DETERMINATION OF VISCOELASTIC PROPERTIES OF THE PERIODONTAL LIGAMENT USING NANOINDENTATION TESTING AND NUMERICAL MODELING

2016 ◽  
Vol 16 (06) ◽  
pp. 1650089 ◽  
Author(s):  
HUIXIANG HUANG ◽  
WENCHENG TANG ◽  
YU YANG ◽  
BIN WU ◽  
BIN YAN
Keyword(s):  
Experimental Data ◽  
Mechanical Properties ◽  
Periodontal Ligament ◽  
Alveolar Bone ◽  
Spherical Indenter ◽  
Berkovich Indenter ◽  
Zener Model ◽  
Nanoindentation Experiment ◽  
Creep Models ◽  
Good Agreement

Viscoelasticity of the periodontal ligament (PDL) plays an important role in load transmission between tooth and alveolar bone, as well as tooth movement. This paper provides a novel nanoindentation experiment in combination with a rheological model to characterize the viscoelastic mechanical properties of the PDL. Two creep models of the indentation experiments with a Berkovich and a spherical indenter based on Zener model were developed. The hardness and reduced modulus were determined by using the Berkovich indenter. The parameters were identified through curve fittings. The fitting results show that the creep models are both in good agreement with the experimental data. Meanwhile, the models were both validated by comparing the numerical curves for load–depth relationship in loading segment with the corresponding experimental data. It is found that the spherical indenter is more suitable for testing the viscoelastic mechanical properties of the PDL than Berkovich indenter. Hence, the nanoindentation experiment with spherical indenter was simulated to further evaluate the Zener model by finite element analysis. The good agreement between the simulated results and experimental data demonstrates that the Zener model is capable of describing the viscoelastic mechanical behavior of the PDL.

ELECTRONIC, OPTICAL AND MECHANICAL PROPERTIES OF AIIBVI SEMICONDUCTORS

2012 ◽  
Vol 26 (08) ◽  
pp. 1250020 ◽  
Author(s):  
DHEERENDRA SINGH YADAV ◽  
A. S. VERMA
Keyword(s):  
Experimental Data ◽  
Mechanical Properties ◽  
Energy Gap ◽  
Average Energy ◽  
Compound Semiconductors ◽  
Electronic Polarizability ◽  
Zinc Blende ◽  
Energy Gaps ◽  
Optical And Mechanical Properties ◽  
Good Agreement

The modified dielectric theory of solids is applied to investigate electronic, optical and mechanical properties of A II B VI binary semiconductors ( ZnO, ZnS, ZnSe, ZnTe, CdO, CdS, CdSe, CdTe, HgS, HgSe & HgTe ). The values of homopolar gaps (Eh), heteropolar gaps (Ec) and average energy gaps (Eg) were evaluated for these A II B VI groups of binary semiconductors with Zinc-blende (ZB) structure. The derived values of average energy gap (Eg) were found to be in excellent agreement with the values obtained from the Penn model except ZnO . The electronic polarizability was investigated using Chemla's relation and the values were found to be in a very good agreement with the results obtained from the Clausius–Mossotti relation. The crystal ionicity (fi) was evaluated and the obtained values were compared with the values obtained by different researchers. The evaluated values of crystal ionicity were used to calculate the electronic, optical, mechanical properties such as bulk modulus (B in GPa) cohesive energy or total energy (U in Ryd. electron) and microhardness (H in GPa) of these compound semiconductors. A good agreement has been found between calculated and experimental data.

Nanoindentation of Poly (Methyl Methacrylate)

2000 ◽  
Vol 649 ◽  
Author(s):  
Michael J. Adams ◽  
David M. Gorman ◽  
Simon A. Johnson
Keyword(s):  
Experimental Data ◽  
Mechanical Properties ◽  
Penetration Depth ◽  
Polymeric Materials ◽  
Polymer Coatings ◽  
Organic Polymer ◽  
Berkovich Indenter ◽  
Homogeneous Half Space ◽  
Rate Dependent ◽  
Thin Polymer

ABSTRACTFor the indentation of an elastic-plastic homogeneous half-space with a pyramidal indenter, the load theoretically increases with the square of the total penetration depth. Experimental data are presented in the current paper that demonstrate the validity of this relationship for an organic polymer and a Berkovich indenter, provided that appropriate account is taken of the tip defect and viscoplasticity. It is also shown that a simple analytical solution exists for the ratio of the contact depth to the total penetration depth. These findings assist in identifying procedures for obtaining the rate-dependent mechanical properties of thin polymer coatings or polymeric materials with depth-dependent mechanical properties.

