Georges Limbert

Georges Limbert
University of Southampton · Faculty of Engineering and Physical Sciences

Doctor of Engineering

About

78
Publications
18,543
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
1,773
Citations
Introduction
Tissue biophysics, constitutive modelling, finite element methods, biotribology, skin

Publications

Publications (78)
Preprint
Full-text available
Objectives: A method for controlling the thermal stimulation in skin photorejuvenation is designed, modelled and evaluated. The method has the ability to precisely administer the thermal dose while controlling the tissue temperature under safe limit. Methods: A model-based treatment controller is developed and assessed on a three-dimensional biophy...
Article
Full-text available
Immersed boundary methods are extensively used for simulations of dynamic solid objects interacting with fluids due to their computational efficiency and modelling flexibility compared to body-fitted grid methods. However, thin geometries, such as shells and membranes, cause a violation of the boundary conditions across the surface for many immerse...
Article
Full-text available
This paper presents the development of a 3D physics-based numerical model of skin capable of representing the laser–skin photo-thermal interactions occurring in skin photorejuvenation treatment procedures. The aim of this model was to provide a rational and quantitative basis to control and predict temperature distribution within the layered struct...
Preprint
Full-text available
Immersed boundary methods are extensively used for simulations of dynamic solid objects interacting with fluids due to their computational efficiency and modelling flexibility compared to body-fitted grid methods. However, thin geometries, such as shells and membranes, cause a violation of the boundary conditions across the surface for many immerse...
Article
There has been increasing experimental evidence of non-affine elastic deformation mechanisms in biological soft tissues. These observations call for novel constitutive models which are able to describe the dominant underlying micro-structural kinematic aspects, in particular relative motion characteristics of different phases. This paper proposes a...
Preprint
Full-text available
There has been increasing experimental evidence of non-affine elastic deformation mechanisms in biological soft tissues. These observations call for novel constitutive models which are able to describe the dominant underlying micro-structural kinematics aspects, in particular relative motion characteristics of different phases. This paper proposes...
Article
Cobalt-chromium alloys are used in reciprocated sliding wear applications where the mated surfaces cannot be lubricated, due to their excellent frictional properties and ability to resist seizure. However, various health risks due to cobalt wear particle generation motivate the replacement of cobalt-based systems. It is suggested that a numerical m...
Preprint
Full-text available
This study aimed at developing a formulation to link microscopic structure and macroscopic mechanics of a fibrous scaffold filled with a hydrogel for use as a tissue-engineered patch for local epicardial support of the infarcted heart. Mori-Tanaka mean field homogenisation, closed-cell foam mechanics and finite element (FE) methods were used to rep...
Article
PurposeThe lack of long-term patency of synthetic vascular grafts currently available on the market has directed research towards improving the performance of small diameter grafts. Improved radial compliance matching and tissue ingrowth into the graft scaffold are amongst the main goals for an ideal vascular graft.Methods Biostable polyurethane sc...
Article
Full-text available
Consistent mechanical performance from implantation through healing and scaffold degradation is highly desired for tissue-regenerative scaffolds, e.g. when used for vascular grafts. The aim of this study was the paired in vivo mechanical assessment of biostable and fast degrading electrospun polyester-urethane scaffolds to isolate the effects of ma...
Preprint
Consistent mechanical performance from implantation through healing and scaffold degradation is highly desired for tissue-regenerative scaffolds, e.g. when used for vascular grafts. The aim of this study was the paired in vivo mechanical assessment of biostable and fast degrading electrospun polyester-urethane scaffolds to isolate the effects of ma...
Preprint
Full-text available
Purpose The lack of long-term patency of synthetic vascular grafts currently available on the market has directed research towards improving the performance of small diameter grafts. Improved radial compliance matching and tissue ingrowth into the graft scaffold are amongst the main goals for an ideal vascular graft. Methods Biostable polyurethane...
Chapter
