蜂窝夹层结构芯子剪切模量的实验方法

Experimental method for shear modulus of honeycomb sandwich structure core

蜂窝夹层结构凭借其优良的力学性能在航空、船舶制造和车辆碰撞防护领域得到了广泛应用。蜂窝夹层结构剪切性能的测量一直是工程人员重点关注的问题,测量蜂窝夹层结构芯子剪切模量时常采用平面剪切实验方法,但对于大厚度蜂窝夹层结构平面剪切实验实现难度大,为改善这一问题,分别采用理论预测分析、平面剪切实验和三点弯曲实验的方法对蜂窝夹层结构芯子剪切模量进行测量,对比3种测量方法的差异性。利用等效板理论进行理论分析,得出芯子剪切模量的理论预测值;依据ASTM C273和ASTM C393试验标准,对蜂窝夹层结构开展了平面剪切实验与三点弯曲实验,利用ABAQUS有限元软件对平面剪切实验和三点弯曲实验分别进行了模拟仿真。结果表明:利用最小势能原理和最小余能原理进行理论分析,可以得出芯子剪切模量的预测值,预测结果误差在16%左右;平面剪切实验的测量结果较为精准,当蜂窝夹层结构厚度增大无法提供剪切试验台实验时,可以使用平面剪切有限元仿真方法获取;三点弯曲实验方法测量误差结果在10%左右,通过对三点弯曲试验的有限元模拟分析,研究三点弯曲实验中跨距深度比对试件剪切模量测量的影响,调整三点弯曲跨距深度比a/d为5时,误差能降低到4%以内。

Honeycomb sandwich structure has been widely used in the fields of aviation,shipbuilding and vehicle collision protection due to its excellent mechanical properties.The measurement of shear performance of honeycomb sandwich structures has always been the focus of engineers.The plane shear tests method are often used to measure the shear modulus of honeycomb sandwich structures.However,it is difficult to realize the plane shear test of the honeycomb sandwich structure with large thickness.In this paper,the shear modulus of honeycomb sandwich core was measured by theoretical prediction analysis,plane shear tests and three-point bending tests.According to ASTM C273 and ASTM C393 test standards,plane shear tests and three-point bending tests were carried out for honeycomb sandwich structure.The plane shear tests and the three-point bending tests were simulated by ABAQUS.The results show that the prediction value of core shear modulus can be obtained by theoretical analysis based on the principle of minimum potential energy and minimum complementary energy.The prediction error is about 16%,when the thickness of honeycomb sandwich structure can not provide the shear test rig.The plane shear finite element simulation method can be used to obtain the results.The influence of span-depth ratio on the measurement of shear modulus in three-point bending test is studied by means of finite element simulation analysis.When the ratio of span-depth ratio of three-point bending is 5,the error can be reduced to less than 4%.