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结合最小余能原理和薄板剪切屈曲失稳理论,给出了蜂窝芯等效剪切屈曲强度的理论表达式。将胞壁等效为受弹性支撑的梁,通过对固支和简支条件下的屈曲强度进行插值求解实际胞壁间为弹性支撑时的剪切屈曲强度。然后,利用三点短梁弯曲试验测量常用Nomex蜂窝芯的剪切屈曲强度,并与弹性支撑下的理论解进行对比,试验结果与理论解吻合较好,验证了理论方法的有效性。最后,讨论了剪切屈曲强度的各向异性及蜂窝高度对剪切屈曲强度的影响。结果表明,剪切屈曲强度的各向异性程度与蜂窝高度无关,但随着蜂窝高度的增加,蜂窝芯的纵向和横向剪切屈曲强度均逐渐减少,减小幅度逐渐减缓。
Combining the principle of minimum residual energy and the theory of thin plate shear buckling, the theoretical expression of equivalent shear buckling strength of honeycomb core is given. The cell wall is equivalent to a beam that is elastically supported. The buckling strength at the actual cell wall is calculated by interpolating the buckling strength under the conditions of solid and simple support. Then, the shear buckling strength of the commonly used Nomex honeycomb core was measured by three-point short beam bending test and compared with the theoretical solution under elastic support. The experimental results agree well with the theoretical one, which verifies the effectiveness of the theoretical method. Finally, the effects of anisotropy of shear buckling strength and honeycomb height on shear buckling strength are discussed. The results show that the anisotropy of shear buckling strength has nothing to do with the height of the honeycomb. However, with the increase of honeycomb height, the buckling strength of honeycomb core in both the longitudinal and transverse directions gradually decreases and the decreasing amplitude decreases gradually.