Comparison of biphasic material properties of equine articular cartilage estimated from stress relaxation and creep indentation tests

2021 ◽  
Vol 7 (2) ◽  
pp. 363-366
Author(s):  
Thomas Reuter ◽  
Christof Hurschler
Keyword(s):  
Articular Cartilage ◽  
Stress Relaxation ◽  
Material Properties ◽  
Soft Tissues ◽  
Sensitivity Analyses ◽  
Creep Model ◽  
Fe Model ◽  
Relaxation Model ◽  
Marquardt Algorithm ◽  
Indentation Tests

Abstract Mechanical parameters of hard and soft tissues are explicit markers for quantitative tissue characterization. In this study, we present a comparison of biphasic material properties of equine articular cartilage estimated from stress relaxation (ε = 6 %, t = 1000 s) and creep indentation tests (F = 0.1 N, t = 1000 s). A biphasic 3D-FE-based method is used to determine the biomechanical properties of equine articular cartilage. The FE-model computation was optimized by exploiting the axial symmetry and mesh resolution. Parameter identification was executed with the Levenberg- Marquardt-algorithm. Additionally, sensitivity analyses of the calculated biomechanical parameters were performed. Results show that the Young’s modulus E has the largest influence and the Poisson’s ratio of ν ≤ 0.1 is rather insensitive. The R² of the fit results varies between 0.882 and 0.974 (creep model) and between 0.695 and 0.930 (relaxation model). The averaged parameters E and k determined from the creep model yield higher values in comparison to the relaxation model. The differences can be traced back to the experimental settings and to the biphasic material model.

scholarly journals Comparison of biphasic material properties of equine articular cartilage from stress relaxation indentation tests with and without tension-compression nonlinearity

2018 ◽  
Vol 4 (1) ◽  
pp. 485-488
Author(s):  
Thomas Reuter ◽  
Christof Hurschler
Keyword(s):  
Articular Cartilage ◽  
Stress Relaxation ◽  
Material Properties ◽  
Collagen Matrix ◽  
Biomechanical Properties ◽  
Resolution Parameter ◽  
Marquardt Algorithm ◽  
Mesh Resolution ◽  
Indentation Tests ◽  
Order Of Magnitude

AbstractThe mechanical parameters of articular cartilage estimated from indentation tests depend on the constitutive model adopted to analyze the data. In this study, we present a 3D-FE-based method to determine the biomechanical properties of equine articular cartilage from stress relaxation indentation tests (ε = 6 %, t = 1000 s) whereby articular cartilage is modeled as a biphasic material without (BM) and with tension-compression nonlinearity (BMTCN). The FEmodel computation was optimized by exploiting the axial symmetry and mesh resolution. Parameter identification was executed with the Levenberg-Marquardt-algorithm. The R² of the fit results varies between 0.695 and 0.930 for the BMmodel and between 0.877 and 0.958 for the BMTCN-model. The differences of the R² occur from the more exact description of the initial stress relaxation behaviour by the fiber modulus from the BMTCN-model. The fiber modulus defines the collagen matrix of cartilage. Furthermore, for both models the determined values of Young’s modulus and permeability were in the same order of magnitude.

scholarly journals Biphasic parameter identification of equine articular cartilage from creep indentation data using an optimized 3D FE-based method

2018 ◽  
Vol 4 (1) ◽  
pp. 481-484
Author(s):  
Thomas Reuter ◽  
Christof Hurschler
Keyword(s):  
Articular Cartilage ◽  
Parameter Identification ◽  
Young’S Modulus ◽  
Poisson’S Ratio ◽  
Soft Tissues ◽  
Young's Modulus ◽  
Poisson's Ratio ◽  
Sensitivity Analyses ◽  
Fe Model ◽  
Marquardt Algorithm

AbstractMechanical parameters of hard and soft tissues are explicit markers for quantitative tissue characterization. In this study, we present a biphasic 3D-FE-based method to determine the biomechanical properties of equine articular cartilage from creep indentation tests (F = 0.1 N, t = 1000 s). The FE-model computation was optimized by exploiting the axial symmetry and mesh resolution. Parameter identification was executed with the Levenberg-Marquardt-algorithm. Additionally, sensitivity analyses of the calculated biomechanical parameters were performed. Results show that the Young’s modulus has the largest influence and the Poisson’s ratio of ν ≤ 0.1 is rather insensitive. The R² of the fit results varies between 0.882 and 0.974. The determined values for the Young’s modulus were 0.806 ± 0.093 MPa, the Poisson’s ratio 0.03 ± 0.06 and the permeability 0.012 ± 0.002 mm4/Ns. Future work will deal with mathematical extensions of the biphasic 3D-FE-model.

