 |
GIOVANNI IARRICCIO
Ricercatore t.d. art. 24 c. 3 lett. A
Dipartimento di Ingegneria "Enzo Ferrari"
|
Home |
Didattica |
Pubblicazioni
2023
- Fluid–Structure Interaction of a thin cylindrical shell filled with a non-Newtonian fluid
[Articolo su rivista]
Zippo, A.; Iarriccio, G.; Bergamini, L.; Colombini, E.; Veronesi, P.; Pellicano, F.
abstract
This paper presents the results of an extensive experimental campaign on the dynamic interactions between an elastic structure and a non-Newtonian fluid. The structure consists of a thin circular cylindrical shell, with the bottom end clamped to a shaking table, and the top end carrying a heavy mass. The fluid is a mixture of water and cornstarch, also known as oobleck. The system dynamics has been analyzed in the presence of different fluid levels (i.e., empty, partially, and full-filled). The experimental modal analysis has been carried out to identify the modal properties of the system. High energy tests have been performed by means of a seismic excitation consisting in a stepped sine sweep, spanning the forcing frequency within the neighborhoods where strong resonance phenomena take place. Different excitation amplitudes have been considered in order to induce phase transitions in the fluid, and the onset of complex dynamics has been detected using Fourier spectra and bifurcation diagrams of the Poincaré maps: when the fluid–solid transition occurs, the entangled non-Newtonian fluid rheology results in a complex dynamic scenario where period-doubling cascades, quasiperiodic and chaotic responses can be observed.
2022
- Asymmetric vibrations and chaos in spherical caps under uniform time-varying pressure fields
[Articolo su rivista]
Iarriccio, G.; Zippo, A.; Pellicano, F.
abstract
This paper presents a study on nonlinear asymmetric vibrations in shallow spherical caps under pressure loading. The Novozhilov’s nonlinear shell theory is used for modeling the structural strains. A reduced-order model is developed through the Rayleigh–Ritz method and Lagrange equations. The equations of motion are numerically integrated using an implicit solver. The bifurcation scenario is addressed by varying the external excitation frequency. The occurrence of asymmetric vibrations related to quasiperiodic and chaotic motion is shown through the analysis of time histories, spectra, Poincaré maps, and phase planes.
2022
- Correction to: Asymmetric vibrations and chaos in spherical caps under uniform time-varying pressure fields (Nonlinear Dynamics, (2022), 107, 1, (313-329), 10.1007/s11071-021-07033-7)
[Articolo su rivista]
Iarriccio, G.; Zippo, A.; Pellicano, F.
abstract
The original article was published with erroneous author information. The correct authorship is as it stands in this correction. The original article has been corrected.
2022
- Digital Twins: Neural-Networks for the implementation of digital twins of gearboxes
[Relazione in Atti di Convegno]
Zippo, A.; Bergamini, L.; D'Elia, G.; Pellicano, F.; Dalpiaz, G.; Iarriccio, G.; Molaie, M.
abstract
2022
- Effects of laser surface texturing on the dynamic performance of spur gears
[Relazione in Atti di Convegno]
Iarriccio, G.; Zippo, A.; Molaie, M.; Bergamini, L.; Pellicano, F.
abstract
Laser Surface Texturing (LST) has been successfully applied to improve the tribological performance of reciprocating surfaces. In this context, although the relative motion between the meshing teeth is a combination of sliding and rolling, gears provided with LST could further reduce losses and vibrations in power transmissions. In this study, experimental results on the efficiency and the vibrations of gears are reported. The tests were carried out through a test bench that allows for evaluating the power losses of the transmission and the dynamic transmission error thanks to a set of torquemeters and accelerometers. Different load and speed conditions were investigated, and a comparison of the results between textured gears and standard carburized gears is provided.
2022
- Experiments on a Quasi-zero Stiffness Suspension for Passive Vibration Control
[Relazione in Atti di Convegno]
Iarriccio, G.; Molaie, M.; Zippo, A.; Pellicano, F.
abstract
Experimental measurements on a quasi-zero stiffness (QZS) isolator under base excitations are reported. The setup is described and the QZS isolator is compared to a standard mass-spring system. The role of the geometric nonlinearities on the dynamic behavior is clear: the QZS isolator transmissibility shows a natural frequency reduction, and the system effectively suppresses the ground vibration about the fundamental frequency of the standard system. The QZS isolator performance has been tested also under real earthquake signals, showing satisfactory acceleration mitigation.
