laurent cangemi - Academia.edu (original) (raw)

Papers by laurent cangemi

Structural and Multidisciplinary Optimization, 2020

In various applications, design problems involving structures and compliant mechanisms experience... more In various applications, design problems involving structures and compliant mechanisms experience fluidic pressure loads. During topology optimization of such design problems, these loads adapt their direction and location with the evolution of the design, which poses various challenges. A new density-based topology optimization approach using Darcy's law in conjunction with a drainage term is presented to provide a continuous and consistent treatment of design-dependent fluidic pressure loads. The porosity of each finite element and its drainage term are related to its density variable using a Heaviside function, yielding a smooth transition between the solid and void phases. A design-dependent pressure field is established using Darcy's law and the associated PDE is solved using the finite element method. Further, the obtained pressure field is used to determine the consistent nodal loads. The approach provides a computationally inexpensive evaluation of load sensitivities using the adjoint-variable method. To show the efficacy and robustness of the proposed method, numerical examples related to fluidic pressure loaded stiff structures and small-deformation compliant mechanisms are solved. For the structures, compliance is minimized, whereas for the mechanisms a multi-criteria objective is minimized with given resource constraints.

ISRM International Symposium - EUROCK 2013, 2013

Journal of Polymer Science Part B, Jul 23, 2002

Poly(vinylidene fluoride) (PVDF) was subjected to a creep test performed at constant true stress.... more Poly(vinylidene fluoride) (PVDF) was subjected to a creep test performed at constant true stress. The use of an original method to control and adjust, in real time, the stress allowed the assessment of volume changes occurring during the test. The adaptation of Bucknall's model enabled us to excerpt the component related to microstructural modifications from the whole volume strain. Mechanisms inducing volume strain are temperature dependent. Above Ϫ40°C and below 80°C, that is, in between both glass transitions of PVDF, a linear increase of volume strain was observed as a result of polymer damage via the crazing phenomenon. In addition, this region is characterized by the presence of two distinct domains that could be attributed to either nucleation and propagation of voids or to an increase of the number of potential sites for nucleation resulting from microstructural modifications taking place during the test. On the contrary, above the secondary glass transition, a regular decrease of volume strain was observed. It was assigned to a material densification as a result of molecular orientation of the amorphous chain segments.

HAL (Le Centre pour la Communication Scientifique Directe), Oct 10, 2022

The ambition to develop simulation methods making it possible to predict the integrity or the pro... more The ambition to develop simulation methods making it possible to predict the integrity or the properties of use (mechanical, diffusive, thermal, electromagnetic, vibratory, etc.) of structures (industrial or natural), materials or processes involved in the development of new advanced technologies is growing consistently. In a global context of permanent development of advanced technologies (notably in the field of energy) and a growing need for cost reduction, the development times for new concepts are increasingly reduced and therefore tend to exclude monolithic design of multiphysic structures. Here, we propose an homogenization based topology optimization method to design multi-scale and multiphysic structures experiencing fluid-pressure loads. Its effect is to allow for micro-perforated composite as admissible designs, where the design is characterized by the material density and its homogenized Hooke's law at each point of the working space, yielding composite designs made of fine mixture between the solid and void phases. The fluid-pressure loads is determined using Biot-Darcy's law and solved using the finite element method. This approach permits a computationally low cost of evaluation of of load sensitivities using the Lagrangian method. As no 1 assumption is impose on the number of micro-perforation inside the solid domain, this method can be seen as a topology optimization algorithm. We seek minimizers of the elastic compliances, fluid-elastic compliances and of the weight of a solid structure under fluid-pressure loads.

Optimization and Engineering, Jun 5, 2023

HAL (Le Centre pour la Communication Scientifique Directe), Nov 15, 2022

L'article compare trois modèles conducto-radiatifs distincts (continu/équation du transfert radia... more L'article compare trois modèles conducto-radiatifs distincts (continu/équation du transfert radiatif, continu/Rosseland, discret) qui peuvent être utilisés pour modéliser le transfert de chaleur à haute température au sein de céramiques réfractaires poreuses. Les 3 modèles sont traités dans un solveur basé sur la méthode des éléments finis. Les non-linéarités inhérentes sont, ici, traitées à l'aide d'une méthode de point fixe couplée à une méthode de linéarisation Newton-Raphson. En se basant sur des lois d'homogénéisation semi-empiriques, il apparaît que l'approche continue/équation du transfert radiatif donne des résultats satisfaisants, et cela même lorsque les transferts radiatifs prédominent. Le modèle homogénéisé à échelle continue est, ici, un bon candidat pour être utilisé à l'avenir dans des problèmes d'optimisation topologique des céramiques en conditions d'usage. Mots clés : Transfert conducto-radiatif, céramique poreuse, échelles discrète et continue, éléments finis, calcul parallèle, Newton-Raphson.