scholarly journals Biphasic parameter identification of 3D scaffold-free cartilage transplants (SFCT) from stress relaxation compression tests using an optimized 3D FE-based method with tension-compression nonlinearity

2021 ◽  
Vol 7 (2) ◽  
pp. 355-358
Author(s):  
Thomas Reuter ◽  
Igor Ponomarev
Keyword(s):  
Articular Cartilage ◽  
Stress Relaxation ◽  
Tissue Characterization ◽  
Soft Tissues ◽  
Biomechanical Properties ◽  
Cartilage Defects ◽  
Fe Model ◽  
Compression Tests ◽  
3D Scaffold ◽  
Mesh Resolution

Abstract Cartilage constructs produced by SFCTtechnology provide promising opportunities to restore cartilage defects. Mechanical parameters of soft tissues are explicit markers for quantitative tissue characterization. In this study, we present a biphasic 3D-FE-based method to determine the biomechanical properties of SFCT from stress relaxation compression tests (ε = 20 %, t = 3400 s) whereby cartilaginous tissue is modeled as a biphasic material with tension-compression nonlinearity (BMTCN). The FE-model computation was optimized by exploiting the axial symmetry and mesh resolution. The R² of the fit results varies between 0.970 and 0.983. The Young’s and fiber modulus determined from SFCT are 37-times and 5-times lower than from native articular cartilage, respectively. Permeability, on the other hand, is 11-times higher than from native articular cartilage.

Removal of Sulfated Glycosaminoglycans Has a Differential Effect on Permeability of Bovine Articular Cartilage as Measured by Direct Permeation and Stress Relaxation

2009 ◽  
Author(s):  
Heath B. Henninger ◽  
Clayton J. Underwood ◽  
Gerard A. Ateshian ◽  
Jeffrey A. Weiss
Keyword(s):  
Articular Cartilage ◽  
Stress Relaxation ◽  
Soft Tissues ◽  
Water Movement ◽  
Experimental Treatment ◽  
Test Methods ◽  
Confined Compression ◽  
Interstitial Fluid Flow ◽  
Bovine Articular Cartilage ◽  
The Impact

Permeability is defined as the ability of a fluid to pass through a porous medium. The ease of water movement is a determinant of the interstitial fluid flow-dependent viscoelastic properties of hydrated soft tissues and also modulates transport of solutes. For articular cartilage, permeability has been quantified directly via permeation experiments and indirectly by analyzing the data from stress relaxation testing under confined compression. It is unclear whether these different methods result in consistent measurements. This further complicates quantification of the effect of an experimental treatment on permeability such as the removal of sulfated glycosaminoglycans (GAGs) [1, 2]. The objective of this study was to elucidate the impact of sulfated GAGs on the permeability of articular cartilage using direct permeation versus stress relaxation testing, and to assess any differences in permeability calculated from the two test methods.

scholarly journals In Situ Microindentation for Determining Local Subchondral Bone Compressive Modulus

2010 ◽  
Vol 132 (9) ◽  
Author(s):  
Mack G. Gardner-Morse ◽  
Nelson J. Tacy ◽  
Bruce D. Beynnon ◽  
Maria L. Roemhildt
Keyword(s):  
Articular Cartilage ◽  
Subchondral Bone ◽  
Reference Values ◽  
Material Properties ◽  
Indentation Test ◽  
Lateral Compartment ◽  
Polyurethane Foams ◽  
Compressive Modulus ◽  
Sprague Dawley ◽  
Indentation Tests

Alterations to joint tissues, including subchondral bone, occur with osteoarthritis. A microindentation technique was developed to determine the local compressive modulus of subchondral bone. This test, in conjunction with a cartilage indentation test at the same location, could evaluate changes of these material properties in both tissues. The accuracy of the technique was determined by applying it to materials of known moduli. The technique was then applied to rat tibial plateaus to characterize the local moduli of the subchondral bone. An established nanoindentation method was adopted to determine the modulus of subchondral bone following penetration of the overlying articular cartilage. Three cycles of repeated loadings were applied (2.452 N, 30 s hold). The slope of the load-displacement response during the unloading portion of the third cycle was used to measure the stiffness. Indentation tests were performed on two polyurethane foams and polymethyl-methacrylate for validation (n=15). Regression analysis was used to compare the moduli with reference values. Subchondral bone moduli of tibial plateaus from Sprague-Dawley rats (n=5) were measured for central and posterior locations of medial and lateral compartments. An analysis of variance was used to analyze the effects of compartment and test location. The measured moduli of the validation materials correlated with the reference values (R2=0.993, p=0.05). In rat tibial plateaus, the modulus of the posterior location was significantly greater than the center location (4.03±1.00 GPa and 3.35±1.16 GPa respectively, p=0.03). The medial compartment was not different from the lateral compartment. This method for measuring the subchondral bone in the same location as articular cartilage allows studies of the changes in these material properties with the onset and progression of osteoarthritis.