2022
- Loaded and unloaded tooth contact analysis of spiral bevel gears in consideration of misalignments
[Articolo su rivista]
Moslem, M.; Zippo, A.; Iarriccio, G.; Bergamini, L.; Pellicano, F.
abstract
Bevel gear pairs are employed extensively in transmission systems, such as vehicle transmissions (rear axle drive), aircraft engines/turbines and helicopter gears, to transfer power between non-parallel shafts at high speed or high torque. The most complex form of bevel gear is the spiral bevel gear (SBG). SBG pairs are commonly used in applications that require high load capacity at higher operating speeds than are typically possible with other types of bevel gear. When manufactured in a metal-cutting process, spiral bevel gears can either be produced using single indexing (a face-milling method, which is considered in this study) or continuous indexing (a face-hobbing method). Due to manufacturing imperfections and the flexibility of components, the system might experience misalignments that intensify or exert a destructive effect on the gear vibration, which causes disruption in the stress distribution, thereby decreasing the lifetime of the gearbox. The main purpose of this study is to carry out loaded tooth contact analysis (LTCA) and unloaded tooth contact analysis (UTCA) for an SBG pair in the presence of two types of misalignment, axial and radial misalignment, and represent their effects on the mesh stiffness (MS). To calculate the MS, it is essential to determine the geometrical mismatch between two mating tooth profiles by means of UTCA. To conduct LTCA, three main approaches can be utilised: the finite element method (FEM) and experimental and analytical approaches. Due to the development of software packages during the last decade, Transmission3D-Calyx, an FEM-based software, is used in this study to carry out LTCA and UTCA. Finally, the MS for different misalignment cases is compared to represent the effect of misalignment on the SBG pair.
2022
- Modal localization in vibrations of circular cylindrical shells with geometric imperfections
[Articolo su rivista]
Hemmatnezhad, M.; Iarriccio, G.; Zippo, A.; Pellicano, F.
abstract
The present study aims to investigate the effect of geometric imperfections in circular cylindrical shells on the vibration characteristics. Perfect circular shells are characterized by the presence of double shell-like modes, i.e., modes having the same frequency with modal shape shifted of a quarter of wave-length in the circumferential direction. However, in the presence of geometric imperfections, the double natural frequencies split into a pair of distinct frequencies, the splitting is proportional to the level of imperfection. In some cases, the imperfections cause an interesting phenomenon on the modal shapes, which present a strong localization in the circumferential direction. The present study has been carried out by means of a semi-analytical approach. Theoretical formulation were derived based on Sanders–Koiter thin shell theory. The analytical results have been compared with those of standard finite element analyses. The results corresponding to the analysis of modal localization are novel and can be used as a benchmark for further studies.
2022
- Planet Load-Sharing and Phasing
[Articolo su rivista]
Molaie, M.; Deylaghian, S.; Iarriccio, G.; Samani, F. S.; Zippo, A.; Pellicano, F.
abstract
2021
- Efficiency and Durability of Spur Gears with Surface Coatings and Surface Texturing
[Relazione in Atti di Convegno]
Iarriccio, G.; Zippo, A.; Barbieri, M.; Pellicano, F.
abstract
Experimental results on mechanical efficiency and durability of spur gears are presented. Reducing the power losses and increasing the reliability of gears are fundamnetal aspects of the design of transmissions. In order to analyze the tribological performance of innovative coatings and laser texturing, three different types of spur gears were tested: standard carburized gears, WC/C-coated carburized gears, and carburized gears with laser texture pattern. Tests have been carried out through a power recirculating test rig equipped with a single-stage transmission; power losses were evaluated by analyzing the torque-meters signals; several pictures of the teeth were taken at scheduled times to monitor the wear progression. In conclusion, results are presented and discussed.
