scholarly journals NANOMECHANICAL CHARACTERIZATION OF INDIUM PHOSPHIDE EPILAYER USING NANOINDENTATION TECHNIQUE

2014 ◽  
pp. 44-48
Author(s):  
DIPIKA ROBIDAS ◽  
ARUNSESHAN C ◽  
DEEPTHI K. R ◽  
ARIVUOLI D
Keyword(s):  
Indium Phosphide ◽  
Modulus Of Elasticity ◽  
Significant Variation ◽  
Applied Load ◽  
Mechanical Characteristics ◽  
Mechanical Parameters ◽  
Nanoindentation Technique ◽  
Hardness Values ◽  
Measured Hardness

The Nanomechanical characteristics of InP epilayer grown on GaAs (100) substrate is studied. The mechanical characteristics of the material such as hardness, modulus of elasticity, stiffness, contact depth etc. were studied by Nanoindentation technique with different probe geometries like Berkovich and Vickers. The results show significant variation in the mechanical parameters with respect to the tip geometry and the measured hardness values were observed to increase with the applied load.

scholarly journals Comparative Study on Micromechanical Properties of ZnO:Ga and ZnO:In Luminiscent Ceramics

2021 ◽  
Vol 58 (1) ◽  
pp. 23-32
Author(s):  
F. Muktepavela ◽  
A. Zolotarjovs ◽  
R. Zabels ◽  
K. Kundzins ◽  
E. Gorokhova ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Modulus Of Elasticity ◽  
Mechanical Characteristics ◽  
X Ray ◽  
Micromechanical Properties ◽  
Doped Zno ◽  
Hardness Values ◽  
Zno Ceramics ◽  
Scanning Electron

Abstract Indium (0.038 at.%) and gallium (0.042 at.%) doped ZnO ceramics were prepared by hot pressing. Ceramics were investigated to determine their structural and mechanical characteristics for the prospective use in scintillators. Based on results of nanoindentation, atom force and scanning electron microscopy as well as energy dispersive X-ray spectra measurements, locations of gallium within grain, indium at grain boundaries (GBs) and their different effect on the mechanical properties of ZnO ceramics were detected. Doping of gallium led to the increased modulus of elasticity in grain, decreased hardness near GBs, stabilization of micropores and brittle intercrystalline fracture mode. ZnO:In ceramic has modulus of elasticity and hardness values close to ZnO characteristics, the increased fracture toughness and some plasticity near GBs. Differences in the micromechanical properties of the ceramics correlate with the location of dopants. Results demonstrate that the ZnO:In ceramic has a greater stress relaxation potential than the ZnO:Ga.

The Mechanical Properties of Some Polymer Composites Based on Natural Rubber

2018 ◽  
Vol 55 (1) ◽  
pp. 115-120
Author(s):  
Maria Daniela Stelescu ◽  
Daniel Comeaga ◽  
Maria Sonmez ◽  
Dana Gurau
Keyword(s):  
Natural Rubber ◽  
Polymer Composites ◽  
Mechanical Characteristics ◽  
Filler Content ◽  
Classical Method ◽  
Mechanical Parameters ◽  
Vibration Frequencies ◽  
Internal Damping ◽  
Polyfunctional Monomer

This paper presents the development and characterization of polymer composites based on natural rubber, crosslinked using two types of vulcanization systems, as follows: the classical method using sulfur and curing accelerators and the method using peroxide in the presence of a polyfunctional monomer - trimethylolpropanetrimethacrylate. The composites were made with 0 parts to 100 parts rubber (phr) and 40 phr filler content. The physical-mechanical characteristics of resulting composites depend on the crosslinking method and on the composition. The mechanical parameters of materials were derived by processing the transmissibility curves, derived for samples with known dimensions and density. The main vibration frequencies and the quality factor, derived in the vicinity of resonances, allow to derive the elasticity and internal damping of materials.

