Constitutive modeling of crimped collagen fibrils in soft tissues

2009 ◽  
Vol 2 (5) ◽  
pp. 522-533 ◽  
Author(s):  
Rafael Grytz ◽  
Günther Meschke
Keyword(s):  
Constitutive Modeling ◽  
Soft Tissues ◽  
Collagen Fibrils

Constitutive Modeling of Corneal Tissue: Influence of Three-Dimensional Collagen Fiber Microstructure

2020 ◽  
Vol 143 (3) ◽  
Author(s):  
Shuolun Wang ◽  
Hamed Hatami-Marbini
Keyword(s):  
Extracellular Matrix ◽  
Constitutive Modeling ◽  
Mechanical Response ◽  
Thickness Distribution ◽  
Three Dimensional ◽  
Vital Role ◽  
Collagen Fibrils ◽  
Model Parameters ◽  
Corneal Tissue ◽  
Numerical Predictions

Abstract The cornea, the transparent tissue in the front of the eye, along with the sclera, plays a vital role in protecting the inner structures of the eyeball. The precise shape and mechanical strength of this tissue are mostly determined by the unique microstructure of its extracellular matrix. A clear picture of the 3D arrangement of collagen fibrils within the corneal extracellular matrix has recently been obtained from the secondary harmonic generation images. However, this important information about the through-thickness distribution of collagen fibrils was seldom taken into account in the constitutive modeling of the corneal behavior. This work creates a generalized structure tensor (GST) model to investigate the mechanical influence of collagen fibril through-thickness distribution. It then uses numerical simulations of the corneal mechanical response in inflation experiments to assess the efficacy of the proposed model. A parametric study is also done to investigate the influence of model parameters on numerical predictions. Finally, a brief comparison between the performance of this new constitutive model and a recent angular integration (AI) model from the literature is given.

scholarly journals A Data-Driven Learning Method for Constitutive Modeling: Application to Vascular Hyperelastic Soft Tissues

Materials ◽  
2020 ◽  
Vol 13 (10) ◽  
pp. 2319 ◽  
Author(s):  
David González ◽  
Alberto García-González ◽  
Francisco Chinesta ◽  
Elías Cueto
Keyword(s):  
Constitutive Modeling ◽  
Soft Tissues ◽  
Topological Data Analysis ◽  
Basic Principles ◽  
Conservation Of Energy ◽  
Tissue Modeling ◽  
Analysis Techniques ◽  
Large Patient ◽  
True Shape ◽  
Production Of Entropy

We address the problem of machine learning of constitutive laws when large experimental deviations are present. This is particularly important in soft living tissue modeling, for instance, where large patient-dependent data is found. We focus on two aspects that complicate the problem, namely, the presence of an important dispersion in the experimental results and the need for a rigorous compliance to thermodynamic settings. To address these difficulties, we propose to use, respectively, Topological Data Analysis techniques and a regression over the so-called General Equation for the Nonequilibrium Reversible-Irreversible Coupling (GENERIC) formalism (M. Grmela and H. Ch. Oettinger, Dynamics and thermodynamics of complex fluids. I. Development of a general formalism. Phys. Rev. E 56, 6620, 1997). This allows us, on one hand, to unveil the true “shape” of the data and, on the other, to guarantee the fulfillment of basic principles such as the conservation of energy and the production of entropy as a consequence of viscous dissipation. Examples are provided over pseudo-experimental and experimental data that demonstrate the feasibility of the proposed approach.

