The nature of friction within a vehicle’s disk brake system can cause a wide range of different n... more The nature of friction within a vehicle’s disk brake system can cause a wide range of different noise phenomena. Especially high-frequency brake squeal was examined during the last decades. Numerous publications treat squeal phenomenology and its mitigation. Increasing shares of electrified powertrains, automatic driving functions such as park assists and further increasing quality demands have now shifted the research interest more and more towards low-frequency phenomena. One of these low-frequency phenomena is creep groan. Defined by its main frequency below 200 Hz, creep groan is characterized by a highly non-linear behavior: Global stick-slip transitions in the disk/pad contacts repeatedly excite the whole brake and axle system. Different bifurcations or even chaotic behavior occur. To ensure good creep groan behavior, defined assessment procedures and rating criteria are necessary. Currently, the German Association of the Automotive Industry recommends a combined rating via th...
2014 22nd Telecommunications Forum Telfor (TELFOR), 2014
This paper describes the realization of an FPGA platform designed for real time acoustic signal a... more This paper describes the realization of an FPGA platform designed for real time acoustic signal acquisition and data processing. The paper presents complete development process, starting from high level system design including signal integrity simulations to real system measurement results based on described platform. A real system for localization of the dominant noise source based on the platform is presented.
The purpose of controlling the quenching process of an orange-hot steel workpiece is to ensure it... more The purpose of controlling the quenching process of an orange-hot steel workpiece is to ensure its required surface hardness. A sound in a cooling liquid generated by the quenching process was experimentally analyzed. It contains sufficient information about the ongoing process for its quantification, and it can be used in real time. Traditionally, the quenching and the resultant hardening can be controlled by selecting different process parameters, like, for example the characteristics of the cooling liquid, the velocity of the cooling liquid flow, its temperature, the temperature of the work-piece, and many others. The possibility of controlling the quenching process by using acoustic cavitation is considered in this article.
Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science, 2003
In this paper sound generated during the gas-metal arc welding process in the short-circuit mode ... more In this paper sound generated during the gas-metal arc welding process in the short-circuit mode was studied. Theoretical and experimental analyses of the acoustic signals have shown that there are two main noise-generating mechanisms. The first mechanism generating characteristic sound impulses is arc extinction and arc ignition; the second noise-generating mechanism is the arc itself, which acts as an ionization sound source and produces mainly high-frequency noise of a low level. The sound signal is used for assessing and monitoring the welding process and for prediction of welding process stability and quality. A new algorithm based on the measured welding current was established for the calculation of emitted sound during the welding process. The algorithm was verified for different supply voltages and for different welding materials. The comparisons have shown that the calculated values are in good agreement with measured values of the sound signal.
Cavitation within a pump causes structural vibration with noise, among other by-products. Experim... more Cavitation within a pump causes structural vibration with noise, among other by-products. Experiments have shown that there is a discrete frequency or broadband peak within the audible noise spectra, which is in strong correlation with the development of the cavitation process in the pump. Furthermore, the peak of the discrete frequency, or broadband peak, coincides with the net positive suction
Safe operation of kinetic pumps, as liquid movers, can be threatened by cavitation phenomenon in,... more Safe operation of kinetic pumps, as liquid movers, can be threatened by cavitation phenomenon in, amongst others. Cavitation is the Achilles’ heel of kinetic pumps. It can cause deterioration of the hydraulic performance, damage of the pump by pitting and material erosion, and structure vibration and noise. Cavitation can appear within the entire range of operating conditions, therefore it must
Stick-Slip effects occur at the contact surface between the brake pads and the brake disc. The Cr... more Stick-Slip effects occur at the contact surface between the brake pads and the brake disc. The Creep Groan phenomenon is associated with stick-slip effects in the frequency range up to 500 Hz. It induces vibrations on the entire brake system and influences the structural vibrations of the vehicle. Vibrations are transmitted to large surfaces which produce audible noise. Creep Groan Noise is unpleasant and can be considered as a defect, especially for drivers of luxury cars. Harshness and annoyance caused by Creep Groan noise depends on many factors. For this reason, vehicle tests often include a subjective analysis of the Creep Groan Noise. Unfortunately, subjective tests suffer from the inherent uncertainties of subjective evaluation. A model for the assessment of Creep Groan noise harshness is necessary to reduce these uncertainties and to improve the Creep Groan assessment. For this purpose, experimental tests with over 1000 measurements were carried out. Many different features ...
