管约束和分子链缠结作用下黏弹性材料力学行为

Mechanical behavior of viscoelastic materials under tube-constraint and molecular entanglement influence

以高斯链模型、三链模型和八链模型为例,从微观角度出发对黏弹性材料的弹性力学性能进行了研究.考虑周围分子链的管道约束和分子链间缠结作用对橡胶基体交联网络的弹性增强效应,对高斯链模型、三链模型和八链模型进行修正.基于单轴拉伸、纯剪切和等双轴拉伸等变形方式下天然橡胶经典试验数据,分别对修正后的高斯链模型、三链模型和八链模型进行分析验证.结果表明,考虑管约束和分子链间缠结作用修正时,3个模型的准确度均得到较大提升.其中,修正三链模型准确度提升程度最大,与修正八链模型较为接近,修正高斯链模型在变形不小于40%时误差依然较大.不同变形模式下修正后的高斯链模型、三链模型和八链模型最大均方根误差分别减小到14.89%、8.09%和10.64%.

The Gaussian chain model,three-chain model and eight-chain model are taken for example to study the elastic mechanical properties of viscoelastic materials from microscale perspective.Considering the tube-constraint effect from the surrounding molecular chains and the elastic enhancement effect from the chain entanglement for the cross-linked network in the rubber matrix,the Gaussian chain model,three-chain model and eight-chain model are modified.Based on the classical test data of natural rubber under uniaxial stretching,pure shear and equal biaxial stretching,the analysis and verification for the modified Gaussian chain model,three-chain model and eight-chain model are carried out.The results show that the accuracy of each model is greatly improved when considering the modification of the tube constraint and entanglement between molecular chains.Among them,the accuracy of the modified three-chain model is the most improved,and is close to the modified eight-chain model.The error of the modified Gaussian chain model is still large when the deformation is not smaller than 40%.With different deformation modes,the maximum root mean square error of the modified Gaussian chain model,three-chain model and eight-chain model is reduced to 14.89%,8.09%and 10.64%,respectively.