Position: Professor at Ensem, Nancy, France.
LEMTA (Laboratory of Energetics and Theoretical and Applied
Mechanics).
Group of Biomechanics and Bioengineering.
Email :
jean-francois.Ganghoffer@ensem.inpl-nancy.fr
Research topics
The main actual research topic is biomechanics
and bioengineering. Activities are
intended to cover a large spectrum of disciplines required in this field
(biology, mechanics of materials, continuum mechanics, applied mathematics, computational
methods) in a pluridisciplinary approach by essence. From a fundamental
viewpoint, sophisticated methods from micromechanics (homogenization methods), Eshelbian
mechanics and continuous symmetries, thermodynamics of irreversible processes or
shape / topology optimization, are currently used and developed. Models for soft
living tissue are elaborated, from the cell level (cell adhesion and motility)
up to tissue level, including the simulation of morphological evolutions such
as surface growth (bones) and volumetric growth (soft tissues). Tissue engineering
is also an important multidisciplinary research activity. The anterior cruciate ligament (ACL) is the most
commonly injured ligament of the knee. Some limitations of current treatment
options, especially in terms of mechanical properties, have prompted a growing
interest in tissue-engineered solutions. A tissue-engineered ACL must fulfil
precise specifications: it has to be biodegradable, biocompatible, porous, very
similar to the native ACL in terms of overall mechanical behaviour, and it must
promote the formation of ligamentous tissue. Our works aim at designing,
simulating and elaborating a new tissue-engineered ACL which best fulfils those
expectations.
1.
Growth of soft and hard biological tissues: volumetric growth models suitable for soft living
tissues and surface growth models appropriate for hard tissues (with a special
emphasis of bone) are currently developed, within the framework of
chemomechanics. In the case of bone growth and remodelling, the proposed
framework involves multiphysical models coupling the kinetics of dissolution of
HA (Hydroxyapatite), the temporal evolution of the superficial density of
minerals, and the determination of the surface growth velocity in relation to
the driving force for growth. Those driving forces are established within the
framework of the irreversible thermodynamics of open systems and under the umbrella
of configurational mechanics; they reflect both the chemical and mechanical
antagonist factors responsible for bone remodelling. The mechanical properties
of bone are predicted from the homogenization of the trabecular architecture,
and surface growth models are currently developed to predict bone internal and
external remodelling. Works in progress aim at modelling the internal
remodelling at the trabecular level.
2. Mechanics
of biological membranes.
Biological membranes are essential constituents of
biological cells, as they play both a protective, chemical (they are
semi-permeable, allowing diffusion of chemical species) and structural role
(mechanical resistance to deformation). Many biological tissues can be
considered from a mechanical point of view as a membrane, i.e., as a sheet-like
structure because of their small thickness from a geometrical viewpoint. Many
bio-membranes present a fibrous structure, with stiff fibers, sometimes with
preferential orientations, embedded in a more compliant matrix. Typical
examples of those tissues include the arterial walls, the amniotic membrane, or
the skin. Biomembranes accordingly display a rich behavior on mesoscopic length
scales, and our goal is to construct micromechanical or statistical models
accounting for the presence of a fibrous structure. Especially, we have
developed discrete homogenization techniques to construct the effective
continuum from the initially discrete structure. FE2 simulations are
currently developed to simulate the shape evolutions of membranes.
3. Conception,
characterization and simulation of substitutes for ligaments and tendons.
The anterior
cruciate ligament (ACL) is the most commonly injured ligament of the knee. Some
limitations of current treatment options, especially in terms of mechanical
properties, have prompted a growing interest in tissue-engineered solutions. A
tissue-engineered ACL must fulfil precise specifications: it has to be
biodegradable, biocompatible, porous, very similar to the native ACL in terms
of overall mechanical behaviour, and it must promote the formation of
ligamentous tissue. Our works aim at designing, simulating and producing a new
tissue-engineered ACL which best fulfils those expectations.
Mechanotransduction is a fundamental aspect to be investigated in the near
future, involving close interactions between appropriate experiments and models
to be developed at the cellular level.
4. Mechanical
models of fibrous media.
Multiscale mechanical
models for fibrous artificial (scaffolds) and biological media (biomembranes) are
developed, starting from the level of the yarn. Such structures are discrete by
nature and show strong couplings and interactions (contact, friction) between
the structural elements (yarns), leading overall to nonlinear behaviours.
