Jean-François Ganghoffer

Jean-François Ganghoffer
University of Lorraine | UdL · LEM3 - UMR CNRS 7239. Université de Lorraine

PhD

About

334
Publications
36,958
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4,135
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Introduction
Jean-François Ganghoffer currently works at the LEM3- Laboratoire d'études des Microstructures et de Mécanique des Matériaux, University of Lorraine. Jean-François does research in Mechanical Engineering and Biomechanics. His research activities are devoted to the following topics: - Mechanics of generalized continua - Homogenization towards higher order and higher grade media - Flexoelectricity and applications to bone - Bone Biomechanics
Additional affiliations
September 2000 - July 2020
University of Lorraine
Position
  • Professor (Full)
Description
  • Research topics: - homogenization towards generalized continua - Architected materials - Felxoelectricity and application to bone - Bone biomechanics
Education
October 1988 - September 1992
Ecole des Mines Nancy
Field of study
  • Micromechanics of solid-solid phase transformations

Publications

Publications (334)
Article
The homogenized classical and higher-order mechanical properties of repetitive lattice materials are evaluated using Timoshenko beam models at a microlevel, and a continualization method towards a Cosserat homogenized substitution medium is applied. The proposed method combines a reduced number of degrees of freedom at a unit cell level with the co...
Article
Full-text available
Unlike inactive systems, living biological systems have the advantage of being able to adapt to their environment through growth. Growth is a phenomenon unique to biological tissues, which is mainly driven by accretion processes, whereby new living tissues are added only on the surface of the growing body, due to the action of generating cells. The...
Chapter
Full-text available
In this chapter, we focus our interest on the dynamic analysis of random fibre networks in the frame of generalised continua. The stochastic fibre networks in general and particularly random ones have many applications in the mechanical vibration area because of their submission to different dynamical loading conditions. We begin by developing and...
Article
Full-text available
Effective elastic properties, and mode I elastic fracture toughness of three isotropic planar lattices—hexagonal, kagome, and triangular—are studied from a micropolar continuum perspective. The hexagonal lattice is bending dominated whereas the kagome and the triangular are stretching dominated for any prescribed macroscopic in-plane loading. Discr...
Chapter
We provide in this chapter a synthetic overview of homogenization methods for the setting up of second gradient linear and nonlinear anisotropic continuum media representative of periodic network materials made of beam-type structural elements, considering successively static and dynamic aspects in the context and linear and nonlinear theories. Gen...
Article
Full-text available
The notion of strain gradients provides a reliable model for capturing size effects and localization phenomena. The difficulty in identifying corresponding constitutive parameters, on the other hand, restricts the practical applicability of such theory. In this work, we aim at developing homogenization based strain-gradient continuum models to comp...
Article
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A methodology based on Lie analysis is proposed to investigate the mechanical behavior of materials exhibiting experimental master curves. It is based on the idea that the mechanical response of materials is associated with hidden symmetries reflected in the form of the energy functional and the dissipation potential leading to constitutive laws wr...
Article
The dynamical homogenization of heterogeneous materials is performed in the low and high frequency regimes using a variational formulation of dynamical equilibrium combined with the Laplace or Fourier-Floquet-Bloch decomposition of the mechanical fields (displacement, velocity, momentum, stress). The assumed periodicity of the initial heterogeneous...
Article
The selection of the most-suited bone scaffold for a given clinical application is challenging, and has motivated numerous studies. They are mostly based on the characterization of cellular structures, generated from the three-dimensional repetition of a unit cell. However, the interest of circular graded bone scaffolds has been emphasized since th...
Article
The effective flexoelectric properties of heterogeneous piezoelectric materials are computed in the context of periodic homogenization, whereby a variational formulation is developed, articulated with the extended Hill macro-homogeneity condition. This framework accounts for higher gradient effects that may be induced by a strong contrast of proper...
Article
The present contribution aims to revisit higher-order homogenization schemes towards micromorphic media based on variational principles and an extension of Hill macrohomogeneity condition. Starting from the microscopic Cauchy balance equations, the local balance equations of the micromorphic continuum are formulated, highlighting the micromorphic s...
Article
The effective piezoelectric and flexoelectric properties of heterogeneous solid bodies with constituents obeying a piezoelectric behavior are evaluated in full generality, based on the asymptotic expansion method. The successive situations of materials obeying a piezoelectric and flexoelectric behavior at the macroscale is envisaged in the present...
