In the future, it is necessary to determine the amount of AE energy correspond to the critical point and to investigate the relation between brittleness.

断裂能、脆性等断裂参数与断裂过程区微裂纹的累积过程密切相关。采用三维声发射源定位方法，研究了混凝土缺口梁在恒载作用下，裂纹张开位移随时间的变化规律，当裂纹张开位移超过某一临界点时，裂纹张开速度由稳态向加速变化。稳态时声发射源位置分布较广，临界点后在断裂过程区前端呈直线分布。为了研究拉伸软化的临界点，采用多元线性反分析方法求出了拉伸软化图。在比较声发射源位置和断裂截面上裂纹类型分布的基础上，考虑了拉伸软化过程中的细观断裂机制。结果表明，累积声发射能量与裂纹形成能量的增加方式相同。这一结果表明，所提出的AE能定量地代表了断裂过程区的微裂纹，今后有必要确定临界点对应的AE能的大小，并研究脆性与断裂过程区微裂纹的关系。