中心直裂纹平台巴西圆盘复合型动态应力强度因子

MIXED MODE DYNAMIC STRESS INTENSITY FACTORS OF CRACKED STRAIGHT THROUGH FLATTENED BRAZILIAN DISC SPECIMENS

  • 摘要: 为了指导用中心直裂纹平台巴西圆盘(CSTFBD)试样进行岩石复合型动态断裂试验,利用有限元法首先验证了文献中对中心直裂纹巴西圆盘(CSTBD)得到的有关结果,分析比较了不同无量纲裂纹长度(即裂纹半长和圆盘半径之比)时两种圆盘的I, II型动态应力强度因子的时间历程,发现两者的差异大部分在10\%以内,同时验证了该文数值方法的可靠性. 然后讨论了CSTFBD试样I, II型动态应力强度因子的复合比、起裂角以及纯II型加载角. 研究成果可为复合型动态断裂试验中CSTFBD试样的加工、试样上应变片的粘贴、起裂方向和起裂时间的估计等提供参考.

     

    Abstract: In order to establish a standard for the test of mixed modedynamic fracture of rock with the cracked straight through flattenedBrazilian disc (CSTFBD) specimen, we use finite element method first tocheck the related results in literature on the cracked straight throughBrazilian disc specimen (CSTBD). The I-II mixed mode dynamic stressintensity factors (SIFs) of the two kinds of discs with differentdimensionless crack lengths (i.e. the half length of the crack normalized bythe radius of the specimen) are obtained to show that the differences of the dynamic SIF's time history between these two kindsof specimens are within 10\%, and the numerical method used in this paperis valid. Then for CSTFBD specimens, the I-II mixed ratio, the angle ofcrack initiation, and the loading angle for pure mode II fracture testare obtained. The results are useful for mixed mode dynamicfracture test of CSTFBD, including specimens preparation, the location anddirectional alignment of the strain gages, as well as the estimation for the crack initiation time andthe crack initiation direction.

     

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