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1

Parameter identification of a full-car model for active suspension design

Guida D., Nilvetti F., Pappalardo C. M.

Journal of Achievements in Materials and Manufacturing Engineering

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2010

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Vol. 40, nr 2

138-148

EN

Purpose: A method for identifying parameters of a full-car model for active suspension design Design/methodology/approach: The method is based on ERA/OKID identification procedure developed by Juang [1]. Findings: Numerical results show a good agreement with real system parameters. Research limitations/implications: Results show that this method works well only with a high signal-to-noise ratio. Practical implications: This method can be used as an aid to active suspension design. Originality/value: This procedure has been tested on the full-car model of suspension system in two cases: a) full-state measurements; b) not full-state measurements.

2

Dry friction of bearings on dynamics and control of an inverted pendulum

Guida D., Nilvetti F., Pappalardo C. M.

Journal of Achievements in Materials and Manufacturing Engineering

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2010

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Vol. 38, nr 1

80-94

EN

Purpose: Investigation of dry friction parameters on the control system of a cart pendulum. Design/methodology/approach: A geometrical approach has been used to analyze the influence of bearing friction on the cart-pendulum dynamics. This approach was developed by one of authors in the paper “ Influence of the Variation between Static and Kinetic Friction on Stick-Slip Instability” pubblished by WEAR 1993. Findings: Relations that allow us to evaluate how the friction parameters of bearings influence the performances of the control system of a cart-pendulum. Research limitations/implications: The “a priori knowing” of friction parameters is the intrinsic limitation of this method. Originality/value: A novel methodology for designing of more effective control systems.

3

Theoretical investigation on the static properties of the finite porous journal bearings

D'Agostino V., Guida D., Ruggiero A., Senatore A.

International Journal of Applied Mechanics and Engineering

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2004

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Vol. 9, no spec.

321-328

EN

A theoretical analysis is carried out to determine the analytical approximate description of the fluid film force of porous finite journal bearings. The investigation has been conducted assuming the Warner solution for the pressure field and the approximate analytical solution for the long porous journal bearings proposed by D'Agostino et al. (2004). The analytical approach for studying the behaviour of a system is more effective than a numerical one because of it allows to cover not only the individual case but the whole class to which the system belongs. Furthermore, the model proposed allows a quick analytical determination of the fluid film force for different values of the permeability coefficient, L/D ratio, eccentricity ratio. The results are in good agreement with those achieved by means of the FDM based solution.

4

An analytical solution for the pressure field in the long porous journal bearings

D'Agostino V., Guida D., Ruggiero A., Senatore A.

International Journal of Applied Mechanics and Engineering

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2004

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Vol. 9, no spec.

313-319

EN

Analytical solutions of the Reynolds equation for the porous journal bearings are not generally achievable and numerical methods must be involved. This paper presents an approximate mathematical model for the one-dimensional lubrication equation for the infinitely long porous journal bearing, obtaining a good agreement over the ranges of operating conditions of this tribological component.

5

On the influence of labyrinth seals on the dynamic behaviour of rotors

D'Agostino V., Guida D.

International Journal of Applied Mechanics and Engineering

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2001

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Vol. 6, no 4

1089-1098

EN

The influence of the labyrinth seals on the dynamic behaviour of a flexible rotor in journal bearings is investigated. In particular a code which makes possible the determination of the stiffness and damping coefficients and the calculus of the stability threshold in the absence of unbalance is discussed. The pressure field in journal bearings and in the labyrinth seal is determined using Warner's hypothesis and the bulk-flow model with two-control-volume, respectively.

6

Active magnetic bearings test rig for experimental investigation of seals

D'Agostino V., Guida D.

International Journal of Applied Mechanics and Engineering

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2001

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Vol. 6, no 4

1099-1107

EN

A test rig for the experimental validation of the rotordynamic coefficients of annular and labyrinth seals using Active Magnetic Bearings (AMBs) exciters is presented. The rotordynamic coefficients for annular and labyrinth seals are obtained, with two computer programs using the Reynolds' gas lubrication equation and the bulk flow model with two volume control, respectively. The AMBs exciters allow the rotor to levitate without contact, and to excite it with user-defined sinusoidal forces at the same time. The dynamic experiments can be conducted at various rotor speeds, whirling speeds, and with different pressure drops across the seal.

7

Analytical fluid film force in the turbulent journal bearings

D'Agostino V., Guida D., Ruggiero A.

Applied Mechanics and Engineering

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1999

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Vol. 4, no spec.

25-31

EN

The aim of this paper is to illustrate a method to determine the analytical description of non-steady fluid film force and of the stiffness and damping coefficients for the "short" liquid-lubricated journal bearings in a fully developed turbulent flow regime. The equation goveming the distribution of pressure around the bearing has been solved analytically; the models has been developed assuming lubricant flow is isoviscous.