本文研究了Ⅰ～Ⅱ复合型裂纹的断裂问题。在薄壁圆筒上开了斜裂纹,其长度为2a=8mm,是用电火花法开出的。为了防止薄壁圆筒扭转时失稳,试验时加了内、外保持器。试验结果表明,和θ_o实验值介于最大周向应力理论和最小应变能密度因子理论的计算值之间。但从工程角度考虑,为了安全起见,建议采用最大周向应力理论。 This paper studies the fracture problem of composite cracks I-II. An oblique crack was opened on the thin-walled cylinder and its length was 2a = 8mm, which was developed by electric spark method. In order to prevent the thin-walled cylinder from destabilizing during torsion, the inner and outer retainers were added during the test. The experimental results show that the experimental values ​​of θ_o are between the calculated values ​​of the maximum circumferential stress theory and the minimum strain energy density factor theory. However, from an engineering point of view, the maximum circumferential stress theory is recommended for safety reasons.