2021
- Gear diagnostic: Experimental data comparison of radial accelerometers, tangential accelerometers and torquemeter
[Abstract in Atti di Convegno]
Zippo, A.; Pellicano, F.; Iarriccio, G.; Bergamini, L.; D'Elia, G.; Dal Piaz, G.
abstract
Industry 4.0 is the next step of the evolution of future companies in order to improve efficiency sustainability and performances. With a view to industry 4.0 and to improve the efficiency of gear transmission a measurement campaign has been performed comparing four gear pair with different surface treatment, damages and coating The experimental results on the measurement of radial accelerometers, tangential accelerometers and torque-meter measurement of spur gears rig with surface coatings, advanced pitting with a crack and damaged gears are presented and analysed with Time Synchronous Averaged (TSA) method and results are explained, comparing the effectiveness of the different sensors used to monitor the system under investigation.
2021
- Gear prognostics: A predictive algorithm for lifetime estimation of operating gearboxes
[Abstract in Atti di Convegno]
Bergamini, L.; Zippo, A.; Pellicano, F.; Iarriccio, G.; Molaie, M.
abstract
For the realization of optimized, effective gearboxes, both the set of design rules and the study of operation conditions, interconnected to each other, have to be taken into account. Condition monitoring is an essential tool when study of gearbox operation is tackled, and many techniques have been developed to detect the onset and the development of wear. However, these techniques fall short when prediction of gearbox conditions is concerned, as in the case of tracking the useful lifetime during operation. Within this framework, a prognostic software is developed and presented. This software is able to estimate the useful lifetime of a gearbox on the base of design features (safety factors and parameters), standards and codes (ISO) and realistic/measured load spectra, representative of the operation condition of the gearbox. This tool opens up the possibility of combining condition monitoring and prediction for a wider, comprehensive study of gearbox operation. Moreover, it potentially allows to detect machinery misuse and plan accurate usage-dependent maintenance in industrial environment.
2021
- Nonlinear dynamics and stability of shallow spherical caps under pressure loading
[Articolo su rivista]
Iarriccio, G.; Pellicano, F.
abstract
The post-buckling and nonlinear dynamic response of shallow spherical caps subjected to external pressure is analyzed. The Novozhilov's nonlinear thin shell theory is used to express the strain-displacement relations. Following the Rayleigh-Ritz method, the displacement fields are expanded using a mixed series: Legendre polynomials in the meridional direction, harmonic functions in the circumferential direction. Once the linear analysis is completed, the displacement fields are re-expanded and the nonlinear dynamic model is obtained by using the Lagrange equations. The response of clamped caps, made of isotropic and homogeneous material, is investigated. The bifurcation analyses of equilibrium points and periodic orbits are presented by using continuation techniques. Benchmark results are provided in terms of natural frequencies and critical buckling loads. The dynamic effects due to the interaction between static and dynamic pressure are investigated. Numerical results pointed out that, under particular load conditions, dynamic bifurcation results in nonnegligible asymmetric states activation in the response of the structure.
2021
- Resonances and nonlinear vibrations of circular cylindrical shells, effects of thermal gradients
[Articolo su rivista]
Iarriccio, G.; Zippo, A.; Pellicano, F.; Barbieri, M.
abstract
In this paper, the results of an experimental campaign focused on the vibrations of shells are presented. More specifically, the goal is to investigate the effect of thermal gradients across the shell thickness on the nonlinear dynamics. The shell is made of polymeric material and an aluminum mass is clamped on one end of the shell; the other shell end is clamped to an electrodynamic shaker, which provides a base harmonic excitation. Tests are performed in a controlled environment where a thermal gradient on the shell thickness is generated by means of a climatic chamber and an internal cartridge heater. Different temperature gradients and base excitation levels have been considered. The nonlinear dynamic scenario is analyzed through amplitude–frequency diagrams, bifurcation diagrams, waterfall diagrams, time histories, Fourier spectra, phase portraits, and Poincaré maps. Results show a strong effect of the temperature on the dynamic response of the shell: subharmonic, quasi-periodic, and chaotic vibrations take place as well as large amplitude vibrations, high sound levels are detected.
