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EMILIANO MUCCHI
Docente Interateneo Dipartimento di Ingegneria "Enzo Ferrari"
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Pubblicazioni
2022
- Parameter estimation algorithm for bearing prognostics through monovariate generalized Gaussian Hidden Markov Models
[Relazione in Atti di Convegno]
Soave, E.; D'Elia, G.; Dalpiaz, G.; Mucchi, E.
abstract
Nowadays, the industrial scenario is driven by the need of costs and time reduction. In this contest, system failure prediction plays a pivotal role in order to program maintenance operations only in the last stages of the real operating life, avoiding unnecessary machine downtime. In the last decade, Hidden Markov Models have been widely exploited for machinery prognostic purposes. The probabilistic dependency between the measured observations and the real damaging stage of the system has usually been described as a mixture of Gaussian distributions. This paper aims to generalize the probabilistic function as a mixture of generalized Gaussian distributions in order to consider possible distribution variations during the different states. In this direction, this work proposes an algorithm for the estimation of the model parameters exploiting the observations measured on the real system. The prognostic effectiveness of the resulting model has been demonstrated through the analysis of several run-to-failure datasets concerning both rolling element bearings and more complex systems.
2021
- A novel approach for increasing test efficiency and realism in multi-axial vibration control testing
[Abstract in Atti di Convegno]
Monco, G.; D’Elia, G.; Troncossi, M.; Mucchi, E.
abstract
Vibration control tests are typically performed on shakers in order to replicate the in-service dynamic response of structures.
The methodologies for performing vibration control tests are constantly evolving thank to the enormous advances of the
available control technologies. The avant-garde test facilities have the capability to address simultaneous multi-axial
vibration testing by exploiting Multi-Input Multi-Output (MIMO) control techniques. Over recent years, numerous
publications point out the advantages in replicating the in-service conditions by using MIMO control strategies, satisfying the
will of the environmental research community to turn multi-axis vibration control testing into the main reference procedure.
This work presents a test campaign carried out on a high performance motorbike engine. In particular, the device under test
(DUT) is the entire exhaust system connected to the head of the engine. A three-axial electrodynamic shaker table is used for
replicating the acceleration time histories previously acquired during field-testing. The test results clearly highlight the
importance of reproducing in the laboratory the operational boundary conditions. Differences between test and in-field
conditions produce mechanical impedance mismatches that alter the dynamic behaviour of the DUT during the control test.
The purpose of the work is to define a MIMO control methodology that makes the test conditions closer to the in-field ones,
thus improving the test result reliability. As a consequence, it is possible to directly assess the dynamic response
(experimentally retrieved) of the exhaust system after introducing design modifications to some components.
2021
- A rattle index formulation for single and multiple branch geartrains
[Articolo su rivista]
Pizzolante, F.; Battarra, M.; D'Elia, G.; Mucchi, E.
abstract
The paper proposes an analytical procedure for the generalization of the rattle index in any type of ordinary transmission layouts, single or multiple branch, both in idle and loaded conditions. Its definition is obtained by a recursive analytical formulation of the rotational dynamics of gears. Numerical analytical studies are exploited to examine the effectiveness and reliability of the introduced index. Several geartrain layouts are investigated and results show its capability to instantaneously describe the vibro-impact events related to any gear pair of the driveline. Moreover, the general definition is shown to be a proper indicator of the potential presence of mutual interactions between different gear pairs pertaining to the same driveline. The analysis of the results reveals an excellent agreement with the expected behavior of the outlined parameter.
