摘要
针对3组应力比分别为0.3、0.5、0.8共24个材质为35K的8.8级M24高强度螺栓进行常幅疲劳试验和数值模拟,基于试验结果建立其相应的S-N曲线,并选取典型高强度螺栓疲劳断口进行宏观和微观分析,重点探讨了高强度螺栓预紧力缺失对其常幅疲劳性能的影响.分析结果表明:相同应力比和应力幅的一组螺栓,对应预紧扭矩变化100 N·m,其2×10^(6)次循环对应允许疲劳强度相差11.35%;疲劳断口特征与预紧力大小明显相关,疲劳断口表面、扩展区和瞬断区范围随着预紧力增大,断口颜色变暗、扩展区范围扩大且瞬断区粗糙度加深;高强度螺栓应力集中位置和大小受预紧力值影响较小,但与常幅疲劳试验断口位置基本吻合;有无加荷装置对高强度螺栓应力大小影响明显,对应最大应力差值先减小后趋于稳定.
Constant amplitude fatigue test and numerical simulation were carried out on three groups of 24 specimens of grade 8.8 M24 high-strength bolts made of 35K under the stress ratios of 0.3,0.5 and 0.8.The corresponding S-N curves were established based on the test results,and typical fractured high-strength bolts were selected for macro and micro fractography analysis,mainly focusing on the influence of the pre-tension loss on the constant amplitude fatigue performance.The analysis results show that:for one group of bolts under the same stress ratio and stress amplitude corresponding to the pre-tension torque change of 100 N·m,the difference between the allowable fatigue strengths at 2×10^(6) cycles is 11.35%;the characteristics of fatigue fractured surfaces are obviously related to the pre-tension force,and with the increase of the pre-tension,the color of the fatigue fractured surface darkens,the area of the extension zone expands,and the roughness of the instantaneous fracture zone deepens;The location and magnitude of stress concentration of high-strength bolts are less affected by the pre-tightening,while the location generally agrees with the constant amplitude fatigue fracture location;the presence and absence of the loading device have a significant influence on the stress of the high-strength bolt,and the corresponding maximum stress difference first decreases and then tends to stabilize.
作者
焦晋峰
刘展翔
刘丹
刘勇
郭琪
雷宏刚
JIAO Jinfeng;LIU Zhanxiang;LIU Dan;LIU Yong;GUO Qi;LEI Honggang(College of Civil Engineering,Taiyuan University of Technology,Taiyuan 030024,China;Shandong Electric Power Engineering Consulting Institute Co.,Ltd.,Jinan 250013,China)
出处
《西安建筑科技大学学报（自然科学版）》
北大核心
2022年第1期35-44,共10页
Journal of Xi'an University of Architecture & Technology(Natural Science Edition)
基金
国家自然科学基金项目(51708384)
山西省留学人员科技活动择优资助项目(DC1900000602)
山西省基础研究青年基金项目(201901D211017)。
关键词
高强度螺栓
预紧力
常幅疲劳
应力集中
断口分析
high-strength bolt
pre-tension force
constant amplitude fatigue
stress concentration
fracture analysis
