scholarly journals Evolution of Meniscal Biomechanical Properties with Growth: An Experimental and Numerical Study

2021 ◽  
Vol 8 (5) ◽  
pp. 70
Author(s):  
Marco Ferroni ◽  
Beatrice Belgio ◽  
Giuseppe M. Peretti ◽  
Alessia Di Giancamillo ◽  
Federica Boschetti
Keyword(s):  
Mechanical Properties ◽  
Stress Relaxation ◽  
Developmental Stage ◽  
Mechanical Response ◽  
Numerical Study ◽  
Numerical Models ◽  
Mechanical Stimulus ◽  
Specific Response ◽  
Mechanical Parameters ◽  
Biochemical Analyses

The menisci of the knee are complex fibro-cartilaginous tissues that play important roles in load bearing, shock absorption, joint lubrication, and stabilization. The objective of this study was to evaluate the interaction between the different meniscal tissue components (i.e., the solid matrix constituents and the fluid phase) and the mechanical response according to the developmental stage of the tissue. Menisci derived from partially and fully developed pigs were analyzed. We carried out biochemical analyses to quantify glycosaminoglycan (GAG) and DNA content according to the developmental stage. These values were related to tissue mechanical properties that were measured in vitro by performing compression and tension tests on meniscal specimens. Both compression and tension protocols consisted of multi-ramp stress–relaxation tests comprised of increasing strains followed by stress–relaxation to equilibrium. To better understand the mechanical response to different directions of mechanical stimulus and to relate it to the tissue structural composition and development, we performed numerical simulations that implemented different constitutive models (poro-elasticity, viscoelasticity, transversal isotropy, or combinations of the above) using the commercial software COMSOL Multiphysics. The numerical models also allowed us to determine several mechanical parameters that cannot be directly measured by experimental tests. The results of our investigation showed that the meniscus is a non-linear, anisotropic, non-homogeneous material: mechanical parameters increase with strain, depend on the direction of load, and vary among regions (anterior, central, and posterior). Preliminary numerical results showed the predominant role of the different tissue components depending on the mechanical stimulus. The outcomes of biochemical analyses related to mechanical properties confirmed the findings of the numerical models, suggesting a specific response of meniscal cells to the regional mechanical stimuli in the knee joint. During maturation, the increase in compressive moduli could be explained by cell differentiation from fibroblasts to metabolically active chondrocytes, as indicated by the found increase in GAG/DNA ratio. The changes of tensile mechanical response during development could be related to collagen II accumulation during growth. This study provides new information on the changes of tissue structural components during maturation and the relationship between tissue composition and mechanical response.

Geometrical nonlinear thermal response of sandwich panels with temperature dependent mechanical properties—Extended high-order approach

2019 ◽  
Vol 21 (5) ◽  
pp. 1700-1725 ◽  
Author(s):  
Yeoshua Frostig ◽  
George Kardomateas
Keyword(s):  
Mechanical Properties ◽  
Sandwich Panel ◽  
Mechanical Response ◽  
Numerical Study ◽  
Thermal Response ◽  
High Order ◽  
Theory Approach ◽  
Temperature Dependent ◽  
The Core ◽  
Compressive Loads

The thermal and the thermo-mechanical responses of a sandwich panel with a compliant core are investigated within the framework of the extended high-order approach where the core properties are temperature dependent or independent. Loads schemes include thermal field within temperature working range simultaneous with in-plane compressive loads applied to the core only and to the face sheets and core in the form of the uniform end—shortening of edge of panel. The mathematical formulations use the extended high-order sandwich panel theory approach that takes into account the in-plane rigidity of the core and uses the deformation patterns of the high-order sandwich panel theory. The linear and nonlinear field equations along with the appropriate boundary conditions are presented. A numerical study is conducted, and it investigates the thermal response with temperature independent and temperature dependent mechanical properties of the core as well as the thermo-mechanical response due to in-plane compressive loads. The results include displacements, stress resultants, and stress at critical locations along the panel as well as equilibria curves. They reveal that, in general, the panel with temperature independent properties response remains almost linear while with temperature dependent ones it takes a general nonlinear response. The addition of an external mechanical load changes the response from a linear/nonlinear one that may be allowable stress controlled to a case where loss of stability occurs.

