Abstract The normal stress along the shear plane has great effect on the composite intralaminar shear strength. However, the influence mechanism on composite interlaminar shear strength under the normal stress along the shear plane was not truly reflected by the double-notch shear experiment. In this paper, the interlaminar shear strength of composite specimens under different external normal stresses was first obtained using the improved double-notch shear experiment. Furthermore, to research the influence mechanism on interlaminar shear strength under normal stress along the shear plane, the characteristic curve method based on the double-notch shear specimen was studied. Finally, the experimental results analyzed by the characteristic curve method were compared with a range of failure criteria presented in the literature. The experimental data obtained in this study agreed best with the NU theory criterion, with a maximum numerical difference of 4%. And the NU theory criterion can reflect the influence mechanism of the composite interlaminar shear strength best.

中文翻译：

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正应力下复合材料层间剪切强度影响机理研究

摘要 沿剪切面的法向应力对复合材料层内剪切强度有很大影响。然而，双缺口剪切实验并未真正反映沿剪切面法向应力作用下对复合材料层间剪切强度的影响机制。本文首先利用改进的双缺口剪切实验获得了复合材料试件在不同外法向应力下的层间剪切强度。此外，为研究沿剪切面法向应力作用下层间剪切强度的影响机理，研究了基于双缺口剪切试件的特征曲线法。最后，将特性曲线法分析的实验结果与文献中提出的一系列失效准则进行了比较。本研究获得的实验数据与NU理论准则最吻合，最大数值差异为4%。而NU理论判据最能反映复合材料层间剪切强度的影响机理。