共查询到20条相似文献,搜索用时 155 毫秒
1.
2.
3.
4.
5.
6.
7.
本文首先简述了声发射的原理及其测量技术。接着对声发射分析方法在淬火、回火和退火等几个方面的具体应用进行了详细的评述和分析研究。马氏体形成时出现强度可测出的信号,奥氏体→铁素体(珠光体)的相转变则不能发生可测出的信号。声发射信号强度与组织形态有关,碳含量高时形成片状马氏体的声发射活性比形成板条状马氏体要强。马氏体回火时不出现可测出的信号。声发射分析对于探测退火时裂纹的发生及其扩展是一种有效的方法。与其它无损检测方比法较起来,声发射分析的特点是,它不仅可作最终检验,而且可以用少量的传感器进行连续监测,这种方法对于大型构件具有特殊重要的经济意义。 相似文献
8.
《中国有色金属学会会刊》2020,(6)
由γ奥氏体和ε马氏体构成的Fe_(66)Mn_(15)Si_5Cr_9Ni_5(质量分数,%)形状记忆合金经机械振动抛光后在压应力作用下发生塑性变形。经机械振动抛光的FeMnSiCrNi形状记忆合金几乎发生完全的ε马氏体相变,其中应力诱发马氏体相变起主导作用。应力诱发马氏体相变与外加应力的取向密切相关。机械振动抛光引起的复杂压应力有助于FeMnSiCrNi形状记忆合金γ奥氏体发生ε马氏体相变。机械振动抛光对FeMnSiCrNi形状记忆合金ε马氏体表面织构具有一定影响,在经机械振动抛光的FeMnSiCrNi形状记忆合金表面形成■0001织构。 相似文献
9.
10.
采用一种新型砂轮破碎状态信号检测方法——声发射(AE)技术,通过采集环境背景、空转、空载和负载AE信号,并对信号进行时频域研究。对比砂轮破碎后和破碎前AE信号特征,时域信号特征电压值增大了2.5倍、能量谱峰值增大了4倍、均方根值(RMS)增加了1.17倍,频域信号经快速傅里叶转换(FFT)后得到了一个高频电压信号。研究结果表明:声发射技术优于目前常用的振动法、音量法和光电法,更适合用于砂轮回转实验破碎识别。 相似文献
11.
Wavelet-based AE characterization of composite materials 总被引:1,自引:0,他引:1
This paper addresses an application of recently developed wavelet-based signal processing technique on a composite fracture behavior study. Here, the wavelet methodology is introduced, and a complete procedure of wavelet-based acoustic emission (AE) analysis methods developed by the author are demonstrated. In this research, the AE signals from glass fiber reinforced (GFR) composites are collected during the standard quasi-static tensile testing and transformed by the Daubechies discrete wavelets using the programs developed by the author. Based on AE tests, the fracture behaviors are studied for the material. In the study of GFR composite fracture behavior, classical linear fracture mechanics method is used for comparison. The exponential constant m value used to determine the relationship between stress and stress intensity factor are compared relative to the classical fracture mechanics and the AE techniques. In order to demonstrate the advantage of the wavelet-based AE techniques, the conventional AE analysis is also provided side-by-side for comparison. The results verify that the wavelet-based method better approximates residual strength relative to the classical AE techniques.In this paper, the results of the wavelet-based AE analysis of glass fiber composites are presented. The results indicate that wavelets-based signal processing is an efficient tool in the analysis and the transformation of AE signals. 相似文献
12.
13.
Jeong-Suk Kim Myeong-Chang Kang Byung-Jin Ryu Young-Kwon Ji 《International Journal of Machine Tools and Manufacture》1999,39(11):1761
Sensing techniques for monitoring machining processes have been one of the focuses of research on process automation. This paper presents the development of on-line tool-life monitoring system for gear shaping that uses acoustic emission (AE). Characteristics of the AE signals are related to the cutting condition, tool material and tool geometry in the cutting of metals. The relationship between AE signal and tool wear was investigated experimentally. Experiments were carried out on the gear shaping of SCM 420 material with a pinion cutter having 44 teeth. Root-mean-square (RMS) AE voltages increase regularly according to tool wear. It is suggested that the maximum value of RMS AE voltage is an effective parameter to monitor tool life. In this study, not only the acquisition method of AE signals for rotating objects but also the signal-processing technique were developed in order to realize the in-process monitoring system for gear shaping. The on-line tool-life monitoring system developed has been successfully applied to gear machining processes. 相似文献
14.
H. Reginald Hardy Jr. 《NDT & E International》1994,27(4)
Since the early 1970s there has been an accelerating interest in the use of acoustic emission/microseismic (AE/MS) techniques for the laboratory and field investigation of geological materials and structures. Basic AE/MS research and the application of AE/MS techniques to a variety of geotechnical problems has been under way in the Penn State Rock Mechanics Laboratory since 1965. To date, studies have involved a wide variety of field topics, including: cavern stability, stability of natural gas storage reservoirs, strata control in longwall coal mines, rock bolt stability monitoring, effects of blasting, mine and tunnel roof stability, subsidence monitoring and rock slope stability evaluation. This paper reviews the development of AE/MS research at Penn State, describes briefly a number of the major field studies undertaken, and discusses on-going and future research programmes. 相似文献
15.
16.
综述了金属电化学腐蚀、应力腐蚀以及高温高压水环境下腐蚀过程中的声发射信号特征与产生机制,及目前研究现状与存在的问题,探讨了进一步研究的方向和思路.
相似文献
17.
18.
19.
20.
热障涂层(TBCs)具有优异的高温抗氧化、高温力学和抗热腐蚀性能而备受关注,广泛应用于航空发动机和燃气轮机热端部件中。热障涂层服役环境的恶劣和涂层体系结构的复杂,极易导致涂层发生界面分层或剥落失效,因此通过对热障涂层的裂纹萌生和扩展问题进行实时监测,对于失效机理研究显得尤为重要。简述光激发荧光压电光谱(PLPS)、红外热成像(IRT)、阻抗谱(IS)的原理及其在热障涂层失效行为研究中的应用,重点介绍声发射技术在热障涂层失效机理方面的研究成果。基于声发射的热障涂层失效过程的信号分析和深度处理,结合声发射技术在热障涂层中的参数分析和波形分析,对热障涂层失效过程及失效形态进行模式识别,通过损伤程度的定量评估来进行热障涂层的寿命预测。对声发射技术在热障涂层失效预测及寿命评估指明了方向,并创新性地对未来声发射技术在热障涂层的疲劳损伤方面研究趋势提出展望。 相似文献