2020
- A laser triangulation sensor for vibrational structural analysis and diagnostics
[Articolo su rivista]
Soave, E.; D'Elia, G.; Mucchi, E.
abstract
The industrial progress has reached a level in which it is necessary to understand the behavior of mechanical components and to monitor their conditions without disassembling them. Nowadays, a suitable methodology is based on vibrational analysis usually performed through acceleration signals measured directly on the system to be tested. However, in the last years, the industrial scenario has deeply changed due to the need for time reduction, in particular, for the control operations at the end of the productive line. The genuine methods based on acceleration measurements, for example, through piezoelectric accelerometers, came into conflict with the industrial need as the sensors used for the quality control have to be easily and fastly mounted and unmounted. A valid alternative is represented by the exploitation of laser triangulation sensors that are able to measure the dynamic displacement in a contactless way, strongly reducing the (un)mounting time. The target of this paper is to highlight pros and cons of the contactless displacement analysis through laser triangulation sensors with respect to the contact one through genuine accelerometers by means of a comparison between the results obtained both for experimental modal analysis and vibrational diagnostics of rotating machines.
2019
- A vibration-based method for contact pattern assessment in straight bevel gears
[Articolo su rivista]
Buzzoni, Marco; D'Elia, Gianluca; Mucchi, Emiliano; Dalpiaz, Giorgio
abstract
So far, the study of gear contacts in lightly loaded gears by means of vibration analysis has not been sufficiently addressed in the literature. Indeed, the complex nature of the physical phenomena involved makes the vibration analysis extremely challenging. This paper deals with the development and the validation of an approach for the contact pattern assessment in straight bevel gears within a pass/fail decision process. The proposed methodology is based on blending vibration-based condition indicators with classification algorithms in order to discriminate proper contact patterns from improper ones. Specifically, three different classification algorithms have been investigated: the Naive Bayes classifier, the weighted k-Nearest Neighbors classifier and a novel classifier proposed by the authors. The classifier accuracies are evaluated with a MC cross-validation that includes an extended experimental campaign consisting of more than one hundred different straight bevel gear pairs. The results show that the proposed classifier is superior to the other considered classifiers in terms of average accuracy. Finally, this manuscript proposes an original methodology that provides a reliable and quick assessment of the contact pattern in straight bevel gears considering different speeds, gear parameters and surface finish. (C) 2018 Elsevier Ltd. All rights reserved.
2019
- On the diagnostics of two degrees of freedom planetary gearboxes
[Abstract in Atti di Convegno]
D'Elia, Gianluca; Dalpiaz, G.; Mucchi, E.
abstract
2019
- UniVibe: A novel user-friendly software for automated condition monitoring and diagnostics of geared transmission
[Relazione in Atti di Convegno]
D'Elia, G.; Daini, I.; Romagnoli, L.; Mucchi, E.
abstract
Nowadays, huge emphasis is given to research on diagnostic tools in order to prevent and monitor the health status of gears and bearings. However, the link between advanced signal processing techniques and ease of use is still missing in commercial software tools. Actually, softwares that implement advanced signal processing techniques leak in ease user interaction and automated diagnostic procedures. Authors have developed a commercial software tool, called UniVibe, that attempts to fill the gap between high sensitivity in the diagnostics of faults in complex geared transmission and user-friendly interface. This work focuses on the description of the UniVibe core, highlighting its diagnostic capabilities on the basis of a real industrial case. Specifically, the automated procedure that shepherds the user to the successfully fault diagnosis of a complex geared transmission is pointed out.
2019
- Vibrational analysis and diagnostics by means of laser triangulation sensor
[Relazione in Atti di Convegno]
Soave, Elia; D'Elia, Gianluca; Mucchi, Emiliano
abstract
Nowadays, vibrational analysis is one of the most exploited methods in order to understand the behavior of mechanical components, by means of modal testing, and to monitor their conditions, by means of vibrational diagnostics. This kind of analysis has usually been performed through acceleration measures and exists a truly rich literature about this. However, in the last years, the genuine methodologies based on acceleration measurement, e.g. through piezoelectric accelerometers, came into conflict with the industrial need for time reduction.
The sensors used have to be easily removable in order to speed up the control operation, for example at the end of the productive line. In this scenario a valid solution is represented by the use of laser triangulation sensors that are able to measure the dynamic displacement without the contact with the component surface and consequently with very high decrement of the time needed to mount and unmount. This work is focused on a comparison of the results obtained by piezoelectric accelerometer and laser triangulation sensor both for vibrational analysis, i.e. experimental modal analysis and vibrational diagnostics of rotating machines. This paper highlights pros and cons of the contactless displacement analysis with respect to the accelerometer measurements.
