频率效应对Q345钢疲劳行为的影响  

Frequency effect on fatigue performance of Q345

作　　者：王睿东[1] 崔仕明[1] 刘永杰[1] 游翔[1] 王清远[1] 

机构地区：[1]破坏力学与工程防灾减灾四川省重点实验室,四川大学建筑与环境学院,四川成都610065

出　　处：《中国建材科技》2015年第1期66-69,共4页China Building Materials Science & Technology

基　　金：11327801;11302142。国家自然科学基金

摘　　要：本文对结构用钢Q345的低周、超低周以及高频试验疲劳行为进行了研究。实验在常温下岛津电液伺服疲劳试验机和QBG-100高频疲劳试验机上进行。低周疲劳试验采用轴向应变控制方法,恒定应变速率为0.005 s^(-1),应变比为-1。超低周疲劳试验采用加载频率控制。高频试验通过增减砝码质量(激励质量)的数目来改变系统的谐振频率,应用共振原理测试高频下试件的载荷-周期(S-N)试验数据。实验结果表明,在同一应力水平下,加载频率更高的高频试验条件下的试件寿命总体上比低频率的低周疲劳试验试件的寿命长。超低周疲劳试验中,随着加载应力的提高,试件寿命曲线逐渐下降,通过频率-寿命(f-N)图可以看出,随着加载频率的增加,试件寿命有所提高。通过SEM扫描电镜对三种试件断口进行观察,可以发现低周及超低周疲劳试验试件的裂纹多从表面起源,高频试验既有表面起源的裂纹也有从内部萌生的裂纹,破坏形式主要取决于加载应力和材料性质,与加载频率无太大关系。In this paper, low cycle fatigue, ultra low cycle fatigue and high frequency properties of structural steel Q345 were experimentally studied. The fatigue tests were conducted on a Shimadzu servo-hydraulic testing machine in fully reversed cyclic axial configurations at constant strain rate of 0.005 s-1 at room temperature. Ultra low cycle fatigue tests were controlled by loading frequency. High frequency tests were conducted on the QBG-100 High frequency fatigue tester. The tester changes the resonant frequency of the system by adding or reducing the number of weight（inspiring weight） to measure the numbers of fatigue life of the specimens by using resonance principle. The result show that, at the same level of stress, the fatigue life of specimens under higher frequency tests are generally longer than those conducted by a lower frequency test machine.Throughout the ultra low fatigue test, as the loading stress increases,the fatigue life curve of specimen declines gradually.It can be seen from the f-N figure that,as the loading frequency increases, the fatigue life of specimen has improved generally. By observing the fractures of three kinds of specimens using the scanning electron microscope（SEM）,it can be seen that almost all specimens of low cycle and ultra low cycle fatigue tests cracks upon their surfaces. In the high frequency test,specimens crack not only upon surface but also from the interior.The crack forms depend mainly upon loading stress and the material properties. It has no obvious relationship with the loading frequency.

关 键 词：Q345 频率效应 低周疲劳 超低周疲劳 高频疲劳试验 

分 类 号：TU318.1[建筑科学—结构工程]