人字形切槽巴西圆盘Ⅰ型渐进断裂数值模拟研究

发布时间：2018-10-09 20:43

【摘要】：对国际岩石力学学会(ISRM)建议的I型断裂韧度测试人字形切槽巴西圆盘(CCNBD)试样进行细观损伤力学模拟,考虑不同切槽宽度、试样几何、力学参数与材料非均质性等,直观获悉其渐进断裂过程。通过模拟的应力和声发射分布,对CCNBD量纲一的应力强度因子标定基于的穿透直裂纹等假设进行严格评估。结果表明:无论岩石材料是否均质,人字形韧带中的裂纹前缘均为曲线形,并不符合传统方法基于的穿透直裂纹假设,而且人字形韧带越狭长的试样,裂纹前缘弯曲越严重;利用模拟得到的临界裂纹保守地标定临界量纲一的应力强度因子,发现传统方法所得结果比真实值偏小5%~10%;CCNBD易从人字形韧带尖端厚度边缘起裂,为了使真实断裂路径更符合测试原理,建议制作和选取较小切缝宽度的试样。数值模拟结果表明,应该重视测试试样的真实渐进断裂机制,量纲一的应力强度因子标定宜考虑更真实的断裂特征,以获取准确的断裂韧度值。
[Abstract]:The model I fracture toughness of the (CCNBD) specimen with herringbone notched Brazilian disk suggested by the International Society of Rock Mechanics (ISRM) was simulated in the light of different groove width, specimen geometry, mechanical parameters and material heterogeneity, etc. It is intuitively informed of its progressive fracture process. Based on the simulated stress and acoustic emission distribution, the stress intensity factor calibration of CCNBD dimensionality I is strictly evaluated. The results show that, no matter whether the rock material is homogeneous or not, the front edge of the herringbone ligament is curved, which does not accord with the hypothesis of straight crack penetration based on the traditional method. Moreover, the longer the herringbone ligament is, the more serious the bending of the front edge of the crack is. Using the simulated critical crack to calibrate the stress intensity factor of critical dimension one conservatively, it is found that the results obtained by the traditional method are 5% less than the true value, and CCNBD is easy to crack from the edge of the tip thickness of the herringbone ligament. In order to make the true fracture path more in line with the testing principle, it is suggested to make and select the specimen with small width of cut joint. The numerical simulation results show that the true progressive fracture mechanism should be paid more attention to and the more true fracture characteristics should be taken into account in the calibration of the stress intensity factor of dimension one in order to obtain the accurate fracture toughness value.
【作者单位】：四川大学水利水电学院;四川大学水力学与山区河流开发保护国家重点实验室;
【基金】：国家自然科学基金资助项目(51374149) 教育部新世纪优秀人才项目(NCET 13 0382) 四川省杰出青年基金项目(2014JQ0004)
【分类号】：TU45

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