2018
- A diagnostic protocol for the monitoring of bearing fault evolution based on blind deconvolution algorithms
[Relazione in Atti di Convegno]
Buzzoni, M.; Elia, Soave; D’Elia, Gianluca.; Mucchi, E.; Dalpiaz, G.
abstract
The detection and identification of bearing faults at their initial stage is pivotal in order to avoid catastrophic
failures. However, the vibration contribution related to early stage bearing faults are frequently weak and
masked by strong background noise and mechanical interferences. In this scenario, blind deconvolution algorithms
can be exploited for extracting impulsive patterns related to incipient bearing faults. Maximum Correlated
Kurtosis Deconvolution (MCKD) and Multipoint Optimal Minimum Entropy Deconvolution Adjusted
(MOMEDA) proved to be effective for fault diagnosis in rotating machines. However, their effectiveness on
monitoring the progressive degradation of rolling element bearings has not yet been exhaustively studied. In
this paper, the experimental data from an endurance test are investigated by means of MCKD and MOMEDA.
The results in terms of incipient fault detection and fault identification accuracy are discussed from different
perspectives, highlighting advantages and limits of such blind deconvolution approaches. In particular, an
original diagnostic protocol is proposed, based on a condition indicator computed from the cumulative of the
blind deconvolution maximized criterion combined with a non-parametric statistical threshold. The proposed
indicator is sensitive to the fault degradation as well as the fault type.
2018
- Development of an Indicator for the Assessment of Damage Level in Rolling Element Bearings Based on Blind Deconvolution Methods
[Articolo su rivista]
Buzzoni, Marco; Soave, Elia; D'Elia, Gianluca; Mucchi, Emiliano; Dalpiaz, Giorgio
abstract
The monitoring of rolling element bearings through vibration-based condition indicators plays a crucial role in the modern machinery. The kurtosis is a very efficient indicator being sensitive to impulsive components within the vibration signature that often are symptomatic of localized faults. In order to improve the diagnostic performance of the kurtosis, blind deconvolution algorithms can be exploited in order to detect bearing faults and, most importantly, their position. In this scenario, this paper focuses on the development of a novel condition indicator specifically designed for the damage assessment in rolling element bearings. The proposed indicator allows to track the bearing degradation process taking into account three different possible positions: outer race, inner race, and rolling element. This indicator fits real-Time monitoring procedures allowing for the automatic detection and identification of the bearing fault. The validation of the proposed indicator has been carried out by means of both simulated signal and a run-To-failure experiment. The results highlight that the proposed indicator is able to detect more efficiently the fault occurrence and, most importantly, quicker than other established techniques.
2018
- Experimental Investigation of Vibrational and Acoustic Phenomena for Detecting the Stall and Surge of a Multistage Compressor
[Articolo su rivista]
Munari, Enrico; D'Elia, G.; Morini, M.; Mucchi, E.; Pinelli, M.; Spina, P. R.
abstract
Nowadays, the operative range limit of compressors is still a key aspect of the research into turbomachinery. In particular, the study of the mass flow rate lower limit represents a significant factor in order to predict and avoid the inception of critical working conditions and instabilities such as stall and surge. The identification of these instabilities and typical precursors of these two phenomena can imply many advantages, in both stationary and aeronautic applications, such as avoiding the loss of production (in industry) and efficiency of systems and reducing the maintenance and repairing cost. Many approaches can be adopted to achieve this target, but one of the most fascinating is the vibro-acoustic analysis of the compressor response during operation. At the Engineering Department of the University of Ferrara, a test bench, dedicated to the study of the performance of an aeronautic turboshaft engine multistage compressor, has been equipped with a high frequency data acquisition system. A set of triaxle accelerometers and microphones, suitable for capturing broad-band vibration and acoustic phenomena, were installed in strategic positions along the compressor and the test rig. A great amount of vibro-acoustic data were first processed through an innovative data analysis technique, and then correlated to the thermodynamic data recorded. Subsequently, the precursor signals of surge were detected and identified demonstrating the reliability of the methodology used for studying compressor instabilities. The experimental data and results offer a valid alternative way of analyzing and detecting unstable compressor behavior characteristics by means of nonintrusive measurements.
