CAJ | 학술논문

利用动焦散线试验方法研究了冲击下预制裂纹梁的动态断裂行为，对比分析了冲击荷载作用下单裂纹与双裂纹试件的应力强度因子、扩展轨迹以及速度、加速度等参数的变化规律。试验结果表明：冲击荷载作用下，含双裂纹且主裂纹在冲击点正下方的试件起裂时间最早，裂纹扩展后期朝向次裂纹方向发生较小的偏移；含Ⅰ型单裂纹的试件起裂时间次之，裂纹扩展路径呈直线；含双裂纹且两条裂纹均偏置于冲击点的试件起裂时间最晚，扩展过程中发生明显的曲裂现象。同时，裂纹扩展过程中曲裂现象越严重，裂纹扩展的最大速度就越小。在落锤冲击试件到试件断裂的整个阶段，应力强度因子一直表现出振荡变化。含双裂纹的试件，在主裂纹扩展中期，次裂纹上的应力强度因子有一个快速下降的过程。
이용동초산선시험방법연구료충격하예제렬문량적동태단렬행위，대비분석료충격하재작용하단렬문여쌍렬문시건적응력강도인자、확전궤적이급속도、가속도등삼수적변화규률。시험결과표명：충격하재작용하，함쌍렬문차주렬문재충격점정하방적시건기렬시간최조，렬문확전후기조향차렬문방향발생교소적편이；함Ⅰ형단렬문적시건기렬시간차지，렬문확전로경정직선；함쌍렬문차량조렬문균편치우충격점적시건기렬시간최만，확전과정중발생명현적곡렬현상。동시，렬문확전과정중곡렬현상월엄중，렬문확전적최대속도취월소。재락추충격시건도시건단렬적정개계단，응력강도인자일직표현출진탕변화。함쌍렬문적시건，재주렬문확전중기，차렬문상적응력강도인자유일개쾌속하강적과정。
By means of experimental method of dynamic caustics,the dynamic fracture behaviors,such as,stress intensity factor,extension track,and crack's extending velocity and acceleration of precast beams with a single crack and double cracks under impact loads were analyzed comparatively.The experiment results indicated that when the impact point is directly upon the main crack,the double-crack beam's cracking initiation time is the earliest with a extension track of the main crack slightly offsetting to the secondary crack in the late stage of cracking extension;the single-crack beam of I-type's cracking initiation time is secondary with a straight line extension track of the main crack;the cracking initiation time of the double-crack beam with two cracks offset to the impact point is the latest with obvious bending fracture;the more serious the bending fracture phenomenon during the process of crack extension,the smaller the maximum extending velocity;in the whole process from the hammer contacting the beams to specimens fracture,their stress intensity factors vary oscillatorily;the stress intensity factors of the secondary crack of the double-crack beam decrease dramatically in the middle stage of the main crack extending.