激振频率对裂纹梁系统振动特性的影响

Influence of Exciting Frequency on Vibrating Characteristics of a Cracked Beam

用ZK-4VIC型振动与控制实验台和ZK-1型电动式激振器分别对相同的Q235裂纹梁系统加载大小相同频率不同的简谐激振力(F=1.12N,w=17Hz、19Hz、21Hz、23Hz),对裂纹梁的振动疲劳过程进行模拟。记录实验过程中裂纹梁的振动幅值随时间变化的趋势,分析在不同激振频率的激振力作用下,疲劳裂纹对裂纹梁振动特性的影响。结果表明:加载简谐激振力的激振频率与固有频率的关系对裂纹梁系统的振幅变化影响显著;裂纹产生后,刚性系统受裂纹的影响大于柔性系统受裂纹的影响,寿命较短;刚性系统比柔性系统更容易从振动变化上发现裂纹故障的存在。

To simulate the vibration fatigue process of Q235 crocked beam, the harmonic excitation force under the same strength level at different frequencies （F=1.12N,w=17Hz,19Hz,21Hz,23Hz）/s loaded respectively on the same cracked beam with ZK--4VIC vibration and control test-bed and ZK-1 electrodynamic vibrators. It records the vibration amplitude＇s change trend over time of the beam in the process of experiment and analyzes the influence that the fatigue crack has on the vibration characteristics of the cracked beam at different exciting frequencies. The results show that the relationship between the exciting frequency loaded harmonic excitation force and the natural frequency has a distinct impact on the change of amplitude of the cracked beam; After the crack is formed, the influence that crack has on the stiff system is larger than that on the flexible system, therefore the fatigue life is longer; It is easier to find the existence of crack faults from the vibration change of the stiff system than from that of the flexible system.