2017
- Diagnosis of Localized Faults in Multistage Gearboxes: A Vibrational Approach by Means of Automatic EMD-Based Algorithm
[Articolo su rivista]
Buzzoni, M.; Mucchi, E.; D'Elia, G.; Dalpiaz, G.
abstract
The gear fault diagnosis on multistage gearboxes by vibration analysis is a challenging task due to the complexity of the vibration signal.The localization of the gear fault occurring in a wheel located in the intermediate shaft can be particularly complex due to the superposition of the vibration signature of the synchronous wheels. Indeed, the gear fault detection is commonly restricted to the identification of the stage containing the faulty gear rather than the faulty gear itself. In this context, the paper advances a methodology which combines the Empirical Mode Decomposition and the Time Synchronous Average in order to separate the vibration signals of the synchronous gears mounted on the same shaft. The physical meaningful modes are selected by means of a criterion based on Pearson’s coefficients and the fault detection is performed by dedicated condition indicators. The proposed method is validated taking into account simulated vibrations signals and real ones.
2017
- Experimental investigation of vibrational and acoustic phenomena for detecting the stall and surge of a multistage compressor
[Relazione in Atti di Convegno]
Munari, Enrico; D'Elia, Gianluca; Morini, Mirko; Mucchi, Emiliano; Pinelli, Michele; Spina, Pier Ruggero
abstract
Nowadays, the operative range limit of compressors is still a key aspect of the research into turbomachinery. In particular, the study of the mass flow rate lower limit represents a significant factor in order to predict and avoid the inception of critical working conditions and instabilities such as stall and surge. The importance of predicting and preventing these dangerous phenomena is vital since they lead to a loss of performance and severe damage to the compression system and the compressor components. The identification of the typical precursors of these two types of compressor unstable behaviors can imply many advantages, in both stationary and aeronautic applications, such as i) avoiding the loss of production (in industry) and efficiency of systems and ii) reducing the cost of maintenance and repairing. Many approaches can be adopted to achieve this target, but one of the most fascinating is the vibroacoustic analysis of the compressor response during operation. At the Engineering Department of the University of Ferrara, a test bench, dedicated to the study of the performance of an aeronautic turboshaft engine multistage compressor, has been equipped with a high frequency data acquisition system. A set of triaxle accelerometers and microphones, suitable for capturing broad-band vibration and acoustic phenomena, were installed in strategic positions along the compressor and the test rig. Tests were carried out at different rotational speeds, and with two different piping system layouts, by varying the discharge volume and the position of the electric control valve. Moreover, two different methodologies were adopted to lead the compressor towards instability. This experimental campaign allowed the inception of compressor stall and surge phenomena and the acquisition of a great amount of vibro-acoustic data which were firstly processed through an innovative data analysis technique, and then correlated to the thermodynamic data recorded. Subsequently, the precursor signals of stall and surge were detected and identified demonstrating the reliability of the methodology used for the study of compressor instability. The results of this paper can provide a significant contribution to the knowledge of the inception mechanisms of these instabilities. In particular, the experimental data can offer a valid support to the improvement of surge and stall avoidance (or control) techniques since it presents an alternative way of analyzing and detecting unstable compressor behavior characteristics by means of non-intrusive measurements.
