高强度螺栓材料全过程真实应力-应变关系研究
Study on Full-range True Stress-strain Relationship of High-strength Bolt Material
刘卓 1杨飞 2陈澳 1张雅俊 3武芳文1
作者信息
- 1. 长安大学 公路学院, 陕西 西安 710064
- 2. 长安大学 建筑工程学院, 陕西 西安 710061
- 3. 厦门理工学院 土木工程与建筑学院, 福建 厦门 361024
- 折叠
摘要
对极限状态下螺栓杆会发生较大变形的高强度螺栓连接节点进行模拟分析时,需考虑螺栓材料的真实应力-应变关系.为此,以 10.9 级M20,M24,M30 高强度螺栓为研究对象,探讨单轴拉伸状态下高强度螺栓材料的全过程真实应力-应变关系.首先制作高强度螺栓材料拉伸试件并通过开展单轴拉伸试验获得材料的全过程工程应力-应变曲线.然后采用有限元方法对单轴拉伸试验进行模拟,通过比较有限元分析和实测工程应力-应变曲线,讨论描述材料真实应力-应变关系的Ludwik,Hollomon,Voce,Swift表达式的适用性.最后基于归一化的颈缩前真实应力-应变关系以及归一化的硬化阶段真实应力-应变关系,提出两种改进的Ramberg-Osgood表达式描述螺栓材料的全过程真实应力-应变关系.结果表明:基于颈缩前硬化阶段真实应力-应变曲线拟合的Ludwik,Hollomon,Voce,Swift表达式中,Ludwik,Hollomon,Swift表达式会高估螺栓材料颈缩后的真实应力,而Voce表达式会低估螺栓材料颈缩后的真实应力;本研究提出基于归一化颈缩前真实应力-应变关系的Ramberg-Osgood表达式可较为准确地描述高强度螺栓材料的全过程真实应力-应变关系,其在强化阶段会略高估螺栓材料的真实应力;提出的基于归一化硬化阶段真实应力-应变关系的Ramberg-Osgood表达式可更准确地描述高强度螺栓材料的全过程真实应力-应变关系.
Abstract
The true stress-strain relationship of bolt material should be considered in the simulation analysis on high-strength bolted joints with large deformation in the bolt shank under the limit state.For this reason,the M20,M24 and M30 high-strength bolts in grade 10.9 are taken as the study objects,and the full-range true stress-strain relationship of the bolt material is discussed.Firstly,the bolt material tensile specimens are fabricated and the material full-range engineering stress-strain curves are obtained by conducting uniaxial tensile tests.Then,the finite element method is used to simulate the tensile tests.The applicability of Ludwik,Hollomon,Voce and Swift expressions for describing material true stress-strain relationship is discussed by comparing the finite element analysis and the measured engineering stress-strain curves.Finally,based on the normalizing pre-necking true stress-strain and the normalizing true stress-strain in strain-hardening stage,2 improved Ramberg-Osgood expressions are proposed for describing the full-range true stress-strain relationship of bolt material.The result shows that(1)in the fitted Ludwik,Hollomon,Voce and Swift expressions based on the pre-necking strain-hardening stage true stress-strain curves,Ludwik,Hollomon and Swift expressions would overestimate the post-necking true stress of bolt material,while Voce expression would underestimate the post-necking true stress of bolt material;(2)the proposed Ramberg-Osgood expression based on the normalizing pre-necking true stress-strain relationship would accurately describe the true stress-strain relationship of the full-range of high-strength bolt material,and slightly overestimate the true stress of the bolt material in the strengthening stage;(3)the proposed Ramberg-Osgood expression based on the true stress-strain relationship at the normalized hardening stage could describe the true stress-strain relationship in the full-range of high strength bolt materials more accurately.
关键词
桥梁工程/真实应力-应变/拉伸试验/高强度螺栓/Ramberg-Osgood表达式Key words
bridge engineering/true stress-strain/tensile test/high-strength bolt/Ramberg-Osgood expression引用本文复制引用
出版年
2024
NETL
NSTL
万方数据