Springer eBooks, 1999

This paper is concerned with a continuum thermodynamic and mathematical formulation of an interfa... more This paper is concerned with a continuum thermodynamic and mathematical formulation of an interface law including unilateral contact, adhesion and friction. The model is based on the notion of material boundary associated to the interface and its derivation follows from the principle of virtual power and the principles of thermodynamics (Cangemi et al., 1996 a). Adhesion and friction are strongly coupled and adhesion is characterized by a new variable, the intensity of adhesion β introduced by Premond. We consider a quasistatic unilateral contact problem for which we present a variational formulation. A time discretization is adopted and we prove that if the friction coefficient is sufficiently small then the incremental formulation that can be derived from this discretization has a unique solution. Finally an application to an indentation problem is mentioned.

Journal of Polymer Science Part B, Oct 2, 2002

ABSTRACT Damage to poly(vinylidene fluoride) was studied under uniaxial tension testing at differ... more ABSTRACT Damage to poly(vinylidene fluoride) was studied under uniaxial tension testing at different temperatures and strain rates. A satisfactory accuracy was reached with an original procedure for the assessment of the principal strains and volume strain. The semicrystalline polymer exhibited an increase in the volume strain with the true axial strain caused by material damage. This damage depended on the temperature and strain rate and was related to the whitening phenomenon generally observed. The use of the general ideas of Bucknall's model, based on the decomposition of the whole volume strain into three components, allowed the extraction of the component of the volume strain corresponding to microstructural mechanisms of plastic deformation other than shearing. Therefore, nucleation and growth stages of cavitation were revealed. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 2516–2522, 2002

Rock Mechanics for Resources, Energy and Environment, 2013

Composites Part A: Applied Science and Manufacturing, 2001

An investigation has been made on effects of fibre surface treatments on transverse mechanical be... more An investigation has been made on effects of fibre surface treatments on transverse mechanical behaviour of unidirectional glass/epoxy composites. Model composite plates were processed by filament winding using glass fibres coated with different sizings changing by their epoxy functionality and their reactivity towards the matrix. In the first part of the study, transverse tension and microindentation characterisations were performed in order to correlate the ultimate behaviour of the composite with interfacial properties. Experiments revealed that the most reactive sizings promote the highest interfacial strength and also increase ultimate properties of laminates in transverse tension. This feature was attributed to the high crosslink density of the polymer network in interfacial areas. In the second part, finite element calculations were used to evaluate local strain and stress concentration in a composite submitted to transverse tension conditions. The general trend for the evolution of composite failure strain as a function of interfacial strength has been established. The modelling showed that a transition of the composite failure mode occurs at a global strain of 1.15%, from an adhesive rupture at the fibre/matrix interface to a cohesive rupture in the matrix. In the domain of adhesive rupture, the value of the composite failure strain appeared to be directly governed by the interfacial strength. Therefore, improving interfacial strength by use of fibre sizings with high epoxy functionality could constitute an interesting way to reduce transverse brittleness of composite structures.

Proceeding of Proceedings of the 10th International Symposium on Radiative Transfer, RAD-23 Thessaloniki, Greece, 12–16 June 2023

… Congrès Français de …, 2007

Certaines structures polymères en PVDF utilisées dans l'industrie pétrolière sont soumises à... more Certaines structures polymères en PVDF utilisées dans l'industrie pétrolière sont soumises à de fortes décompressions de CO2, induisant un endommagement sous forme de mousses. Lors d'une décompression, la croissance sous forme de cavités de défauts initiaux dans le ...