HETEROGENEITY OF TIME-DEPENDENT MECHANICAL PROPERTIES OF HUMAN CORTICAL BONE AT THE MICRO SCALE

2015 ◽  
Vol 18 (04) ◽  
pp. 1550017 ◽  
Author(s):  
Sebastián Jaramillo-Isaza ◽  
Pierre-Emmanuel Mazeran ◽  
Karim El-Kirat ◽  
Marie-Christine Ho Ba Tho
Keyword(s):  
Mechanical Properties ◽  
Cortical Bone ◽  
Mineral Content ◽  
Mechanical Response ◽  
Extreme Values ◽  
Numerical Models ◽  
Time Dependent ◽  
Femoral Diaphysis ◽  
Interstitial Tissue ◽  
Micro Scale

Background: Remodeling process affects the mineral content of osteons and imparts heterogeneity through secondary mineralization; the aim of the present study is to assess the elastic and plastic time-dependent mechanical properties of osteons reflecting different mineral content as well as interstitial tissue of human femoral cortical bone by nanoindentation. Methods: Four trapezoiform blocks approximately 3[Formula: see text]mm thick were cut from the distal end of different human femoral diaphysis. Osteons with different apparent mineral degrees were classified by means of gray levels imaging using Environmental Scanning Electron Microscopy (ESEM). Nanoindentation tests were performed in the longitudinal direction of the bone axis using a four-stage protocol (load-hold-unload-hold) and the experimental curves were fitted by a mechanical model allowing the determination of the time-dependent mechanical properties. Results: Apparent low mineral content impact negatively the mechanical response of bone material at the micro-scale. Mechanical response varies among osteons exhibiting different mineral degrees. The values of the apparent elastic modulus double when the strain rate is analyzed at the extreme values ([Formula: see text] and infinity) whatever the bone component. Conclusions: These results evidence the mechanical heterogeneity of bone microstructure due to remodeling process. The quantification of the time-dependent mechanical properties could be useful to improve numerical models of bone behavior and provide new insights to build up original biomimetic materials.

scholarly journals Influence of Particle Shape on the Macroscopic and Mesolevel Mechanical Properties of Slip Zone Soil Based on 3D Scanning and 3D DEM

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Zechuang Li ◽  
Zhibin Liu
Keyword(s):  
Mechanical Properties ◽  
Particle Shape ◽  
Shear Test ◽  
Numerical Models ◽  
Displacement Vector ◽  
3D Scanning ◽  
Slip Zone ◽  
Mechanical Parameters ◽  
Contact Density ◽  
Soil Zone

The macroscopic and mesolevel mechanical mechanisms of slip zone soil are a crucial subject for the research of landslide deformation evolution and slope control, but the effects of the shape and psephicity of coarse particles in a slip zone soil on the mechanical properties of the slip soil zone still need to be explored. Discrete element method (DEM) can effectively monitor and track the mesolevel mechanical parameters of geotechnical materials, such as displacement vector field, contact force chain, and particle coordination number. The rock blocks in the medium-sized shear test undergo a sophisticated process by 3D scanning technology, and a database of the blocks is established and accurately modeled by combining 3D DEM to simulate the indoor medium-sized shear test for numerical investigation in line with the test conditions. The numerical simulation results demonstrate that the psephicity and particle shape of the rock blocks significantly affect the dilatancy and mesolevel mechanical parameters of the slip zone soil specimens. In addition, the numerical models featured by poorer psephicity and more irregular particle shape display more evident dilatancy, larger particle coordination numbers, as well as better contact density inside the model. Some references for the study of the macroscopic and mesolevel mechanical mechanisms of slip zone soil are provided.

Numerical Study of Deformation and Fracture of Ceramics Nanocomposite with Different Structural Parameters under Mechanical Loading

2016 ◽  
Vol 683 ◽  
pp. 601-608
Author(s):  
Igor S. Konovalenko ◽  
Egor M. Vodopjyanov ◽  
Evgenii V. Shilko
Keyword(s):  
Mechanical Properties ◽  
Mechanical Response ◽  
Numerical Study ◽  
Structural Parameters ◽  
Phenomenological Approach ◽  
Sample Volume ◽  
Model Composite ◽  
Deformation And Fracture ◽  
Kinetics Of ◽  
Geometrical Dimensions

