The Influence of Fiber Orientation on the Equilibrium Properties of Neutral and Charged Biphasic Tissues

2010 ◽  
Vol 132 (11) ◽  
Author(s):  
Thomas Nagel ◽  
Daniel J. Kelly
Keyword(s):  
Computational Study ◽  
Constitutive Models ◽  
Biological Tissues ◽  
Compression Tests ◽  
Unconfined Compression ◽  
Aligned Fibers ◽  
Compressive Loads ◽  
Vertically Aligned ◽  
Tissue Models ◽  
Biphasic Tissues

Constitutive models facilitate investigation into load bearing mechanisms of biological tissues and may aid attempts to engineer tissue replacements. In soft tissue models, a commonly made assumption is that collagen fibers can only bear tensile loads. Previous computational studies have demonstrated that radially aligned fibers stiffen a material in unconfined compression most by limiting lateral expansion while vertically aligned fibers buckle under the compressive loads. In this short communication, we show that in conjunction with swelling, these intuitive statements can be violated at small strains. Under such conditions, a tissue with fibers aligned parallel to the direction of load initially provides the greatest resistance to compression. The results are further put into the context of a Benninghoff architecture for articular cartilage. The predictions of this computational study demonstrate the effects of varying fiber orientations and an initial tare strain on the apparent material parameters obtained from unconfined compression tests of charged tissues.

scholarly journals FEA Based on 3D Micro-CT Images of Mesoporous Engineered Hydrogels

2015 ◽  
Vol 5 (6) ◽  
pp. 885-890
Author(s):  
L. Siad ◽  
J. Jing ◽  
J. Braux ◽  
M. Dubus ◽  
F. Velard ◽  
...  
Keyword(s):  
Computational Study ◽  
Compression Tests ◽  
Unconfined Compression ◽  
Fe Modelling ◽  
3D Images ◽  
Linear Elastic ◽  
Polymeric Biomaterials ◽  
Compressive Loads ◽  
Preliminary Study ◽  
Tomography Scan

The objective of this computational study was to propose a rapid procedure in obtaining an estimation of elastic moduli of solid phases of porous natural-polymeric biomaterials used for bone tissue engineering. This procedure was based on the comparison of experimental results to finite element (FE) responses of parallelepiped so-called representative volume elements (rev) of the material at hand. To address this issue a series of quasi-static unconfined compression tests were designed and performed on three prepared cylindrical biopolymer samples. Subsequently, a computed tomography scan was performed on fabricated specimens and two 3D images were reconstructed. Various parallelepiped revs of different sizes and located at distinct places within both constructs were isolated and then analyzed under unconfined compressive loads using FE modelling. In this preliminary study, for the sake of simplicity, the dried biopolymer solid is assumed to be linear elastic.

scholarly journals The mechanical properties of tibiofemoral and patellofemoral articular cartilage in compression depend on anatomical regions

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Heng Li ◽  
Jinming Li ◽  
Shengbo Yu ◽  
Chengwei Wu ◽  
Wei Zhang
Keyword(s):  
Mechanical Properties ◽  
Articular Cartilage ◽  
Knee Joint ◽  
Strain Rate ◽  
Constitutive Models ◽  
Biological Tissues ◽  
Rate Dependency ◽  
Unconfined Compression ◽  
Femoral Groove ◽  
Stiffening Effect

AbstractArticular cartilage in knee joint can be anatomically divided into different regions: medial and lateral condyles of femur; patellar groove of femur; medial and lateral plateaus of tibia covered or uncovered by meniscus. The stress–strain curves of cartilage in uniaxially unconfined compression demonstrate strain rate dependency and exhibit distinct topographical variation among these seven regions. The femoral cartilage is stiffer than the tibial cartilage, and the cartilage in femoral groove is stiffest in the knee joint. Compared with the uncovered area, the area covered with meniscus shows the stiffer properties. To investigate the origin of differences in macroscopic mechanical properties, histological analysis of cartilage in seven regions are conducted. The differences are discussed in terms of the cartilage structure, composition content and distribution. Furthermore, the commonly used constitutive models for biological tissues, namely Fung, Ogden and Gent models, are employed to fit the experimental data, and Fung and Ogden models are found to be qualified in representing the stiffening effect of strain rate.

