A simple microindentation technique for mapping the microscale compliance of soft hydrated materials and tissues

2006 ◽  
Vol 79A (3) ◽  
pp. 485-494 ◽  
Author(s):  
Jeffrey G. Jacot ◽  
Scott Dianis ◽  
Joshua Schnall ◽  
Joyce Y. Wong
Keyword(s):  
Microindentation Technique

A microindentation technique to measure rheological properties of the vascular intima

1975 ◽  
Vol 38 (2) ◽  
pp. 344-350 ◽  
Author(s):  
B. S. Gow ◽  
R. N. Vaishnav
Keyword(s):  
Time Dependent ◽  
Rigid Support ◽  
Adjacent Tissue ◽  
Surface Probe ◽  
Arterial Tissue ◽  
Lower Variation ◽  
The Mean ◽  
Hydrodynamic Stresses ◽  
Aortic Intima ◽  
Microindentation Technique

A microindentor was developed to measure the depth of indentation of the intimal surface of arterial tissue loaded by flat-ended, cylindrical probes. The depth of indentation depended on the initial stretch of the tissue which required a rigid support (plaster of Paris) beneath the adventitial surface. Probe tips used ranged from 550-mum down to 65-mum diameter while loads ranged from 800 to 15 mg. The depth of indentation was markedly time dependent; that obtained 30 s after loading (variation of 30) was reproducible and served as a useful parameter of viscoelasticity of the aortic intima and supporting tissues of dog and man. The mean variation of 30 (0.19-mm diam tip, 120-mg load), obtained from longitudinal series of indentations of nine dog aortas, ranged from 40.8 to 68.8 mum while coefficient of variation in these series ranged from 4.8 to 15.9%. Intimal pads were found to have greater resistance to identation than adjacent tissue; likewise the tissue on the dorsal, intimal surface of the aorta had lower variation of 30 values compared with the rest of the intima. Lipid-filled intimal regions were about twice as complaint as macroscopically spared areas. The technique should prove useful in understanding the microrheological response of the blood vascular interface to hydrodynamic stresses.

Relationship Between Stress and Surface Roughness in Krypton Implanted MgO

1994 ◽  
Vol 356 ◽  
Author(s):  
Laurence Gea ◽  
Jean-Luc Loubet ◽  
Roger Brenier ◽  
Paul Thevenard
Keyword(s):  
Surface Roughness ◽  
Atomic Force Microscope ◽  
Single Crystals ◽  
Internal Stresses ◽  
Post Irradiation ◽  
Implantation Damage ◽  
Atomic Force ◽  
Microindentation Technique ◽  
Good Agreement

Abstract(001) MgO single crystals were implanted with 150 keV krypton ions (Kr+) at a fluence of 5.1016 ions.cm-2 . The implanted surface, observed with an Atomic Force Microscope (AFM) exhibits striking features that can be described as undulations with a wavelength of 0.5 [μm. We correlate these features to the decrease in density and the stresses induced by the implantation damage. As a matter of fact, a model of surface instabilities provides a relationship between the wavelength of the ondulations and internal stresses. Using this model, implantation stresses are calculated to 2.2 GPa. This is in good agreement with the value of 2 GPa obtained with the help of the microindentation technique and the literature data. Some effects of an ionizing post-irradiation on stress and surface roughness are described.

scholarly journals Synthesis and Characterization of Nanostructured Blends of Epoxy Resin and Block Copolymers

2013 ◽  
Vol 13 (1) ◽  
pp. 81-88 ◽  
Author(s):  
Rajesh Pandit ◽  
Albrecht Berkessel ◽  
Ralf Lach ◽  
Wolfgang Grellmann ◽  
Rameshwar Adhikari
Keyword(s):  
Fourier Transform ◽  
Block Copolymer ◽  
Block Copolymers ◽  
Bisphenol A ◽  
Epoxy Resin ◽  
Layered Silicate ◽  
Diglycidyl Ether ◽  
Synthesis And Characterization ◽  
Microindentation Technique

