树脂基搭接碳纤维智能层的力阻特性

Piezoresistivity of overlapped carbon fiber polymer-matrix smart layer

提出一种具有局部搭接结构的树脂基碳纤维智能层,将其敷设于结构表面以检测结构受载时的变形,实现对结构大范围监测。基于该智能层,采用单轴拉伸和三点弯曲的加载方式,对构件进行应变和位移检测。实验发现,碳纤维局部搭接结构是引起力阻效应的主要因素,其单位应变的电阻率变化的灵敏度达到104,相当于非搭接连续碳纤维复合材料力阻效应灵敏度的34倍。实验结果还进一步表明,树脂基搭接碳纤维智能层力阻曲线光滑稳定,其传感极限约为8500με。建立了树脂基搭接碳纤维复合材料的电学模型,揭示了这种力阻效应主要来源于搭接界面处层间电阻的变化,并从纤维轴向力、搭接面积和层间剪应变三个方面解释了这种层间电阻变化的机制。

A smart layer was developed by effectively overlapping continuous carbon fibers in a local area in epoxy matrix.The smart layer was stuck on the structure surface to sense its deformation and perform a large-region monitoring.Based on the smart layer,the strain and displacement of the components were detected in the uniaxial tension and three-point bending experiments.The results indicate that the local overlapped structure is the essence of the overlapped carbon fiber polymer-matrix smart layer.The gauge factor of the overlapped carbon fiber polymer-matrix smart layer,defined as fractional change in resistance per unit strain,is as high as 104,which is 34 times as that in continuous carbon fiber composites without an overlapped part.The results further show that the piezoresistivity curve of overlapped carbon fiber polymer-matrix smart layer is smooth and stable,and exhibits a sensing limit of around 8500 με.An electrical model of the overlapped carbon fiber polymer smart layer was established,which revealed that the change of interlaminar resistance in the overlapping region is the source of its piezoresistivity.Furthermore,a preliminary explanation of the mechanism of the change of interlaminar resistance was made from fiber axial load,overlapped area and interlaminar shear strain.