Engineering with Computers, 2019

The strong dependent behavior of semi-crystalline polymers can lead to the use of simplified mate... more The strong dependent behavior of semi-crystalline polymers can lead to the use of simplified material laws in Finite Element structural calculations for reasons of robustness to the detriment of the quantitative response of the models. This work focuses on numerical integration methods as a solution to overcome the possible convergence and robustness limitations of mean-stress dependent elastoviscoplastic material laws, typical of the semi-crystalline polymers mechanical behavior. What is proposed here is a rational application of three explicit integration methods (fourth and second order Rung-Kutta method, a hybrid schema between Runge-Kutta and Euler method) in engineering structural calculations, which provide a reliable solution for constitutive models of semi-crystalline polymer. These methods are examined for structure creep test and tensile test, in comparison with experimental data. The investigations have been done in terms of the stability toward convergence, the accuracy of results, the plastic consistency, and CPU time efficiency. This work, proposes an easy implementation of integration methods in any computational Finite Element code. It also provides a flexible modular implementation which is applicable to any different constitutive equations. An integration step subdivision technique is recommended. It is a powerful technique to improve the convergence of solution and accuracy of result by damping oscillation around stress Gauss point integration solution. The results obtained illustrate the effect of numerical integration schemas on structural analysis and provide an insight to select suitable method.

Computational Materials Science, 2019

The raw/processed data required to reproduce these findings cannot be shared at this time as the ... more The raw/processed data required to reproduce these findings cannot be shared at this time as the data also forms part of an ongoing study.   RVE size validation Mesostructures A, B and C should not be compared: used material data are not the same, these results have only been used to check the RVE size. Stiffness matrices (GPa) for several samples of mesostructure type A.

Ce travail repond a une preoccupation petroliere souvent rencontree lors de l'emploi de mater... more Ce travail repond a une preoccupation petroliere souvent rencontree lors de l'emploi de materiaux polymeres au contact de gaz sous pression et en temperature : gaines d'etancheite, revetements detubes ou joints d'etancheite. En effet, les polymeres absorbent les gaz contenus dans les hydrocarbures transportes et ceci en fonction de leur nature chimique, de celle du gaz, et des conditions de temperature et de pression. Une rupture de l'equilibre, telle une chute de pression, entraine une sursaturation du polymere en gaz. Cette sursaturation conduit alors a des gradients de concentration en gaz et de temperature qui peuvent generer des endommagements irreversibles tels que l'apparition de cloques ou de fissures, ou encore la formation d'une microporosite repartie de facon homogene dans le materiau (phenomene de moussage). Ce processus de degradation, appele « cloquage » (« blistering ») ou encore « endommagement par decompression explosive », peut etre veritabl...

SSRN Electronic Journal, 2021

An increasing number of oil and gas fields around the world are coming to the end of their produc... more An increasing number of oil and gas fields around the world are coming to the end of their production lifetime and have been earmarked as potential targets for deploying large-scale carbon capture, utilization and storage (CCUS) operations. Existing oil and gas fields offer several advantages such as availability of existing infrastructure including wells as well as significant prior knowledge about the field through characterization and operational data. Existing wells at these fields could potentially be used as CO 2 injection wells, monitoring wells or production wells for pressure management. Re-using existing oil and gas infrastructure may be particularly crucial for offshore environments where new well development costs could otherwise be prohibitive. Prior to converting the existing oil and gas wells, feasibility of their use as part of a CO 2 storage operation will have to be evaluated while taking into consideration operational and safety requirements. Currently there are no standard approaches available for assessing the potential of converting existing wells for re-use in CCUS operations, and no public tools are available to aid the assessment process. As part of the REX-CO 2 (Re-using EXisting wells for CO 2 storage operations) project funded by the ACT (Accelerating CCS Technologies) program, we have developed a workflow and a well screening tool that will aid in evaluating the feasibility of repurposing existing wells as CO 2 storage site wells. The workflow was informed by applicable standards such as ISO 27914, regulatory requirements such as the US-EPA's Class VI regulation and publicly available information from projects that have performed detailed assessments of using existing oil and gas wells for CO 2 storage, including the Peterhead, Kingsnorth and PORTHOS projects. Our assessment approach and the tool are designed to simultaneously save CO 2 storage projects resources and time by identifying existing infrastructure that is safe to re-use, while determining which wells must be remediated to ensure safe, long-term storage. The functionality of the tool will be evaluated and validated on six case study sites, one in each of the REX-CO 2 project's partner countries (France, the Netherlands, Norway, Romania, the UK, and the USA).