The objective of this chapter is to review the main biomechanical and structural aspects associated with both intrinsic and extrinsic skin ageing, and to present potential research avenues to account for these effects in mathematical and computational models of the skin. This will be illustrated through recent work of the authors which provides a b...
Chapter
The objective of this chapter is to provide a structured review of constitutive models of skin mechanics valid for finite deformations, with special emphasis on state-of-the-art anisotropic formulations which are essential in most advanced modelling applications. The fundamental structural and material characteristics of the skin, necessary for und...
Book
This book presents state-of-the-art experimental and modelling techniques for skin biophysics that are currently used in academic and industrial research. It also identifies current and future challenges, as well as a growing number of opportunities in this exciting research field. The book covers the basics of skin physiology, biology, microstruct...
Article
p>Cobalt-chromium alloys find usage in environments where reliable wear and friction properties are required. However, the sliding wear particles generated presents significant health risks in nuclear and medical applications. Thus, there is great motivation to develop cobalt-free alternatives. These alloys are known to undergo several physical cha...
Article
The measurement of the mechanical properties of skin (such as stiffness, extensibility and strength) is a key step in characterisation of both dermal ageing and disease mechanisms and in the assessment of tissue engineered skin replacements. However, the biomechanical terminology and plethora of mathematical analysis approaches can be daunting to t...
Article
The quest for efficient anti-wrinkle treatments has mainly focused on biochemical approaches aiming to mitigate or slow down the effects of both intrinsic and extrinsic ageing. However, the biophysical principles that govern the formation and evolution of wrinkles remain to be elucidated. Georges Limbert shares the findings of a study his computati...
Article
Full-text available
This review summarizes recent advances in the area of tribology based on the outcome of a Lorentz Center workshop surveying various physical, chemical and mechanical phenomena across scales. Among the main themes discussed were those of rough surface representations, the breakdown of continuum theories at the nano- and micro-scales, as well as mult...
Article
A multiphasic constitutive model of the skin that implicitly accounts for the process of intrinsic (i.e. chronological) ageing via variation of the constitutive parameters is proposed. The structurally-motivated constitutive formulation features distinct mechanical contributions from collagen and elastin fibres. The central hypothesis underpinning...
Article
Over the course of a life time, as a result of adaptive mechanobiological processes (e.g. ageing), or the action of external physical factors such as mechanical loading, the human skin is subjected to, and hosts complex biophysical processes. These phenomena typically operate through a complex interplay, that, ultimately, is responsible for the evo...
Article
Full-text available
The role of contact pressure on skin friction has been documented in multiple experimental studies. Skin friction significantly raises in the low-pressure regime as load increases while, after a critical pressure value is reached, the coefficient of friction of skin against an external surface becomes mostly insensitive to contact pressure. However...
Article
Full-text available
The original version of this article unfortunately contained a mistake. The presentation of Eq. (6) was incorrect in the original version of this article. The denominator corresponding to the described κ0 contains the coefficient “4” that should be “6”.
Article
A multiphasic constitutive model of the skin capturing the process of intrinsic (i.e. chronological) ageing is proposed. The structurally-motivated constitutive formulation features distinct mechanical contributions from collagen and elastin fibres. The central hypothesis underpinning this study is that the effects of ageing on the mechanical prope...
Article
The objective of this paper is to provide a review on some aspects of the mathematical and computational modelling of skin biophysics, with special focus on constitutive theories based on nonlinear continuum mechanics from elasticity, through anelasticity, including growth, to thermoelasticity. Microstructural and phenomenological approaches combin...
Article
Bone is a heterogeneous material and its mechanical properties vary within the body. Variations in the mechanical response of different bone samples taken from the body cannot be fully explained by only looking at local compositional information at the tissue level. Due to different states of the stress within bones, one might expect that mechanica...
Article
Full-text available