Validation Studies for the Dual Optimization of Indentation Creep and Stress Relaxation of Biological Soft Tissues Using Biphasic Poroviscoelasticity: Potential Method for Brain Tissue

2004 ◽  
Author(s):  
Joseph E. Olberding ◽  
Jun-Kyo Francis Suh
Keyword(s):  
Stress Relaxation ◽  
Brain Tissue ◽  
Material Properties ◽  
Computational Models ◽  
Soft Tissues ◽  
Optimization Technique ◽  
Biomechanical Testing ◽  
Potential Method ◽  
Indentation Creep ◽  
Creep And Stress Relaxation

Traumatic brain injury (TBI) is highly fatal and has profound physical and psychological repercussions for survivors. Knowledge of the precise material properties of brain tissue is crucial in developing holistic computational models to predict and prevent TBI. Despite the recent proliferation of material models of brain tissue, none have utilized porous media theory to explicitly include the significant fluid component of the hydrated soft tissue. Furthermore, the delicate composition of brain tissue limits the number of suitable biomechanical testing methodologies. In order to incorporate these considerations, in situ indentation creep and stress relaxation tests and linear biphasic poroviscoelasticity (BPVE) [1] were proposed to characterize the material properties of cerebral brain tissue. The objective of the present study was to evaluate these experimental and computational protocols in which the data from indentation creep and stress relaxation tests were simultaneously curve-fitted using a dual-optimization technique to determine the material parameters of the linear BPVE model.

On the Effects of Residual Stress in Microindentation Tests of Soft Tissue Structures

2004 ◽  
Vol 126 (2) ◽  
pp. 276-283 ◽  
Author(s):  
Evan A. Zamir ◽  
Larry A. Taber
Keyword(s):  
Residual Stress ◽  
Soft Tissue ◽  
Elastic Foundation ◽  
Elastic Properties ◽  
Material Properties ◽  
Soft Tissues ◽  
Elastic Half Space ◽  
Fe Model ◽  
Linear Elastic ◽  
Tissue Structures

Microindentation methods are commonly used to determine material properties of soft tissues at the cell or even sub-cellular level. In determining properties from force-displacement (FD) data, it is often assumed that the tissue is initially a stress-free, homogeneous, linear elastic half-space. Residual stress, however, can strongly influence such results. In this paper, we present a new microindentation method for determining both elastic properties and residual stress in soft tissues that, to a first approximation, can be regarded as a pre-stressed layer embedded in or adhered to an underlying relatively soft, elastic foundation. The effects of residual stress are shown using two linear elastic models that approximate specific biological structures. The first model is an axially loaded beam on a relatively soft, elastic foundation (i.e., stress-fiber embedded in cytoplasm), while the second is a radially loaded plate on a foundation (e.g., cell membrane or epithelium). To illustrate our method, we use a nonlinear finite element (FE) model and experimental FD and surface contour data to find elastic properties and residual stress in the early embryonic chick heart, which, in the region near the indenter tip, is approximated as an isotropic circular plate under tension on a foundation. It is shown that the deformation of the surface in a microindentation test can be used along with FD data to estimate material properties, as well as residual stress, in soft tissue structures that can be regarded as a plate under tension on an elastic foundation. This method may not be as useful, however, for structures that behave as a beam on a foundation.

A Biphasic Transversely Isotropic Poroviscoelastic Model for the Unconfined Compression of Hydrated Soft Tissue

2016 ◽  
Vol 138 (3) ◽  
Author(s):  
H. Hatami-Marbini ◽  
R. Maulik
Keyword(s):  
Articular Cartilage ◽  
Soft Tissue ◽  
Stress Relaxation ◽  
Soft Tissues ◽  
Transverse Isotropy ◽  
Viscoelastic Model ◽  
Transversely Isotropic ◽  
Solid Matrix ◽  
Unconfined Compression ◽  
Material Parameters

