Split Hopkinson pressure bar(SHPB)has been used to study the dynamic failure pattern of flattened mortar Brazilian disc under impact load.Each disc contains several prefabricated cracks paralleled to each other.Dynami...Split Hopkinson pressure bar(SHPB)has been used to study the dynamic failure pattern of flattened mortar Brazilian disc under impact load.Each disc contains several prefabricated cracks paralleled to each other.Dynamic FEM has also been adopted to simulate such failure behavior.The mechanism of crack initiation,propagation and cut-through have been scrutinized with both experimental and numerical approaches.Influence of the number of the prefabricated cracks on the specimen strength and acoustic emission(AE)performance can be observed and studied.The results show that the strength decreases and AE counts increases,when the number of the prefabricated cracks increases.展开更多
Both experimental and numerical approaches were used to study dynamic failure properties and patterns of flattened Brazilian discs,containing two prefabricated cracks intersected at a varying angle.Mechanism of crack ...Both experimental and numerical approaches were used to study dynamic failure properties and patterns of flattened Brazilian discs,containing two prefabricated cracks intersected at a varying angle.Mechanism of crack initiation,propagation,and cut-through were scrutinized and influences of the intersection angle on specimen strength and acoustic emission performance were also studied.All primary cracks initialize near the middle or the tip points of the upper prefabricated crack,and they continue to develop along the load direction and finally cut through the specimen.The secondary cracks could be observed in directions almost horizontal or parallel to the directions of prefabricated cracks.Furthermore,it is found that stress intensity factor reaches its maximum for specimen with intersection angle of 0 degree.展开更多
制作了中心直裂纹平台巴西圆盘(cracked straight through flattened Brazilian disc-CSTFBD)试样,利用分离式霍普金森压杆(split Hopkinson pressure bar SHPB)加载,进行了岩石纯Ⅰ型和复合型(Ⅰ+Ⅱ型)动态断裂实验。由于加载角(载荷...制作了中心直裂纹平台巴西圆盘(cracked straight through flattened Brazilian disc-CSTFBD)试样,利用分离式霍普金森压杆(split Hopkinson pressure bar SHPB)加载,进行了岩石纯Ⅰ型和复合型(Ⅰ+Ⅱ型)动态断裂实验。由于加载角(载荷方向与裂纹线的夹角)在制作试样时已经通过裂纹线与试样平台的位置关系确定,因此在实验中可以方便而准确地实施加载。比较了纯Ⅰ型加载和复合型加载下压杆上记录的入射波、反射波和透射波的波形。采用实验与数值相结合的方法,将实验得到的动态载荷输入有限元程序,得到了纯Ⅰ型试样的动态断裂韧度和复合型试样的两种动态应力强度因子的时间历程。计算了加载角为15°的试样应力强度因子的复合比(KⅠ(t)/KⅡ(t)),此计算值与文献结果吻合较好,验证了实验方法的有效性。展开更多
基金Funded by the National Natural Science Foundation of China(Nos.51678170,51878190)。
文摘Split Hopkinson pressure bar(SHPB)has been used to study the dynamic failure pattern of flattened mortar Brazilian disc under impact load.Each disc contains several prefabricated cracks paralleled to each other.Dynamic FEM has also been adopted to simulate such failure behavior.The mechanism of crack initiation,propagation and cut-through have been scrutinized with both experimental and numerical approaches.Influence of the number of the prefabricated cracks on the specimen strength and acoustic emission(AE)performance can be observed and studied.The results show that the strength decreases and AE counts increases,when the number of the prefabricated cracks increases.
基金Funded by the National Natural Science Foundation of China(Nos.51878190 and 51678170)。
文摘Both experimental and numerical approaches were used to study dynamic failure properties and patterns of flattened Brazilian discs,containing two prefabricated cracks intersected at a varying angle.Mechanism of crack initiation,propagation,and cut-through were scrutinized and influences of the intersection angle on specimen strength and acoustic emission performance were also studied.All primary cracks initialize near the middle or the tip points of the upper prefabricated crack,and they continue to develop along the load direction and finally cut through the specimen.The secondary cracks could be observed in directions almost horizontal or parallel to the directions of prefabricated cracks.Furthermore,it is found that stress intensity factor reaches its maximum for specimen with intersection angle of 0 degree.
文摘制作了中心直裂纹平台巴西圆盘(cracked straight through flattened Brazilian disc-CSTFBD)试样,利用分离式霍普金森压杆(split Hopkinson pressure bar SHPB)加载,进行了岩石纯Ⅰ型和复合型(Ⅰ+Ⅱ型)动态断裂实验。由于加载角(载荷方向与裂纹线的夹角)在制作试样时已经通过裂纹线与试样平台的位置关系确定,因此在实验中可以方便而准确地实施加载。比较了纯Ⅰ型加载和复合型加载下压杆上记录的入射波、反射波和透射波的波形。采用实验与数值相结合的方法,将实验得到的动态载荷输入有限元程序,得到了纯Ⅰ型试样的动态断裂韧度和复合型试样的两种动态应力强度因子的时间历程。计算了加载角为15°的试样应力强度因子的复合比(KⅠ(t)/KⅡ(t)),此计算值与文献结果吻合较好,验证了实验方法的有效性。
