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Effective vibration control of multimodal structures with low power requirement
Thamina Loukil,Mohamed Ichchou,Olivier Bareille,Mohamed Haddar 국제구조공학회 2014 Smart Structures and Systems, An International Jou Vol.13 No.3
In this paper, we investigate the vibration control of multimodal structures and present anefficient control law that requires less energy supply than active strategies. This strategy is called modal global semi-active control and is designed to work as effectively as the active control and consume less power which represents its major limitation. The proposed law is based on an energetic management of theoptimal law such that the controller follows this latter only if there is sufficient energy which will beextracted directly from the system vibrations itself. The control algorithm is presented and validated for acantilever beam structure subjected to external perturbations. Comparisons between the proposed lawperformances and those obtained by independent modal space control (IMSC) and semi-active controlschemes are offered.
Effective vibration control of multimodal structures with low power requirement
Loukil, Thamina,Ichchou, Mohamed,Bareille, Olivier,Haddar, Mohamed Techno-Press 2014 Smart Structures and Systems, An International Jou Vol.13 No.3
In this paper, we investigate the vibration control of multimodal structures and present an efficient control law that requires less energy supply than active strategies. This strategy is called modal global semi-active control and is designed to work as effectively as the active control and consume less power which represents its major limitation. The proposed law is based on an energetic management of the optimal law such that the controller follows this latter only if there is sufficient energy which will be extracted directly from the system vibrations itself. The control algorithm is presented and validated for a cantilever beam structure subjected to external perturbations. Comparisons between the proposed law performances and those obtained by independent modal space control (IMSC) and semi-active control schemes are offered.
Simplified model to study the dynamic behaviour of a bolted joint and its self loosening
Olfa Ksentini,Bertrand Combes,Mohamed Slim Abbes,Alain Daidié,Mohamed Haddar 국제구조공학회 2015 Structural Engineering and Mechanics, An Int'l Jou Vol.55 No.3
Bolted joints are essential elements of mechanical structures and metal constructions. Although their static behaviour is fairly well known, their dynamic behaviour due to shocks and vibrations has been less studied, because of the large size of the finite element models needed for a detailed simulation. This work presents four different simplified models suitable for studying the dynamic behaviour of an elementary bolted joint. Three of them include contact elements to allow sliding of the screw head and the nut on the assembled parts, and the last one allows rotation between screw and nut. A penalty approach based on the Coulomb friction model is used to model contact. The results show that these models effectively represent the dynamic behaviour, with different accuracy depending on the model details. The last model simulates the self loosening of a bolt subjected to transversal vibrations.
Noureddine Baaka,Manel Ben Ticha,Wafa Haddar,Maria Teresa Pessoa Amorim,Mohamed Farouk Mhenni 한국섬유공학회 2018 Fibers and polymers Vol.19 No.2
The desire to offer clothes protective properties against the harmful UV rays continues to attract the interest of researchers. Several works have been elaborated in this topic and have proved that the clothes do not protect sufficiently against the solar ultraviolet radiation. Their protectiveness depends on the fiber type, the fabric composition, the fabric construction and the dyeing method. This research presents a novel approach which target the improvement of the textile protective properties against UV rays by their dyeing with grape pomace aqueous extract. These properties were tested in combination with several fabrics (natural and synthetic) and mordants (potassium alum and ferrous sulphate). Through this study, it has been shown that the UV-protective properties of the several dyed fibers were upgraded after dyeing with the grape pomace extract, and is intensely relying on the types of fibers and mordants.
Parametric analysis of the damage characterization tests of aluminum bulk material
Chaima Hammami,Nouha Kammoun,Hamdi Hentati,Mounir Ben Amar,Mohamed Haddar 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.10
Several models have been developed to study materials behaviors under different states of stress. In manufacturing processes, several types of stresses are observed in workpieces. In this context, this paper presents an analysis of the failure behavior of aluminum bulk specimens through parametric characterization tests covering most of these solicitations. The goal is to choose better configuration to reduce experimental tests costs later. First, numerical models used for damage characterization tests are described and validated. Johnson Cook models and stress triaxiality parameter are introduced to study the ductile damage mechanism in the material. Second, the influence of specimens geometries on characterization tests results is under investigation. Tension, compression, shear, torsion, and combined torsion-tension tests are carried out using finite element models and thermo-mechanical coupling method.
Abdelmonaam Abid,Moncef Hammadi,Maher Barkallah,Jean-Yves Choley,Jamel Louati,Alain Rivière,Mohamed Haddar 한국정밀공학회 2018 International Journal of Precision Engineering and Vol.19 No.12
Globalization and mass customization are demanding a higher level of productivity. The relevance of modelling approaches to the study and design of reconfigurable manufacturing system (RMS) is widely claimed to achieve the highest productivity. Principally, reconfigurability in manufacturing systems should support the changeability with precisely the production capacity and functionality needed and exactly when needed. Simulation of such reconfigurable systems has become more and more difficult with the increasing complexity of system requirements. In spite of the promising methodology for designing RMS, an effective framework that bridges the gap between conceptual modelling level process and simulation level process is still a major challenge for Scientist. For this reason, we propose in this paper a generic framework especially designed for building and running executable agent-based models of RMS. This framework relies on SysML (Systems Modelling Language) models specifications, the holonic system techniques and multi-agent system in order to generate executable models of RMS. The considered case study for this paper is based on a steel converter process. Results showed an increase in the productivity rate after simulating the reconfigurability test cases through the developed agent-based models.