Papers by Keyword: Vibration Measurement

Abstract: During machining any material, vibrations play a major role in deciding the life of the cutting tool as well as machine tool. The magnitude acceleration of vibrations is directly proportional to the cutting forces. In other words, if we are able to measure the acceleration experienced by the tool during machining, we can get a sense of force. There are many commercially available, pre-calibrated accelerometer sensors available off the shelf. In the current work, an attempt has been made to measure vibrations using ADXL335 accelerometer. This accelerometer is interfaced to computer using Arduino. The measured values are then used to optimize the machining process. Experiments are performed on Brass. During machining, it is better to have lower acceleration values. Thus, the first objective of the work is to minimize the vibrations. Surface roughness is another major factor which criterion “lower is the better” applies. In order to optimize the values, a series of experiments are conducted with three factors, namely, tool type (2 levels), Depth of cut (3 levels) and Feed are considered (3 levels). Mixed level optimization is performed using Taguchi analysis with L18 orthogonal array. Detailed discussion of the parameters shall be given in the article.

Abstract: A hybrid active-passive noise control system for a HVAC duct combines both a physicalnoise absorber and an active system. Due to the presence of the passive component, requirements forthe active system can be relaxed, removing the need for detecting and suppressing noise in the frequencyrange already covered by the passive elements. A typical noise measurement system adaptedto working in airflow usually uses a microphone with a housing designed to reduce the noise generateddue to local turbulent flow introduced by the housing itself. Alternatively, there are microphonesspecifically designed to work in the airflow.During work on the hybrid active-passive noise control system both a microphone designed forairflow and a microphone with special housing were tested. While these solutions can be used forresearch, both have issues making them impractical when designing a commercial product. This, alongwith the required narrow frequency range motivated the authors to consider vibration measurementsperformed by appropriately installed accelerometers. An audio signal is then synthesized using thosemeasurements and it is confronted with signals obtained at the same time with microphones.In the paper the proposed method is presented and validated with a laboratory HVAC installation ofa large cross-section and an originally designed passive absorber. Obtained results encourage further research.

Abstract: With the aim to determine parameter influences of a measurement system based on optical feedback interference in a laser diode, a mathematic model of optical feedback interference effect is built. LabVIEW which is a kind of graphical programming language is used to realize parameter setting and graphic display by front panel and program chart. Experimental results show that the stripes of optical feedback interference effect are saw-tooth-like waveform when feedback level factor is less than and close to 1, which can be used to determine moving direction of external reflecting object. Feedback interferences generate when vibration amplitude of reflecting surfaces is greater than λ/4. The stripe number is 4N when vibration amplitude dL equals Nλ. Vibrational frequency of external reflecting surface equals the frequency of feedback interference signal and has no influence on stripe number in a period. Measurement of external reflecting object based on optical feedback interference effect has measurement precision less than laser wavelength and real time direction recognition ability.

Abstract: With the rapid development of metro, the vibration induced by metro is the more and more common and widely concerned. In this paper, test and analysis of vibration induced by metro is discussed, and the five aspects of the research status at home and abroad are emphasized, which are the analysis of the vibration causes, the analysis of vibration influence, the summary of vibration test technology, the analysis of the relevant theoretical results and the analysis of vibration reduction application measures. This paper will provide the theory basis and the practice reference for the vibration design of environmental vibration induced by metro.

Abstract: In order to verify the feasibility and validity of frequency ratio as diagnostic parameter in structural damage detection proposed in the Musical Tone Law Method (MTLM), steel pipes and three-story steel frame structure model tests are carried out. According to the experiment results, it is clear that the diagnostic parameter is effective for symmetrical structure in structural damage detection, such as cable structure, framed structure, and so on. Model tests prove that the frequency ratio is effective in detecting the 3mm width crack damage of steel pipe. In the damage detection test of three-story steel frame structure, the parameter also successfully diagnosed the damage caused by bolts loosening at the node of model.

Abstract: The vibration of belt affected the transmission stability of automotive synchronous belt. The mathematical model of longitudinal vibration was established through analyzing the longitudinal vibration of automotive synchronous belt. Developed the vibration dynamic measurement device, aiming at RU style arc teethed synchronous belt transmission process, measured the variety of amplitude over time at the middle of the belt span obtained the rules of amplitude and frequency change along with the rotation speed. It is of certain importance to improving the transmission stability of arc teethed synchronous belt.

Abstract: The design of foot-bridge is often influenced by natural frequency. Consequently, vibration frequency becomes important. The empirical expressions used to quantify this parameter at the design phase have not been developed enough to give guideline to Korea foot-bridge. This paper is concerned with the frequency of steel foot-bridges. It describes the vibration measurement methods employed for testing structures and presents reliable methods of assessing natural frequency from jumping vibration tests. Data from measurements on 30 structures in Seoul are given. Regression formulas of natural frequency for steel-framed foot-bridges are suggested. Finally, obtained formula is compared with empirical expressions of Seoul Citys guideline and Bachmanns curve.

Abstract: Scanning tunneling microscopy is one of the surface measurement instruments in nanotechnology field, and the vertical resolution is about 0.01nm. So it is easily affected by the external micro vibration, conversely, we can measure the micro vibration using the working principle of STM. As we all know, the tunneling effect is the negative index relation between the tunneling current and the tunneling gap. On the other hand, the vibration measurement results can be used to offer the foundation in order to reduce the influence of micro random vibration for STM, it is necessary to measure the external vibration to compensate the experiment results of scanning tunneling microscoy. So the experimental device is developed and experiment of vibration detection is made. The experiment results show that results have high sensitivity, good frequency characteristic and the same vibratory response characteristic consistent with scanning tunneling microscopy.

Abstract: The flow-induced micro-vibration in Shuifu County Town near Xiangjia Dam is studied in this paper. First the characteristics of the micro-vibration are investigated based on the in situ measurement, and then the dynamic property of the still basin which is thought to be the vibration source is analyzed with the effect of fluid-structure interaction (FSI) considered. Finally, the reason of the micro-vibration in Shuifu county town is discussed and several possible engineering suggestions for vibration reduction are also proposed.

Abstract: Based on LabVIEW, vibration measurement and diagnosis system of equipment was developed for experimental teaching. On the platform, vibration signals from running equipment can be sampled, displayed, stored, and analyzed in time domain, frequency domain and time-frequency domain. The advanced signal processing technology such as power spectrum analysis, cepstrum analysis, demodulation analysis can also be executed. Using pattern recognition technology, the processed signals can be integrated for intelligent diagnosis of equipment state. The experimental system is helpful for students to learn signal processing methods, and to design virtual instrument.