Ifsttar PhD subject

French version
Detailed form :

Title : Contribution to the development of wooden road restraint systems.

Main host Laboratory - Referent Advisor TS2 - LBMC  -  BRIZARD Denis      tél. : +33 472142386

Director of the main host Laboratory MITTON David  -

PhD Speciality mécanique

Axis of the performance contract 1 - COP2017 - Efficient transport and safe travel

Main location Bron

Doctoral affiliation UNIVERSITE CLAUDE-BERNARD-LYON 1

PhD school MEGA (MECANIQUE, ENERGETIQUE, GENIE CIVIL, ACOUSTIQUE)

Planned PhD supervisor RONEL Sylvie  -  Université Gustave Eiffel  -  TS2 - LBMC

Planned financing Contrat doctoral  - Ifsttar

Abstract

Context
The vast majority of road restraint systems is made of galvanized steel. These road restraint systems are designed to prevent a vehicle leaving the road from hitting a sideways obstacle. They are installed on hundreds of kilometres along the roads and highways. Urban devices (such as bodyguards, barriers, anti-intrusion bollards) are also mainly made of metallic material.
In a global context of sustainable development, it is now necessary to take into account the embodied energy (sum of all the energy required to produce the goods [1]) and the greenhouse gases emissions of the construction materials that are used at a large scale. Protection devices along the roads and in the urban environment are therefore concerned by theses ecological considerations.
Wood has a lower environmental impact than steel [2]. It is however scarcely used for road restraint systems. Wood-steel structures exist, in which a wood covering hides an underlying steel barrier. But in these mixed structures, the wood is only here for aesthetics reasons. It would therefore be appropriate to better make use of the properties of the wood in these applications, i.e. in crash mitigation applications.

Objective
The thesis work will consist in studying the viability of the use of wood material in structural and non-aesthetic applications of impact protection for road users.
The first step will be a bibliographic study to make an inventory of the different wood species that would be worth considering for the construction of devices make entirely of partially of wood. It will also be necessary to study the material laws for wood available in the scientific literature. The material law must take into account the strain rate, which is an important parameter in the context of impact mechanics and crash mitigation.
An experimental study will follow, to feed the material laws which are necessary for the design and simulation of these safety devices. Indeed, the material laws integrated in the finite element programs (e.g. LS-DYNA) and dedicated to wood are generic and require adjustments and calibrations [3]. The thesis work will be based on the use of the experimental characterization facilities available in the laboratory : Split Hopkinson Pressure Bars with a diameter of 30mm for the dynamic testing small samples ; block-bar device with a diameter of 80mm for the dynamic testing of larger samples or small structures ; universal testing machine for static tests. It will likely be necessary to conduct tests at various deformation rates (from quasi-static to high strain rate [5]) and at various scales of the wood material.
Furthermore, wood -for a given species- can exhibit an important variability of its properties, be it within the same tree or from one tree to another. It is also subject to various defects (knots, cracks, shakes, etc.). These uncertainties have to be considered and uncertainty propagation will be an important aspect to be considered throughout the thesis, both at the experimental level [6] and in the numerical models developed.

This project is in the continuity of the previous PhD work carried out in the laboratory :
– Clément Goubel [7] has studied the modelling of wood-steel barriers (2012) ;
– Gengjian Qian [8] has applied global sensitivity analysis methods to the simulation of vehicle impacting road restraint systems (2017) ;
– Biswarup Bhattacharyya [9] is developing uncertainty propagation methods which can be applied to impact mechanics (defense scheduled for September 2020).

Ifsttar
This work is part of the scientific strategy of Ifsttar : it can be linked to the research axes 1 (Mobility and safety) and 2 (infrastructure). It is also part of the scientific strategy of Ifsttar on the sustainable arrangement of territories.

Valorization
The results of the work are intended to be published in peer-reviewed international journals. Participation to international or national conferences is also expected.

Candidate profile
Master in mechanics. Impact mechanics knowledge would be a appreciated (numerical simulation or experimental work), as well as knowledge on wood material. Scientific programming experience (Python, Octave, ...). Motivation of the candidate will be an advantage.