Cellular Roles in Physiological Root Resorption of Deciduous Teeth in the Cat

1990 ◽  
Vol 69 (1) ◽  
pp. 67-74 ◽  
Author(s):  
T. Sasaki ◽  
T. Shimizu ◽  
C. Watanabe ◽  
Y. Hiyoshi
Keyword(s):  
Soft Tissues ◽  
Root Resorption ◽  
Active Phase ◽  
Mesenchymal Cells ◽  
Collagen Fibrils ◽  
Mononuclear Phagocytes ◽  
Deciduous Teeth ◽  
Clear Zone ◽  
Dentin Surface ◽  
Ruffled Border

This study has attempted to assess the importance of mesenchymal cells, fibroblasts, cementoblasts, and mononuclear phagocytes (i.e., macrophages) in physiological root resorption of feline deciduous teeth. Deciduous incisors of three- to six-month-old kittens undergoing root resorption were investigated by means of electron microscopy. In an early phase of root resorption, the resorption organ consisted of many fibroblasts and relatively few macrophages and odontoclasts, the last with a wide, clear zone and narrow, immature, ruffled border. In the active phase of root resorption, the resorption organ contained many odontoclasts with a well-developed ruffled border and a reduced clear zone, cementoblasts, fibroblasts, macrophages, neutrophils, and many blood vessels. Cementoblasts were present usually on the resorbing dentin surface adjacent to odontoclasts and, in many cases, these cells communicated with each other via gap junctions. Cementoblasts frequently extended broad cell processes with secretion granules and with phagosomes containing collagen fibrils into the dentinal tubules exposed to resorption lacunae. Some macrophages exhibiting a clear zone-like structure also appeared on resorbing dentin surfaces. In the resting phase of root resorption, the dentin surface was covered mostly with cementoblasts resembling bone lining cells. There was an occasional macrophage, but no odontoclasts were observed during this phase. During removal of the periodontal ligament concomitant with root resorption, many fibroblasts phagocytosed mature collagen fibrils, as well as amorphous fluffy material. These results suggest that these mesenchymal cells, as well as odontoclasts, are essential for the cellular removal of dental hard and soft tissues during shedding of feline deciduous teeth.

EFFECTS OF CULTURE PERIODS AND LOADING ON BIOMECHANICAL PROPERTIES OF SHEEP COLLAGEN FASCICLES

2014 ◽  
Vol 14 (06) ◽  
pp. 1440010
Author(s):  
AHMET C. CILINGIR
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Soft Tissues ◽  
Culture Media ◽  
Experimental Studies ◽  
Biomechanical Properties ◽  
Collagen Fibrils ◽  
Tangent Modulus ◽  
Control Group ◽  
Stress Strain

Soft tissues (e.g., tendon, skin, cartilage) change their dimensions and properties in response to applied mechanical stress/strain, which is called remodeling. Experimental studies using tissue cultures were performed to understand the biomechanical properties of collagen fascicles under mechanical loads. Collagen fascicles were dissected from sheep Achilles tendons and loaded under 1, 2, and 3 kg for 2, 4, and 6 days under culture. The mechanical properties of collagen fascicles after being loaded into the culture media were determined using tensile tester, and resultant stress–strain curves, tangent modulus, tensile strength, and strain at failure values were compared with those in a non-loaded and non-cultured control group of fascicles. The tangent modulus and tensile strength of the collagen fascicles increased with the increasing remodeling load after two days of culture. However, these values gradually decreased with the increasing culture period compared with the control group. According to the results obtained in this study, the mechanical properties of collagen fascicles were improved by loading at two days of culture, most likely due to the remodeling of collagen fibers. However, after a period of remodeling, local strains on the collagen fibrils increased, and finally, the collagen fibrils broke down, decreasing the mechanical properties of the tissue.

Constitutive Modeling of Solute Diffusivity in Hydrated Soft Tissues

2004 ◽  
Author(s):  
Wei Yong Gu ◽  
Hai Yao
Keyword(s):  
Electrical Conductivity ◽  
Constitutive Model ◽  
Constitutive Modeling ◽  
Functional Relationship ◽  
Soft Tissues ◽  
Hydraulic Permeability ◽  
Cartilaginous Tissues ◽  
Tissue Constructs ◽  
Solute Diffusivity ◽  
Relative Diffusivity

Based on the experimental results of electrical conductivity and hydraulic permeability, a new constitutive model for relative diffusivity (D/Do) of solutes in gels and tissues was developed. This model could predict the functional relationship between solute diffusivity and tissue deformation. This model could also quantitatively predict the effect of solute size on solute diffusivity in tissues. This study is important for the understanding of nutritional transport in cartilaginous tissues. It is also useful for the prediction of nutrition levels in tissue constructs during growth.

