Papers by Francesco Pellicano
Fluid–Structure Interaction of a thin cylindrical shell filled with a non-Newtonian fluid
Journal of Fluids and Structures, Feb 1, 2023
Spiral Bevel Gears: Bifurcation and Chaos Analysis of Pure Torsional System
Modal localization in vibrations of circular cylindrical shells with geometric imperfections
Thin-Walled Structures
Loaded and unloaded tooth contact analysis of spiral bevel gears in consideration of misalignments
Insight - Non-Destructive Testing and Condition Monitoring
Bevel gear pairs are employed extensively in transmission systems, such as vehicle transmissions ... more 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 stud...
Identification of dynamic behaviour of forearm for active control of pathological tremor
Pathological tremor is defined as an oscillatory and rhythmic movement of a segment of the body c... more 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 discusse
In this paper an experimental study on circular cylindrical shells subjected to axial compressive... more In this paper an experimental study on circular cylindrical shells subjected to axial compressive and periodic loads is presented. The setting of the experiment is explained and deeply described along with a complete analysis of the results. The linear and the nonlinear dynamic behaviour associated with a combined effect of compressive static and a periodic axial load has been considered and a chaotic response of the structure has been observed close to the resonance. The linear shell behaviour is also investigated by means of a theoretical and finite element model, in order to enhance the comprehension of experimental results, i.e. the natural frequencies of the system and their ratios.
Francesco Pellicano \ue8 Editore Associato Rivista Internazionale:"Mathematical Problems in Engineering
Complex dynamics of planetary gear systems
A full 2D dynamic model of a single-stage planetary gear system with backlash and time varying st... more A full 2D dynamic model of a single-stage planetary gear system with backlash and time varying stiffness is considered here. This dynamic model is time variant and non-smooth, due to the presence of time varying meshing stiffness and backlash for all sun- planets and ring-planets meshes; moreover, bearing compliance is accounted for. The linear averaged equations of motion are solved to obtain the natural frequencies; conversely, the fully nonlinear equations of motion are analyzed numerically to study the effect of time varying stiffness and backlash and to point out the nonlinear dynamics of the system. The complex dynamics is deeply investigated over the meaningful mesh frequency ranges. The dynamic scenario is obtained by means of bifurcation analysis and completed with time spectral and topological properties of the response
EHL lubrication in spur and helical gear pairs
Gear efficiency is highly relying on elasto-hydrodynamic lubrication (EHL), and gear lubrication ... more Gear efficiency is highly relying on elasto-hydrodynamic lubrication (EHL), and gear lubrication is significantly dependent upon non stationary conditions in gear pairs. Furthermore, the presence of lubricant is the main responsible of the damping effect in gear pair vibration. For these reasons, gear vibration and gear lubrication are to be considered as coupled problems. In the present work, a dynamic model of gear pairs taking into account for EHL lubrication is presented. The multilevel technique is used to solve the EHD lubrication problem, together with the equation describing the relative motion of the mating gears. Gear lubrication conditions at different gear rotation speed are investigated, in order to point out the effect of coupling between a thin lubricant film and elastic deformations in contacting bodies; a comparison between a dry contact and a lubricated contact is drawn, in order to clarify the amount of damping introduced by the lubricant film
Nonlinear dynamics of carbon nanotubes
Nona Giornata di Studio “Ettore Funaioli”, 2015
Eleventh International Symposium on Vibrations of Continuous Systems ISVCS11, 2017
The goal of the present paper is the analysis of the effect of geometric imperfections in circula... more The goal of the present paper is the analysis of the effect of geometric imperfections in circular cylindrical shells. 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 wavelength in the circumferential direction. In 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. This study is carried out by means of a semi-analytical approach compared with standard finite element analyses.
Fifth International Conference on Nonlinear Dynamics ND-KhPI2016, 2016
The nonlinear dynamics o f circular cylindrical shells under combined axial static and periodic f... more The nonlinear dynamics o f circular cylindrical shells under combined axial static and periodic forces are experimentally investigated. The goal is to study the dynamic scenario and to analyze non-linear regimes. The linear behavior under static preload is analyzed by means o f the usual modal testing techniques. The complex dynamics arising when a periodic axial load excites the first axisymmetric mode are analyzed by means o f amplitude frequency diagrams, waterfall spectrum diagrams, bifurcation diagrams o f Poincare maps, time histories, spectra, phase portraits.
In this paper, the linear vibrations of Triple-Walled Carbon Nanotubes (TWNTs) are analysed. A mu... more In this paper, the linear vibrations of Triple-Walled Carbon Nanotubes (TWNTs) are analysed. A multiple elastic shell model is considered. The shell dynamics is studied in the framework of the Sanders-Koiter shell theory. The van der Waals (vdW) interaction between two layers of the TWNT is modelled by a radius-dependent function. The circular cylindrical shell deformation is described in terms of longitudinal, circumferential and radial displacements. Simply supported, clamped and free boundary conditions are considered. The three displacement fields are expanded by means of a double mixed series based on Chebyshev orthogonal polynomials for the longitudinal variable and harmonic functions for the circumferential variable. The Rayleigh-Ritz method is applied to obtain approximate natural frequencies and mode shapes. The present model is validated in linear field by means of data derived from the literature. This study is focused on determining the effect of the geometry and boundary conditions on the natural frequencies of TWNTs.
