Papers by Francesco PELLICANO
Post-Critical Response of an Axially Moving Beam
In this paper the dynamic response of a simply supported traveling beam, subjected to a pointwise... more In this paper the dynamic response of a simply supported traveling beam, subjected to a pointwise transversal load, is investigated. The motion is described by means of a high dimensional system of ordinary differential equations with linear gyroscopic part and cubic nonlinearities obtained through the Galerkin method. The system is studied in the super-critical speed range with emphasis on the stability and the global dynamics that exhibits special features after the first bifurcation. A sample case of a physical beam is developed and numerical results are presented concerning bifurcation analysis and stability, and direct simulations of global postcritical dynamics. In the supercritical speed range a regular motion around a bifurcated equilibrium position becomes chaotic for particular values of frequency and force. The bifurcation diagram for varying force intensity is shown, it can be noticed that a chaotic motion occurs in a wide range of the forcing parameter, co-existing with a 3T periodic solution in a limited window.
Condition monitoring of parkinson pathological tremor for functional electrical stimulation control
The aim of this work is to identify the correlation of accelerometric and electromyographic signa... more 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
Experimental durability test for condition monitoring of carburized spur gears
An experimental study on the durability of spur gears has been carried out. Tests have been perfo... more 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
Adaptive Grid-Size Modelling of Helical Gear Pairs
Influence of dynamic effects on point EHL contacts in gear systems
In this paper, the effect of vibrations in elastohydrodynamical lubrication of spur gear pairs wi... more In this paper, the effect of vibrations in elastohydrodynamical lubrication of spur gear pairs will be described. The relevance of inertial effects in the contacting bodies on film fluid lubrication will be clarified with comparisons to static formulations. A new model describing the dynamic behavior of two coupled transient EHL elliptical contacts will be presented and applied to characterize the dynamics of a spur gear pair
Nonlinear Vibrations and Multiple Resonances of Fluid-Filled, Circular Shells, Part 2: Perturbation Analysis
Journal of Vibration and Acoustics, May 1, 2000
The nonlinear ordinary differential equations describing the dynamics of a fluid filled circular ... more The nonlinear ordinary differential equations describing the dynamics of a fluid filled circular cylindrical shell, obtained in Part 1 of the present study, is studied by using a second order perturbation approach and direct simulations. Strong modal interactions are found when the structure is excited with small resonant loads. Modal interactions arise in the whole range of vibration amplitude, showing that the internal resonance condition makes the system non-linearizable even for extremely small amplitudes of oscillation. Stationary and nonstationary oscillations are observed and the complex nature of modal interactions is accurately analyzed. No chaotic motion is observed in the case of 1:1:1:2 internal resonance studied. [S0739-3717(00)01304-0]
Nonlinear Vibrations and Multiple Resonances of Fluid-Filled, Circular Shells, Part 1: Equations of Motion and Numerical Results
Journal of Vibration and Acoustics, May 1, 2000
The response-frequency relationship in the vicinity of a resonant frequency, the occurrence of tr... more The response-frequency relationship in the vicinity of a resonant frequency, the occurrence of travelling wave response and the presence of internal resonances are investigated for simply supported, circular cylindrical shells. Donnell’s nonlinear shallow-shell theory is used. The boundary conditions on radial displacement and the continuity of circumferential displacement are exactly satisfied. The problem is reduced to a system of four ordinary differential equations by means of the Galerkin method. The radial deflection of the shell is expanded by using a basis of four linear modes. The effect of internal fluid is also investigated. The equations of motion are studied by using a code based on the Collocation Method. The present model is validated by comparison of some results with others available. A water-filled shell presenting the phenomenon of 1:1:1:2 internal resonances is investigated for the first time; it shows intricate and interesting dynamics. [S0739-3717(00)01204-6]
Vibration of gears: A global optimization approach
The importance of studying dynamic aspects of gear transmissions has been well established since ... more The importance of studying dynamic aspects of gear transmissions has been well established since many years; however, recently a new interest on this topics grew up because of significant improvement in gear design technology. The literature can supply different approaches to evaluate the vibrations response of simple and complex gears system. Numerical and analytical methods can provide important information on resonances, non linear behaviours and combined dynamic interactions in existing systems. In particular the reduction of vibrations is strictly related to minimize the value of the peak to peak of the static transmission error in a mesh cycle, through modifications of the tooth profile. The present paper combines a numerical model to study spur gear pair dynamics, with a genetic optimization technique to define the best profile modification capable to reduce the vibration. The numerical model is able to take into account gear geometry, profile modifications and profile manufacturing errors. The genetic optimization routine can provide the best set of profile modification considering the peak to peak value of the static transmission error or a generic number of its harmonic components. In the last part of this work some testcases are investigated and the improvement in the dynamics is shown. \ua9 (2006) by the Katholieke Universiteit Leuven Department of Mechanical Engineering All rights reserved
Experimental study on the nonlinear vibrations of a circular cylindrical shells: Effects of thermal gradients
In this paper, an experimental study on the large amplitude vibrations of a thin polymeric cylind... more 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 analysi
Nonlinear dynamics of axially loaded shells: experimental study
