超声波焊接电源频率自动跟踪方式

在介绍超声焊接中的声学系统频率特性的基础上，着重阐述了超声波电源的几种主要的频率跟踪方式，并指出其发展方向。     

助卷辊电液伺服系统相关辨识法研究

用相关辨识法分析了卷取机助卷辊电液伺服系统的频率特性 ,采用 Levy法求出系统的传递函数 ,并且给出该系统频率特性相关参数。     

Chirp信号激励的电液伺服系统辨识

为得到某电液伺服转台系统的频率特性,采用Chirp信号作为激励。为解决原始时域采样信号直接经FFT处理得到的频率特性曲线严重畸变问题,对原始时域采样信号依次进行传统低通滤波、小波包去噪、高频段相位跳变修正后,再进行FFT,最后采用Smooth平滑滤波方法得到系统最终的频率特性曲线,满足了系统调试和性能评价的要求。     

超声金属焊接双法兰结构声学系统设计

针对超声金属焊接声学系统需承载径向分力,而传统单法兰支承结构难以同时满足超声传递和结构刚度双重要求的问题,基于Ansys数值仿真与单因素实验相结合的方法,开展了超声金属焊接双法兰结构声学系统优化设计研究。首先,对声学系统进行分析,提出了一种声学系统双法兰支承方案;其次,进行法兰厚度尺寸对超声传递效率和支承结构刚度的影响规律研究;最后,通过实验对所设计的声学系统进行性能测试。结果表明:振动系统振幅放大倍数大于2.5,在满足焊接振幅要求的前提下,结构刚度大幅提高。通过仿真分析和实验,验证了双法兰结构的有效性,为超声金属焊接声学组件设计提供了新思路。     

超声波塑料焊机声学系统连接界面破坏及PIII强化

对超声波塑料焊机的声学系统连接界面破坏进行了分析研究。表明硬铝合金焊头极易发生表面的粘着磨损破坏,使得声学系统谐振特性变坏,效率降低。采用等离子体浸没离子注入（ＰⅢ）的方法对声学系统的连接面进行了氮的注入强化。高、低压的交替处理使得表面显微硬度提高６０％,而且在材料近表面生成了ＡｌＮ相,从而改变了其表面化学特性,使处理后的声学系统连接表面粘着倾向大大降低。     

管网频率特性分析试验设计与研究

介绍了管网频率特性分析试验系统构成及试验过程，该系统可用来分析各结构参数对管路中压力脉动特性的影响。     

超声波塑料焊机声学系统连接界面破坏及PIII强化

对超声波塑料焊机的声学系统连接界面破坏进行了分析研究。表明硬铝合金焊头极易发生表面的粘着磨损破坏,使得声学系统谐振特性变坏,效率降低。采用等离子体浸没离子注入（ＰＩＩＩ）的方法对声学系统的连接面进行了氮的注入强化。高、低压的交替处理使得表面显微硬度提高６０ ％ ,而且在材料近表面生成了ＡｌＮ 相,从而改变了其表面化学特性,使处理后的声学系统连接表面粘着倾向大大降低。     

电液负载仿真台加载系统的校正与综合

本文针对电液负载仿真台加载系统的特点,设计了加载系统的控制模型,仿真分析了该模型对克服加载系统的干扰和改善加载系统的频率特性的效果。     

液压系统软参数的确定与故障诊断

本文基于实测频率特性,利用系统辨识程序确定了试验台的实际模型,快速、准确地确定了液压系统中的软参数,进而查明了系统动态特性较差的起因。     

超声振动钻削系统固有频率和振型的分析

用传输矩阵的方法建立了复杂声学系统——超声钻削系统的传输矩阵模型，对超声振动钻削系统的固有频率和振型进行了系统的分析研究，得出了声学夹头长度变化、组合系统中工具长度变化对系统固有频率的影响规律。     

基于USB AE模块的便携式管道声发射泄漏检测系统开发

基于USB AE模块的便携式声发射仪是一种新型的声发射检测设备。阐述了采用声发射方法检测管道泄漏的原理、USB声发射设备的结构和特性,分析了现有USB声发射检测系统存在的局限性。以Visual Studio C++作为程序开发平台,设计了针对管道泄漏这一特定环境和对象的便携式USB声发射检测系统。通过管道泄漏模拟试验,验证了系统设计方案的合理性,实现了声发射信号采集、数据处理和声发射源定位等功能。     

Study of acoustic signal in the process of resistance spot welding based on array sensor system

This investigation was performed to study acoustic field signal in order to improve RSW quality. Researchers firstly built an acoustic array sensor system, which included 8 MPA-416 acoustic sensors, data acquisition card and LabVIEW. The system obtained the acoustic field information in the process of nugget growing. Due to the nonlinearity field signal, array sensor algorithm was utilized to quantitatively analyze the characteristics of acoustic field and reduced noise. The experiment and calculation results show that array sensor system can acquire acoustic field signal of nugget growing in the RSW process and array processing algorithm based on acoustic field can extract characteristic parameters to evaluate RSW quality. It was concluded that the acoustic array sensor system offers a new methodology for RSW quality inspection.     