2017
- METRICHE VIBRAZIONALI PER IL MONITORAGGIO DELL’USURA DISTRIBUITA IN RIDUTTORI EPICICLOIDALI
[Relazione in Atti di Convegno]
Francesco, Berlato; D'Elia, G.; Mucchi, E.; Dalpiaz, G.
abstract
Oggigiorno il monitoraggio dei riduttori è un’esigenza sempre più sentita ed importante
nell’industria. In particolare, questo lavoro riguarda il monitoraggio dell’usura distribuita
(pitting) nei riduttori epicicloidali, mediante l’impiego di alcune metriche della media
sincrona del segnale vibratorio, basate sul momento statistico del quart’ordine: si tratta di
FM4, NA4 e NA4*; si propone inoltre un nuovo indicatore di condizione chiamato NA4mod.
L’efficacia di queste metriche nell’individuare l’insorgere di difetti distribuiti è stata valutata
e confrontata conducendo una prova di usura accelerata su banco prova in configurazione
back-to-back della durata di circa 700 ore, in cui uno dei due riduttori è stato portato a fine
vita. L’articolo introduce le metriche impiegate, descrive la prova condotta e ne presenta e
discute i risultati. La nuova metrica proposta, NA4mod, ha evidenziato una soddisfacente
capacità di rilevamento dell’insorgere del pitting, con maggiore affidabilità rispetto ad
altre metriche presenti in letteratura; NA4mod risulta inoltre sensibile sia all’innesco sia
all’evoluzione del pitting.
2016
- Analyzing wind turbine flow interaction through vibration data
[Relazione in Atti di Convegno]
Castellani, Francesco; D'Elia, Gianluca; Astolfi, Davide; Mucchi, Emiliano; Dalpiaz, Giorgio; Terzi, Ludovico
abstract
Wind turbines commonly undergo non-stationary flow and, not rarely, even rather extreme phenomena. In particular, rough terrains represent a challenging testing ground, because of the combination of terrain-driven flow and wakes. It is therefore crucial to assess the impact of dynamic loads on the turbines. In this work, tower and drive-train vibrations are analyzed, from a subcluster of four turbines of a wind farm sited in a very complex terrain. The main outcome of the study is that it is possible to start from the analysis of wind conditions and interpret how wakes manifest in the vibrations of the turbines, both at structural level (tower vibrations) and at the drive-train level. This wind to gear approach therefore allows to build a connection between a flow phenomenon and a mechanical phenomenon (vibrations) and can be precious to assess loads in different working conditions.
2014
- Use of cyclostationary analysis for rust detection on the hub of heavy duty
wheels
[Relazione in Atti di Convegno]
Mucchi, Emiliano; D'Elia, Gianluca; Dalpiaz, Giorgio
abstract
Heavy duty wheels are used in applications as automatic vehicles and are mainly composed of a polyurethane tread glued to a cast iron hub. In the manufacturing process, the adhesive application between tread and hub is the most critical assembly phase, since it is completely made by an operator and a contamination of the link area may happen. Furthermore the presence of rust on the hub surface can contribute to worsen the adherence interface, reducing the wheel operating life. In this scenario, a fault detection procedure to be use at the end of the manufacturing process has been developed. The fault detection procedure is based on vibration processing techniques. In this paper, several wheels with rust presence on the hub have been manufactured ‘ad hoc’ with anomalies similar to the ones that can really be originated. Signal processing techniques have been used in order to detect the presence of rust; in particular, cyclostationary theory is applied to extract information from the frequency/order domain of the processed signals. Indicators based on cyclostationary theory can be considered as the key parameters to be adopted in a monitoring test station at the end of the production line.
2013
- On the time synchronous average in planetary gearboxes
[Relazione in Atti di Convegno]
D'Elia, Gianluca; Mucchi, Emiliano; Dalpiaz, Giorgio
abstract
Generally, in planetary gearbox diagnostics, transducers are placed on the gearbox case near the ring gear.