Springback Behavior of an Invar Sheet and Its Perforated Form

2006 ◽  
Vol 505-507 ◽  
pp. 781-786
Author(s):  
Yi Che Lee ◽  
Fuh Kuo Chen
Keyword(s):  
Experimental Data ◽  
Mechanical Properties ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Tensile Tests ◽  
Test Results ◽  
Bending Tests ◽  
Predicted Values ◽  
Springback Behavior ◽  
Good Agreement

The springback behavior of an invar sheet and its perforated form were examined in the present study. The mechanical properties for invar sheet and perforated invar-sheet at elevated temperatures were first obtained from tensile tests. The test results suggest that both invar sheet and perforated invar-sheet have favorable formability at temperature higher than 200oC. An analytical model was also established to predict the springback of the invar sheet and its perforated form under bending conditions at various elevated temperatures. In order to verify the predicted results, the V-bending tests were conducted for the invar sheet at various temperatures ranging from room temperature to 300. The experimental data indicate that the springback decreases with the rise in temperature for both invar sheet and perforated invar-sheet. The good agreement between the experimental data and the predicted values confirms the validity of the proposed theoretical model as well.

scholarly journals Polymer-Ceramic Bionanocomposites for Dental Application

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
Jung-Hwan Lee ◽  
Hae-Won Kim ◽  
Seog-Jin Seo
Keyword(s):  
Mechanical Properties ◽  
Polymer Blends ◽  
Periodontal Ligament ◽  
Alveolar Bone ◽  
Dental Application

Multiphasic bionanocomposites have been highlighted in the biotechnology field since they have offered mechanical flexibility during operation. This interest has been increased mainly through polymer/ceramic/metal manipulation techniques and modifications in formulation. Recently, a number of studies on bionanocomposites have been examined due to their favorable mechanical properties and cellular activities when compared to the neat polymers or polymer blends. This paper critically reviews recent applications of bionanocomposites for regeneration of pulp-dentin complex, periodontal ligament, and alveolar bone, and substitute of enamel in dentistry.

Effect of Chain Morphology and Carbon-Nanotube Additives on the Glass Transition Temperature of Polyethylene

2013 ◽  
Vol 23 ◽  
pp. 16-23 ◽  
Author(s):  
S. Herasati ◽  
H.H. Ruan ◽  
Liang Chi Zhang
Keyword(s):  
Experimental Data ◽  
Mechanical Properties ◽  
Glass Transition ◽  
Carbon Nanotube ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Md Simulation ◽  
Md Simulations ◽  
Crystalline Polymers ◽  
Good Agreement

Glass transition temperature Tg is the most important parameter affecting the mechanical properties of amorphous and semi-crystalline polymers. However, the atomistic origin of glass transition is not yet well understood. Using Polyethylene (PE) as an example, this paper investigates the glass transition temperature Tg of PE with the aid of molecular dynamics (MD) simulation. The effects of PE chain branches, crystallinity and carbon-nanotube (CNT) additives on the glass transition temperature are analyzed. The MD simulations render a good agreement with the relevant experimental data of semi-crystalline PE and show the significant effects of crystallinity and addition of CNTs on Tg.

Study of Local Mechanical Properties of Fe78Al22 Alloy

2018 ◽  
Vol 784 ◽  
pp. 27-32 ◽  
Author(s):  
Vilma Buršíková ◽  
Vojtěch Homola ◽  
Yvonna Jirásková ◽  
Naděžda Pizúrová ◽  
Ivana Miháliková ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Grain Orientation ◽  
Quantum Mechanical ◽  
Quantum Mechanical Calculations ◽  
Berkovich Indenter ◽  
Indentation Tests ◽  
Anisotropic Elastic ◽  
Crystallographic Orientations ◽  
Good Agreement

The local mechanical properties of Fe78Al22alloy were studied using nanoindentation techniques. Sharp Berkovich indenter was used to perform load-controlled nanoindentation experiments on the studied sample. Hardness and elastic modulus maps were created on the basis of the indentation tests carried out in different grains. The focus of the work was to study the dependence of mechanical properties on the grain orientation. The results were in good agreement with quantum-mechanical calculations of anisotropic elastic properties of the studied alloy. It was explained that the maximum detected elastic modulus values are likely for grains with [111] crystallographic orientations which we theoretically identified as the hard ones.