计算机辅助声发射源检测定位系统

针对普通声发射（ＡＥ）检测仪缺乏源定位功能，开发了计算机辅助ＡＥ源检测定位系统，并详细论述了该系统的组成、接口、源定位算法和程序、剔除噪声等问题     

声阻法胶接结构缺陷实时成像检测

为了有效检测胶接结构缺陷,构建了基于声阻法的成像检测系统. 系统包括声学信号采集、声学探头定位、数据处理及绘图三部分. 利用两轮式编码器,实现了动态扫查过程探头位置信息的采集;利用结合质量检测仪采集缺陷信息;采用C + + 编写了数据处理及图像绘制程序,实现了胶接结构缺陷声阻法实时成像检测. 利用声阻法及常规超声C扫描成像方法对铝合金/环氧树脂/铝合金三明治胶接结构进行了检测,并对检测结果进行了分析对比. 结果表明,声阻法能更有效识别胶接结构中的缺陷,且单面检测即可满足缺陷表征需求.     

Fatigue damage monitoring of round shape specimen by acoustic microscopy

Acoustic microscope can detect microstructural features with high resolving power compared to other lower frequency acoustic techniques. Many non-destructive evaluations using acoustic microscope, several of them used in industrial fields, were investigated. However, acoustic measurement of curved surface structure was restricted to basic studies as conventional acoustic microscope system was designed for flat specimen. We have developed a modified acoustic microscope for curved surface specimen testing and have measured acoustic image of round bar specimen. In this study, using this system, velocities of round bar specimen during fatigue test are monitored using the V(z) curve method. Measurement errors depending on curved surface measurement were investigated and it was found that the acoustic velocity tends to increase as fatigue damage increases.     

An approach to use an array of three acoustic emission sensors to locate uneven events in machining—Part 1: method and validation

The paper reports on an approach to use the triangulation technique applied to arrays of acoustic emission sensors for the location of uneven events occurring during machining. The generation of some uneven events (e.g. workpiece surface discontinuities, plucking, smearing) in machining can be associated with the release of acoustic emission energy. When more than one cutting edge is in contact with the workpiece (e.g. broaching, milling) it is difficult to associate the burst of acoustic emission signal with the tooth that generated it and therefore to locate, relatively to the workpiece surface, the position of acoustic source. The location of the acoustic source, related to the occurrence of the uneven event, is evaluated by feeding the time delays in detecting the same burst signal by three acoustic sensors placed on the workpiece, into an analytical geometry model. Using numerical methods in Matlab, the analytical solution for the location of acoustic source was found by adding to the system formed by three spherical analytical equations, with the acoustic emission sensors as their centres, the characteristics of the cutting tool path. The methodology has been calibrated using pencil break lead tests to asses the accuracy of the acoustic source location and the requirements of the data acquisition system. ‘Near-orthogonal’ cutting trials were carried out using two different arrays of acoustic emission sensors and the uneven events located relatively to the workpiece surface. It was found that the proposed methodology has potential to locate, at a reasonable accuracy, the acoustic sources that are related to the occurrence of uneven events in machining. This work represents a preliminary investigation to be used for the location of workpiece defects during machining with multiple cutting edge tools.     

基于USB的电磁超声数据采集及分析系统的设计

针对电磁超声信号的微弱性、多样性特点以及电磁超声系统的便携式检测需求,设计了基于USB的电磁超声数据采集及分析系统。该系统通过USB实现上位机与采集电路的数据交换,采用FPGA实现电磁超声发射/接收电路控制和数据采集,并利用LabWindows CVI编写了上位机软件。试验表明,系统具有较高的采样速率和采样精度,使用方便灵活,具有广阔的应用前景。     

Characterization of the grinding process by acoustic emission

The properties of a ground surface can be estimated on-line during manufacturing based on the analysis of acoustic signals emitted by the grinding process. This possibility is demonstrated using an experimental system comprising an external grinding machine, a data acquisition unit and an artificial neural network. In the initial phase of system application, an empirical model of the grinding process is formed in the memory of the neural network by self-organized learning driven by empirical data consisting of the acoustic emission spectrum and a surface roughness correlation function. After learning, the system applies the model to estimate the correlation function of the surface profile from the input acoustic emission spectrum. For this purpose, non-parametric regression, based on the conditional average estimator, is utilized. Experiments were done on the grinding of hardened steel workpieces by a corundum wheel. During formation of the model, the surface profile and its correlation function were determined off-line, while in testing system performance the surface correlation function was estimated on-line from the acoustic emission spectrum. With respect to the estimation error, three characteristic periods of the process were observed corresponding to grinding with a newly dressed, slightly worn, and worn out wheel. The best estimation is obtained during grinding by a slightly worn wheel.     

海底沉积物压力自动控制系统的仿真和实验研究

通过控制海底沉积物的压力环境可以研究不同压力环境对海底沉积物声学特性的影响程度和机制。根据海底沉积物声学特性实验的压力控制要求,设计并实现了海底沉积物压力自动控制系统,构建了其机械传动装置及测试舱的数学模型。通过仿真和实验研究,对系统进行了性能分析。实验结果表明:通过采用一定的控制策略,海底沉积物压力自动控制系统达到系统设计指标,为在海底沉积物声学特性实验提供了很好的实验研究条件。