超声红外热像技术中预紧力对金属平板振动特性的影响

发布时间：2018-03-14 00:14

本文选题：预紧力　切入点：振动频谱　出处：《机械工程学报》2016年05期 　论文类型：期刊论文

【摘要】：在超声红外热像检测过程中,超声脉冲激励下被测对象的振动状态直接决定了缺陷区域的生热效果,而工具杆与被测对象之间的预紧力是影响被测对象振动状态的重要因素之一。试验结果表明:预紧力的增大使得振动能量呈上升趋势并伴随着小范围不稳定,同时被测对象的振动频谱由混沌振动开始,经历次谐波、准次谐波后达到超谐波振动状态。针对上述现象,采用显式动力学方法建立了与试验条件相对应的有限元模型,并进行了瞬态动力学分析。模型采用压电-力类比方法来模拟压电陶瓷的逆压电效应,同时引入了动态松弛来更准确模拟试验工况。仿真结果验证了试验观察到的现象,并进一步揭示了预紧力的增大将改变超声工具杆和被测平板之间的接触力状态,从而改变被测试件的振动能量分布和振动频谱。研究成果有助于实现通过预紧力来控制被测对象振动状态,进而达到优化超声红外热像检测的目的。
[Abstract]:In the process of ultrasonic infrared thermal image detection, the vibration state of the object under ultrasonic pulse excitation directly determines the heat generation effect in the defect region. The pretightening force between the tool rod and the measured object is one of the important factors affecting the vibration state of the tested object. The experimental results show that the increase of the pretension force makes the vibration energy increase and accompanied by a small range of instability. At the same time, the vibration spectrum of the measured object begins with chaotic vibration, goes through subharmonics and quasi-harmonics, and then reaches the state of hyperharmonic vibration. In view of the above phenomena, a finite element model corresponding to the experimental conditions is established by using explicit dynamic method. The model uses piezoelectric force analogy method to simulate the inverse piezoelectric effect of piezoelectric ceramics, and dynamic relaxation is introduced to simulate the test conditions more accurately. The simulation results verify the observed phenomena. It is further revealed that the increase of pretightening force will change the contact force between the ultrasonic tool rod and the plate to be measured. Thus, the vibration energy distribution and vibration spectrum of the tested object can be changed. The research results are helpful to control the vibration state of the tested object by pre-tightening force, and then to optimize the ultrasonic infrared thermal image detection.
【作者单位】：装甲兵工程学院机械工程系;
【基金】：军内计划科研资助项目
【分类号】：TG115.28

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