In this paper recent experiments on nonlinear dynamics of shells are described, such experiments ... more In this paper recent experiments on nonlinear dynamics of shells are described, such experiments were focused to circular cylindrical shells subjected to axial loads. Different types of axial loads were considered: inertial loads due to rigid bodies connected to the shell; static and dynamic loads induced by direct shell excitation. The latter type of loading allows to study the effect of pre-compression, which typically induces natural frequency variation and changing of the dynamic scenario. The experiments show an extremely complex dynamic scenario, which needs a deep analysis to be interpreted and explained. The goal of the present work is twice: describe experimental evidence of complex dynamics and furnish explanation when possible
Modellazione bidimensionale CAD FEM di coppie d’ingranaggi cilindrici
Modelling lubrication in gear pairs
5th World Tribology Congress, WTC 2013, 2013
Non-Linear Dynamics and Stability of Circular Cylindrical Shells Containing Flowing Fluid, Part II: Large-Amplitude Vibrations Without Flow
Journal of Sound and Vibration, Dec 1, 1999
The non-linear response of empty and fluid-filled circular cylindrical shells to harmonic excitat... more The non-linear response of empty and fluid-filled circular cylindrical shells to harmonic excitations is investigated. Both modal and point excitations have been considered. The model is suitable to study simply supported shells with and without axial constraints. Donnell's non-linear shallow-shell theory is used. The boundary conditions on radial displacement and the continuity of circumferential displacement are exactly satisfied. The radial
Experiments on Dynamic Non-Newtonian Fluid Interaction With Shells
Volume 5: Dynamics, Vibration, and Control, Oct 30, 2022
In this work the nonlinear vibrations of a fluid-filled circular cylindrical shell under base exc... more In this work the nonlinear vibrations of a fluid-filled circular cylindrical shell under base excitation is investigated. A polymeric (P.E.T.) thin shell with an aluminum top mass is harmonically excited from the base through an electrodynamic shaker in the neighbourhood of the natural frequency of the first axisymmetric mode. Experiments are carried out both in presence and absence of a contained fluid, which is non-Newtonian (dilatant); the dilatant fluid is composed of a cornstarch-water mixture with 60% cornstarch and 40% water of total weight, it is commonly known as oobleck. The 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 scenario. The system has been excited in the axial direction (vertical) through a harmonic load, with a stepped-sine sweep controlled output. Tests have been performed on empty shell, fully or partially filled shell with oobleck 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.
Non-Linear Dynamics and Stability of Circular Cylindrical Shells Containing Flowing Fluid. Part IV: Large-Amplitude Vibrations with Flow
Journal of Sound and Vibration, Nov 1, 2000
The response of a shell conveying fluid to harmonic excitation, in the spectral neighbourhood of ... more The response of a shell conveying fluid to harmonic excitation, in the spectral neighbourhood of one of the lowest natural frequencies, is investigated for different flow velocities. The theoretical model has already been presented in Part I of the present study. Non-linearities due to moderately large-amplitude shell motion are considered by using Donnell's non-linear shallow-shell theory. Linear potential flow theory
Tuneable High-Static-Low-Dynamic Stiffness Vibration Isolator Under Harmonic and Seismic Loads: Experiments and System Identification
Fluid-Structure Interaction of Non-Newtonian Fluid-Filled Thin Cylindrical Shell
Social Science Research Network, 2022
Nonlinear Stability of Circular Cylindrical Shells in Axially Flowing Fluid
The stability of supported, circular cylindrical shells in compressible, inviscid axial flow is i... more The stability of supported, circular cylindrical shells in compressible, inviscid axial flow is investigated. Nonlinearities due to large amplitude shell motion are considered by using the nonlinear Donnell shallow shell theory and the effect of viscous structural damping is taken into account. Two different in-plane constraints are applied to the shell edges: zero axial force and zero axial displacement; the other boundary conditions are those for simply supported shells. Linear potential flow theory is applied to describe the fluid-structure interaction. Both annular and unbounded external flow are considered by using two different sets of boundary conditions for the flow beyond the shell length: (i) a flexible wall of infinite extent in the longitudinal direction, and (ii) rigid extensions of the shell (baffles). The system is discretised by Galerkin projections and is investigated by using a model involving seven degrees of freedom, allowing for travelling wave response of the shell and shell axisymmetric contraction. Results for both annular and unbounded external flow show that the system loses stability by divergence through strongly subcritical bifurcations. Jumps to bifurcated positions can happen much before the onset of instability predicted by linear theories, showing the necessity of a nonlinear study.
Geometrically Nonlinear Forced Vibrations of Circular Cylindrical Shells Containing Flowing Fluid
The response of a shell conveying fluid to harmonic excitation, in the spectral neighbourhood of ... more The response of a shell conveying fluid to harmonic excitation, in the spectral neighbourhood of one of the lowest natural frequencies, is investigated for different flow velocities. Nonlinearities due to moderately large amplitude shell motion are considered by using the nonlinear Donnell shallow shell theory. Linear potential flow theory is applied to describe the fluid-structure interaction by using the model proposed by Païdoussis and Denise. For different amplitude and frequency of the excitation and for different flow velocities, the following are investigated numerically: (i) periodic response of the system; (ii) unsteady and stochastic motion; (iii) loss of stability by jumps to bifurcated branches. The effect of the flow velocity on the nonlinear periodic response of the system has also been investigated. Poincaré maps and bifurcation diagrams are used to study the unsteady and stochastic dynamics of the system. Amplitude-modulated motions, multi-periodic solutions, chaotic responses and the so-called “blue sky catastrophe” phenomenon have been observed for different values of the system parameters; the latter two have been predicted here probably for the first time for the dynamics of circular cylindrical shells.
Nonlinear Dynamics and Stability of Pressure-Loaded Shallow Spherical Caps
In this work, the nonlinear dynamic response of a shallow spherical cap subjected to a time-depen... more 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.
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Papers by Francesco PELLICANO