scholarly journals Modeling of the Mechanical Behavior of 3D Bioplotted Scaffolds Considering the Penetration in Interlocked Strands

2018 ◽  
Vol 8 (9) ◽  
pp. 1422 ◽  
Author(s):  
Saman Naghieh ◽  
M. Sarker ◽  
Mohammad Karamooz-Ravari ◽  
Adam McInnes ◽  
Xiongbiao Chen
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Mechanical Behavior ◽  
Model Development ◽  
Three Dimensional ◽  
The Finite Element Method ◽  
Hydrogel Scaffolds ◽  
Important Index ◽  
Geometrical Features ◽  
Scaffold Structure

Three-dimensional (3D) bioplotting has been widely used to print hydrogel scaffolds for tissue engineering applications. One issue involved in 3D bioplotting is to achieve the scaffold structure with the desired mechanical properties. To overcome this issue, various numerical methods have been developed to predict the mechanical properties of scaffolds, but limited by the imperfect representation of one key feature of scaffolds fabricated by 3D bioplotting, i.e., the penetration or fusion of strands in one layer into the previous layer. This paper presents our study on the development of a novel numerical model to predict the elastic modulus (one important index of mechanical properties) of 3D bioplotted scaffolds considering the aforementioned strand penetration. For this, the finite element method was used for the model development, while medium-viscosity alginate was selected for scaffold fabrication by the 3D bioplotting technique. The elastic modulus of the bioplotted scaffolds was characterized using mechanical testing and results were compared with those predicted from the developed model, demonstrating a strong congruity between them. Once validated, the developed model was also used to investigate the effect of other geometrical features on the mechanical behavior of bioplotted scaffolds. Our results show that the penetration, pore size, and number of printed layers have significant effects on the elastic modulus of bioplotted scaffolds; and also suggest that the developed model can be used as a powerful tool to modulate the mechanical behavior of bioplotted scaffolds.

scholarly journals Modeling of the Mechanical Behavior of 3D Bioplotted Scaffolds Considering the Penetration in Interlocked Strands

2018 ◽  
Author(s):  
Saman Naghieh ◽  
Md Sarker ◽  
Mohammad Reza Karamooz-Ravari ◽  
Adam D. McInnes ◽  
Xiongbiao Chen
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Mechanical Behavior ◽  
Model Development ◽  
Three Dimensional ◽  
The Finite Element Method ◽  
Hydrogel Scaffolds ◽  
Important Index ◽  
Geometrical Features ◽  
Scaffold Structure

Three-dimensional (3D) bioplotting has been widely used to print hydrogel scaffolds for tissue engineering applications. One issue involved in 3D bioplotting is to achieve the scaffold structure with the desired mechanical properties. To overcome this issue, various numerical methods have been developed to predict the mechanical properties of scaffolds, but limited by the imperfect representation of one key feature of scaffolds fabricated by 3D bioplotting, i.e., the penetration or fusion of strands in one layer into the previous layer. This paper presents our study on the development of a novel numerical model to predict the elastic modulus (one important index of mechanical properties) of 3D bioplotted scaffolds considering the aforementioned strand penetration. For this, the finite element method was used for the model development, while medium-viscosity alginate was selected for scaffold fabrication by the 3D bioplotting technique. The elastic modulus of the bioplotted scaffolds was characterized using mechanical testing and results were compared with those predicted from the developed model, demonstrating a strong congruity between them. Once validated, the developed model was also used to investigate the effect of other geometrical features on the mechanical behavior of bioplotted scaffolds. Our results show that the penetration, pore size, and number of printed layers have significant effects on the elastic modulus of bioplotted scaffolds; and also suggest that the developed model can be used as a powerful tool to modulate the mechanical behavior of bioplotted scaffolds.

scholarly journals Influence of Crosslinking on the Mechanical Behavior of 3D Printed Alginate Scaffolds: Experimental and Numerical Approaches

2018 ◽  
Author(s):  
Saman Naghieh ◽  
Mohammad Reza Karamooz-Ravari ◽  
Md Sarker ◽  
Eva Karki ◽  
Xiongbiao Chen
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Mechanical Behavior ◽  
Three Dimensional ◽  
Decisive Role ◽  
Element Model ◽  
Tissue Scaffolds ◽  
3D Bioprinting ◽  
3D Printed ◽  
Numerical Approaches