Deformation, fracture and effective mechanical properties of sintered ceramics composite under uniaxial compression were studied. To perform this investigation the plain numerical model of ceramics composites based on oxides of zirconium and aluminum with different structural parameters was developed. The model construction was carried out within the frame of particle based method, namely the movable cellular automaton method (MCA). The implementation of the phase transition in the MCA-model composite was carried out on the basis of the phenomenological approach, the main point of which was the formulation of the principle of irreversible mechanical behavior of the material. Increase the fracture toughness of ceramics after (T-M) transition in its structure was realized in the model by introducing transition kinetics of the automata pair from "bound" to an "unbound" state. The structure of model composite was generated on the basis of scanning electron microscope images of micro-sections of real composite. The influence of such structural parameters as geometrical dimensions of layers, inclusions, and their spatial distribution in the sample, volume content of the composite components and their mechanical properties, as well as the amount of zirconium dioxide undergone the phase transformation on the mechanical response were investigated

MECHANICAL CHARACTERIZATION OF ANIMAL DERIVED GRAFTS FOR SURGICAL IMPLANTATION

2016 ◽  
Vol 16 (03) ◽  
pp. 1650023 ◽  
Author(s):  
PIERO GIOVANNI PAVAN ◽  
PAOLA PACHERA ◽  
SILVIA TODROS ◽  
CESARE TIENGO ◽  
ARTURO NICOLA NATALI
Keyword(s):  
Stress Relaxation ◽  
Constitutive Model ◽  
Relaxation Process ◽  
Mechanical Response ◽  
Numerical Models ◽  
Experimental Testing ◽  
Axial Stress ◽  
Experimental Tests ◽  
Tissue Samples

Bioprostheses obtained from animal models are often adopted in abdominal surgery for repair and reconstruction. The functionality of these prosthetic implants is related also to their mechanical characteristics that are analyzed here. This work illustrates a constitutive model to describe the short-term mechanical response of Permacol[Formula: see text] bioprostheses. Experimental tests were developed on tissue samples to highlight mechanical non-linear characteristics and viscoelastic phenomena. Uni-axial tensile tests were developed to evaluate the strength and strain stiffening. Incremental uni-axial stress relaxation tests were carried out at nominal strain ranging from 10% to 20% and to monitor the stress relaxation process up to 400[Formula: see text]s. The constitutive model effectively describes the mechanical behavior found in experimental testing. The mechanical response appears to be independent on the loading direction, showing that the tissue can be considered as isotropic. The viscoelastic response of the tissue shows a strong decay of the stress in the first seconds of the relaxation process. The investigation performed is aimed at a general characterization of the biomechanical response and addresses the development of numerical models to evaluate the biomechanical performance of the graft with surrounding host tissues.

Role of some modifiers on the thermo-mechanical properties of Se90In10 chalcogenide glass (ChGs)

2021 ◽  
Author(s):  
A. Dahshan ◽  
H. Kumar ◽  
Neeraj Mehta
Keyword(s):  
Mechanical Properties ◽  
Mechanical Response ◽  
The Other ◽  
Mechanical Parameters ◽  
Micro Hardness ◽  
Optical Elements ◽  
Infrared Optics ◽  
Glassy Alloys ◽  
Direct Use

The studies on the micro-hardness of ChGs provide useful information regarding their straightforward involvement in the fabrication of sensors, fibers, and other optical elements for direct use in infrared optics. This work deals with the mechanical response of the glassy Se90In10 alloy under the influence of additives (Sn, Ag, Sb, and Ge). For this, we have determined the micro-hardness of all glassy alloys. Using the values of Vickers hardness (Hv), glass transition temperature (Tg), and present glasses, we have calculated the other significant thermo-mechanical parameters. The effect of Sn, Ag, Sb, and Ge additives on the micro-hardness of glassy Se90In10 alloy is also discussed.

scholarly journals Influence of Crumb-Rubber in the Mechanical Response of Modified Portland Cement Concrete

2017 ◽  
Vol 2017 ◽  
pp. 1-9
Author(s):  
J. Retama ◽  
A. G. Ayala
Keyword(s):  
Mechanical Properties ◽  
Portland Cement ◽  
Damage Evolution ◽  
Mechanical Response ◽  
Numerical Models ◽  
Experimental Tests ◽  
Crumb Rubber ◽  
Portland Cement Concrete ◽  
Cement Concrete ◽  
Main Hypothesis