A computational study of discrete mechanical tissue models

2009 ◽  
Vol 6 (3) ◽  
pp. 036001 ◽  
Author(s):  
P Pathmanathan ◽  
J Cooper ◽  
A Fletcher ◽  
G Mirams ◽  
P Murray ◽  
...  
Keyword(s):  
Computational Study ◽  
Tissue Models ◽  
Mechanical Tissue

Microstructural changes in soft quick clay at failure

1970 ◽  
Vol 7 (1) ◽  
pp. 1-7 ◽  
Author(s):  
Roland Pusch
Keyword(s):  
Shear Deformation ◽  
Shear Zone ◽  
Residual Strength ◽  
Rigid Bodies ◽  
Compression Tests ◽  
Unconfined Compression ◽  
Shear Forces ◽  
Microstructural Investigation ◽  
Shear Process ◽  
Quick Clay

A series of unconfined compression tests has been made on a marine, quick clay and small specimens were extracted for microstructural investigation. The natural microstructural pattern was characterized by a network of small aggregates connected by links of particles. The links broke down successively at increasing shear deformation and formed domain-like groups of particles. In the macroscopic shear zone the shear forces tended to orient and deform the aggregates.The aggregates behaved as rigid bodies to a certain stress level during the shear process. The concept of residual strength may correspond to the state where the majority of the links have been broken while the aggregates are still intact.

Constitutive Modeling for Flow Stress Behavior of Nimonic 80A Superalloy During Hot Deformation Process

2016 ◽  
Vol 35 (3) ◽  
pp. 327-336 ◽  
Author(s):  
Sendong Gu ◽  
Liwen Zhang ◽  
Chi Zhang ◽  
Wenfei Shen
Keyword(s):  
Flow Stress ◽  
Constitutive Model ◽  
Hot Deformation ◽  
Critical Strain ◽  
Volume Fraction ◽  
Constitutive Models ◽  
Avrami Equation ◽  
Peak Strain ◽  
Compression Tests ◽  
Nimonic 80A

AbstractThe hot deformation characteristics of nickel-based alloy Nimonic 80A were investigated by isothermal compression tests conducted in the temperature range of 1,000–1,200°C and the strain rate range of 0.01—5 s–1on a Gleeble-1500 thermomechanical simulator. In order to establish the constitutive models for dynamic recrystallization (DRX) behavior and flow stress of Nimonic 80A, the material constantsα,nand DRX activation energyQin the constitutive models were calculated by the regression analysis of the experimental data. The dependences of initial stress, saturation stress, steady-state stress, dynamic recovery (DRV) parameter, peak strain, critical strain and DRX grain size on deformation parameters were obtained. Then, the Avrami equation including the critical strain for DRX and the peak strain as a function of strain was established to describe the DRX volume fraction. Finally, the constitutive model for flow stress of Nimonic 80A was developed in DRV region and DRX region, respectively. The flow stress values predicted by the constitutive model are in good agreement with the experimental ones, which indicates that the constitutive model can give an accurate estimate for the flow stress of Nimonic 80A under the deformation conditions.

Stabilization of clayey subgrade with waste pumice for road infrastructure

2015 ◽  
Vol 22 (5) ◽  
Author(s):  
Ömür Çimen ◽  
Mehmet Saltan ◽  
S. Nilay Keskin
Keyword(s):  
Mechanical Properties ◽  
Road Construction ◽  
High Plasticity ◽  
Test Results ◽  
Index Properties ◽  
Compression Tests ◽  
Unconfined Compression ◽  
Swelling Potential ◽  
Project Costs ◽  
High Plasticity Clay

AbstractHigh-plasticity clayey subgrade, which is unsuitable for road construction, may sometimes occur along highway routes. In such cases, engineers need to change the route of a highway project, resulting in an increase in road length and project costs. In this study, waste pumice was examined for stabilization of high-plasticity clayey subgrade, which is inappropriate for road construction. For this purpose, the physical and index properties of clay and pumice were determined. Then, the pumice was mixed with high plasticity clay at different ratios by weight. By performing standard Proctor compaction tests on the mixtures, the effects of adding pumice on compaction were also studied. Unconfined compression tests and California bearing ratio (CBR) tests were performed on all pumice-clay mixtures, and the test results and the CBR ratios were compared for each sample, respectively. The results showed that pumice stabilization improved the mechanical properties and reduced the swelling potential of high plasticity clayey subgrade.

scholarly journals The Effect of Polymer-Cement Stabilization on the Unconfined Compressive Strength of Liquefiable Soils

2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
Ali Ateş
Keyword(s):  
Compressive Strength ◽  
Compression Strength ◽  
Unconfined Compressive Strength ◽  
Soil Stabilization ◽  
Sandy Soils ◽  
Pulse Velocity ◽  
Unit Weight ◽  
Unconfined Compression Strength ◽  
Compression Tests ◽  
Unconfined Compression