Characterization of Indentation Size Effect of Hardness Using a Loading Curve from Crystalline Materials

2007 ◽  
Vol 29-30 ◽  
pp. 55-58 ◽  
Author(s):  
Y.L. Chiu ◽  
W. George Ferguson
Keyword(s):  
Size Effect ◽  
Indentation Size Effect ◽  
Indentation Test ◽  
Indentation Size ◽  
Depth Sensing ◽  
Crystalline Materials ◽  
Nanoindentation Technique ◽  
Series Measurement ◽  
Hardness Values

Nanoindentation technique has been widely used for measuring mechanical properties from a very small volume of material. The hardness measured using the depth sensing nanoindentation technique often decreases with increasing indentation size, the so called indentation size effect (ISE)[1, 2]. It has been generally acknowledged that the ISE in crystalline materials originates from the density change of geometrically necessary dislocations (GND) needed to accommodate a permanent indentation imprint. Conventionally, to characterize an ISE often requires a series measurement of hardness values at different indentation size. Based on the celebrated Oliver-Pharr scheme[3]. We propose a method to derive the ISE from the loading curve of one single indentation test. The application and limitation of the proposed method will be discussed.

scholarly journals Experimental Evaluation of Shear Behavior of Stone Masonry Wall

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2313
Author(s):  
Maria Luisa Beconcini ◽  
Pietro Croce ◽  
Paolo Formichi ◽  
Filippo Landi ◽  
Benedetta Puccini
Keyword(s):  
Shear Behavior ◽  
Stone Masonry ◽  
Masonry Walls ◽  
Mechanical Parameters ◽  
In Situ Tests ◽  
Capacity Curves ◽  
Historical Structures ◽  
Definition Of

The evaluation of the shear behavior of masonry walls is a first fundamental step for the assessment of existing masonry structures in seismic zones. However, due to the complexity of modelling experimental behavior and the wide variety of masonry types characterizing historical structures, the definition of masonry’s mechanical behavior is still a critical issue. Since the possibility to perform in situ tests is very limited and often conflicting with the needs of preservation, the characterization of shear masonry behavior is generally based on reference values of mechanical properties provided in modern structural codes for recurrent masonry categories. In the paper, a combined test procedure for the experimental characterization of masonry mechanical parameters and the assessment of the shear behavior of masonry walls is presented together with the experimental results obtained on three stone masonry walls. The procedure consists of a combination of three different in situ tests to be performed on the investigated wall. First, a single flat jack test is executed to derive the normal compressive stress acting on the wall. Then a double flat jack test is carried out to estimate the elastic modulus. Finally, the proposed shear test is performed to derive the capacity curve and to estimate the shear modulus and the shear strength. The first results obtained in the experimental campaign carried out by the authors confirm the capability of the proposed methodology to assess the masonry mechanical parameters, reducing the uncertainty affecting the definition of capacity curves of walls and consequently the evaluation of seismic vulnerability of the investigated buildings.

scholarly journals PDMS electrodes for recording and stimulation

2017 ◽  
Vol 3 (1) ◽  
pp. 63-67 ◽  
Author(s):  
Alexander Brensing ◽  
Roman Ruff ◽  
Benjamin Fischer ◽  
Sascha L. Wien ◽  
Klaus-Peter Hoffmann
Keyword(s):  
Mechanical Characteristics ◽  
Surrounding Tissue ◽  
Similar Form ◽  
Flexible Electrodes ◽  
Young’S Moduli

Abstract:The usability of flexible electrodes in moving environment is limited due to different mechanical characteristics of their metallic and polymeric components. To achieve structure compatible electrodes, all used materials need to have similar Young’s moduli as the surrounding tissue. This paper describes the characterization of macroscopic as well as miniaturized electrodes entirely made out of modified silicone (PDMS). Electrochemical, mechanical, biological, optical, and applicative methods were used. It could be shown, that PDMS electrodes are capable to be used for recording electrocardiograms with similar form and amplitude as with standard electrodes.

scholarly journals Correlation of Global Quantities at Material Characterization of Pressure-Sensitive Materials Using Sharp Indentation Testing