Article
A homogenization methodology for the construction of effective Cosserat substitution media for heterogeneous materials is proposed, combining a variational principle in linear elasticity with the extended Hill-Mandel lemma accounting for the introduced generalized kinematics. A general methodology is proposed which can be applied to a wide class of...
Article
Full-text available
The thermodynamics of open systems exchanging mass, heat, energy and entropy with their environment is examined as a convenient unifying framework to describe the evolution of growing solid bodies subjected to electromechanical stimulations in the context of volumetric growth. Extending the framework of non-equilibrium thermodynamics to open system...
Article
Constitutive models for bone remodeling are constructed from micromechanical analyses at the scale of a representative volume element (RVE) consisting of individual trabeculae defining the representative unit cell, taking into consideration both first and second order deformation gradients. Trabeculae experience deposition of new bone are modeled b...
Article
We propose in this study a two-dimensional constitutive model for trabecular bone combining continuum damage with embedded strong discontinuity. The model is capable of describing the three failure phases of trabecular bone tissue which is considered herein as a quasi-brittle material with strains and rotations assumed to be small and without visco...
Article
Full-text available
We analyze in this contribution the propagation of bulk and Rayleigh surface waves in periodic architectured materials undergoing internal damage. An elastic damageable continuum-based model is developed in the framework of the thermodynamics of irreversible processes, whereby the displacement experiences a jump across the faces of the propagating...
Article
A methodology for the construction of effective strain gradient media for heterogeneous materials is proposed, combining a variational principle in linear elasticity with the extended Hill lemma accounting for the generalized kinematics in the framework of periodic homogenization. The microscopic displacement field of the heterogeneous continuum is...
Article
The effective piezoelectric properties of heterogeneous materials are evaluated in the context of periodic homogenization, whereby a variational formulation is developed, articulated with the extended Hill macrohomogeneity condition. The entire set of homogenized piezoelectric moduli is obtained as the volumetric averages of the microscopic propert...
Article
A homogenization methodology for the construction of effective Cosserat substitution media for heterogeneous materials is proposed, combining a variational principle in linear elasticity with the extended Hill-Mandel lemma accounting for the introduced generalized kinematics. The proposed method is general and can be applied to a wide class of arch...
Article
Full-text available
The homogenization of viscoelastic composite materials gives rise to long-memory effects, reflected by the presence in the homogenized viscoelastic constitutive law of a delayed stress response expressed as a convolution integral involving the past material strain history. Computations reveal that the long-memory has the ability to delay or even ab...
Chapter
A unifying mechanical constitutive framework for growing solid bodies exhibiting scale effects is presented, relying on the principle of virtual power, and energy, and entropy principles. We focus in this chapter on strain gradient constitutive models and expose different variants of higher gradient theories, adopting a phenomenological viewpoint....
Article
Full-text available
A finite-strain theory for the study of the overall behavior of polymeric gels containing microvoids is presented. The swollen porous polymeric gel is modeled as a two-component body composed of two incompressible materials, namely, an elastic porous polymer imbibed with a solvent. The chemical equilibrium is assumed to be preponderate at the inter...
Chapter
A unifying mechanical constitutive framework for growing solid bodies exhibiting scale effects is presented, relying on the principle of virtual power, and energy, and entropy principles. We focus in this chapter on strain gradient constitutive models and expose different variants of higher gradient theories, adopting a phenomenological viewpoint....
Article
We analyze in this contribution the phase velocities of Rayleigh waves in periodic beam-lattices materials. The effective mechanical properties for the virgin and damaged structures are evaluated. The damaged lattice is modeled by removing beams within full networks made of repetitive unit cells. An evaluation of the phase velocities for the longit...
Article
In the current work, we study the role of chirality and non-centrosymmetry on the nonlinear wave propagation characteristics of periodic architectured media. The considered nonlinearities arise from the higher-order inner element kinematics of the periodic media and are therefore directly related to its structural pattern. Regarding centrosymmetric...
Article
The Hill macrohomogeneity condition is revisited in the context of strain gradient homogenization for heterogeneous materials prone to interfacial displacement jumps. The consideration of strain gradient effects is motivated by their use as a regularization method for strain-softening constitutive damage models leading to strain localization and di...
Article
Full-text available
In the current work, we study the role of higher-order and micro-inertia contributions on the mechanical behavior of composite structures. To that scope, we compute the complete set of the effective static and dynamic properties of composite beam structures using a higher-order dynamic homogenization method which incorporates micro-inertia effects....
Chapter
Full-text available
The influence of surface energy terms on the wave propagation characteristics of network materials is analyzed in this contribution. The asymptotic homogenization technique is extended to account for additional surface properties of network materials made of the periodic repetition of a unit cell consisting of beam type elements. The presence of a...
