基于超声波谱的钢构件绝对应力识别方法及影响因素研究

发布时间：2018-03-05 02:04

本文选题：超声波　切入点：谱分析　出处：《哈尔滨工业大学》2017年硕士论文　论文类型：学位论文

【摘要】：钢构件绝对应力是判断钢结构能否正常服役的指标。检测钢构件绝对应力状态对于掌握结构安全性能、预测结构服役寿命、判定结构加固改造等具有重要意义。超声波法相对于传统结构应力监测和应力检测方法具有检测对象范围广、检测效率高、设备便于携带等优点。现有基于声时测量的超声波法在测试过程中易受环境影响,且检测仪器往往需具备高采样率。谱分析技术作为信号分析的重要手段,能反应钢构件绝对应力对超声波频域信号的影响规律。基于此,本文提出了基于超声波谱分析的钢构件绝对应力识别方法,主要开展以下研究工作:基于超声波谱分析的钢构件绝对应力识别理论公式建立。本文选择具有宽频带的高频窄脉冲横波作为检测钢构件绝对应力的超声波波型,利用超声波双折射现象,建立数学推导模型得到幅度谱调整函数。通过讨论幅度谱调整函数特性,明确其物理含义并确定了幅度谱特征频率的表达式。在此基础上结合不同类型超声波声弹性公式推导出应力与幅度谱特征频率的关系式。基于超声波谱分析的钢构件绝对应力识别及验证。依据用于检测的超声波特点和理论推导,选择合适的仪器进行组合,并编译信号数据处理模块,完成基于超声波谱分析的钢构件绝对应力检测硬件系统及软件系统的搭建。由超声横波偏振角优选试验,定性验证了幅度谱调整函数的正确性,同时确定了最佳检测偏振角。通过标定试验得到应力与幅度谱特征频率的关系式,利用关系式进一步完成超声波谱识别钢构件绝对应力试验,并对结果进行误差计算,验证了检测方法的可行性。基于超声波谱分析的钢构件绝对应力识别影响因素探究。通过试验研究了检测点位对检测结果的影响,评价了检测方法的稳定性。改变钢构件的厚度进行绝对应力检测试验,分析了钢构件厚度对检测敏感性的影响。同时鉴于钢构件在服役阶段会处于不同的环境温度,考虑温度效应对检测结果的影响,推导出考虑温度效应的超声波谱识别钢构件绝对应力公式。通过标定试验确定温度效应系数,进而利用超声波对考虑温度效应的钢构件绝对应力实现检测并采用应变计法验证检测结果。同时针对试验中反应出的超声波信号在高温条件下发生衰减的原因进行探究。
[Abstract]:The absolute stress of steel member is the index to judge whether the steel structure can be in service or not. The detection of the absolute stress state of steel member is helpful to master the safety performance of the structure and predict the service life of the structure. Compared with the traditional structural stress monitoring and stress detection methods, ultrasonic method has a wide range of detection objects and high detection efficiency. The existing ultrasonic method based on acoustic time measurement is easy to be affected by the environment in the testing process, and the detection instruments often need to have a high sampling rate. Spectral analysis technology is an important means of signal analysis. The influence of absolute stress on ultrasonic signal in frequency domain is studied. Based on this, a method of identifying absolute stress of steel component based on ultrasonic spectrum analysis is proposed. The main research work is as follows: the theoretical formula of absolute stress identification for steel members based on ultrasonic spectrum analysis is established. In this paper, the high frequency narrow pulse shear wave with wide frequency band is selected as the ultrasonic wave pattern to detect the absolute stress of steel members. By using the phenomenon of ultrasonic birefringence, a mathematical derivation model is established to obtain the amplitude spectrum adjustment function, and the characteristics of the amplitude spectrum adjustment function are discussed. The relationship between stress and characteristic frequency of amplitude spectrum is derived by combining with different types of ultrasonic acoustic elastic formula. Steel based on ultrasonic spectrum analysis. Identification and verification of absolute stress of components. Based on ultrasonic characteristics and theoretical derivation for testing, The proper instrument is selected and the signal data processing module is compiled to complete the hardware system and software system of absolute stress detection based on ultrasonic spectrum analysis. The correctness of amplitude spectrum adjustment function is verified qualitatively, and the optimum detection polarization angle is determined. The relationship between stress and characteristic frequency of amplitude spectrum is obtained by calibration test. By using the relation formula, the absolute stress test of steel members identified by ultrasonic spectrum is further completed, and the error calculation of the results is carried out. The feasibility of the detection method is verified. The influence factors of absolute stress identification of steel members based on ultrasonic spectrum analysis are explored. The stability of the test method is evaluated. The absolute stress test is carried out by changing the thickness of the steel member, and the influence of the thickness of the steel member on the detection sensitivity is analyzed. At the same time, in view of the fact that the steel member will be in different ambient temperature during the service phase, Considering the influence of temperature effect on the test results, the formula of absolute stress identification of steel members by ultrasonic spectrum considering temperature effect is deduced. The coefficient of temperature effect is determined by calibration test. Then the absolute stress of steel member considering temperature effect is detected by ultrasonic wave and the test result is verified by strain gauge method. At the same time, the reason of attenuation of ultrasonic signal under high temperature is discussed.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU511.3

【参考文献】