This paper presents an experimental study of the composite beams with elastic couplings subjected to the end-notched flexure (ENF) test. The object of research were carbon/epoxy composite laminates with specific stacking sequences exhibiting the bending–extension and the bending–twisting couplings. In addition, multidirectional laminates with different delamination interfaces were tested. Influence of elastic coupling phenomena on behavior of laminates subjected to the bending moment as well as on fracture toughness and delamination surfaces after the ENF tests was discussed. All experiments were performed according to the ASTM D7905 Standard. Determination of crack initiation was supported by the acoustic emission technique. Data analysis of the ENF test was performed by using both the direct beam theory and the corrected beam theory. Results obtained by using the classical data reduction schemes were compared with the compliance-based beam method (CBBM). Greater values of the fracture toughness obtained by using the non-standardized methods can be explained by the effect of the fracture process zone which was taken into account in the CBBM calculation scheme. Delamination surfaces of coupled laminates after the ENF tests were investigated by using the scanning electron microscopy. Results revealed that the effect of elastic couplings might influenced on intense bridging phenomena, more extensive fracture process zone and contribution of the mode III in total delamination resistance. Nevertheless, application of the standardized ENF procedure to determination of the fracture toughness of laminates exhibiting elastic couplings is still possible, provided assistance of additional data reduction schemes and techniques or numerical analysis.

本文介绍了带有弹性耦合的组合梁经过端槽挠曲（ENF）测试的实验研究。研究的对象是具有特定堆叠顺序的碳/环氧复合材料层压板，这些层压板表现出弯曲-延伸和弯曲-扭曲耦合。另外，测试了具有不同分层界面的多向层压板。讨论了弹性耦合现象对层压板在弯矩作用下的行为以及断裂韧性和分层表面的影响。所有实验均根据ASTM D7905标准进行。声发射技术支持确定裂纹萌生。通过使用直接射束理论和校正射束理论对ENF测试进行数据分析。使用经典数据缩减方案获得的结果与基于一致性的波束方法（CBBM）进行了比较。通过使用非标准化方法获得的更大的断裂韧性值可以通过在CBBM计算方案中考虑的断裂过程区域的影响来解释。通过使用扫描电子显微镜研究了ENF测试后的耦合层压板的分层表面。结果表明，弹性联轴器的作用可能会影响强烈的桥连现象，更广泛的断裂过程带和模式III对总抗分层性的影响。尽管如此，仍然可以将标准ENF程序用于确定表现出弹性耦合的层压板的断裂韧性，