The nature of friction within a vehicle’s disk brake system can cause a wide range of different n... more The nature of friction within a vehicle’s disk brake system can cause a wide range of different noise phenomena. Especially high-frequency brake squeal was examined during the last decades. Numerous publications treat squeal phenomenology and its mitigation. Increasing shares of electrified powertrains, automatic driving functions such as park assists and further increasing quality demands have now shifted the research interest more and more towards low-frequency phenomena. One of these low-frequency phenomena is creep groan. Defined by its main frequency below 200 Hz, creep groan is characterized by a highly non-linear behavior: Global stick-slip transitions in the disk/pad contacts repeatedly excite the whole brake and axle system. Different bifurcations or even chaotic behavior occur. To ensure good creep groan behavior, defined assessment procedures and rating criteria are necessary. Currently, the German Association of the Automotive Industry recommends a combined rating via th...
2014 22nd Telecommunications Forum Telfor (TELFOR), 2014
This paper describes the realization of an FPGA platform designed for real time acoustic signal a... more This paper describes the realization of an FPGA platform designed for real time acoustic signal acquisition and data processing. The paper presents complete development process, starting from high level system design including signal integrity simulations to real system measurement results based on described platform. A real system for localization of the dominant noise source based on the platform is presented.
The purpose of controlling the quenching process of an orange-hot steel workpiece is to ensure it... more The purpose of controlling the quenching process of an orange-hot steel workpiece is to ensure its required surface hardness. A sound in a cooling liquid generated by the quenching process was experimentally analyzed. It contains sufficient information about the ongoing process for its quantification, and it can be used in real time. Traditionally, the quenching and the resultant hardening can be controlled by selecting different process parameters, like, for example the characteristics of the cooling liquid, the velocity of the cooling liquid flow, its temperature, the temperature of the work-piece, and many others. The possibility of controlling the quenching process by using acoustic cavitation is considered in this article.
Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science, 2003
In this paper sound generated during the gas-metal arc welding process in the short-circuit mode ... more In this paper sound generated during the gas-metal arc welding process in the short-circuit mode was studied. Theoretical and experimental analyses of the acoustic signals have shown that there are two main noise-generating mechanisms. The first mechanism generating characteristic sound impulses is arc extinction and arc ignition; the second noise-generating mechanism is the arc itself, which acts as an ionization sound source and produces mainly high-frequency noise of a low level. The sound signal is used for assessing and monitoring the welding process and for prediction of welding process stability and quality. A new algorithm based on the measured welding current was established for the calculation of emitted sound during the welding process. The algorithm was verified for different supply voltages and for different welding materials. The comparisons have shown that the calculated values are in good agreement with measured values of the sound signal.
Cavitation within a pump causes structural vibration with noise, among other by-products. Experim... more Cavitation within a pump causes structural vibration with noise, among other by-products. Experiments have shown that there is a discrete frequency or broadband peak within the audible noise spectra, which is in strong correlation with the development of the cavitation process in the pump. Furthermore, the peak of the discrete frequency, or broadband peak, coincides with the net positive suction
Safe operation of kinetic pumps, as liquid movers, can be threatened by cavitation phenomenon in,... more Safe operation of kinetic pumps, as liquid movers, can be threatened by cavitation phenomenon in, amongst others. Cavitation is the Achilles’ heel of kinetic pumps. It can cause deterioration of the hydraulic performance, damage of the pump by pitting and material erosion, and structure vibration and noise. Cavitation can appear within the entire range of operating conditions, therefore it must
Stick-Slip effects occur at the contact surface between the brake pads and the brake disc. The Cr... more Stick-Slip effects occur at the contact surface between the brake pads and the brake disc. The Creep Groan phenomenon is associated with stick-slip effects in the frequency range up to 500 Hz. It induces vibrations on the entire brake system and influences the structural vibrations of the vehicle. Vibrations are transmitted to large surfaces which produce audible noise. Creep Groan Noise is unpleasant and can be considered as a defect, especially for drivers of luxury cars. Harshness and annoyance caused by Creep Groan noise depends on many factors. For this reason, vehicle tests often include a subjective analysis of the Creep Groan Noise. Unfortunately, subjective tests suffer from the inherent uncertainties of subjective evaluation. A model for the assessment of Creep Groan noise harshness is necessary to reduce these uncertainties and to improve the Creep Groan assessment. For this purpose, experimental tests with over 1000 measurements were carried out. Many different features ...
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Papers by Jurij Prezelj