Ifsttar PhD subject

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Title : Experimental study and modelling of friction dampers

Main host Laboratory - Referent Advisor Navier  -  PEIGNEY Michaël      tél. : +33 164153746

Director of the main host Laboratory SULEM Jean  -

Laboratory 2 - Referent Advisor COSYS - LISIS  -  SIEGERT Dominique  -    -  tél. : +33 181668314

PhD Speciality matériaux et structures

Axis of the performance contract 2 - COP2017 - More efficient and resilient infrastructure

Main location Marne-la-Vallée

Doctoral affiliation UNIVERSITE PARIS-EST

PhD school SCIENCES, INGENIERIE ET ENVIRONNEMENT (SIE)

Planned PhD supervisor PEIGNEY Michaël  -  Université Gustave Eiffel  -  Navier

Planned financing Contrat doctoral  - Ifsttar

Abstract

Vibrations damping is a major issue in civil engineering. Tuned Mass Damper (TMD) are among the most studied solutions. These systems are usually linear (viscous dampers) and their effectiveness islimited to a low range of excitation frequencies. The use of this type of device therefore requires a precise tuning, which in some cases is difficult to guarantee. For viscous fluid-based TMDs there is also the question of long-term waterproofing. In addition, linear TMDs are usually designed for low-amplitude excitations
.
Nonlinear friction dampers address some of these drawbacks: they are effective over a relatively wide frequency range and suitable for large-amplitude excitationss. The use of metallic cables under bending is one of the simplest and most robust solutions for a non-linear damper. The physical mechanism involved is related to the friction between the constituent strands of the cable. It is a nonlinear and hysterical phenomenon. Such systems are found in various applications of civil engineering, such as Stockbridge shock absorbers( used in particular on high voltage power lines). A. Trad's thesis [3] also suggests that friction within metal cables contributes significantly to yhe total energy dissipation in block nets.
However, designing such non-linear friction dampers poses some difficulties. The Bouc-Wen model is the most commonly used [1]. This model is phenomenological in nature and has the advantage of being relatively simple, but a recent study [2] has shown that it does not allow the accurate reproduction of experimental hysteresis curves, making it risky to identify parameters model.
The main objective of the proposed thesis is to establish a model (more adapted than the Bouc-Wen model) to describe the hysterical behaviour of bending cable dampers, based on the physical understanding of the mechanisms involved. The framework of elasto-plasticity with internal variables is a possible avenue. An important issue is to ensure that the model remains simple enough (reduced number of degrees of freedom) to remain easily usable in a design process. Integrating the material model into CESAR is also one of the objectives.
In addition to the modelling aspect (theoretical and numerical), the proposed thesis will draw on experimental work conducted at COSYS to guide the development of the model, identify its constituent parameters and validity limits. In order to direct work towards large-scale applications, the monitoring committee would include representatives of CEREMA (interested in Stockbridge shock absorbers) and industrialists involved in the manufacture of block nets (national project C2ROP).

Profile sought: engineer or master from a background in mechanics, with skills in digital modeling and interested in experimental mechanics. The doctoral student will be enrolled at Gustave Eiffel University. He will be supervised by Michael Peigney (thesis director, personal page: https://www.ifsttar.fr/menu-haut/annuaire/fiche-personnelle/personne/peigney-michael/), Cyril Douthe (personal page:https://www.ifsttar.fr/menu-high/directory/personal file/person/douthe-cyril/) and Dominique Siegert (personal page: https://www.ifsttar.fr/menu-haut/annuaire/fiche-personnelle/personne/siegert-dominique/).

Keywords : vibration damping in civil engineering, hysteretic systems

Main host Laboratory - Referent Advisor	Navier - PEIGNEY Michaël tél. : +33 164153746
Director of the main host Laboratory	SULEM Jean -
Laboratory 2 - Referent Advisor	COSYS - LISIS - SIEGERT Dominique - - tél. : +33 181668314
PhD Speciality	matériaux et structures
Axis of the performance contract	2 - COP2017 - More efficient and resilient infrastructure
Main location	Marne-la-Vallée
Doctoral affiliation	UNIVERSITE PARIS-EST
PhD school	SCIENCES, INGENIERIE ET ENVIRONNEMENT (SIE)
Planned PhD supervisor	PEIGNEY Michaël - Université Gustave Eiffel - Navier
Planned financing	Contrat doctoral - Ifsttar
Abstract Vibrations damping is a major issue in civil engineering. Tuned Mass Damper (TMD) are among the most studied solutions. These systems are usually linear (viscous dampers) and their effectiveness islimited to a low range of excitation frequencies. The use of this type of device therefore requires a precise tuning, which in some cases is difficult to guarantee. For viscous fluid-based TMDs there is also the question of long-term waterproofing. In addition, linear TMDs are usually designed for low-amplitude excitations . Nonlinear friction dampers address some of these drawbacks: they are effective over a relatively wide frequency range and suitable for large-amplitude excitationss. The use of metallic cables under bending is one of the simplest and most robust solutions for a non-linear damper. The physical mechanism involved is related to the friction between the constituent strands of the cable. It is a nonlinear and hysterical phenomenon. Such systems are found in various applications of civil engineering, such as Stockbridge shock absorbers( used in particular on high voltage power lines). A. Trad's thesis [3] also suggests that friction within metal cables contributes significantly to yhe total energy dissipation in block nets. However, designing such non-linear friction dampers poses some difficulties. The Bouc-Wen model is the most commonly used [1]. This model is phenomenological in nature and has the advantage of being relatively simple, but a recent study [2] has shown that it does not allow the accurate reproduction of experimental hysteresis curves, making it risky to identify parameters model. The main objective of the proposed thesis is to establish a model (more adapted than the Bouc-Wen model) to describe the hysterical behaviour of bending cable dampers, based on the physical understanding of the mechanisms involved. The framework of elasto-plasticity with internal variables is a possible avenue. An important issue is to ensure that the model remains simple enough (reduced number of degrees of freedom) to remain easily usable in a design process. Integrating the material model into CESAR is also one of the objectives. In addition to the modelling aspect (theoretical and numerical), the proposed thesis will draw on experimental work conducted at COSYS to guide the development of the model, identify its constituent parameters and validity limits. In order to direct work towards large-scale applications, the monitoring committee would include representatives of CEREMA (interested in Stockbridge shock absorbers) and industrialists involved in the manufacture of block nets (national project C2ROP). Profile sought: engineer or master from a background in mechanics, with skills in digital modeling and interested in experimental mechanics. The doctoral student will be enrolled at Gustave Eiffel University. He will be supervised by Michael Peigney (thesis director, personal page: https://www.ifsttar.fr/menu-haut/annuaire/fiche-personnelle/personne/peigney-michael/), Cyril Douthe (personal page:https://www.ifsttar.fr/menu-high/directory/personal file/person/douthe-cyril/) and Dominique Siegert (personal page: https://www.ifsttar.fr/menu-haut/annuaire/fiche-personnelle/personne/siegert-dominique/).
Keywords :	vibration damping in civil engineering, hysteretic systems

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