Tissue scaffolds fabricated by three-dimensional (3D) bioprinting are attracting considerableattention for tissue engineering applications. Because the mechanical properties of hydrogelscaffolds should match the damaged tissue, changing various parameters during 3D bioprintinghas been studied to manipulate the mechanical behavior of the resulting scaffolds. Crosslinkingscaffolds using a cation solution (such as CaCl2) is also important for regulating the mechanicalproperties, but has not been well documented in the literature. Here, the effect of variedcrosslinking agent volume and crosslinking time on the mechanical behavior of 3D bioplottedalginate scaffolds was evaulated using both experimental and numerical methods. Compressiontests were used to measure the elastic modulus of each scaffold, then a finite element model wasdeveloped and a power model used to predict scaffold mechanical behavior. Results showed thatcrosslinking time and volume of crosslinker both play a decisive role in modulating the mechanicalproperties of 3D bioplotted scaffolds. Because mechanical properties of scaffolds can affect cellresponse, the findings of this study can be implemented to modulate the elastic modulus ofscaffolds according to the intended application.

scholarly journals The effect of the outlet angle β2 on the thermomechanical behavior of a centrifugal compressor blade

2020 ◽  
Vol 29 (1) ◽  
pp. 1-8
Author(s):  
Ahmed Allali ◽  
Sadia Belbachir ◽  
Ahmed Alami ◽  
Belhadj Boucham ◽  
Abdelkader Lousdad
Keyword(s):  
Mechanical Behavior ◽  
Centrifugal Compressor ◽  
Three Dimensional ◽  
Complex Form ◽  
Compressor Blade ◽  
Stress Fields ◽  
The Finite Element Method ◽  
Mechanical Fatigue ◽  
Outlet Angle ◽  
The Impact

AbstractThe objective of this work lies in the three-dimensional study of the thermo mechanical behavior of a blade of a centrifugal compressor. Numerical modeling is performed on the computational code "ABAQUS" based on the finite element method. The aim is to study the impact of the change of types of blades, which are defined as a function of wheel output angle β2, on the stress fields and displacements coupled with the variation of the temperature.This coupling defines in a realistic way the thermo mechanical behavior of the blade where one can note the important concentrations of stresses and displacements in the different zones of its complex form as well as the effects at the edges. It will then be possible to prevent damage and cracks in the blades of the centrifugal compressor leading to its failure which can be caused by the thermal or mechanical fatigue of the material with which the wheel is manufactured.

Tissue-Engineered Cartilage in Three-Dimensional Cultured Chondrocytes by Ultrasound Stimulation and Collagen Sponge as Scaffold

2009 ◽  
Author(s):  
Toshihiko Shiraishi ◽  
Ietomo Matsunaga ◽  
Shin Morishita ◽  
Ryohei Takeuchi ◽  
Tomoyuki Saito ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Three Dimensional ◽  
Collagen Sponge ◽  
Cartilage Tissue ◽  
Mechanical Environment ◽  
Ultrasound Stimulation ◽  
Scaffold Structure ◽  
Matrix Production ◽  
Engineered Cartilage ◽  
Cultured Chondrocytes

This paper describes the effects of ultrasound stimulation on chondrocytes in three-dimensional culture in relation to the production of regenerative cartilage tissue, using collagen sponges as a carrier and supplementation with hyaluronic acid (used in the conservative treatment of osteoarthritis). It has been shown that cell proliferation and matrix production can be facilitated by considering the mechanical environment of the cultured chondrocytes and the mechanical properties of the scaffold structure used in the culture and of the stimulation used.

scholarly journals The Influence of Thermal Residual Stresses on Mechanical Properties of Silicon Nitride-Based Composites

Materials ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1092
Author(s):  
Aleksandra Dubiel ◽  
Grzegorz Grabowski ◽  
Marcin Goły ◽  
Stanisław Skrzypek
Keyword(s):  
Mechanical Properties ◽  
Finite Element Method ◽  
Phase Composition ◽  
Silicon Nitride ◽  
Thermal Stresses ◽  
Three Dimensional ◽  
The Finite Element Method ◽  
Thermal Residual Stresses ◽  
Microstructure Parameters ◽  
Xrd Method

In this work, two kinds of silicon nitride-based composites, namely, those with titanium nitride or silicon carbide additives, were sintered using the hot pressing technique (HP). The phase composition, microstructure, and mechanical and elastic properties of the materials were characterized. Three-dimensional geometric models of the composites were created on the basis of microstructure parameters. Using these models, bulk residual thermal stresses were calculated by the finite element method (FEM). Surface stresses were determined using the XRD method of sin2ψ.

