目的 探究取样方向对含单边裂纹牛卡纸拉伸断裂行为的影响，以期提高牛卡纸为原料制作的包装盒等成品的强度。方法 首先在不同取样方向上制备含单边裂纹的牛卡纸试样，然后基于数字图像相关(Digital Image Correlation, DIC)方法，结合显微张力测试台测得不同取样方向与拉伸断裂载荷的关系图，分析不同取样方向下裂纹尖端微观应变场，最后结合电镜扫描测试进行对比分析。结果 结果表明，通常情况下，含单边裂纹的牛卡纸依然符合纸张纵向拉伸载荷大于横向拉伸载荷的规律，取样方向越靠近横向，裂尖区域应变值越大，发生断裂时的拉伸载荷越小。结论 牛卡纸取样方向和纤维与纤维的结合强度是影响牛卡纸拉伸断裂行为的重要因素。

The work aims to explore the effect of sampling direction on tensile fracture behavior of kraft paper with unilateral crack, in order to improve the strength of finished products such as packaging boxes made of kraft paper. First of all, the kraft paper specimens with unilateral cracks in different sampling directions were prepared, and then the relationship graph between different sampling directions and tensile fracture load was measured based on the digital image correlation (DIC) method combined with the micro tension test bed. Next, the micro strain field at the crack tip in different sampling directions was analyzed. Finally, comparative analysis was carried out in combination with the scanning electron microscope test. The results showed that, in general, the kraft paper with unilateral crack still conformed to the law that the longitudinal tensile load of the paper was greater than the transverse tensile load, and the closer the sampling direction to the transverse direction, the greater the strain value in the crack tip area and the smaller the tensile load when fracture occurred. The sampling direction and fiber to fiber bonding strength are two important factors that affect the tensile fracture behavior of kraft paper.