Micromechanical techniques are currently developed to construct hyperelastic
anisotropic models from the homogenization of the (discrete) architecture of
the armour for plain weave and fabric built as mono or multilayers.
Recent publications
– ‘Equivalent mechanical
properties of auxetic lattices from discrete homogenization’. F. Dos Reis, J.F.
Ganghoffer. Comput. Mat. Science. 2011, 51,
314-321.
– ‘Equivalent
properties of monolayer fabric from mesoscopic modelling strategies’. M.
Assidi, B. Ben Boubaker, J.F. Ganghoffer. Int. J. Solids Struct., 48,
Issue 20, 1 October 2011,
2920-2930.
– ‘Mechanics and thermodynamics
of surface growth viewed as moving discontinuities’. Mech. Res. Comm., 38, 2011, 372-377.
- ‘Equivalent properties of Biological Membranes from Lattice
Homogenization’. M. Assidi, F.
Dos Reis, J.F. Ganghoffer. Journal of the Mechanical Behavior of Biomedical
Materials. 2011, doi: 10.1016/j.jmbbm.2011.05.040.
– ‘A contribution to the
mechanics and thermodynamics of surface growth. Application to bone external
remodeling’. Int. J. Engng Sci. 2011, doi: 10.1016/j.ijengsci.2011.08.004.
- ‘Eshelby tensors,
thermodynamics and calculus of variations. Application to volumetric growth’.
J.F. Ganghoffer. Int. J. Egng Sci. 48, Issue 12, 2010, 2081-2098.
- ‘Stochastic modelling of the
aggregation of cells during their rolling’. N. Mefti, N. Kabouya, J.F. Ganghoffer.
J. Biomechanics. 43, Issue 2, 2010,
248-253.
- ‘Discrete homogenization of
architectured materials: implementation of the method in a simulation tool for
the systematic prediction of their effective elastic properties’. F. Dos Reis,
J.F. Ganghoffer. Technische Mechanik, 2010. 30, 1-3, 85-109.
- ‘Relevance of symmetry methods
in mechanics of materials’. J.F.
Ganghoffer, V. Magnenet, R. Rahouadj. Int. J. Engng Math. 66, 2010, 103-119.
– ‘Morphological characterization
of a novel scaffold for anterior cruciate ligament tissue engineering’. C. P. Laurent, J.F. Ganghoffer, J. Babin, J.L. Six, X.
Wang, R. Rahouadj. J. Biomechanical Engng, 133,
2011, 065001-1-065001-9.
– ‘Analytical description of the
shapes of the beaded nerve fibers’. M.. Hadzhilazova, J.F.
Ganghoffer, I. Mladenov. Compte Rendu Académie des Sciences Bulgares, Sofia,
August 2010. 66, Issue 1-3, 103-119.
– ‘Mechanical modeling of growth considering domain variation Part II:
volumetric and surface growth involving Eshelby tensors’. J.F. Ganghoffer. J. Mech. Phys.
Solids. 2010. DOI: 10.1016/j.jmps.2010.05.003.
- ‘On the virial theorem and
Eshelby stress’. J.F. Ganghoffer. Int. J. Solids Struct., 2010. 47, No. 9, 1209-1220.
- ‘Continuous
symmetry analysis of a dissipative constitutive law: application to the
time-temperature superposition’.
V. Magnenet, R. Rahouadj, J.F. Ganghoffer, C. Cunat. European Journal of Mechanics - A/Solids, 28, Issue 4, 2009, 744-751.
- ‘Finite element simulation of
interactions between pelvic organs: predictive model of the prostate motion in
the context of radiotherapy’. M. B.
Boubaker, J.-F. Ganghoffer,
M. Haboussi, P. A.. Aletti. J.
Biomechanics. 2009, 25;42(12):1862-1868.
– ‘Consideration of the yarn-yarn interactions in meso/macro discrete model of fabric.
Part I: single yarn behaviour’. B. Ben Boubaker, B. Haussy, J.F. Ganghoffer. Mech. Res. Comm. 34, Issue
4, 2007, 359-370. Part II: Woven fabric under uniaxial and biaxial
extension’. Mech. Res. Comm. 34, Issue
4, 2007, 371-379.