The relative angular position of the planet gears with respect to the transducer is a pivotal information for the
evaluation of vibration signals related to planet/sun gears. This angular position is usually unknown, or it is
known with a large tolerance. The present work seeks to propose two alternative methods for the identification
of the angular position of the planet gears with respect to the transducer. The first one is based on the study of
how the power flows inside the Time Synchronous average of the ring gear, whilst the second method is based
on a modified statistical parameter such as the Crest Factor. The effectiveness of these methods is assessed on
the basis of actual vibration signals acquired from a faulty planetary gearbox.
2013
- ON THE WEAR AND LUBRICATION REGIME IN VARIABLE DISPLACEMENT VANE PUMPS
[Articolo su rivista]
Mucchi, Emiliano; Agazzi, Alessandro; D'Elia, Gianluca; Dalpiaz, Giorgio
abstract
This paper proposes an experimental methodology for the analysis of the lubrication regime and wear that occur between vanes and pressure ring in variable displacement vane pumps. The knowledge of the lubrication regime is essential for the improvement of the performance of high pressure vane pumps by reducing wear, increasing the volumetric efficiency and decreasing maintenance costs. Tests using pressure rings of different materials were carried out in order to identify the best material in terms of wear and friction. The proposed methodology is based on Archard’s law and takes advantage of wear experimental measurements, an empirical model for the estimation of contact pressure forces and hardness standard tests. The results of the analysis state that low wear and reduced friction can be obtained if elasto-hydrodynamic lubrication between vanes and pressure ring is established. Results have been also verified by an analytical elasto-hydrodynamic model.
2012
- Assessment of the lubrication regime in variable displacement vane pumps
[Relazione in Atti di Convegno]
Mucchi, Emiliano; Agazzi, Alessandro; D'Elia, Gianluca; Dalpiaz, Giorgio
abstract
This paper proposes a combined numerical-experimental methodology for the analysis of the lubrication regime and wear that occur between vanes and pressure ring in variable displacement vane pumps. The knowledge of the lubrication regime is essential for the improvement of the performance of high pressure vane pumps by reducing wear, increasing the volumetric efficiency and decreasing maintenance costs. Tests using pressure rings of different materials were carried out in order to identify the best material in terms of wear and friction. The proposed methodology is based on Archard’s law and takes advantage of wear experimental measurements, an empirical model for the estimation of contact pressure forces and hardness standard tests. The results of the analysis state that low wear and reduced friction can be obtained if elasto-hydrodynamic lubrication between vanes and pressure ring is established. Results have been also verified by analytical elasto-hydrodynamic models.
2012
- Simulation of the running in process in external gear pumps and experimental verification
[Articolo su rivista]
Mucchi, Emiliano; D'Elia, Gianluca; Dalpiaz, Giorgio
abstract
Before marketing external gear pumps are subjected to a running in process to increase their efficiency. However, this is one of the most time-consuming tasks of the entire manufacturing process. Therefore, a mathematical model for optimizing the running in process can be a useful tool for time-to-market reduction. In particular, in this paper a model for the analysis of the dynamic behaviour of external gear pumps, developed by the authors in previous works, is modified and used for simulating the running in process. The modified model is presented and validated via experimental data. A good correlation between simulation and test results guarantees the effectiveness of the model in determining the amount and the distribution of the removed material during the running in process. A meaningful reduction (16%) of the global running in time has been achieved with the introduction of a modified running in process drawn from simulation results.
2010
- Advanced signal processing tools for the vibratory surveillance of assembly faults in diesel engine cold tests
[Articolo su rivista]
Delvecchio, Simone; D'Elia, Gianluca; Mucchi, Emiliano; Dalpiaz, Giorgio
abstract
This paper addresses the use of several signal processing tools for monitoring and diagnosis
of assembly faults in diesel engines through the cold test technology. One specific fault is
considered here as an example: connecting rod with incorrectly tightened screws. Firstly, the
experimental apparatus concerning the vibration tests is introduced. Subsequently, the
dynamic analysis of the engine has been carried out in order to calculate the connecting rod
forces against the crankpin for predicting the position where mechanical impacts are expected.
