Mohamed Slim Abbes

VIBRATORY BEHAVIOR OF A DOUBLE PANEL SYSTEM BY THE OPERATIONAL MODAL ANALYSIS

The present study tackles the vibratory behavior of a double panel system by operational modal analysis (OMA) using one of the major techniques of blind source separation (BSS), which is the independent component analysis (ICA). For this purpose, the OMA method and the ICA concept are presented and exploited in order to identify the eigenmodes of a double panel system. Then, results obtained by the OMA technique are presented and compared with those achieved by the modal recombination method. Since a good argument is observed, this approach can be used in conjunction with experimental works.

Multidisciplinary approach for optimizing mechatronic systems: Application to the optimal design of an electric vehicle

Optimization of integrated mechatronic design is a complex process characterized by an important number of requirements, design variables, constraints and objectives. Therefore, it is very important to efficiently decompose the system design problem into a set of quasi-separable sub-problems to reduce the design complexity and minimize the computational cost of a mechatronic design. In this study, a constraint-based method is proposed for the partitioning of the mechatronic design optimization problem. This approach allows designers to optimize the mechatronic system taking into account the interaction between the different use cases of the system. By applying the approach to the case of a preliminary design of an electric vehicle, the electric motor and the transmission gearbox have been optimized. It is shown that the presented approach allows designers to easily decompose the problem and integrate performance analysis with multidisciplinary optimization for efficient design verification and validation of mechatronic systems.

One stage spur gear transmission crankcase diagnosis using the independent components method

The preventive diagnosis of mechanical systems presents a promising tool for increasing the production because it allows the industry to save time and money. In fact, the conventional diagnosis process is based on the FRF method which can be used to determine the inside defects frequencies of the system. Hence, this paper presents a new and a useful idea based on the blind source separation (BSS) which allow determining the wave form and the excitation frequency of internal defects present in a given mechanism by using only the structural vibratory response of the system. Numerical example of a one stage spur gear transmission crankcase including a spur gear pairs, shafts, rolling element bearings and a casing composed by three rigid plates and one flexible plate is presented and analysed in this paper. The separation results show a good agreement between original and estimated sources. This demonstrates the usefulness of the proposed method in the diagnosis process.

Application of the Operational Modal Analysis Using the Independent Component Analysis for a Quarter Car Vehicle Model

This paper investigates the dynamic behavior of a quarter car vehicle system using the Operational Modal Analysis (OMA) . This method is applied using one of the major techniques of the Blind Source Separation (BSS) which is the Independent Component Analysis (ICA) . Compared to the classical modal analysis, the Operational Modal Analysis presents the advantage that it is only based on the vibratory responses of the structure in order to identify its modal parameters. To validate this approach in the case of a quarter car vehicle model , the estimated results obtained by the OMA methods are presented and compared with those obtained by the modal recombination method.

Multidisciplinary Optimization of Mechatronic Systems: Application to an Electric Vehicle

Preliminary design of mechatronic systems is an extremely important step in the development process of multi-disciplinary products. The great challenge in mechatronic design lies in the multidisciplinary optimization of a complete system with various physical phenomena related to interacting heterogeneous subsystems. In this chapter we combine model-based technique using modeling language Modelica with multidisciplinary optimization approach using ModelCenter framework for integrated modeling, simulation and optimization of mechatronic systems. This approach has been applied to the preliminary design of an electric vehicle. Modeling language Modelica has been used to model and simulate the electric vehicle and ModelCenter has been used for the multidisciplinary optimization of the electric motor and the transmission gear ratio. The presented integrated approach allows designers to integrate EV performance analysis with multidisciplinary optimization for efficient design verification and validation.

Nonlinear modeling and simulation of spur gear with defected bearings

Purpose – The aim of this paper is to present a theoretical model to simulate the dynamic behavior of a spur gear, taking into account its ball bearings defects.Design/methodology/approach – The proposed model is based on the implicit Newmark‐β with Newton‐Raphson numerical integration technique in order to analyze the impact of the worn bearings on the non linear dynamic behavior of one stage spur gear transmission system.Findings – The dynamic behavior of spur gear is studied taking into account ball bearings defects thanks to the proposed model.Originality/value – A new numerical model is proposed to simulate the dynamic behavior of rotating spur gear system taking into account both waviness and backlash defects.

ESTIMATION OF DYNAMIC SYSTEM'S EXCITATION FORCES BY THE INDEPENDENT COMPONENT ANALYSIS

This paper deals with a numerical investigation for the estimation of dynamic systems excitation sources using the independent component analysis (ICA). In fact, the ICA concept is an important technique of the blind source separation (BSS) method. In this case, only the dynamic responses of a given mechanical system are supposed to be known. Thus, the main difficulty of such problem resides in the existence of any information about the excitation forces. For this purpose, the ICA concept, which consists on optimizing a fourth-order statistical criterion, can be highlighted. Hence, a numerical procedure based on the signal sources independency in the ICA concept is developed. In this work, the analytical or the finite element (FE) dynamic responses are calculated and exploited in order to identify the excitation forces applied on discrete (mass-spring) and continuous (beam) systems. Then, estimated results obtained by the ICA concept are presented and compared to those achieved analytically or by the FE and the modal recombination methods. Since a good agreement is obtained, this approach can be used when the vibratory responses of a dynamic system are obtained through sensors measurements.

Influence of disk brake friction on the dynamic behaviour of a directly coupled spur gear transmission

Purpose – The purpose of this paper is to study the influence of friction phenomenon generated by a disc brake on the dynamic behaviour of a one-stage spur gear. Design/methodology/approach – A theoretical model is proposed and is based on both theories of Coulomb and Dahl in order to analyse the influence of disc brake friction phenomenon on the dynamic behaviour of one-stage spur gear transmission. Findings – The influence of brake friction on the dynamic behaviour of the transmission is investigated using the proposed model and leads to observe higher vibration levels when the braking is occurring as well as the emergence of significant efforts at the gear teeth. Originality/value – A new numerical model based on the implicit numerical integration technique of Newmark coupled with Newton-Raphson method is proposed to study the influence of friction phenomenon of a disc brake on the dynamic behaviour of one-stage spur gear.

Experimental study of passive vibration suppression using absorber with spherical ball impact damper

Impact dampers are efficient in many industrial applications with a wide range of frequencies. An experimental analysis of the impact damping of spherical balls is investigated to simplify the particle impact damping design and improve the vibration suppression. The objective of the study is to analyze some of the design parameters of impact damper using spherical balls. The experimental investigation consists to test the effect of the ball size for each mass level, the number of balls for each size level and different exciting force levels on vibrations of the main structure. The parametric study provided useful information to understand and optimize Particle Impact Damping design.

Vibration reduction of an assembly by control of the tightening load

Due to their lightness, the aerospace structures are vulnerable to vibrations. Their amplitudes need to be mitigated through damping devices. The aim of this paper is to control the tightening forc...