Research on Cutting Tool Wear Based on Fractional Brownian Motion
Liang Jian-kai,
Song Wan-qing,
Li Qing
Issue:
Volume 3, Issue 1, February 2015
Pages:
1-5
Received:
6 January 2015
Accepted:
22 January 2015
Published:
1 February 2015
Abstract: Cutting tool wear is a very complex process. Various factors have a direct or indirect effect on cutting tool wear, resulting in uncertainty, so it is difficult for experimental data and result to have good stability. However, Vibration analysis is a very important means for condition monitoring and fault diagnosis. This paper aims to study the methods of tool vibration signal processing, pattern recognition and trend prediction. Collected on tool vibration signal at different times, wavelet noise reduction is used to pretreat the vibration signals. Then, for the self-similar vibration signals, we propose the fractional Brownian motion (FBM) theory with long-range dependence (LRD). Combined with Wigner-Ville spectrum, characteristic parameter can be extracted, so the cutting tool wear state can be determined according to fractal dimension and average slope of the fitting curve of the logarithm power spectrum. Finally, we use FBM model to predict the trend of tool vibration signals. Experiments show that the methods have a good effect on tool wear state recognition and trend prediction.
Abstract: Cutting tool wear is a very complex process. Various factors have a direct or indirect effect on cutting tool wear, resulting in uncertainty, so it is difficult for experimental data and result to have good stability. However, Vibration analysis is a very important means for condition monitoring and fault diagnosis. This paper aims to study the met...
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Prediction of Cycle Life of Flexible Pipe Bellows
Abdulrahman Th. Mohammad,
Jasim Abdulateef,
Zaid Hammoudi
Issue:
Volume 3, Issue 1, February 2015
Pages:
6-15
Received:
28 November 2014
Accepted:
12 January 2015
Published:
2 February 2015
Abstract: This paper aims to investigate the relationship between maximum stresses produced and cycle life of different shaped bellows expansion joints. Flexible pipe bellows which have been selected in the present study are made of stainless (STS 304) and (STS 316) material based on two types of (axial, and axial with control ring) with three shapes of bellow section (U-shape, Ω-shape and disc-shape). Our calculation is done using simulation model written by MATLAB. The simulation results show that, U-shaped bellow has smaller internal pressure-induced stress, longer fatigue life, and is more suited for higher internal pressure situations. The most essential bellow design factor is the correct specification of the bellow movement requirements.
Abstract: This paper aims to investigate the relationship between maximum stresses produced and cycle life of different shaped bellows expansion joints. Flexible pipe bellows which have been selected in the present study are made of stainless (STS 304) and (STS 316) material based on two types of (axial, and axial with control ring) with three shapes of bell...
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Numerical Analysis of Influence on Gas Supply Hole Number and Radial Clearance for the Characteristics of Hydroinertia Gas Journal Bearings
Tomohiko Ise,
Sayuri Nakano,
Toshihiko Asami,
Yuki Endo,
Itsuro Honda
Issue:
Volume 3, Issue 1, February 2015
Pages:
16-21
Received:
12 November 2014
Accepted:
21 November 2014
Published:
28 February 2015
Abstract: Hydroinertia gas journal bearings have been applied to solid state nuclear magnetic resonance spectroscopy. These bearings, which require a larger radial clearance than conventional externally pressurized bearings, achieve stable operation for ultra high-speed rotation of spinner shaft at several million rpm. However, their small diameters, which range within 1-6 mm, have limited experimental verifications of their static characteristics. A computational fluid dynamics analysis was therefore performed to fill this gap. The effects of radial clearance and gas supply hole number on bearing characteristics, such as pressure distribution and load capacity, were investigated. This analysis showed that negative and positive pressures generated some clearance. Pressure distribution also changes in the gas supply hole number. A large load capacity was obtained at this clearance. To verify the phenomenon, measurement of pressure distribution was performed using experimental setup. Negative pressure could be confirmed actually in the large radial clearance condition.
Abstract: Hydroinertia gas journal bearings have been applied to solid state nuclear magnetic resonance spectroscopy. These bearings, which require a larger radial clearance than conventional externally pressurized bearings, achieve stable operation for ultra high-speed rotation of spinner shaft at several million rpm. However, their small diameters, which r...
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