Then, a vibration signal model for this type of faults is introduced. It deals with the
cyclostationary model in which the signal is subdivided into two main parts: deterministic and
non-deterministic. Finally, the acceleration signals acquired from the engine block during a
cold test cycle at the end of the assembly line are analyzed. For quality control purposes in
order to obtain reliable thresholds for the pass/fail decision, a method based on the image
correlation of Symmetrized Dot Patterns (SDP) is proposed. This method visualizes vibration
signals in a diagrammatic representation in order to quickly detect the faulty engines in cold
tests. Moreover the fault identification is discussed on the basis of the cyclostationary model
of the signals. The first-order cyclostationarity is exploited by the analysis of the Time
Synchronous Average (TSA). In addition the residual signal is evaluated by subtracting the
TSA from the raw synchronized signal, and thus the second-order cyclostationarity analysis is
developed by means of the Wigner-Ville Distribution (WVD), Wigner-Ville Spectrum (WVS)
and Mean Instantaneous Power (MIP). Moreover, Continuous Wavelet Transform (CWT) is
presented and compared with the WVD and WVS.
2010
- CONDITION MONITORING BY MEANS OF VIBRATION ANALYSIS TECHNIQUES: SOME CASE STUDIES
[Relazione in Atti di Convegno]
Cavallari, Marco; D'Elia, Gianluca; Delvecchio, Simone; Malago', Marco; Mucchi, Emiliano; Dalpiaz, Giorgio
abstract
This paper evaluates the effectiveness of some vibration processing techniques for quality control at the end of the assembly line in two industrial cases: the detection of contamination faults in polyurethane wheels, and tooth fault detection in helical gears. These applications illustrate the capability of vibration analysis as condition monitoring tool, as well as the importance of the proper selection of test and processing parameters.
2010
- On the monitoring and diagnosis of assembly faults in diesel engine cold tests: a case study
[Relazione in Atti di Convegno]
Delvecchio, Simone; D'Elia, Gianluca; Mucchi, Emiliano; DI GREGORIO, Raffaele
abstract
tools as a means for the monitoring and the diagnosis of
assembly faults in internal combustion (i.c) engines through
the cold test technology. Firstly, an approach based on the use
of symmetrized dot patterns for the visual characterization of
vibration signatures is proposed. This method is applied in
order to obtain reliable thresholds for the pass/fail decision
after the cold test. Secondly, the fault identification is
discussed on the basis of the cyclostationary modeling of the
signals. First of all, first-order cyclostationarity is exploited
through the analysis of the Time Synchronous Average (TSA).
Subsequently, second-order cyclostationarity is developed by
means of the mean instantaneous power, Wigner-Ville
Distribution (WVD) and Wigner-Ville Spectrum (WVS).
Finally, the Continuous Wavelet Transform (CWT) is
presented and compared with the Wigner Ville Distribution. In
order to show the effectiveness and the limitations of the
above-mentioned techniques, tests were carried out for a
number of different faults. In this paper the results relative to a
specific fault are shown as example.
2009
- On the use of vibration signal analysis for industrial quality control
[Relazione in Atti di Convegno]
Cavallari, Marco; D'Elia, Gianluca; Delvecchio, Simone; Malago', Marco; Mucchi, Emiliano; Dalpiaz, Giorgio
abstract
2006
- Modeling run in process in external gear pumps
[Relazione in Atti di Convegno]
Dalpiaz, Giorgio; D'Elia, Gianluca; Mucchi, Emiliano; A., FERNANDEZ DEL RINCON
abstract
2006
- Pressure phenomena in dynamic analysis of external gear pumps
[Relazione in Atti di Convegno]
Dalpiaz, Giorgio; Mucchi, Emiliano; D'Elia, Gianluca; A., FERNANDEZ DEL RINCON
abstract
2006
- Vibro-acoustic measurements for the identification of incoming stall in axial compressors
[Relazione in Atti di Convegno]
Dalpiaz, Giorgio; D'Elia, Gianluca; Mucchi, Emiliano; A., Rivola
abstract