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| 2. |
- Andrén, Linus, et al.
(författare)
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Piezo Ceramic Actuators versus High Magnetostrictive Actuators in the Active control of Tool Vibration
- 1999
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Konferensbidrag (refereegranskat)abstract
- In the turning operation chatter or vibration is a frequent problem, which affects the result of the machining, and, in particular, the surface finish. Tool life is also influenced by vibration. Severe acoustic noise in the working environment frequently occurs as a result of dynamic motion between the cutting tool and the workpiece. These problems can be reduced by active control of machine-tool vibration. In the active control system for the control of tool vibration a tool holder construction with integrated high magnetostrictive actuators was used. However, high magnetostrictive actuators generally have a non-linear behavior and it is a well known fact that non-linear properties in the forward path in an active control system is likely to degrade the robustness of the control system. A new generation embedded active tool holder shanks based on piezo ceramic actuators has been developed. Based on spectrum estimates, both coherence spectrum and frequency response function estimates has been calculated for both the old tool holder construction and the new generation active tool holder shank. From the results it follows that the phase delay is smaller and the linearity of the new generation active tool holder shank are superior compared to the old technology. The physical features and properties of the new generation active tool holders are superior to the old tool holder.
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| 3. |
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| 4. |
- Brandt, Anders, et al.
(författare)
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Actual Accuracy in Flight Data Collection and Analysis
- 2005
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Konferensbidrag (refereegranskat)abstract
- In aerospace applications it is often vital to understand what is happening when analyzing sound and vibration data and what total accuracy one receives. The tradition has been to spend money on yearly calibration of sensors and part of the measurement equipment, but not on the software used for analysis of the data collected by these sensors. While the sensors might be accurate to a percentage level, erroneous analysis procedures can give arbitrarily high errors! Usually, there is no “calibration option” or “benchmark” for sound and vibration analysis software. This paper will present some common pitfalls and what can happen if the user is not aware how the software is handling the data, or even worse, the code was not correctly implemented in the first place. Some real life examples of the latter and suggested solutions to avoid such harmful situations will be presented. Also, some good guidelines for aerospace data collection and analysis, with focus on sound and vibration applications, will be discussed.
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| 5. |
- Brandt, Anders, et al.
(författare)
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Main principles and limitations of current order tracking methods
- 2005
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Ingår i: SOUND AND VIBRATION. - BAY VILLAGE : ACOUSTICAL PUBL INC. - 0022-460X. ; , s. 19-22:March, s. 19-22
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Tidskriftsartikel (refereegranskat)abstract
- Order tracking is a widely used tool for analysis of vibrations generated in vehicle drivetrain components, since many vibrations are related to engine RPMs. In recent years, offline order tracking has become suitable due to enhanced computer speeds. Many methods, some patented, for both online and offline order tracking have been presented over the years. This article reviews some basic ideas behind current methods and compares their main advantages and limitations. Some basic time-frequency concepts and time window effects are reviewed. Questions on suitable tachometers and their number of pulses per revolution are also addressed. The possibility of processing RPM dependent data without tachometers is also discussed.
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| 7. |
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| 8. |
- Brandt, Anders, et al.
(författare)
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Noise and vibration measurement system basics
- 2006
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Ingår i: SOUND AND VIBRATION. - BAY VILLAGE : ACOUSTICAL PUBL INC. - 0022-460X. ; 40:4, s. 9-11:April, s. 9-10
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Tidskriftsartikel (refereegranskat)
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| 9. |
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| 10. |
- Brandt, Anders, et al.
(författare)
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Using MATLAB for Advanced Noise and Vibration Analysis
- 2004
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Konferensbidrag (refereegranskat)abstract
- Commercial tools for measurement and analysis of noise and vibration signals have traditionally been very expensive. In the last decade, however, multi-channel measurement systems have become relatively inexpensive. The analysis functionality in most inexpensive instruments is limited. Therefore, many companies are using alternatives for post processing of measurement results. Matlab is a platform that is popular for this purpose and which offers many advantages over dedicated, menu driven systems. The open functions in Matlab assure flexibility and the possibility to modify functions for specific needs. In addition, a command based programming environment provides for traceability and quality assurance, including qualification of used algorithms, important aspects particularly in the aerospace industry. In the past, basic functions for signal analysis and vibration analysis have had to be developed before taking full advantage of the Matlab platform. In this paper we present a new suite of toolboxes that turn Matlab into state-of-the-art software for noise and vibration analysis. The toolboxes presented here have been well proven in applications in aerospace industry. Parts of the toolboxes are provided as freeware, and everyone is encouraged to download this from Internet.
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