Polystyrene–polybutadiene block copolymers having different molecular architectures were epoxidized by using meta-chloroperoxybenzoic acid (MCPBA). Then, the blends with epoxy resin (diglycidyl ether of bisphenol-A; DGEBA) and their nanocomposites with boehmite and layered silicate nanofiller in presence of methylene dianiline (MDA) as a hardener were prepared. The epoxidized copolymers and the composites were characterized by Fourier transform infrared (FTIR) spectroscopy and microindentation technique. In this way, it was possible to tune the morphology of the nanostructured blends of the epoxy resin using the functionalized block copolymer as the template. The presence of nanostructured morphology was attested by the optical transparency of the blends as well as of the composites with nanofiller. The microhardness properties were improved by the incorporation of the nanoparticles, viz. boehmite and layered silicate. Nepal Journal of Science and Technology Vol. 13, No. 1 (2012) 81-88 DOI: http://dx.doi.org/10.3126/njst.v13i1.7445

The AC-Indentation Technique and its Application to Al and Al-Si Coatings

1991 ◽  
Vol 226 ◽  
Author(s):  
T.W. Wu
Keyword(s):  
Penetration Depth ◽  
High Sensitivity ◽  
Small Displacement ◽  
Depth Profiles ◽  
Indentation Technique ◽  
Indentation Process ◽  
Microindentation Technique ◽  
Penetration Depths ◽  
Selection Of

AbstractAn ac-microindentation technique, namely indenting with a small displacement modulation superimposed on an otherwise linear indenter motion, will be introduced. The basic principle and theory will also be illustrated by using a mechanical model to simulate the indenter behavior.Other than being as capable as conventional indentation, the ac-technique acquires the unloading slope simultaneously and continuously with the penetration depth and applied load during an entire indentation process. With this extra information, the conversion between the total depth and plastic depth can be executed right after a single indentation, and in turn the hardness as well as. contact modulus depth profiles can be calculated. This is in contrast to the conventional indentation technique where a group of indentations associated with different maximum loads are required in order to achieve the same purpose. Furthermore, it also avoids the subjectivity in the selection of the fitting portions from the unloading stage of an indentation curve to extract the unloading slopes as well as the plastic penetration depths.Another important advantage of using this ac-technique is the high sensitivity in detecting the indenter/surface contact. This advantage is very useful in the determination of the origins of penetration depths as well as in the investigation the evolution of the contact area, and both issues are very crucial in the microhardness calculations.The strain rate effect on the hardness measurements of a 1 μm thick Al-2%Si coating has been demonstrated by using the ac-technique. As the indenter loading speed increases from 2.5 to 10 nm/sec, the measured hardness of the coating can be increased from ∼20% to ∼80% depending on the penetration depth, and the shallower the penetration depth the larger the increment is. However, the contact modulus depth profiles remain unchanged for all the indentation rates.

Determination of elastic moduli of GaN epitaxial layers by microindentation technique

2000 ◽  
Vol 42 (3) ◽  
pp. 437-440 ◽  
Author(s):  
V. I. Nikolaev ◽  
V. V. Shpeizman ◽  
B. I. Smirnov
Keyword(s):  
Elastic Moduli ◽  
Epitaxial Layers ◽  
Microindentation Technique

Fiberoptic microindentation technique for early osteoarthritis diagnosis: an in vitro study on human cartilage

2019 ◽  
Vol 21 (1) ◽  
Author(s):  
G. Marchi ◽  
P. Foehr ◽  
S. Consalvo ◽  
A. Javadzadeh-Kalarhodi ◽  
J. Lang ◽  
...  
Keyword(s):  
In Vitro Study ◽  
Vitro Study ◽  
Early Osteoarthritis ◽  
Human Cartilage ◽  
Microindentation Technique
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