Delayed Photoactivation of Dual-cure Composites: Effect on Cuspal Flexure, Depth-of-cure, and Mechanical Properties

2019 ◽  
Vol 44 (2) ◽  
pp. E97-E104 ◽  
Author(s):  
KO Hughes ◽  
KJ Powell ◽  
AE Hill ◽  
D Tantbirojn ◽  
A Versluis
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Flexural Strength ◽  
Maximum Stress ◽  
Three Dimensional ◽  
Degree Of Cure ◽  
Bending Tests ◽  
Depth Of Cure ◽  
Four Point Bending ◽  
Tooth Surfaces

SUMMARY Objectives: This study tested whether delayed photoactivation could reduce shrinkage stresses in dual-cure composites and how it affected the depth-of-cure and mechanical properties. Methods and Materials: Two dual-cure composites (ACTIVA and Bulk EZ) were subjected to two polymerization protocols: photoactivation at 45 seconds (immediate) or 165 seconds (2 minutes delayed) after extrusion. Typodont premolars with standardized preparations were restored with the composites, and cuspal flexure caused by polymerization shrinkage was determined with three-dimensional scanning of the external tooth surfaces before restoration (baseline) and at 10 minutes and one hour after photoactivation. Bond integrity (intact interface) was verified with dye penetration. Depth-of-cure was determined by measuring Vickers hardness through the depth at 1-mm increments. Elastic modulus and maximum stress were determined by four-point bending tests (n=10). Results were analyzed with two- or three-way analysis of variance and pairwise comparisons (Bonferroni; α=0.05). Results: Delayed photoactivation significantly reduced cuspal flexure for both composites at 10 minutes and one hour (p≤0.003). Interface was >99% intact in every group. Depth-of-cure, elastic modulus, and flexural strength were not significantly different between the immediate and delayed photoactivation (p>0.05). The hardness of ACTIVA reduced significantly with depth (p<0.001), whereas the hardness of Bulk EZ was constant throughout the depth (p=0.942). Conclusions: Delayed photoactivation of dual-cure restorative composites can reduce shrinkage stresses without negatively affecting the degree-of-cure or mechanical properties (elastic modulus and flexural strength).

Measurement of the axial and circumferential mechanical properties of rat skin tissue at different anatomical locations

2015 ◽  
Vol 60 (2) ◽  
Author(s):  
Alireza Karimi ◽  
Maedeh Haghighatnama ◽  
Mahdi Navidbakhsh ◽  
Afsaneh Motevalli Haghi
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Mechanical Behavior ◽  
Clinical Decision Making ◽  
Mechanical Response ◽  
The Body ◽  
Skin Tissue ◽  
Linear Elastic ◽  
Biomechanical Models ◽  
Nonlinear Mechanical

AbstractSkin tissue is not only responsible for thermoregulation but also for protecting the human body from mechanical, bacterial, and viral insults. The mechanical properties of skin tissue may vary according to the anatomical locations in the body. However, the linear elastic and nonlinear hyperelastic mechanical properties of the skin in different anatomical regions and at different loading directions (axial and circumferential) so far have not been determined. In this study, the mechanical properties during tension of the rat abdomen and back were calculated at different loading directions using linear elastic and nonlinear hyperelastic material models. The skin samples were subjected to a series of tensile tests. The elastic modulus and maximum stress of the skin tissues were measured before the incidence of failure. The nonlinear mechanical behavior of the skin tissues was also computationally investigated through a constitutive equation. Hyperelastic strain energy density function was calibrated using the experimental data. The results revealed the anisotropic mechanical behavior of the abdomen and the isotropic mechanical response of the back skin. The highest elastic modulus was observed in the abdomen skin under the axial direction (10 MPa), while the lowest one was seen in the back skin under axial loading (5 MPa). The Mooney-Rivlin material model closely addressed the nonlinear mechanical behavior of the skin at different loading directions, which can be implemented in the future biomechanical models of skin tissue. The results might have implications not only for understanding of the isotropic and anisotropic mechanical behavior of skin tissue at different anatomical locations but also for providing more information for a diversity of disciplines, including dermatology, cosmetics industry, clinical decision making, and clinical intervention.

