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.

Modelling the nano indentation behaviour of recast layer and heat affected zone on reverse micro EDMed hemispherical feature

2021 ◽  
pp. 1-15
Author(s):  
Tribeni Roy ◽  
Anuj Sharma ◽  
Prabhat Ranjan ◽  
R. Balasubramaniam
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Heat Affected Zone ◽  
Parent Material ◽  
Recast Layer ◽  
Machined Surface ◽  
Nano Indentation ◽  
Fea Simulation ◽  
Load Displacement ◽  
Good Agreement

Abstract Electrical discharge machined surfaces inherently possess recast layer on the surface with heat affected zone (HAZ) beneath it and these have a detrimental effect on the mechanical properties viz. hardness, elastic modulus, etc. It is very difficult to experimentally characterise each machined surface. Therefore, an attempt is made in this study to numerically calculate the mechanical properties of the parent material, HAZ and the recast layer on a hemispherical protruded micro feature fabricated by reverse micro EDM (RMEDM). In the 1st stage, nano indentation was performed to experimentally determine the load-displacement plots, elastic modulus and hardness of the parent material, HAZ and the recast layer. In the 2nd stage, FEA simulation was carried out to mimic the nano indentation process and determine the load-displacement plots for all the three cases viz. parent material, recast layer and HAZ. Results demonstrated that the load'displacement plots obtained from numerical model in each case was in good agreement with that of the experimental curves. Based on simulated load-displacement plots, hardness was also calculated for parent material, HAZ and the recast layer. A maximum of 11% error was observed between simulated values of hardness and experimentally determined values.

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.

scholarly journals Biomechanical Modeling of Human Skin Tissue Surrogates

Biomimetics ◽  
2018 ◽  
Vol 3 (3) ◽  
pp. 18 ◽  
Author(s):  
Arnab Chanda
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Human Skin ◽  
Sports Injuries ◽  
Biomechanical Testing ◽  
Material System ◽  
Load Response ◽  
Nonlinear Stress ◽  
Indentation Tests ◽  
Dynamic Loading Conditions

Surrogates, which precisely simulate nonlinear mechanical properties of the human skin at different body sites, would be indispensable for biomechanical testing applications, such as estimating the accurate load response of skin implants and prosthetics to study the biomechanics of static and dynamic loading conditions on the skin, dermatological and sports injuries, and estimating the dynamic load response of lethal and nonlethal ballistics. To date, human skin surrogates have been developed mainly with materials, such as gelatin and polydimethylsiloxane (PDMS), based on assumption of simplified mechanical properties, such as an average elastic modulus (estimated through indentation tests), and Poisson’s ratio. In addition, pigskin and cowhides, which have widely varying mechanical properties, have been used to simulate human skin. In the current work, a novel elastomer-based material system is developed, which precisely mimics the nonlinear stress–stretch behavior, elastic modulus at high and low strains, and fracture strengths of the natural human skin at different body sites. The manufacturing and fabrication process of these skin surrogates are discussed, and mechanical testing results are presented.

A Method to Determine Fracture Toughness Using Berkovich Indenter for Bulk Materials

2013 ◽  
Vol 331 ◽  
pp. 456-460
Author(s):  
Min He ◽  
Duan Hu Shi ◽  
Feng Yang ◽  
Ning Zhang ◽  
Hua Feng Guo
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Elastic Modulus ◽  
Penetration Depth ◽  
Effective Elastic Modulus ◽  
Berkovich Indenter ◽  
Bulk Materials ◽  
Ductile Materials ◽  
Penetration Depths ◽  
Determine Fracture Toughness

An indentation approach with Berkovich indenter is proposed to determine fracture toughness for ductile materials. With decrease of effective elastic modulus, an approximate linear relationship between logarithmic plastic penetration depth and logarithmic effective elastic modulus, and a quadratic polynomial relationship between the plastic penetration depths and penetration loads are exhibited by indentation investigation with Berkovich indenter. The damage constructive equation of effective elastic modulus is proposed to determine the critical effective elastic modulus at the fracture point, which is the key problem to calculate the indentation energy to fracture. The critical plastic penetration depth is identified after the critical effective elastic modulus can be predicted by conventional mechanical properties. The fracture toughness is calculated according to the equation of penetration load, plastic penetration depth and the critical plastic penetration depth.

Magnetic Circular Dichroism and Molecular Orbital Studies on Condensed Thiadiazoles

1983 ◽  
Vol 38 (11) ◽  
pp. 1263-1269 ◽  
Author(s):  
Akio Tajiri ◽  
Johannes Winkler
Keyword(s):  
Circular Dichroism ◽  
Molecular Orbital ◽  
Magnetic Circular Dichroism ◽  
Quantum Mechanical ◽  
Quantum Mechanical Calculations ◽  
Reasonable Explanation ◽  
Circular Dichroïsm ◽  
Good Agreement

Magnetic circular dichroism (MCD) spectra of some thiadiazoles have revealed the characteristic π → π* transitions in cata-condensed thiadiazoles. Within the framework of the PPP method quantum mechanical calculations have been carried out in order to give a reasonable explanation for the MCD spectra, resulting in a fairly good agreement between the experimental and theoretical Faraday parameters

A Numerical Study of the Effect of the Berkovich Indenter Orientation on the Elastic Response of Anisotropic Material

