水利学报2017，Vol.48Issue(8)：955-967,13.DOI:10.13243/j.cnki.slxb.20161175
边界效应与尺寸效应模型的本质区别及相关设计应用
Essential difference and design application of boundary effect model and size effect model
摘要
Abstract
A comparative study of the essential difference,design,and application of boundary effect model (BEM) and size effect model (SEM) was conducted.SEM applies the four different multi-parameter empirical equations to the different ratio of initial crack length and specimen depth α.SEM is limited to a data-fitting function.BEM model involves the use of a unique analytical solution.On one hand,BEM can determine the material parameters-fracture toughness KIC and tensile strength f through the fitting of experimental data.On the other hand,it can establish a complete designed curve that describes the overall fracture of structure based on the identified KIC and f.The effect on three fracture controlled model (f-controlled,KIC-controlled and quasi-brittle fracture) were systematically calculated and analyzed from specimen to structure (size W=25-25000mm).The results show that linear elastic fracture mechanics (LEFM) applies for very long crack and very large structures,and there is no further need for size effect study.The size effect model is only relevant when the crack tip is close to either the front or back boundaries.The so-called "size effect" is only a special case of boundary effect.Based on the results of fracture tests (the specimen size W is 40,93,215 and 500 mm,and the ratio of initial crack length and specimen depth α is 0,0.02,0.075,0.15 and 0.3),the different combination conditions of tested data that BEM systematically studied are adopted to determine the influence law of KIC and f.The results are shown that,values are basically consistent to KIC and f,which have been determined by BEM,when the test data reaches a certain amount and one or two groups of data are removed from the overall data,either the specimens have the different W with same α=a0/W,or the same W but different α=a0/W.The studied results of this paper gave a new ideal to solve the problem that the material parameters cannot be accurately obtained using small size specimen,as well as the problem on predicting the actual structure fracture by using the material parameters.关键词
边界效应/尺寸效应/三点弯曲/骨料最大粒径/断裂韧度/拉伸强度Key words
boundary effect/size effect/three-point-bend/maximum aggregate size/fracture toughness/tensile strength分类
建筑与水利引用本文复制引用
管俊峰,胡晓智,李庆斌,吴智敏..边界效应与尺寸效应模型的本质区别及相关设计应用[J].水利学报,2017,48(8):955-967,13.基金项目
国家自然科学基金重点项目(51339003) （51339003）
国家自然科学基金项目(51779095) （51779095）
郑州市科技攻关项目(153PKJGG111) （153PKJGG111）
