导电水凝胶黏结界面力电学疲劳损伤行为仿真研究

SIMULATION ON THE ELECTRICAL AND MECHANICAL FATIGUE DAMAGE BEHAVIOR OF CONDUCTIVE HYDROGEL INTERFACE UNDER CYCLIC LOADING

为了研究导电水凝胶电极贴片在疲劳载荷下因界面损伤而导致的电阻变化规律,本文提出了一种力电学内聚力模型.首先基于水凝胶的黏弹性力学行为,采用Wiechert模型构建了应变率相关的内聚力牵引力-牵引位移关系方程,并将界面电阻率定义为牵引力和损伤变量的函数,然后通过ABAQUS的UEL子程序对黏弹性力电学内聚力模型进行了数值实现.通过搭接剪切试验确定了模型的黏弹性参数和不同应变率下内聚力模型的损伤起始和界面断裂的能量释放率,以及应变率下界面电阻率随牵引力的变化规律.采用单个单元对模型的有效性进行了验证,最后将模型应用于导电水凝胶电极贴片的在疲劳载荷下的界面电阻变化规律仿真预测,结果表明随着电极贴片的电阻随着加载循环次数的增加呈波动上升趋势,且随着加载速率增大,电阻随加载次数上升的趋势逐渐减缓,电阻的波动也越小,有限元仿真结果与实验结果吻合良好.

In order to study the resistance change of conductive hydrogel patch electrode caused by interface damage under fatigue load,an electrical-mechanical cohesive zone model was proposed in this work.Firstly,based on the viscoelastic mechanical behavior of hydrogel,the Wiechert model was applied to construct the rate-dependent tractiondisplacement jump relationship of the hydrogel adhesive layer.And the interfacial resistivity was defined as a function of traction force and damage variables.Then,the viscoelastic electrical-mechanical cohesive zone model was numerically implemented by ABAQUS/UEL subroutine.The viscoelastic parameters of the model and the energy release rate of damage initiation and interface fracture of the cohesion model at different strain rates,as well as the variation law of interfacial resistivity with traction force under different loading rates,were determined by shear tests.Afterwards,the effectiveness of the proposed model was verified by a single element simulation.Finally,the model was applied to predict the interfacial resistance growth of the patch electrode adhered by conductive hydrogel under fatigue loading.The results showed that the resistance of the patch electrode presented a fluctuating increase trend with the increment of loading cycles.With the increase of the loading rate,the resistance rising rate gradually decrease,and the resistance fluctuation was smaller.The finite element simulation results were in good agreement with the experiments.