Références
[1] Manish K. Dixit. Embodied energy and cost of building materials : correlation analysis. Building Research & Information, 45(5) :508–523, July 2017.
[2] Chihiro Kayo and Ryu Noda. Climate change mitigation potential of wood use in civil engineering in Japan based on life-cycle assessment. Sustainability, 10(2) :561, February 2018.
[3] Y. D. Murray, J. D. Reid, R. K. Faller, B. W. Bielenberg, and T. J. Paulsen. Evaluation of LS-DYNA Wood Material Model 143. Technical Report FHWA-HRT-04-096, August 2005.
[4] E. Jacquelin and P. Hamelin. Block-bar device for energy absorption analysis. Mechanical Systems and Signal Processing, 15(3) :603–617, May 2001.
[5] Tiberiu Polocoşer, Bohumil Kasal, and Frank Stöckel. State-of-the-art : intermediate and high strain rate testing of solid wood. Wood Science and Technology, pages 1–56, June 2017.
[6] D. Brizard, S. Ronel, and E. Jacquelin. Estimating Measurement Uncertainty on Stress-Strain Curves from SHPB. Experimental Mechanics, 57(5) :735–742, June 2017.
[7] C. Goubel, M. Massenzio, and S. Ronel. Wood–steel structure for roadside safety barriers. International Journal of Crashworthiness, 17(1) :63–73, February 2012.
[8] Gengjian Qian. Analyse de sensibilité et robustesse dans le génie industriel - Méthodologies et applications aux essais de chocs. PhD thesis, Université Claude Bernard - Lyon 1, Lyon, France, April 2017.
[9] Biswarup Bhattacharyya, Eric Jacquelin, and Denis Brizard. Uncertainty quantification of nonlinear stochastic dynamic problem using a kriging-narx surrogate model. In Uncertainty Quantification in Computational Sciences and Engineering, page 13, Crete, Greece, June 2019.

Keywords : wood, road restraint system, impact mechanics, material law, uncertainty quantification and propagation, mechanical characterization