Lubricants ◽  
2021 ◽  
Vol 9 (3) ◽  
pp. 29
Author(s):  
Carl F. O. Dahlberg ◽  
Jonas Faleskog ◽  
Per-Lennart Larsson
Keyword(s):  
Finite Element ◽  
Material Characterization ◽  
Pressure Sensitivity ◽  
Pressure Sensitive ◽  
The Mean ◽  
Sharp Indentation ◽  
Von Mises ◽  
Von Mises Plasticity ◽  
Hardness Values

Correlation of sharp indentation problems is examined theoretically and numerically. The analysis focuses on elastic-plastic pressure-sensitive materials and especially the case when the local plastic zone is so large that elastic effects on the mean contact pressure will be small or negligible as is the case for engineering metals and alloys. The results from the theoretical analysis indicate that the effect from pressure-sensitivity and plastic strain-hardening are separable at correlation of hardness values. This is confirmed using finite element methods and closed-form formulas are presented representing a pressure-sensitive counterpart to the Tabor formula at von Mises plasticity. The situation for the relative contact area is more complicated as also discussed.

Influence of the Residue of Casting by Lost Wax in the Modulus of Elasticity and Porosity of Concretes

2014 ◽  
Vol 805 ◽  
pp. 343-349
Author(s):  
Carine F. Machado ◽  
Weber G. Moravia
Keyword(s):  
Construction Industry ◽  
Modulus Of Elasticity ◽  
Chemical Characterization ◽  
Microstructural Characterization ◽  
Cement Matrix ◽  
X Ray Diffraction ◽  
X Ray ◽  
Hardened State ◽  
Material Powder

This work evaluated the influence of additions of the ceramic shell residue (CSR), from the industries of Lost Wax Casting, in the modulus of elasticity and porosity of concrete. The CSR was ground and underwent a physical, chemical, and microstructural characterization. It was also analyzed, the environmental risk of the residue. In the physical characterization of the residue were analyzed, the surface area, and particle size distribution. In chemical characterization, the material powder was subjected to testing of X-ray fluorescence (XRF). Microstructural characterization was performed by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The residue was utilized like addition by substitution of cement in concrete in the percentages of 10% and 15% by weight of Portland cement. It was evaluated properties of concrete in the fresh and hardened state, such as compressive strength, modulus of elasticity, absorption of water by total immersion and by capillarity. The results showed that the residue can be used in cement matrix and improve some properties of concrete. Thus, the CSR may contribute to improved sustainability and benefit the construction industry.

Characterization of a Liquid-Metal Micro Droplets Thermal Interface Material

2010 ◽  
Author(s):  
Amer M. Hamdan ◽  
Aric R. McLanahan ◽  
Robert F. Richards ◽  
Cecilia D. Richards
Keyword(s):  
Liquid Metal ◽  
Thermal Resistance ◽  
Contact Resistance ◽  
Applied Load ◽  
Thermal Interface Material ◽  
Thermal Interface ◽  
Interface Resistance ◽  
Thermal Interface Resistance ◽  
Droplet Array

This work presents the characterization of a thermal interface material consisting of an array of mercury micro droplets deposited on a silicon die. Three arrays were tested, a 40 × 40 array (1600 grid) and two 20 × 20 arrays (400 grid). All arrays were assembled on a 4 × 4 mm2 silicon die. An experimental facility which measures the thermal resistance across the mercury array under steady state conditions is described. The thermal interface resistance of the arrays was characterized as a function of the applied load. A thermal interface resistance as low as 0.253 mm2 K W−1 was measured. A model to predict the thermal resistance of a liquid-metal micro droplet array was developed and compared to the experimental results. The model predicts the deformation of the droplet array under an applied load and then the geometry of the deformed droplets is used to predict the thermal resistance of the array. The contact resistance of the mercury arrays was estimated based on the experimental and model data. An average contact resistance was estimated to be 0.14 mm2 K W−1.

Sign in / Sign up

Export Citation Format

Share Document