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RISS 인기검색어
- 검색키워드
- 저자 : Andrew Ball (검색결과 6 건)
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Hybrid model for the analysis of the modal properties of a ball screw vibration system
Qin Wu,Feng-shou Gu,Andrew Ball,Hua Huang 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.2
In accordance with the vibration characteristics of ball screw feed systems, a hybrid modeling method is proposed to study its dynamic behavior. Partially, the ball screw is modeled as a continuous body, and the remaining components are considered lumped masses, allowing for a realistic description of the dynamics of the feed system. The axial, torsional, transverse, and bending vibration models of a ball screw carriage system are established via the Rayleigh-Ritz series method based on the Timoshenko beam assumption. The established model that added the Timoshenko beam assumption obtains the coupling vibration displacement between the transverse and bending vibrations of the lead screw, which is close to real situations. Numerical simulations are conducted to investigate the changes of the natural frequency and modal shapes of ball screw systems with carriage positions. Results show that the carriage position has significant influence on the amplitude and direction of axial and transverse vibrations, substantial influence on the direction of the bending vibration, and minimal influence on the amplitude and direction of torsional vibration. These results indicate that the proposed hybrid model performs well to predict the vibration characteristics of the feed system. Moreover, the carriage position and carriage load also have a remarkable effect on the frequency response of the feed system. These results, along with the modeling approach, provide an important basis for the further study of in-machining monitoring and vibration controller design.
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Measurement and Diagnostic of Engine Belt Physical Condition from Acoustic Signals
Bruno Fazenda,Fengshou Gu,Mark Avis,Andrew Ball 제어로봇시스템학회 2009 제어로봇시스템학회 국제학술대회 논문집 Vol.2009 No.8
This paper presents an investigation into the diagnosis of transmission belt condition through acousticmonitoring. A relevant belt model and laser interferometry measurements are used to guide the design and analysis of the acoustic monitoring system. The fault under scrutiny is the development of a loss of tension in the belt which mayoccur due to degradation of belt material. Results show that it is possible to diagnose this kind of fault using acoustic diagnostic techniques. Analysis of acoustic signals reveals changes in the natural frequencies of the belt which arematched by results for laser interferometry.
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( Sheppard Petra J ),( Keryn L Simons ),( Krishna K Kadali ),( Sayali S Patil ),( Andrew S Ball ) 한국미생물 · 생명공학회 2012 Journal of microbiology and biotechnology Vol.22 No.9
This study investigated the hydrocarbonoclastic microbial community present on weathered crude oil and their ability to degrade weathered oil in seawater obtained from the Gulf St. Vincent (SA, Australia). Examination of the native seawater communities capable of utilizing hydrocarbon as the sole carbon source identified a maximum recovery of just 6.6 × 101 CFU/ml, with these values dramatically increased in the weathered oil, reaching 4.1 × 104 CFU/ml. The weathered oil (dominated by >C30 fractions; 750,000 ± 150,000 mg/l) was subject to an 8 week laboratory-based degradation microcosm study. By day 56, the natural inoculums degraded the soluble hydrocarbons (initial concentrations 3,400 ± 700 mg/l and 1,700 ± 340 mg/l for the control and seawater, respectively) to below detectable levels, and biodegradation of the residual oil reached 62% (254,000 ± 40,000 mg/l) and 66% (285,000 ± 45,000 mg/l) in the control and seawater sources, respectively. In addition, the residual oil gas chromatogram profiles changed with the presence of short and intermediate hydrocarbon chains. 16S rDNA DGGE sequence analysis revealed species affiliated with the genera Roseobacter, Alteromonas, Yeosuana aromativorans, and Pseudomonas, renowned oil-degrading organisms previously thought to be associated with the environment where the oil contaminated rather than also being present in the contaminating oil. This study highlights the importance of microbiological techniques for isolation and characterisation, coupled with molecular techniques for identification, in understanding the role and function of native oil communities.
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Luyang Guan,Yimin Shao,Fengshou Gu,Bruno Fazenda,Andrew Ball 제어로봇시스템학회 2009 제어로봇시스템학회 국제학술대회 논문집 Vol.2009 No.8
In this paper, a new method is proposed by combining ensemble empirical mode decomposition (EEMD) with order tracking techniques to analyse the vibration signals from a two stage helical gearbox. The method improves EEMD results in that it overcomes the potential deficiencies and achieves better order spectrum representation for fault diagnosis. Based on the analysis, a diagnostic feature is designed based on the order spectra of extracted IFMs for detection and separation of gearbox faults. Experimental results show this feature is sensitive to different fault severities and robust to the influences from operating conditions and remote sensor locations.
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Acoustic Based Safety Emergency Vehicle Detection for Intelligent Transport Systems
Bruno Fazenda,Hidajat Atmoko,Fengshou Gu,Luyang Guan,Andrew Ball 제어로봇시스템학회 2009 제어로봇시스템학회 국제학술대회 논문집 Vol.2009 No.8
A system has been investigated for the detection of incoming direction of an emergency vehicle. Acoustic detection methods based on a cross microphone array have been implemented. It is shown that source detection based on time delay estimation outperforms sound intensity techniques, although both techniques perform well for the application. The relaying of information to the driver as a warning signal has been investigated through the use of ambisonic technology and a 4 speaker array which is ubiquitous in most modern vehicles. Simulations show that accurate warning information may be relayed to the driver and afford correct action.
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Motor Current Signal Analysis using a Modified Bispectrum for Machine Fault Diagnosis
Fengshou Gu,Yimin Shao,Niaoqin Hu,Bruno Fazenda,Andrew Ball 제어로봇시스템학회 2009 제어로봇시스템학회 국제학술대회 논문집 Vol.2009 No.8
This paper presents the use of the induction motor current to identify and quantify common faults within a two-stage reciprocating compressor. The theoretical basis is studied to understand current signal characteristics when themotor undertakes a varying load under faulty conditions. Although conventional bispectrum representation of currentsignal allows the inclusion of phase information and the elimination of Gaussian noise, it produces unstable results dueto random phase variation of the sideband components in the current signal. A modified bispectrum based on theamplitude modulation feature of the current signal is thus proposed to combine both lower sidebands and highersidebands simultaneously and hence describe the current signal more accurately. Based on this new bispectrum a more effective diagnostic feature namely normalised bispectral peak is developed for fault classification. In association with the kurtosis of the raw current signal, the bispectrum feature gives rise to reliable fault classification results. Inparticular, the low feature values can differentiate the belt looseness from other fault cases and discharge valve leakage and intercooler leakage can be separated easily using two linear classifiers. This work provides a novel approach to theanalysis of stator current for the diagnosis of motor drive faults from downstream driving equipment.
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