【作者】 胡享平；

【导师】 黄亚宇；

【作者基本信息】 昆明理工大学 ， 机械制造及其自动化， 2010， 硕士

【摘要】 在现代的生活中,随着系统结构越来越复杂,由金属材料的断裂所造成的问题也越来越严重,其原因大概可以分为脆性断裂,韧性断裂,疲劳开裂和环境腐蚀等等。但是,断裂力学的理论体系还不够健全,不足以完全避免此类失效。从事断裂力学的研究,要求研究者们有着扎实的数学背景,以及丰富的力学知识和机械工程领域的相关知识。值得欣慰的是,如今越来越多的研究人员开始关注该领域,他们的研究为理解和解决现实生活中的实际问题提供了理论指导,使工程设计人员更好地了解材料的断裂力学特性和更好地认识系统结构及零部件的力学特征。同时,对断裂力学基本理论的研究和进行相关的仿真,在实际的应用领域有着重要的价值。为了分析电磁激振器中缓冲弹簧的失效问题,本文是通过将对标准测试试件三点弯曲试样特性的研究来完成的。本文选用的载荷为周期作用力来模拟电磁激振器中作用锤对缓冲弹簧的作用。本文将集中对如下几个方面进行研究：电磁激振器中缓冲弹簧三点弯曲试样断裂力学理论模型的建立与分析计算,恒定载荷下静态应力强度因子的计算,等效三点弯曲模型的系统方程和周期作用力下的动态应力强度因子的理论分析和计算,最后再进行基于ABAQUS的有限元仿真及分析。同时,对该三点弯曲试样的寿命也进行相应的理论分析和计算,同时也对材料的选择的一般原则进行了基本的分析。本文也讨论了关于三点弯曲试样的等效质量-阻尼-刚度系统的系统方程与理论模型,理论上获得了动态应力强度因子的解析解的一般形式。这也为将来的研究中进一步分析缓冲弹簧的断裂力学特性打下了理论基础。总之,本文基于工程实际使用中的电磁激振器中的缓冲弹簧实例,使用标准三点弯曲试样,对弹簧材料的断裂力学结构特性进行相关的理论研究和仿真分析。从而为未来进一步的研究奠定坚实的基础。更多还原

【Abstract】 Fracture mechanics, as we all know, are closely related to our daily life. There are a lot of the disasters due to fracture, fatigue, or fraction. Even in the modern society, failure due to fracture, fatigue and fracture is going on all the time, because the theory in this field is not well established. Doing research in this field requires solid background in Mathematics together with knowledge in Solid Mechanics and Mechanical Engineering. Nowadays, however, more and more researchers are working in this field. These researches will give the better understanding with the materials and also the structure. It will be definitely a promising field in the future.In order to do research for the the cushion spring from the Electromagnetic Exciter, a 3 Point-Bend Specimen (3PBS) has been chosen. The analyses will be carried on this specimen with different loading conditions. Failure will occur due to fracture or fatigue in the spring. Cyclic load are chosen as candidates for analysis in this paper.In this dissertation, the following parts will be carried on:theoretical modelling for the 3PBS, the principal of material selection, analytical analysis for Dynamic Stress Intensity Factor, FEM analysis in ABQUS and discussion with the results. The Stress Intensity Factor (SIF) for different loading cases will be compared. The life time of the specimen in our model has also been evaluated. Further, some mathematical method for finding Dynamic Stress Intensity Factor (DSIF) will be discussed in this dissertation. The research for DSIF will be continued in future.This dissertation will provide the general idea how to do the fracture mechanics analysis in a standard way for the cushion spring from the Electromagnetic Exciter. It can form the solid basis for deeper research in future.更多还原