Article
Full-text available
In the current work, we demonstrate the potential of structures made of chiral artificial materials to balance bending loads through tensile loads, exploiting their inner normal to shear strain coupling. To that scope, we employ beam structures which we architecture with tetrachiral unit-cells. For the latter, we quantify their inherently coupled n...
Article
Full-text available
We discuss a homogenized model of a pantographic bar considering flexoelectricity. A pantographic bar consists of relatively stiff small bars connected by small soft flexoelectric pivots. As a result, an elongation of the bar relates almost to the torsion of pivots. Taking into account their flexoelectric properties we find the corresponding electr...
Article
A methodology for the computation of the homogenized response of stratified piezoelectric materials is proposed. The stratified composite consists of the periodic repetition of piezoelectric layers. Its effective piezoelectric properties are obtained through a homogenization approach based on the method of oscillating functions. The method can full...
Conference Paper
Dans cet article, nous construisons un modèle micropolaire (Cosserat) de membranes biologiques, considérées comme des réseaux aléatoires de filaments élastiques dans le plan, basé sur la méthode des éléments finis. Les propriétés mécaniques effectives calculées reposent sur des approches micromécaniques pour étudier les effets d'échelle liés à la m...
Chapter
The micromechanics of regular fibrous materials is first investigated to evaluate the large strains effective elastic response of repetitive fibrous microstructures at the level of a repetitive unit cell. This is representative for instance of 3D interlocks subjected to complex macroscopic loadings leading to internal stresses; unit cell based anal...
Article
Full-text available
In the current work, we provide a Bernoulli beam-mechanics based code for the computation of the effective static properties of two-dimensional, metamaterial lattice structures. The software makes use of the asymptotic expansion form of the inner kinematic and static variables of the lattice structure, exploiting its spatial periodicity. As such, i...
Book
The book explores the state of the art in the mechanics of fibrous media, providing an overview of the theoretical, modelling and practical aspects of designing and working with these materials. It also describes the advanced methods needed to handle their specific features, including the mechanics of generalized continua, dedicated homogenization...
Article
In the current work, we develop a higher gradient dynamic homogenization method with micro-inertia effects. To that scope, we compute the macroscopic constitutive parameters up to the second gradient, using two distinct approaches, namely the Hamilton's principle and the total internal energy formulation. Thereupon, we analyze the sensitivity of th...
Article
In the current work, we elaborate upon a beam mechanics-based discrete dynamics approach for the computation of the dispersion characteristics of periodic structures. Within that scope, we compute the higher order asymptotic expansion of the forces and moments developed within beam structural elements upon dynamic loads. Thereafter, we employ the o...
Article
The asymptotic homogenization of periodic network materials modeled as beam networks is pursued in this contribution, accounting for surface effects arising from the presence of a thin coating on the surface of the structural beam elements of the network. Cauchy and second gradient effective continua are considered and enhanced by the consideration...
Article
In this paper, a linear size-dependent Timoshenko beam model based on the consistent couple stress theory is developed to capture the size effects. The extended Hamilton's principle is utilized to obtain the governing differential equations and boundary conditions. The general form of boundary conditions and the concentrated loading are employed to...
Article
Full-text available
Constitutive models for bone remodeling are established from micromechanical analyses at the scale of individual trabeculae defining the representative unit cell (RUC), accounting for both first- and second-order deformation gradients. On the microscale, trabeculae undergo apposition of new bone modeled by a surface growth velocity field driven by...
Article
BACKGROUND AND OBJECTIVE: Tendons are hierarchical structures, with a viscoelastic, time-dependent mechanical response upon axial loading. Their mechanical behavior strongly depends on the inner composition and on the material attributes of their subunits. With tens of thousands of damaged tendons each year all over the world, an increasing need fo...
Article
Full-text available
In this paper, we account for the research efforts that have been started, for some among us, already since 2003, and aimed to the design of a class of exotic architectured, optimized (meta) materials. At the first stage of these efforts, as it often happens, the research was based on the results of mathematical investigations. The problem to be so...
Article
Full-text available
The purpose of this paper is to develop a homogeneous, couple-stress continuum model as a representation of 2D random fiber networks in the small deformation regime. The couple-stress substitution continuum is calibrated based on the response of a network model (window of analysis, WOA) subjected to prescribed kinematic boundary conditions applied...
