聚氨酯注浆材料在循环压缩加载下疲劳性能与微观结构演化

发布时间：2018-03-22 02:00

本文选题：聚氨酯　切入点：压缩疲劳　出处：《复合材料学报》2017年03期 　论文类型：期刊论文

【摘要】：应用于基础设施维修加固的聚氨酯注浆材料通常承受反复荷载作用,对聚氨酯注浆材料进行循环压缩加载试验以测试其压缩疲劳性能,全程记录材料的应变响应,并在SEM下观测材料泡孔结构疲劳破坏的微观形貌特征。试验结果表明:材料在循环荷载下的响应分为三个阶段,第一阶段持续数十次,弹性应变递次增大;第二阶段应变值稳定;第三阶段在高应力水平下表现为疲劳破坏,在低应力水平下表现为循环硬化。对于0.3g/cm3的试件,导致疲劳破坏的应力阈值α在0.7~0.8之间;而0.5g/cm3试件的阈值在0.6~0.7之间。发生疲劳破坏时,材料的宏观表现为垂直于荷载方向的鼓出,微观表现为泡壁裂纹扩张和棱边屈曲。此外,提出疲劳损伤参数D表征材料模量在循环荷载下的演化,D可以敏感地捕捉低应力水平下第三阶段材料的循环硬化。
[Abstract]:Polyurethane grouting materials used in infrastructure maintenance and reinforcement are usually subjected to repeated loads. Cyclic compression loading tests are carried out to test the compressive fatigue properties of polyurethane grouting materials, and the strain response of the materials is recorded in the whole process. The results show that the response of the material under cyclic load is divided into three stages, the first stage lasts for dozens of times, and the elastic strain increases step by step. The strain value of the second stage is stable, the third stage is fatigue failure at high stress level and cyclic hardening at low stress level. For the specimen of 0.3g/cm3, the stress threshold 伪 leading to fatigue failure is between 0.7 and 0.8; However, the threshold value of 0.5g/cm3 specimen is between 0.6 and 0.7. When fatigue failure occurs, the macroscopic behavior of the material is bulging perpendicular to the load direction, and the microscopic behavior is crack expansion and edge buckling of the bubble wall. It is suggested that the fatigue damage parameter D can sensitively capture the cyclic hardening of the third stage material at low stress level by describing the evolution of the modulus of the material under cyclic loading.
【作者单位】：清华大学土木工程系土木工程安全与耐久教育部重点实验室;郑州大学水利与环境学院;
【分类号】：TU532

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