Main host Laboratory - Referent Advisor	TS2 - LBMC - BRIZARD Denis tél. : +33 472142386
Director of the main host Laboratory	MITTON David -
PhD Speciality	mécanique
Axis of the performance contract	1 - COP2017 - Efficient transport and safe travel
Main location	Bron
Doctoral affiliation	UNIVERSITE CLAUDE-BERNARD-LYON 1
PhD school	MEGA (MECANIQUE, ENERGETIQUE, GENIE CIVIL, ACOUSTIQUE)
Planned PhD supervisor	RONEL Sylvie - Université Gustave Eiffel - TS2 - LBMC
Planned financing	Contrat doctoral - Ifsttar
Abstract Context The vast majority of road restraint systems is made of galvanized steel. These road restraint systems are designed to prevent a vehicle leaving the road from hitting a sideways obstacle. They are installed on hundreds of kilometres along the roads and highways. Urban devices (such as bodyguards, barriers, anti-intrusion bollards) are also mainly made of metallic material. In a global context of sustainable development, it is now necessary to take into account the embodied energy (sum of all the energy required to produce the goods [1]) and the greenhouse gases emissions of the construction materials that are used at a large scale. Protection devices along the roads and in the urban environment are therefore concerned by theses ecological considerations. Wood has a lower environmental impact than steel [2]. It is however scarcely used for road restraint systems. Wood-steel structures exist, in which a wood covering hides an underlying steel barrier. But in these mixed structures, the wood is only here for aesthetics reasons. It would therefore be appropriate to better make use of the properties of the wood in these applications, i.e. in crash mitigation applications. Objective The thesis work will consist in studying the viability of the use of wood material in structural and non-aesthetic applications of impact protection for road users. The first step will be a bibliographic study to make an inventory of the different wood species that would be worth considering for the construction of devices make entirely of partially of wood. It will also be necessary to study the material laws for wood available in the scientific literature. The material law must take into account the strain rate, which is an important parameter in the context of impact mechanics and crash mitigation. An experimental study will follow, to feed the material laws which are necessary for the design and simulation of these safety devices. Indeed, the material laws integrated in the finite element programs (e.g. LS-DYNA) and dedicated to wood are generic and require adjustments and calibrations [3]. The thesis work will be based on the use of the experimental characterization facilities available in the laboratory : Split Hopkinson Pressure Bars with a diameter of 30mm for the dynamic testing small samples ; block-bar device with a diameter of 80mm for the dynamic testing of larger samples or small structures ; universal testing machine for static tests. It will likely be necessary to conduct tests at various deformation rates (from quasi-static to high strain rate [5]) and at various scales of the wood material. Furthermore, wood -for a given species- can exhibit an important variability of its properties, be it within the same tree or from one tree to another. It is also subject to various defects (knots, cracks, shakes, etc.). These uncertainties have to be considered and uncertainty propagation will be an important aspect to be considered throughout the thesis, both at the experimental level [6] and in the numerical models developed. This project is in the continuity of the previous PhD work carried out in the laboratory : – Clément Goubel [7] has studied the modelling of wood-steel barriers (2012) ; – Gengjian Qian [8] has applied global sensitivity analysis methods to the simulation of vehicle impacting road restraint systems (2017) ; – Biswarup Bhattacharyya [9] is developing uncertainty propagation methods which can be applied to impact mechanics (defense scheduled for September 2020). Ifsttar This work is part of the scientific strategy of Ifsttar : it can be linked to the research axes 1 (Mobility and safety) and 2 (infrastructure). It is also part of the scientific strategy of Ifsttar on the sustainable arrangement of territories. Valorization The results of the work are intended to be published in peer-reviewed international journals. Participation to international or national conferences is also expected. Candidate profile Master in mechanics. Impact mechanics knowledge would be a appreciated (numerical simulation or experimental work), as well as knowledge on wood material. Scientific programming experience (Python, Octave, ...). Motivation of the candidate will be an advantage. Références [1] Manish K. Dixit. Embodied energy and cost of building materials : correlation analysis. Building Research & Information, 45(5) :508–523, July 2017. [2] Chihiro Kayo and Ryu Noda. Climate change mitigation potential of wood use in civil engineering in Japan based on life-cycle assessment. Sustainability, 10(2) :561, February 2018. [3] Y. D. Murray, J. D. Reid, R. K. Faller, B. W. Bielenberg, and T. J. Paulsen. Evaluation of LS-DYNA Wood Material Model 143. Technical Report FHWA-HRT-04-096, August 2005. [4] E. Jacquelin and P. Hamelin. Block-bar device for energy absorption analysis. Mechanical Systems and Signal Processing, 15(3) :603–617, May 2001. [5] Tiberiu Polocoşer, Bohumil Kasal, and Frank Stöckel. State-of-the-art : intermediate and high strain rate testing of solid wood. Wood Science and Technology, pages 1–56, June 2017. [6] D. Brizard, S. Ronel, and E. Jacquelin. Estimating Measurement Uncertainty on Stress-Strain Curves from SHPB. Experimental Mechanics, 57(5) :735–742, June 2017. [7] C. Goubel, M. Massenzio, and S. Ronel. Wood–steel structure for roadside safety barriers. International Journal of Crashworthiness, 17(1) :63–73, February 2012. [8] Gengjian Qian. Analyse de sensibilité et robustesse dans le génie industriel - Méthodologies et applications aux essais de chocs. PhD thesis, Université Claude Bernard - Lyon 1, Lyon, France, April 2017. [9] Biswarup Bhattacharyya, Eric Jacquelin, and Denis Brizard. Uncertainty quantification of nonlinear stochastic dynamic problem using a kriging-narx surrogate model. In Uncertainty Quantification in Computational Sciences and Engineering, page 13, Crete, Greece, June 2019.
Keywords :	wood, road restraint system, impact mechanics, material law, uncertainty quantification and propagation, mechanical characterization

List of topics

Applications closed