Structural and Mechanical Properties of RT2Zn20 and RFe2-xCoxZn20(R=Y, Sm; T=Fe, Ru, Os, Co, Rh and Ir)

2011 ◽  
Vol 689 ◽  
pp. 204-210 ◽  
Author(s):  
Yi Chen ◽  
Jiang Shen
Keyword(s):  
Crystal Structure ◽  
Experimental Data ◽  
Mechanical Properties ◽  
Bulk Modulus ◽  
Elastic Constants ◽  
Interatomic Potentials ◽  
Lattice Constants ◽  
Quaternary Compounds ◽  
Cohesive Energies ◽  
Good Agreement

The phase stability, crystal structure and mechanical properties of YT2Zn20 and SmT2Zn20 (T=Fe, Ru, Os, Co, Rh and Ir) compounds have been investigated by using interatomic potentials based on the lattice inversion technique. The calculated lattice constants are in good agreement with the experimental data. The lattice constants increase and Bulk modulus decrease as the transition metal T varies from 3d to 5d. The Y-based compounds with lower energies are more stable than the Sm analogs. Also, the Bulk modulus of YT2Zn20 series are larger than SmT2Zn20 series. Moreover, the mechanical properties of the quaternary compounds YFe2-xCoxZn20 and SmFe2-xCoxZn20­, such as the elastic constants and bulk modulus, have been calculated in this work. The substitution of Co atoms would decrease the cohesive energies and increase the bulk modulus of materials.

Modeling of Mechanical Behavior of Porous Sintered Timing Wheel in Contact with Chain Wheels

2007 ◽  
Vol 561-565 ◽  
pp. 1649-1652
Author(s):  
M. Alizadeh ◽  
H. Khorsand ◽  
Ali Shokuhfar
Keyword(s):  
Experimental Data ◽  
Mechanical Properties ◽  
Finite Element ◽  
Tensile Strength ◽  
Mechanical Behavior ◽  
Sintered Density ◽  
Fem Model ◽  
Gear Contact ◽  
The Relationship ◽  
Good Agreement

The mechanical properties of sintered timing wheel in contact with chain wheels were analysed using Finite Element Methods (FEM), in which the timing wheel is modelled as a metal powder. The mechanical properties of sintered timing wheel were investigated as a function of sintered density. Tensile strength and Young’s modulus increased with a decrease in porosity. Current methods of calculating gear contact stresses use Hertz’s equations, which were originally derived for contact between sintered timing wheel and chain wheels. The results of the 2D dimensional FEM analyses from ANSYS are presented. The relationship between relative density of P/M steels and mechanical behavior is also obtained from FEM and compared with the experimental data. Good agreement between the experimental and FEM results is observed, which demonstrates that FEM can capture the major features of the P/M steels behaviour during loading. This indicates that the FEM model is accurate.

Indenter Tip Dependence in the Determination of Elastic Modulus in Polymers

2013 ◽  
Author(s):  
Seyed Hamid Reza Sanei ◽  
F. Alisafaei ◽  
Chung-Souk Han
Keyword(s):  
Mechanical Properties ◽  
Surface Roughness ◽  
Elastic Modulus ◽  
Indentation Depth ◽  
Length Scale ◽  
Berkovich Indenter ◽  
Thin Wires ◽  
Length Scale Dependent Deformation ◽  
Nanoindentation Experiment

The two most common outputs of nanoindentation experiment are hardness and elastic modulus. Length scale dependent deformation in polymers has however been observed in different experiments such as microbeam bending, torsional thin wires and indentation testing which may affect the mechanical testing. Unlike in metals where the size dependency is attributed to necessary geometry dislocations, the origin of length scale dependent deformation in polymers is not well understood. In this study, elastic modulus of polydimethylsiloxane (PDMS) is determined using both Berkovich and spherical tips. Observing different trends for elastic modulus upon the change of indentation depth using these two different tips brings up the question which tip should be used to get the real mechanical properties of PDMS which is discussed here. Surface roughness, surface effects and the imperfection of the Berkovich indenter tip are negligible at the studied length scale.

Energy Levels and Electromagnetic Transition of 90-94mo Nuclei Using Ibm-1

2020 ◽  
pp. 149-152
Keyword(s):  
Experimental Data ◽  
Transition Probability ◽  
Energy Levels ◽  
Dynamical Symmetry ◽  
Interacting Boson Model ◽  
Excitation Energies ◽  
Electromagnetic Transition ◽  
Boson Model ◽  
Energy States ◽  
Good Agreement

The energy states for the J , b , ɤ bands and electromagnetic transitions B (E2) values for even – even molybdenum 90 – 94 Mo nuclei are calculated in the present work of "the interacting boson model (IBM-1)" . The parameters of the equation of IBM-1 Hamiltonian are determined which yield the best excellent suit the experimental energy states . The positive parity of energy states are obtained by using IBS1. for program for even 90 – 94 Mo isotopes with bosons number 5 , 4 and 5 respectively. The" reduced transition probability B(E2)" of these neuclei are calculated and compared with the experimental data . The ratio of the excitation energies of the 41+ to 21+ states ( R4/2) are also calculated . The calculated and experimental (R4/2) values showed that the 90 – 94 Mo nuclei have the vibrational dynamical symmetry U(5). Good agreement was found from comparison between the calculated energy states and electric quadruple probabilities B(E2) transition of the 90–94Mo isotopes with the experimental data .

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