Due to its multifactorial nature, skin friction remains a multiphysics and multiscale phenomenon poorly understood despite its relevance for many biomedical and engineering applications (from superficial pressure ulcers, through shaving and cosmetics, to automotive safety and sports equipment). For example, it is unclear whether, and in which measu...
Article
Full-text available
The modelling and computation of the coupled thermal and mechanical response of human skin at finite deformations is considered. The model extends current thermal models to account for thermally-and mechanically-induced deformations. Details of the solution of the highly nonlin-ear system of governing equations using the finite element method are p...
Article
Electro-spun biodegradable polymer fibrous structures exhibit anisotropic mechanical properties dependent on the degree of fibre alignment. Degradation and mechanical anisotropy need to be captured in a constitutive formulation when computational modelling is used in the development and design optimisation of such scaffolds. Biodegradable polyester...
Article
Global and local effects of interface structures in the biomechanics of Haversian bone are elucidated by forming experimental based finite element (FE) models of the bone tissue. Geometry of microstructural features in the bone was extracted by polishing and optical microscopy from the surface of each specimen. These measurements were then incorpor...
Chapter
This chapter provides a review of what are considered state-of-the-art of constitutive models used to describe and predict the biomechanics of skin. The focus is on the mathematical constitutive formulations which, ultimately, have also to be implemented into computational codes so that practical problems featuring complex geometries and boundary c...
Article
Considerable progress has been made in understanding implant wear and developing numerical models to predict wear for new orthopaedic devices. However any model of wear could be improved through a more accurate representation of the biomaterial mechanics, including time-varying dynamic and inelastic behaviour such as viscosity and plastic deformati...
Article
Formulae are derived from first principles which predict the wear depth of a ball and a flat surface through time as they slide against each other, in relation to any phenomenological law for wear volume, and taking into account the effect of component geometry. The equations can be fit using experimental wear volume data from ball-on-flat tribomet...
Article
Bone is multi-scale hierarchical composite material making the prediction of fragility, as well as pinning it to a certain cause, complicated. For proper mechanical simulation and reflection of bone properties in models, microscopic structural features of bone tissue need to be included. This study sets out to gain a mechanistic insight into the ro...
Article
Diamond-like carbon (DLC) coatings are known to provide beneficial mechanical and tribological properties in harsh environments. Their combination of high wear resistance and low friction has led to their extensive use in any number of industries. The tribological performance of a DLC coating is varied however, and the frictional response is known...
Article
Three commercially available Diamond-Like Carbon (DLC) coatings were investigated to help understand the dynamics of transfer layer formation and decay, when sliding against AISI 52100 steel balls in distilled water. Optimum tribological behaviour was observed during interfacial sliding between the transfer layer and DLC coating. Alternatively, she...
Article
Biofilms are bacterial communities encapsulated within a self-secreted extra-cellular polymeric substance and are responsible for a wide range of chronic medical device related infections. Understanding and addressing the conditions that lead to the attachment and detachment of biofilms from biomedical surfaces (orthopaedic implants, sutures, intra...
Article
We present here a multi-objective and multi-disciplinary coronary stent design optimization paradigm. Coronary stents are tubular, often mesh-like, structures which are deployed in diseased (stenosed) artery segments to provide a scaffolding feature that compresses atheromatus plaque, hence restoring luminal area and maintaining vessel patency. A t...
Article
Characterising and modelling the mechanical behaviour of biological soft tissues is an essential step in the development of predictive computational models to assist research for a wide range of applications in medicine, biology, tissue engineering, pharmaceutics, consumer goods, cosmetics, transport or military. It is therefore critical to develop...
Article
Full-text available
Coronary stents are tubular type scaffolds that are deployed, using an inflatable balloon on a catheter, most commonly to recover the lumen size of narrowed (diseased) arterial segments. A common differentiating factor between the numerous stents used in clinical practice today is their geometric design. An ideal stent should have high radial stren...
Article
