考虑界面应变传递机制的内埋FBGs环氧树脂固化过程模拟

Simulation of curing process of epoxy resin with embedded FBGs considering interfacial strain transfer mechanism

采用实验与数值分析相结合的手段对光纤布拉格光栅传感器(Fiber Bragg grating sensor,FBGs)与基体间应变传递机制这一固化监测的基础问题进行了探索。首先,对树脂的固化动力学、热膨胀、化学收缩和玻璃化转变等物化变化进行了表征,然后,借助热电偶和FBGs开展了环氧树脂固化过程的温度和应变监测实验,最后,基于固化过程热-化-力多场耦合数值分析方法开展了固化过程模拟。通过对比纯树脂模型、界面采用绑定约束的含FBGs模型和界面采用内聚力行为的含FBSs模型分析结果,对界面传递机制进行了探讨。结果表明:固化前期界面处存在的剪滞效应和界面滑移行为导致FBGs监测应变相较树脂本体应变明显偏小,其中剪滞效应占主导作用。采用内聚力行为可以较好地描述固化过程界面应变传递机制,数值预测结果与实验值误差较小。

The strain transfer mechanism between fiber Bragg grating sensor(FBGs)and matrix,which is the basic problem of cure monitoring,was explored by combining of experimental and numerical analysis.Firstly,curing kinetics,thermal expansion,chemical shrinkage and glass transition behavior of the resin were characterized.Then,the developments of temperature and strain were monitored by thermocouple and FBGs during the curing process of epoxy resin.Finally,the thermal-chemical-mechanical multi-field coupling numerical analysis was used to simulate the curing process.The interface transfer mechanism was discussed by comparing the results of pure resin model,FBGs model with binding constraint and FBSs model with cohesive behavior.The results indicate that the strain monitored by FBGs is significantly smaller than that of the resin due to the shear lag effect and interface slip behavior at the early curing stage,and the shear lag effect plays a dominant role.The interfacial strain transfer mechanism during curing process can be described properly by cohesive behavior,and the error between numerical prediction and experimental value is small.