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形状记忆聚氨酯热力耦合变形行为实验和有限元模拟
引用本文:梁志鸿,李建,阚前华,康国政. 形状记忆聚氨酯热力耦合变形行为实验和有限元模拟[J]. 材料工程, 2019, 47(10): 133-140
作者姓名:梁志鸿  李建  阚前华  康国政
作者单位:西南交通大学力学与工程学院,成都,610031;西南交通大学力学与工程学院,成都,610031;西南交通大学力学与工程学院,成都,610031;西南交通大学力学与工程学院,成都,610031
基金项目:国家自然科学基金;四川省杰出青年基金
摘    要:在室温下对形状记忆聚氨酯进行不同应变率下的单调拉伸实验,结合红外测温仪对试样表面温度进行同步监测,研究拉伸过程中的热力耦合效应。结果表明:当应力达到屈服峰后,分子链解缠导致了屈服软化,同时分子链之间的摩擦诱发了局部化温升;随着载荷继续增加,分子链在拉伸方向优先取向导致应变硬化发生,响应的应力和温度不断升高。同时发现,屈服峰和局部化温升均随着应变率的增加而显著增加,然而材料耗散生热诱导的应变软化和应变硬化之间存在竞争机制,使得局部化塑性流动过程对应变率的敏感性降低。基于有限元软件ABAQUS建立板状试样拉伸的有限元模型,对形状记忆聚氨酯的拉伸变形进行热力耦合分析。通过比较不同时刻的塑性应变场和温度场云图发现,局部化的塑性流动和温升均从初始缺陷处萌生,并逐渐向中间移动直至扩展到整个试样。进而提取不同加载速率下的平均温升曲线与实验结果进行了对比,发现二者吻合度较高。

关 键 词:形状记忆聚氨酯  热力耦合  塑性流动局部化  温升  率相关

Experiment and finite element simulation on thermo-mechanically coupled deformation behavior of shape memory polyurethane
LIANG Zhi-hong,LI Jian,KAN Qian-hua,KANG Guo-zheng. Experiment and finite element simulation on thermo-mechanically coupled deformation behavior of shape memory polyurethane[J]. Journal of Materials Engineering, 2019, 47(10): 133-140
Authors:LIANG Zhi-hong  LI Jian  KAN Qian-hua  KANG Guo-zheng
Affiliation:(School of Mechanics and Engineering,Southwest JiaotongUniversity,Chengdu 610031,China)
Abstract:Monotonic tensile tests of shape memory polyurethane(SMPU)at different strain rates were carried out at room temperature,and the surface temperature of samples was monitored synchronously with the infrared thermometer to investigate the thermo-mechanical coupling effect during stretching.The results show that the post-yield softening is observed due to the disentanglement of molecular chains,after the stress approaches the yield peak,and a localized temperature rise is induced by the friction between molecular chains;with the progressive increasing of load,the strain hardening occurs due to the preferred orientation of molecular chains in the direction of stretching,which induces the stress and temperature rise increase.In the meantime,it is found that both the yield peak and localized temperature rise are increased significantly with the increase of strain rates;however,the competition exists between the strain softening induced by the dissipation heat generation and the strain hardening,making the sensitivity of localized plastic flow on the strain rate decreased.Based on the finite element software ABAQUS,the finite element model of a plate specimen was established to study the thermo-mechanically coupled behavior on the tensile deformation of SMPU.By comparing the contours of plastic strain field with that of temperature field at different moments,it is found that the forming of the localized plastic flow and temperature rise start from the initial defect and gradually move towards the middle and the expand to the entire sample,simultaneously.Furthermore,the simulated average temperature rise curves at different loading rates are in good agreement with the experimental ones.
Keywords:shape memory polyurethane  thermo-mechanical coupling  plastic flow localization  temperature rise  rate dependence
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