The unconfined compression experiments are commonly used for characterizing the mechanical behavior of hydrated soft tissues such as articular cartilage. Several analytical constitutive models have been proposed over the years to analyze the unconfined compression experimental data and subsequently estimate the material parameters. Nevertheless, new mathematical models are still required to obtain more accurate numerical estimates. The present study aims at developing a linear transversely isotropic poroviscoelastic theory by combining a viscoelastic material law with the transversely isotropic biphasic model. In particular, an integral type viscoelastic model is used to describe the intrinsic viscoelastic properties of a transversely isotropic solid matrix. The proposed constitutive theory incorporates viscoelastic contributions from both the fluid flow and the intrinsic viscoelasticity to the overall stress-relaxation behavior. Moreover, this new material model allows investigating the biomechanical properties of tissues whose extracellular matrix exhibits transverse isotropy. In the present work, a comprehensive parametric study was conducted to determine the influence of various material parameters on the stress–relaxation history. Furthermore, the efficacy of the proposed theory in representing the unconfined compression experiments was assessed by comparing its theoretical predictions with those obtained from other versions of the biphasic theory such as the isotropic, transversely isotropic, and viscoelastic models. The unconfined compression behavior of articular cartilage as well as corneal stroma was used for this purpose. It is concluded that while the proposed model is capable of accurately representing the viscoelastic behavior of any hydrated soft tissue in unconfined compression, it is particularly useful in modeling the behavior of those with a transversely isotropic skeleton.

Relevance of Indentation Test to Characterize Soft Biological Tissue: Application to Human Skin

2018 ◽  
Vol 10 (07) ◽  
pp. 1850074 ◽  
Author(s):  
Khouloud Azzez ◽  
Makram Chaabane ◽  
Marie-Angele Abellan ◽  
Jean-Michel Bergheau ◽  
Hassan Zahouani ◽  
...  
Keyword(s):  
Human Skin ◽  
Soft Tissues ◽  
Indentation Test ◽  
Problem Solution ◽  
Fe Model ◽  
Viscoelastic Parameters ◽  
Linear Viscoelastic Material ◽  
Indentation Tests ◽  
Soft Biological Materials ◽  
The Stability

This contribution presents a new investigation to identify the viscoelastic parameters of soft biological materials using indentation test. The purpose is to present a new independent method on experimental specificities in order to characterize these materials. The identification was done using inverse analysis based on combining finite element (FE) numerical simulations and experimental indentation tests. By considering soft tissues as an isotropic linear viscoelastic material, we firstly validate our proposed FE model via a comparison between analytic and numerical indentation responses. Secondly, the existence and uniqueness of inverse problem solution based on the comparison of numerical/numerical responses is shown. Finally, we validate the stability of the inverse approach using sensitivity analysis by setting up a design of experiment (DOE) technique which proves the relevance of this proposed method. An application is made on the forearm of human skin and shows performances of this proposed method to identify viscoelastic human skin properties in spherical loading–unloading indentation test. This method can be applied to evaluate other viscoelastic materials.

Nanoscale Indentation of Simulated Soft Tissues

2004 ◽  
Author(s):  
Shikha Gupta ◽  
Fernando Carrillo ◽  
Lisa Pruitt ◽  
Christian Puttlitz
Keyword(s):  
Animal Models ◽  
Material Properties ◽  
Soft Tissues ◽  
Tissue Sample ◽  
Small Animal ◽  
Element Model ◽  
Small Time ◽  
Fe Model ◽  
Testing Procedures ◽  
Small Animal Models

The use of small animal models, such as murine and rabbit models, are currently being explored to help elucidate the mechanobiological mechanisms of clinically relevant orthopaedic conditions such as fracture healing and osteoarthritis progression, with the goal of developing a comprehensive view of the biomechanical structure-function relationships at the tissue and cellular level. In addition to the heterogeneous nature of these tissues, the miniature size of the test specimens from these small animal models precludes the use of conventional bulk mechanical testing procedures to obtain material properties. Nanoindentation is a technique that is used to assess mechanical properties on a cellular scale. Though traditionally used to study hard, elastic-plastic materials, it has been effectively utilized to measure the material properties of mineralized biological materials [1, 2]. More recently, there have been some preliminary studies on soft, hydrated tissues, such as demineralized dentin, cartilage, and vascular tissues [3, 4]. However, this technique has not been validated for measuring the properties of tissues with extremely small, time- dependent tissue matrices (elastic moduli below 5 MPa). A finite element model (FE) of the nanoscale indentation process has been developed to assess some of the experimental issues associated with using nanoindentation on physical tissue specimens. In addition, we have used this FE model to predict the distribution of stresses and strains within the indenting substrate (tissue sample), mechanical parameters that cannot be mapped using currently-available experimental methods.

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