The influence of crumb-rubber on the mechanical properties of Portland cement concrete (PCC) is studied by experimental tests and numerical simulations. The main hypothesis of the study is that replacing part of the stone aggregate with crumb-rubber in the mix modifies the energy dissipation during the cracking process and affects the concrete behaviour under monotonically increasing loads. The experimental research program characterizes the mechanical properties of PCC for three different types of concrete with a variable content of crumb-rubber. The experimental results showed that fracture energy and other properties are directly related to the rubber fineness used in the mixture. The material properties derived for these laboratory tests are used to study, by numerical models, its response through its damage evolution. The numerical model used to simulate the damage evolution of the concrete is the Embedded Discontinuity Method (EDM). One characteristic of the EDM is that it does not need to modify the mesh topology to propagate the damage through the continuum solid. For this study, the Disk-Shaped Compact Tension specimen geometry, normed by the D7313-13 of the ASTM, is used. Results showed that the numerical methods provide good approximation of the experimental curve in the elastic and softening branches.

Influence of the basilar membrane shape and mechanical properties in the cochlear response: A numerical study

2021 ◽  
pp. 095441192110034
Author(s):  
Bruno Areias ◽  
Marco Parente ◽  
Fernanda Gentil ◽  
Renato Natal Jorge
Keyword(s):  
Mechanical Properties ◽  
Root Mean Square ◽  
Basilar Membrane ◽  
Numerical Study ◽  
Numerical Models ◽  
Transversely Isotropic ◽  
Travelling Wave ◽  
Mean Square ◽  
Spiral Model ◽  
Mean Square Errors

Hearing impairment is one of the most common health disorders, affecting individuals of all ages, reducing considerably their quality of life. At present, it is known that during an acoustic stimulation a travelling wave is developed inside the cochlea. Existing mathematical and numerical models available in the literature try to describe the shape of this travelling wave, the majority of them present a set of approaches based on some limitations either or both of the mechanical properties used and the geometrical description of the realistic representation. The present numerical study highlights the distinctions of using a spiral model of the cochlea, by comparing the obtained results with a straight, or simplified model. The influence of the implantation of transversely isotropic mechanical models was also studied, by comparing the basilar membrane with isotropic and transversely isotropic mechanical properties. Values of the root mean square error calculated for all models show a greater proximity of the cochlear mapping to the Greenwood function when the basilar membrane is assumed with transversely isotropic mechanical properties for both straight and spiral model. The root-mean square errors calculated were: 2.05, 1.70, 2.72, 2.08 mm, for the straight-isotropic, straight-transversely isotropic, spiral-isotropic and spiral-transversely isotropic model, respectively.

scholarly journals Nonlinear modelling of the seismic response of masonry structures: Calibration strategies

2021 ◽  
Author(s):  
Antonio Maria D’Altri ◽  
Francesco Cannizzaro ◽  
Massimo Petracca ◽  
Diego Alejandro Talledo
Keyword(s):  
Mechanical Properties ◽  
Numerical Models ◽  
Shear Stiffness ◽  
Model Material ◽  
National Standards ◽  
National Standard ◽  
Masonry Structures ◽  
Nonlinear Modelling ◽  
Various Boundary Conditions ◽  
Panel Stiffness

AbstractIn this paper, a simple and practitioners-friendly calibration strategy to consistently link target panel-scale mechanical properties (that can be found in national standards) to model material-scale mechanical properties is presented. Simple masonry panel geometries, with various boundary conditions, are utilized to test numerical models and calibrate their mechanical properties. The calibration is successfully conducted through five different numerical models (most of them available in commercial software packages) suitable for nonlinear modelling of masonry structures, using nonlinear static analyses. Firstly, the panel stiffness calibration is performed, focusing the attention to the shear stiffness. Secondly, the panel strength calibration is conducted for several axial load ratios by attempts using as reference the target panel strength deduced by well-known analytical strength criteria. The results in terms of panel strength for the five different models show that this calibration strategy appears effective in obtaining model properties coherent with Italian National Standard and Eurocode. Open issues remain for the calibration of the post-peak response of masonry panels, which still appears highly conventional in the standards.

scholarly journals Stress relaxation in tunable gels

Soft Matter ◽  
2021 ◽  
Author(s):  
Chiara Raffaelli ◽  
Wouter G Ellenbroek
Keyword(s):  
Mechanical Properties ◽  
Drug Delivery ◽  
Tissue Engineering ◽  
Stress Relaxation

Hydrogels are a staple of biomaterials development. Optimizing their use in e.g. drug delivery or tissue engineering requires a solid understanding of how to adjust their mechanical properties. Here, we...

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