Article
Full-text available
The purpose of this work is to develop anisotropic strain gradient linear elastic continuum models for two-dimensional random fiber networks. The constitutive moduli of the strain gradient equivalent continuum are assessed based on the response of the explicit network representation in so-called windows of analysis, in which each fiber is modeled a...
Conference Paper
Random fiber networks are the structural element of many biological and man-made materials, including connective tissue, various consumer products and packaging materials. In all cases of practical interest the scale at which the material is used and the scale of the fiber diameter or the mean segment length of the network are separated by several...
Chapter
We analyze the dispersion of elastic waves in periodic beam networks based on second order gradient models obtained by the homogenization of the initially discrete network, relying on the discrete asymptotic method extended up to the second gradient of the displacement. The lattice beams have a viscoelastic behavior described by Kelvin-Voigt model...
Poster
Full-text available
L'objectif général de la recherche est de développer des outils d'analyse du comportement mécanique de membranes biologiques, aux échelles microscopiques et mésoscopiques. Le principal constituant des membranes biologiques supportant les contraintes du tissu connectif est le collagène, qui se présente sous forme de fibres. Outre le collagène présen...
Article
Full-text available
In the current work, we investigate the effect of aging on the viscosity of tendon subunits. To that scope, we make use of experimental relaxation curves of healthy and aged tendon fascicles and fibers, upon which we identify the viscosity parameters characterizing the time-dependent behavior of each tendon subunit. We subsequently combine the obta...
Article
Full-text available
Despite several decades of research on biomedical implant materials, the identification of predictive and robust in vitro characteristics of cell support ability and viabilities—as indicators of biocompatibility and future implant‐tissue integration—remain elusive. This study addresses the phenomenology of cell–implant interfaces based on experimen...
Article
Full-text available
Designing biomimetic artificial tendons requires a thorough, data-based understanding of the tendon's inner material properties. The current work exploits viscoelastic experimental observations at the tendon fascicle scale, making use of mechanical and data analysis methods. More specifically, based on reported elastic, volumetric and relaxation fa...
Data
Summary of the MAP values for the datasets D1–D5 of Table 1.
Article
In the current work, we analyse the role of non-slender inner structural designs on the wave propagation characteristics of periodic, two-dimensional architectured materials. In particular, we study the effect of non-negligible inner transverse shear strains on the linear and non-linear dispersion characteristics of different periodic inner materia...
Article
The consideration of nonclassical beam theories beyond Timoshenko beam model is necessary in applications involving complex yarns subjected to transverse compaction, for which the section dilatation and in-plane shear require a detailed kinematic and static modeling. In the present work, new enriched beam elements with additional degrees of freedom...
Article
A mechanobiological model of bone remodeling is developed involving mineralization in a moving diffuse interface separating the marrow containing the bone cells responsible for the remodeling from the newly formed bone. A scalar phase field quantifies the degree of mineralization within the interface at the level of the bone microstructure, varying...
Article
In the present paper, the influence of the loading conditions on the trabecular architecture of a femur is investigated by using the cubic material design and an evolutionary approach based on internal remodeling. The response of bone to mechanical loading stimuli leads to alterations of the internal architecture of bone, traduced by a modification...
Article
Full-text available
The present paper aims at developing a homogenization scheme for the identification of strain-gradient elastic moduli, based on the mathematical approach of homogenization introduced by L. Tartar. We expose in the first part of this paper the needed mathematical apparatus in view of the derivation of the effective first and second gradient mechanic...
Article
Full-text available
The model of volumetric material growth is introduced in theframework of finite elasticity. The new results obtained for themodel are presented with complete proofs. The state variablesinclude the deformations, temperature and the growth factor matrixfunction. The existence of global in time solutions for thequasistatic deformations boundary value...
Article
Full-text available
As a living tissue, bone is subjected to internal evolutions of its trabecular architecture under normal everyday mechanical loadings leading to damage. The repeating bone remodeling cycle aims at repairing the damaged zones in order to maintain bone structural integrity; this activity of sensing the peak stress at locations where damage or microcr...
Article
Full-text available
The present paper aims at introducing a homogenization scheme for the identification of strain–gradient elastic moduli of composite materials, based on the unfolding mathematical method.We expose in the first part of this paper the necessary mathematical apparatus in view of the derivation of the effective first- and second-gradient mechanical prop...
Article
We investigate the capacity of tendons to bear substantial loads by exploiting their hierarchical structure and the viscous nature of their subunits. We model and analyze two successive tendon scales: the fibril and fiber subunits. We present a novel method for bridging intra-scale experimental observations by combining a homogenization analysis te...