高密度钢纤维混凝土疲劳裂纹扩展的分形描述

A FRACTAL DESCRIPTION OF CRACK PROPAGATION IN HIGH PERCENTAGE FIBER REINFORCED CONCRETE UNDER FATIGUE LOADING

在对局部高密度钢纤维混凝土疲劳裂纹扩展规律的研究中发现，裂纹并非是由一条主裂纹循序渐进地发展，而是随着循环次数的增加，呈多条短裂纹陆续出现、弥散式发展的趋势；纤维掺量越大，临近破坏前试件表面裂纹越密集、弯曲．本文阐述了用分形语言描述表面裂纹演化的必要性并且探讨了描述方法，借助分形语言对试验结果分析后发现，纤维混凝土裂纹失稳扩展前的临界分维值Ｄｃ随着纤维掺量的增加而增加．

In the fatigue crack propagation of PH- PFRC (partially high percentage fiber reinforced concrete), it was discovred that, some short cracks gradually appeared at random in the vicinity of the notch tip during the cycle loading. And the higher the fiber volume fraction is, the more the short cracks appear just before the specimen fails and the rougher the fracture surface becomes. The necessity of describing the evolution of surface cracks with fractal dimension is explained and the description method is introduced in this paper. In an effec- tive mathematical description, it is discovered that, with the increasing of the fiber volume fraction, the value of fractal dimension D_c just before the failure increases.