Circular Cylindrical Shells under combined axial loads: an experimental study
Thin shells structures have an important role in engineering; several important examples can be f... more Thin shells structures have an important role in engineering; several important examples can be found in Structural Engineering, Mechanical Engineering and Aerospace: water tanks, containment shells of nuclear power plants, concrete arch domes, piping systems, pressure vessels, aircrafts, missiles, rockets, ships. Even though many researchers have extensively studied nonlinear vibrations of cylindrical shells, experimental studies are rather limited in number; in particular, rare experimental reports have been published about shells loaded with in-plane . In this paper the response of a circular cylindrical shells subjected to axial compressive and periodic loads has been experimentally investigated. The experimental setup is explained and deeply described along with the analysis of preliminary results. The linear shell behavior is investigated by means of a finite element model in order to enhance the comprehension of experimental results in the linear field. The main goal is to investigate the nonlinear phenomena associated with a combined effect of compressive static and a periodic axial loads, the investigation have been carried out for different combinations of loads. Several interesting nonlinear phenomena have been observed such as softening-type non-linearity and non stationary response when the periodic axial load is resonant with one of the shell modes
Non-smooth active control of seismic vibrations
In order to prevent seismic damage in civil buildings and mechanical equipment, e.g. during trans... more In order to prevent seismic damage in civil buildings and mechanical equipment, e.g. during transport, passive isolators and dampers are commonly used. In the present work, a non-smooth strategy for active seismic isolation is presented. The method provides isolation from base excitation by dynamically switching the stiffness of the foundation. The controller works as follows: when the seismic movement is active, the velocity of the moving mass is monitored as the reference velocity. When such reference velocity is positive, the stiffness is reduced; when it is negative, the stiffness is increased. Numerical investigations show that the controller is capable to filter seismic excitation close to the natural frequency of the controlled system, and to reduce the total seismic energy transfer up to 5 times. The role played by the gravity in the active vibration filtering is pointed out by showing that no filtering action can be observed in gravity-free simulations. Even though the controlled system is linear, the controller presents a non-smooth fluctuation of the stiffness, so that a limit cycle occurs within the system
Tredicesima Giornata di Studio “Ettore Funaioli”, 2019
Machines
This paper presents an analysis of the scientific literature devoted to the problem of load shari... more This paper presents an analysis of the scientific literature devoted to the problem of load sharing and phasing in planetary gearboxes. The wide range of research topics demonstrates the technical challenges of understanding planetary load-sharing and planet phasing. This review includes studies having the goal of developing models for load sharing and exploring the positive or negative effects of different parameters such as phasing on the load distribution among planets. Practical aspects are also considered, for example, the effects of some errors that are unavoidable during manufacturing or working conditions, e.g., misalignments or position errors. Methods for improving the load-sharing characteristics, e.g., flexible ring or floating components, are discussed as well.
In this paper pitting phenomenon and stress distribution of gears are investigated by means of ex... more In this paper pitting phenomenon and stress distribution of gears are investigated by means of experimental activities and numerical finite element analyses. In the first part, results of experimental accelerated endurance tests for the investigation of the pitting phenomenon of gears are reported. These durability tests are made at a specific nominal load and far from the resonance. After a short time, a visible pitting phenomenon arises. In the second part, finite element numerical analyses for the evaluation of gear stresses are given. The numerical analyses start from stress-vibration correlations and dynamic factors obtained by means of a 2-dof dynamic model previously developed; these results are used in the dynamic FEM simulations to calculate maximum normal stress and contact pressure on the contact tooth of the pinion vs. vibration amplitude for different dynamic factors.
Nonlinear oscillations of carbon nanotubes
In this paper, the low-frequency nonlinear oscillations and energy localizations of Single-Walled... more In this paper, the low-frequency nonlinear oscillations and energy localizations of Single-Walled Carbon Nanotubes (SWNTs) are analysed. The SWNTs dynamics is studied within the framework of the Sanders-Koiter thin shell theory. The circumferential flexure vibration modes (CFMs) are considered. Simply supported boundary conditions are investigated. Two different approaches are compared, based on numerical and analytical models. The numerical model uses a double series expansion for the displacement fields based on the Chebyshev polynomials and harmonic functions. The Lagrange equations are considered to obtain a set of nonlinear ordinary differential equations of motion which are solved using the implicit Runge-Kutta numerical method. The analytical model considers a reduced form of the shell theory assuming small circumferential and tangential shear deformations. The Galerkin procedure is used to get the nonlinear ordinary differential equations of motion which are solved using the multiple scales analytical method. The natural frequencies obtained by considering the two approaches are compared in linear field. The effect of the aspect ratio on the analytical and numerical values of the localization threshold is investigated in nonlinear field
Nonlinear Dynamics, 2021
This paper presents a study on nonlinear asymmetric vibrations in shallow spherical caps under pr... more 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 modelling 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 quasi-periodic and chaotic motion is shown through the analysis of time histories, spectra, Poincaré maps, and phase planes.
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Papers by Francesco Pellicano