Experimental study on the mechanical properties of biological hydrogels of different concentrations

2020 ◽  
Vol 28 (6) ◽  
pp. 685-695
Author(s):  
Khurshid Alam ◽  
Anwarul Hasan ◽  
Muhammad Iqbal ◽  
Jamal Umer ◽  
Sujan Piya
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Precise Measurement ◽  
Three Dimensional ◽  
Crosslinking Density ◽  
Compression Tests ◽  
Cell Functions ◽  
Wide Range ◽  
Tension And Compression ◽  
Cellular Mechanobiology

BACKGROUND: Biological hydrogels provide a conducive three-dimensional extracellular matrix environment for encapsulating and cultivating living cells. Microenvironmental modulus of hydrogels dictates several characteristics of cell functions such as proliferation, adhesion, self-renewal, differentiation, migration, cell morphology and fate. Precise measurement of the mechanical properties of gels is necessary for investigating cellular mechanobiology in a variety of applications in tissue engineering. Elastic properties of gels are strongly influenced by the amount of crosslinking density. OBJECTIVE: The main purpose of the present study was to determine the elastic modulus of two types of well-known biological hydrogels: Agarose and Gelatin Methacryloyl. METHODS: Mechanical properties such as Young’s modulus, fracture stress and failure strain of the prescribed gels with a wide range of concentrations were determined using tension and compression tests. RESULTS: The elastic modulus, failure stress and strain were found to be strongly influenced when the amount of concentration in the hydrogels was changed. The elastic modulus for a lower level of concentration, not considered in this study, was also predicted using statistical analysis. CONCLUSIONS: Closed matching of the mechanical properties of the gels revealed that the bulk tension and compression tests could be confidently used for assessing mechanical properties of delicate biological hydrogels.

scholarly journals Effect of Extrusion Temperature on the Microstructure and Mechanical Properties of SiCnw/2024Al Composite

Materials ◽  
2019 ◽  
Vol 12 (17) ◽  
pp. 2769
Author(s):  
Shanliang Dong ◽  
Bin Zhang ◽  
Yuli Zhan ◽  
Xin Liu ◽  
Ling Xin ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Mechanical Strength ◽  
Mechanical Behavior ◽  
Average Length ◽  
Research Work ◽  
Extrusion Temperature ◽  
Sic Nanowires ◽  
Peak Aged ◽  
Higher Temperature

In the present research work, the effect of extrusion temperature from 480 to 560 °C on the microstructure and mechanical behavior of the SiCnw/2024Al composite (15 vol.%) has been explored. It has been found that extrusion at higher temperature (above 520 °C) was beneficial for the densification of the composite, while the residual average length and alignment of the SiC nanowires were also increased with the extrusion temperature. Moreover, higher extrusion temperature was helpful for the mechanical strength of the SiCnw/2024Al composite, and the peak-aged SiCnw/2024Al composite extruded at 560 °C revealed the highest strength (709.4 MPa) and elastic modulus (109.8 GPa).

scholarly journals Enhanced Mechanical Properties in Organofluorosilica Thin Films

2008 ◽  
Vol 2008 ◽  
pp. 1-5 ◽  
Author(s):  
Mario Pagliaro ◽  
Giovanni Palmisano ◽  
Eric Le Bourhis ◽  
Rosaria Ciriminna ◽  
Laura M. Ilharco ◽  
...  
Keyword(s):  
Thin Films ◽  
Mechanical Properties ◽  
Elastic Modulus ◽  
Angular Velocity ◽  
Mechanical Behavior ◽  
Spin Coating ◽  
Coating Process ◽  
Silica Xerogels ◽  
Modified Silica ◽  
Spin Coating Process

Fluorinated hybrid organic-inorganic silicates (ORMOSIL) thin films display exceptional mechanical properties in terms of both hardness and elastic modulus that can be finely tuned by varying the angular velocity of the spin coating process. Hence, as traditional alkyl-modified silica xerogels generally show poor mechanical behavior, these materials offer a solution to a major limitation to applicability of ORMOSIL-based films.

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