2021
- Seismic vibration of shells with non-Newtonian fluid interaction: Experiments
[Abstract in Atti di Convegno]
Pellicano, F.; Zippo, A.; Iarriccio, G.
abstract
In the presented study the nonlinear vibrations of a fluid-filled circular cylindrical shell under seismic excitation is investigated. A PET thin shell with an aluminum top mass is harmonically excited from the base through an electrodynamic shaker in the neighborhood of the natural frequency of the first axisymmetric mode. The dilatant fluid is composed of a cornstarch-water mixture with 60% cornstarch and 40% water of total weight. The preliminary results show a strong non-linear response due to the coupling between the fluid and structure and the shaker-structure interaction that leads to a very interesting dynamic response of the system. The specimen is a polymeric circular cylindrical shell: an aluminum cylindrical mass is glued on the shell top edge; conversely, the bottom edge of the shell is clamped to a shaking table. The following sensors have been adopted: three triaxial accelerometers placed on the top mass at 120°, a monoaxial accelerometer at the base of the shell, a laser vibrometer to measure the lateral velocity on the mid-height of the shell. The test article has been excited in the axial direction through a harmonic load, with a step-sweep controlled output, the voltage signal sent to the shaker amplifier is closed-loop controlled; to avoid interaction between the control system and the specimen under study, no controls have been used for controlling the shaker base motion. The harmonic forcing load consists of a stepped-sine sweep of frequency band 100-500 Hz with a step of 2.5 Hz. All the tests have been performed with the shell full filled with quiescent fluid. The dynamic scenario is carefully analyzed by means of time histories, spectra, phase portraits and Poincaré maps. The experiments show the onset of complex dynamics: subharmonic and quasiperiodic responses, Chaos.
2021
- Synchronicity Phenomena in Circular Cylindrical Shells Under Random Excitation
[Capitolo/Saggio]
Zippo, A.; Iarriccio, G.; Pellicano, F.
abstract
In many engineering areas, the structures are subjected to external forcing with a prevalent harmonic component in conjunction with significant likely non-deterministic contribution; moreover, the coupling between loading conditions and extreme environmental temperatures can lead to complex dynamic phenomena. In this paper, an experimental study on the nonlinear dynamics of a thin polymeric circular cylindrical shell, carrying a top mass, subjected to thermal gradients and random excitation is presented. Tests have been performed in controlled temperature conditions and the shell has been excited through an electrodynamic shaker. The experimental results pointed out that a broadband random excitation at the base of the shell can give rise to the synchronicity of the response to the resonance corresponding to the first axisymmetric mode of the shell; the vibration energy is conveyed to specific harmonics, some of which are outside and far from the excitation band.
2021
- Time series analysis of arm and forearm measurement for functional electrical stimulation control
[Abstract in Atti di Convegno]
Zippo, A.; Pellicano, F.; Iarriccio, G.
abstract
Identify the dynamics of the muscular group of arm and forearm related to accelerometric and surface electromyographic signals is not an easy task especially in persons affected by pathological tremor, in which irregular tremor is not voluntary. The vibrational phenomena studied in this work regards the arm and forearm vibration that are monitored by means of SEMG (surface electro-myographic) sensor and accelerometer sensor with the purpose to detect and recognize the dynamic properties and correlations of onset of pathological tremor in patients affected by Parkinson disease and essential tremor. These pathologies that affect skeletal muscles present a typical characteristic vibration frequency between 1Hz and 12Hz, this property is monitored in out-patient tests. A condition monitoring system has been developed to monitor the tremor and produce an electrical stimulation to reduce the tremor: the system allows data monitoring with a portable microcontroller board powered with low voltage batteries and is based on a cDAQ9191 data acquisition system with a chassis controller module designed for data input, controlling and output generation. The algorithm generates functional electrical stimulation signals for control purpose. Experimental measurement data on parkinsonian patient are presented. Data are analyzed, and the results are presented.
2020
- Efficiency and Durability of DLC-Coated Gears
[Relazione in Atti di Convegno]
Barbieri, M.; Iarriccio, G.; Pellicano, F.; Strozzi, M.; Zippo, A.
abstract
This paper presents an experimental study on spur gears. Gears with and without tungsten-carbide coatings (WC/C) are compared in terms of efficiency, durability and vibration performance. In order to carry out the experiments, a test rig including two electric motors/brakes is described. Gears are designed for this specific experimental campaign, so that the number of teeth, the selected materials and thermochemical treatments are optimal to investigate gear efficiency and durability. The experimental procedure allows for a simultaneous evaluation of efficiency and dynamic transmission error by varying the rotational velocity of the gear pair. An additional investigation has been performed for varying load, so that a complete characterization of the effect of WC/C coating on gear performance is presented.