Soil stabilization has been widely used as an alternative to substitute the lack of suitable material on site. The use of nontraditional chemical stabilizers in soil improvement is growing daily. In this study a laboratory experiment was conducted to evaluate the effects of waterborne polymer on unconfined compression strength and to study the effect of cement grout on pre-venting of liquefiable sandy soils. The laboratory tests were performed including grain size of sandy soil, unit weight, ultrasonic pulse velocity, and unconfined compressive strength test. The sand and various amounts of polymer (1%, 2%, 3%, and 4%) and cement (10%, 20%, 30%, and 40%) were mixed with all of them into dough using mechanical kneader in laboratory conditions. Grouting experiment is performed with a cylindrical mould of  mm. The samples were subjected to unconfined compression tests to determine their strength after 7 and 14 days of curing. The results of the tests indicated that the waterborne polymer significantly improved the unconfined compression strength of sandy soils which have susceptibility of liquefaction.

ANTICYTOSKELETAL DRUGS AND TIME CULTURE EFFECTS UPON THE MECHANICAL BEHAVIOR OF DERMAL EQUIVALENT TISSUE SUBMITTED TO UNCONFINED COMPRESSION LOADING

2008 ◽  
Vol 08 (03) ◽  
pp. 339-352 ◽  
Author(s):  
S. RAMTANI ◽  
D. GEIGER
Keyword(s):  
Mechanical Behavior ◽  
Internal State ◽  
Skin Grafting ◽  
Biological Tissues ◽  
Matrix Remodeling ◽  
Unconfined Compression ◽  
Compression Loading ◽  
Dermal Equivalent ◽  
Variable Approach ◽  
Time Culture

The dermal equivalent (DE), a dermis substitute consisting of human skin fibroblasts growing into a three-dimensional collagen matrix, is extensively used in many applications: wound-healing response, pharmacological studies, skin grafting, fibroblast proliferation and migration, extracellular matrix remodeling, and efficacy of cosmetic products. The widespread growth of numerical modeling in biomechanical research has placed a heightened emphasis on accurate material property data for soft biological tissues, in particular for equivalent dermis which has not been so thoroughly investigated. Under unconfined compression loading, the effects of the strain rate, time culture, and cytoskeleton-disrupting agents are experimentally investigated. In order to model the observed mechanical behavior of the DE under the above conditions, the internal state variable approach is adopted for finite deformation viscoelasticity and the optimized material parameters are identified with respect to the stated thermodynamic restriction (i.e. positive viscous dissipation).

scholarly journals A Comparative Study on Johnson Cook, Modified Zerilli–Armstrong, and Arrhenius-Type Constitutive Models to Predict Compression Flow Behavior of SnSbCu Alloy

Materials ◽  
2019 ◽  
Vol 12 (10) ◽  
pp. 1726 ◽  
Author(s):  
Tongyang Li ◽  
Bin Zhao ◽  
Xiqun Lu ◽  
Hanzhang Xu ◽  
Dequan Zou
Keyword(s):  
Experimental Data ◽  
Flow Behavior ◽  
Constitutive Models ◽  
Strain Range ◽  
Type Model ◽  
Strain Rates ◽  
Compression Tests ◽  
Predictive Values ◽  
Specific Strain ◽  
Optimum Model

The flow behavior of the SnSbCu alloy is studied experimentally by the compression tests in the range of the strain rates from 0.0001 to 0.1 s−1 and temperature from 293 to 413 K. Based on the experimental data, three constitutive models including the Johnson–Cook (J–C), modified Zerilli–Armstrong (Z–A), and Arrhenius-type (A-type) models are compared to find out an optimum model to describe the flow behavior of the SnSbCu alloy. The results show that the J–C model could predict the flow behavior of the SnSbCu alloy accurately only at some specific strain rates and temperature near the reference values. The modified Z–A and A-type constitutive models can give better fitting results than the J–C model. While, at high strains, the predictive values of the modified Z–A model have larger errors than those at low strains, which means this model has limitations at high strains. By comparison, the A-type model could predict the experimental results accurately at the whole strain range, which indicates that it is a more suitable choice to describe the flow behavior of the SnSbCu alloy in the focused range of strain rates and temperatures. The work is beneficial to solve the tribological problem of the bearing of the marine engine by integrating the accurate constitutive model into the corresponding numerical model.

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