2014 ◽  
Vol 606 ◽  
pp. 65-68 ◽  
Author(s):  
Aleš Materna ◽  
Petr Haušild
Keyword(s):  
Grain Orientation ◽  
Numerical Study ◽  
Elastic Response ◽  
Berkovich Indenter ◽  
The Finite Element Method ◽  
Aisi 304 ◽  
Practical Applications ◽  
Steel Aisi ◽  
Stainless Steel Aisi ◽  
Crystallographic Orientations

The effect of the grain orientation of the stainless steel AISI 304 and the effect of the indenter orientation on the indentation moduli was numerically studied by means of the finite element method. The contact areas were evaluated numerically and the indentation moduli was determined according to the Oliver-Pharr method. As a result, the crystallographic orientations in which the indenter orientation plays the most important role were identified. However, the observed indentation moduli variation is within the scatter of the experimental data in practical applications.

scholarly journals Inverse elastographic method for analyzing the ocular lens compression test

2017 ◽  
Vol 10 (06) ◽  
pp. 1742009 ◽  
Author(s):  
Matthew A. Reilly ◽  
Andre Cleaver
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Molecular Basis ◽  
Human Lens ◽  
Ocular Lens ◽  
Loss Of Function ◽  
Manual Compression ◽  
Wild Type ◽  
Genetic Manipulations ◽  
Good Agreement

The ocular lens stiffens dramatically with age, resulting in a loss of function. However, the mechanism of stiffening remains unknown, at least in part due to difficulties in making reliable measurements of the intrinsic mechanical properties of the lens. Recent experiments have employed manual compression testing to evaluate the stiffness of murine lenses which have genotypes pertinent to human lens diseases. These experiments compare the extrinsic stiffness of lenses from the genotype of interest to the wild-type lens in an effort to reach conclusions regarding the cellular or molecular basis of lens stiffening. However, these comparisons are confounded by alterations in lens size and geometry which invariably accompany these genetic manipulations. Here, we utilize manual lens compression to characterize the stiffness of a porcine lens and a murine lens. An inverse elastographic technique was then developed to estimate the intrinsic shear modulus of each lens as well as the elastic modulus of the lens capsule. The results were in good agreement with the previous literature values.

scholarly journals Infrared spectroscopy, nano-mechanical properties, and scratch resistance of esthetic orthodontic coated archwires

2014 ◽  
Vol 85 (5) ◽  
pp. 777-783 ◽  
Author(s):  
Dayanne Lopes da Silva ◽  
Emanuel Santos ◽  
Sérgio de Souza Camargo ◽  
Antônio Carlos de Oliveira Ruellas
Keyword(s):  
Mechanical Properties ◽  
Infrared Spectroscopy ◽  
Elastic Modulus ◽  
Scratch Test ◽  
Scratch Resistance ◽  
Load Removal ◽  
Indentation Tests ◽  
Orthodontic Archwires ◽  
Scratch Tests ◽  
Coating Hardness

ABSTRACT Objective:  To evaluate the material composition, mechanical properties (hardness and elastic modulus), and scratch resistance of the coating of four commercialized esthetic orthodontic archwires. Materials and Methods:  The coating composition of esthetic archwires was assessed by Fourier-transform infrared spectroscopy (FTIR). Coating hardness and elastic modulus were analyzed with instrumented nano-indentation tests. Scratch resistance of coatings was evaluated by scratch test. Coating micromorphologic characteristics after scratch tests were observed in a scanning electron microscope. Statistical differences were investigated using analysis of variance and Tukey post hoc test. Results:  The FTIR results indicate that all analyzed coatings were markedly characterized by the benzene peak at about 1500 cm−1. The coating hardness and elastic modulus average values ranged from 0.17 to 0.23 GPa and from 5.0 to 7.6 GPa, respectively. Scratch test showed a high coating elasticity after load removal with elastic recoveries >60%, but different failure features could be observed along the scratches. Conclusion:  The coatings of esthetic archwires evaluated are probably a composite of polyester and polytetrafluoroethylene. Delamination, crack propagation, and debris generation could be observed along the coating scratches and could influence its durability in the oral environment.

The Deformation Mechanism at Pop-In: Monocrystalline Silicon under Nanoindentation with a Berkovich Indenter

2008 ◽  
Vol 389-390 ◽  
pp. 453-458 ◽  
Author(s):  
Li Chang ◽  
Liang Chi Zhang
Keyword(s):  
Mechanical Properties ◽  
Phase Transition ◽  
Loading Rate ◽  
Monocrystalline Silicon ◽  
Displacement Curve ◽  
Berkovich Indenter ◽  
Rapid Loading ◽  
Slope Change ◽  
Indentation Tests ◽  
Load Displacement

This paper investigates the “pop-in” behavior of monocrystalline silicon under nanoindentation with a Berkovich indenter. The indentation tests were carried out under ultra-low loads, i.e. 100 μN and 300 μN, with different loading/unloading rates. It was found that with the experimentally determined area function of the indenter tip, the mechanical properties of silicon can be accurately calculated from the load-displacement data, that a pop-in event represents the onset of phase transition, and that a lower loading rate favours a sudden volume change but a rapid loading process tends to generate a gradual slope change of the load-displacement curve.

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