2020
- Experimental Study on Nonlinear Random Excitation
[Relazione in Atti di Convegno]
Pellicano, F.; Zippo, A.; Iarriccio, G.; Barbieri, M.
abstract
Experimental design methods are instruments for directing useful, time-effective and efficient experiments and an accurate strategy in experimental activities lead to successful results. In the present paper is explained an experimental campaign focused on the random vibrations of circular cylindrical shells under thermal gradients across the shell thickness and broadband random loading to identify a particular phenomenon called synchronicity: the investigation is fully experimental. Nuclear, aerospace and automotive are some of the engineering fields involved in this subject, and in these real environments non-deterministic excitations can be coupled with a thermal load; extreme thermal conditions can cause differences of the temperature inside and outside the shell, e.g. thermal ex-changers. Due to the importance of the subject, the literature on shell vibration is extremely wide, it is not analyzed here for the sake of brevity; however, it is to note that the number of papers containing experimental results is not large. Under a random forcing, a system generally expects a random response, the statistical properties of the random response are correlated with the forcing through the transfer function in the case of linear systems, or more complicated relationships in the case of nonlinear systems. However, in some particular conditions (e.g. internal resonances, parametric resonances, ...) the presence of nonlinearity in the systems can give rise to a surprising phenomenon, said synchronicity or entrainment. In this work a shell subjected to a random base excitation is analyzed experimentally, the excitation is random (flat or limited frequency band), and takes advantage of previous setup and experimental techniques [3–5] developed by the present research team. The phenomenon of synchronicity is clearly observed for some particular thermal conditions: a strong transfer of energy from a broadband excitation signal to an almost harmonic response is experimentally observed, confirming the general findings of refs. [1, 2].
2020
- Experimental study on large amplitude vibrations of a circular cylindrical shell subjected to thermal gradients
[Relazione in Atti di Convegno]
Iarriccio, G.; Zippo, A.; Barbieri, M.; Pellicano, F.
abstract
In this paper, an experimental study on large amplitude vibrations of a thin-walled shell, subjected to thermal gradient across the thickness, is presented. The temperature gradient effects on the shell dynamic behavior are investigated. The vibration tests are performed on a polymeric cylindrical shell that carries a top mass. The structure is harmonically excited in the longitudinal direction by means of an electrodynamic shaker. The results of the experimental study are here reported and discussed.
2020
- Nonlinear dynamics and stability of pressure-loaded shallow spherical caps
[Relazione in Atti di Convegno]
Iarriccio, G.; Pellicano, F.
abstract
In this work, the nonlinear dynamic response of a shallow spherical cap subjected to a time-dependent pressure load is analyzed. The Novozhilov s nonlinear thin shell theory is used to express the strain-displacement relations, geometric imperfections are considered. Using the Rayleigh-Ritz method, the displacement fields are expanded using a mixed series: Legendre polynomials are considered in the azimuthal direction and harmonic functions in the circumferential one. The dynamic model is derived by using the Lagrange equations. The response of a homogeneous shell, made of isotropic material, clamped at its ends, and subjected to an external pressure load is investigated: using the continuation software AUTO, the bifurcation analysis of equilibrium points and periodic responses has been performed. The model is validated by means of comparison with the existing results in literature for spherical shells having a circular base, in particular with models developed through the Marguerre s theory.
2020
- Nonlinear vibrations of circular cylindrical shells with thermal effects: an experimental study
[Articolo su rivista]
Zippo, Antonio; Barbieri, Marco; Iarriccio, Giovanni; Pellicano, Francesco
abstract
The nonlinear dynamics of a polymeric cylindrical shell carrying a top mass under axial harmonic excitation are experimentally investigated; the tests have been carried out in a controlled environment under several conditions of homogeneous temperature and excitation amplitude. The thermal effects on shells dynamics have been studied. The purpose of this paper is to fill an important gap in the literature regarding the effect of the temperature on the complex dynamics of shells. The cylindrical shell is excited in the axial direction by means of a seismic excitation provided by an electrodynamic shaker. The analysis is focused on the range of frequencies of excitation close to the first axisymmetric mode resonance; the base motion induces a parametric excitation. A saturation phenomenon of the top mass vibration is observed; the vibrating energy directly transferred from the shaker to the first axisymmetric mode is transferred to radial motion of the shell. The experimental data are examined and discussed in detail; a complete dynamic scenario is analyzed by means of: amplitude–frequency curves, bifurcation diagrams, spectrograms, Poincaré maps, phase portraits, Fourier spectra and time histories. Results show that: (i) the temperature strongly affects the instability regions and the magnitude of the measured kinematic quantity, (ii) high environmental temperature leads to a more complex shell dynamics.