The first objective of this computational study was to assess the strain magnitude and distribution within the three-dimensional (3D) trabecular bone structure around an osseointegrated dental implant loaded axially. The second objective was to investigate the relative micromotions between the implant and the surrounding bone. The work hypothesis a...
Article
This study is devoted to the development of a non-linear anisotropic model for the human periodontal ligament (PDL). A thorough knowledge of the behaviour of the PDL is vital in understanding the mechanics of orthodontic tooth mobility, soft tissue response and proposed treatment plans. There is considerable evidence that the deformation of the PDL...
Article
Further to our previous work on the development of a general constitutive framework for transversely isotropic viscohyperelasticity (Limbert, G, Middleton, J. A transversely isotropic viscohyperelastic material. Application to the modelling of biological soft connective tissues. Int J Solids Struct 2004;41(15):4237-60.), we propose a phenomenologic...
Chapter
A structurally motivated phenomenological constitutive law to describe the anisotropic viscous hyperelastic behaviour of the human posterior cruciate ligament (PCL) at high strain rate is proposed. The mechanical formulation is based on the definition of a Helmholtz free energy function containing a hyperelastic and a viscous potentials which depen...
Article
In this study, a three-dimensional finite element model of the human anterior cruciate ligament (ACL) was developed and simulations of passive knee flexion were performed. The geometrical model of the ACL was built from experimental measurements performed on a cadaveric knee specimen which was also subjected to kinematics tests. These experiments w...
Article
A general transversely isotropic viscohyperelastic constitutive law including strain rate effects was proposed. It is based on a definition of a general Helmholtz free energy function which depends explicitly on the right Cauchy–Green deformation tensor, its material time derivative and a structural tensor characterizing the preferred direction fro...
Article
In this study, a constitutive law based on a nearly incompressible transversely isotropic hyperelastic potential is proposed to describe the mechanical behaviour of the anterior cruciate ligament (ACL). The constitutive formulation is valid for arbitrary kinematics (finite elasticity) and is thermodynamically admissible. Based on anatomic measureme...
Article
Current materials used for maxillofacial prostheses are far from ideal and there is a need for new improved materials which better simulate the tissues they are replacing. This study was based on a mixed experimental/analytical/numerical approach. A new polymeric material was developed to provide a better alternative to the materials currently used...
Chapter
This chapter introduces a new constitutive model of the periodontal ligament. It is based on the definition of a compressible transversely isotropic hyper elastic free energy function satisfying essential constitutive requirements. The material is assumed to be a continuum fiber-reinforced composite operating at the finite strain regime. The consti...
Article
The aim of this work was to improve the constitutive model of the human mandible and dentition system by taking into account the non-linear material properties of the structural boney matrix that forms the human jaw bone or mandible. Due to the specific structure of the jaw bone the time dependence of the mechanical properties also forms an importa...
Article
This study describes the development of a constitutive law for the modelling of the periodontal ligament (PDL) and its practical implementation into a commercial finite element code. The constitutive equations encompass the essential mechanical features of this biological soft tissue: non-linear behaviour, large deformations, anisotropy, distinct b...
Article
This research describes a general theoretical framework for the constitutive modeling of biological soft connective tissues. The approach is based on the theory of continuum fiber-reinforced composites at finite strain. Explicit expressions of the stress tensors in the material and spatial configurations are first established in the general case, w...
Article
This research describes a general theoretical framework for the constitutive modeling of biological soft connective tissues. The approach is based on the theory of continuum fiber-reinforced composites at finite strain. Explicit expressions of the stress tensors in the material and spatial configurations are first established in the general case, w...
Article
OBJECTIVE: The study presents a method allowing the in vivo homogenised characteristics of the tibiae of children to be assessed. DESIGN: Studies have been performed on two groups of children: six normal children, aged from 5 to 16 yr, and on four children, aged from 8 to 11 yr with tibial deformities. We analysed the tibial transverse sections fro...

Network

Cited By