Micromechanics and constitutive modeling of connective soft tissues

2016 ◽  
Vol 60 ◽  
pp. 157-176 ◽  
Author(s):  
A. Fallah ◽  
M.T. Ahmadian ◽  
K. Firozbakhsh ◽  
M.M. Aghdam
Keyword(s):  
Constitutive Modeling ◽  
Soft Tissues

Transversely Isotropic Hyperelastic Constitutive Models for Plastic Thermoforming Simulation

2013 ◽  
Vol 554-557 ◽  
pp. 1715-1728 ◽  
Author(s):  
Zied Oueslati ◽  
Mohamed Rachik ◽  
Marie France Lacrampe
Keyword(s):  
Constitutive Modeling ◽  
Strain Energy ◽  
Soft Tissues ◽  
Measurement Data ◽  
Constitutive Models ◽  
Transversely Isotropic ◽  
Tensile Tests ◽  
Energy Potential ◽  
Transversally Isotropic ◽  
Made In

For several years, modeling hyperelasticity has been focused on and leaded to a large choice of strain energy potential forms. Since then, many advances have been made in constitutive modeling of rubber like materials. These models are nowadays widely used in many applications like constitutive modeling of soft tissues in biomechanics problems or plastic thermoforming simulation. In this work, constitutive modeling of TPO sheets for thermoforming application is considered. Experimental measurements have shown that the material is transversely isotropic. To take into account this anisotropy, we implemented some new transversally isotropic hyperelastic constitutive models in Abaqus software with the help of user subroutines. Furthermore, different particular forms of the strain energy potential are investigated and their hyperelatic constants are fitted to the measurement data from tensile tests performed in different directions. Based on the results of these investigations, a transversely isotropic form of the energy potential derived from the Yeoh constitutive model is adopted and several tests are analyzed for validation purpose. The chosen model is a good compromise that achieves accurate predictions with limited amount of tests and limited identification efforts. Another key finding of this work is the influence of the anisotropy on the thermoformed parts.

Proteoglycan-type I collagen fibril interactions in bone and non-calcifying connective tissues

1985 ◽  
Vol 5 (1) ◽  
pp. 71-81 ◽  
Author(s):  
J. E. Scott ◽  
M. Haigh
Keyword(s):  
Biochemical Analysis ◽  
Type I Collagen ◽  
Soft Tissues ◽  
Chondroitin Sulphate ◽  
Specific Binding ◽  
Uranyl Acetate ◽  
Collagen Fibrils ◽  
Type I ◽  
Connective Tissues ◽  
Oriented Parallel

The association of proteogtycans with type I collagen fibrils in skin, tendon, cornea and bone has been determined by electron microscopy using an electrondense dye, Cupromeronic blue, in the critical electrolyte concentration mode, backed up by biochemical analysis and digestion by hyaluronidase or keratanase. A major proteoglycan of the soft tissues, containing dermatan sulphat, is shown to be regularly and orthogonally arranged at the surface of the fibrils. Uranyl acetate counterstaining revealed that the main specific binding site is the ‘d’ band, which previous work indicated is very close to the initial site of calcification of type I collagen fibrils. Bone, deminer-alized by a ‘non-aqueous’ technique which preserves the proteoglycan in the tissue does not contain orthogonal arrays; the interfibrillar proteoglycan filaments are oriented parallel to the fibril axis. The main proteoglycan in bone is chondroitin sulphate-rich. It is suggested that dermatan sulphate proteoglycan plays a role in preventing soft connective tissues from calcifying.

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