2020
- Vibrations of circular cylindrical shells under random excitation and thermal gradients
[Relazione in Atti di Convegno]
Zippo, A.; Pellicano, F.; Iarriccio, G.; Barbieri, M.
abstract
The present paper is focused on the random vibrations of circular cylindrical shells subjected to thermal gradients across the shell thickness; the investigation is fully experimental. The topic is of practical interest in many engineering fields such as: Aerospace, Automotive, Civil, Nuclear. Indeed, in real environments the excitations are likely non deterministic, moreover, extreme thermal conditions can cause differences of temperature inside and outside the shell, e.g. thermal exchangers. Due to the importance of the subject the literature on shell vibration is extremely wide, it is not analyzed here for the sake of brevity; however, it is to note that the number of papers containing experimental results is not large. When a system is excited with random forcing one generally expects a random response of the system, the statistical properties of the random response are correlated with the forcing through the transfer function in the case of linear systems, or more complicated relationships in the case of nonlinear systems. However, in some particular conditions (e.g. internal resonances, parametric resonances,…) the presence of a nonlinearity in the systems can give rise to a surprising phenomenon, said synchronicity or entrainment (see [1, 2]), which consists in a response made of a combination of random and harmonic signals. In this work a shell subjected to a random base excitation is analyzed experimentally, the excitation is random (flat or limited frequency band). The work take advantage from previous setup and experimental techniques [3–5] developed by the present research team. The phenomenon of synchronicity is clearly observed for some particular thermal conditions: a strong transfer of energy from a broad band excitation signal to an almost harmonic response is experimentally observed, confirming the general findings of refs. [1, 2].
2020
- Vibrations of plates with complex shape: Experimental modal analysis, finite element method, and R-functions method
[Articolo su rivista]
Zippo, A.; Iarriccio, G.; Pellicano, F.; Shmatko, T.
abstract
In this paper, the dynamic behavior of 3D-printed plates with different shapes and boundary conditions is investigated. The natural frequencies and mode shapes were determined using three different methods: the experimental analysis, the finite element method, using Nastran, and the R-functions method. The experimental and theoretical results are compared. Thespecimens tested included four cases. The test procedure is deeply described, and the material properties of the plates are given. The fixed-fixed configuration shows a better agreement both in the rectangular plate and in the plate with rectangular cuts, and the R-functions method gives better convergence with respect to the experimental and finite element analysis. The simply supported arrangement indicates some uncertainty in the boundary realization of the specimen.
2019
- Condition monitoring of parkinson pathological tremor for functional electrical stimulation control
[Relazione in Atti di Convegno]
Zippo, A.; Pellicano, F.; Iarriccio, G.; Valzania, F.; Cavallieri, F.
abstract
The aim of this work is to identify the correlation of accelerometric and electromyographic signals and the difference between healthy patients (control group) and patients affected by Parkinson disease (PD) and essential tremor (ET). The vibrational phenomena studied in this work regards the forearm and hand vibration that are monitored by means of SEMG (surface electro-myographic) sensor and accelerometer sensor with the purpose to detect and recognize the dynamic properties of onset of pathological tremor in patients affected by (PD) and (ET). PD and ET present a typical characteristic vibration frequency between 3Hz and 12Hz, this property is monitored in out-patient tests. Two condition monitoring systems have been developed and deep described to monitor the tremor: the former system allows data monitoring with a portable lightweight microcontroller board powered with low voltage batteries (5Volt); and the latter is based on a CompactRio data acquisition system with a chassis controller module designed for data input, controlling and output generation, powered by 12 Volt battery. The CRio System provide an algorithm to generate functional electrical stimulation signals for control purpose. Experimental measurement data on healthy control subjects are presented. Data are analyzed, and results are presented.
2019
- Experimental durability test for condition monitoring of carburized spur gears
[Relazione in Atti di Convegno]
Iarriccio, G.; Zippo, A.; Barbieri, M.; Pellicano, F.
abstract
An experimental study on the durability of spur gears has been carried out. Tests have been performed through a power re-circulating test rig at a fixed speed and torque load. For condition monitoring purpose, vibrations have been measured through a triaxial accelerometer mounted on the shaft frame. Acquired data have been post-processed and preliminary results are shown. The aim of the present work is to analyze the changes in the vibrations signal in order to depict a clear view on the onset and progression of the wear and damages in gear transmissions.
2019
- Experimental investigation on spur gears with novel coatings and surface micro texturing
[Relazione in Atti di Convegno]
Zippo, A.; Pellicano, F.; Iarriccio, G.; Barbieri, M.
abstract
Gears fault diagnostic and prognostic techniques have been the significant subjects of the condition-based monitoring systems in recent time due to the potential advantages that could be gained from. The present work is part of a more extensive study regarding efficiency and durability of novel tungsten carbide coatings and surfaces laser micro-texturing applied on carburized and nitride gears for several industrial application. In this paper, the effect of the different gear coatings and texturing on the vibration level is investigated experimentally. The durability and the pitting arising have been examined. The test rig consists of two electric motors with an electric power recirculating layout and is equipped with a temperature monitoring of the oil-jet type lubrication system. Vibrations phenomena are measured through triaxial accelerometer mounted on the shaft frame, close to the bearings, in order to detect spectral characteristics of vibration signals due to gear fault. Tests have been conducted far from the resonances of the system at a fixed speed and torque load; Vibration measurements have been performed at planned intervals. Results are presented and discussed
2019
- Experimental study on the nonlinear vibrations of a circular cylindrical shells: Effects of thermal gradients
[Relazione in Atti di Convegno]
Iarriccio, G.; Zippo, A.; Barbieri, M.; Pellicano, F.
abstract
In this paper, an experimental study on the large amplitude vibrations of a thin polymeric cylindrical shell subjected to a thermal gradient across the thickness is presented. The effects of the temperature gradient on the shell dynamic behavior are investigated. The present study has the aim of providing a deeper contribution to the experimental literature on the shell structures. Test have been carried out in controlled environment condition thanks to a climatic chamber and a heater cartridge placed inside the shell. The shell carries a top mass and an electro-dynamic shaker has been used in order to excite, with a harmonic load, the test specimen in the longitudinal direction. The harmonic forcing load consists of a stepped-sine sweep with frequency band limits containing the resonance frequency of the first axisymmetric vibration mode. Four different excitation amplitude levels and two different thermal gradients have been considered. The experimental results are presented and discussed in detail by means of frequency response analysis and bifurcation analysis
2019
- Identification of dynamic behaviour of forearm for active control of pathological tremor
[Relazione in Atti di Convegno]
Zippo, A.; Pellicano, F.; Iarriccio, G.; Franco, V.; Francesco, C.
abstract
Pathological tremor is defined as an oscillatory and rhythmic movement of a segment of the body caused by the alternating activation of muscle groups in antagonism between them; a typical pathological condition known as essential tremor, which is the most common form of tremor also having a family character (2-5% of the population) have a characteristic frequency between 5 Hz and 7 Hz, such as Parkinsonian tremor that arises at frequencies higher than 8 Hz. The purpose of this study is to investigate the dynamic behavior of the forearm induced by the hand movements, measured due to the electromyographic sensors and accelerometers. The relationships of accelerometric and electromyographic signals are compared between a control group of healthy subjects and patients affected by Parkinson disease (PD) and essential tremor (ET). The vibrational phenomena analyzed in this experimental investigation are observed by means of SEMG (surface electro-myographic) sensors placed on flexor and extensor muscle compartment of forearm and accelerometer sensors for the hand vibration with the aim to detect and recognize the dynamic properties of onset of pathological tremor in patients affected by (PD) and (ET). A real-time monitoring and data logger system have been developed and deep described to monitor the tremor: the system allows data monitoring with a portable lightweight microcontroller board based on a CompactRio data acquisition system with a chassis controller module designed for data input, controlling and output generation, powered by 12 Volt battery. The CRio System provides an algorithm to generate functional electrical stimulation signals with different waveforms for control purpose. Experimental measurement data on healthy control subjects are presented. Data are analyzed, and the results are discussed