scholarly journals Application of Nanoindentation in the Characterization of a Porous Material with a Clastic Texture

Materials ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4579
Author(s):  
Sathwik S. Kasyap ◽  
Kostas Senetakis
Keyword(s):  
Materials Science ◽  
Complex Structure ◽  
Elastic Stiffness ◽  
Indentation Load ◽  
Nanoindentation Test ◽  
Displacement Curve ◽  
Indentation Tests ◽  
Materials Science And Engineering ◽  
Loading And Unloading ◽  
Load Displacement

In materials science and engineering, a significant amount of research has been carried out using indentation techniques in order to characterize the mechanical properties and microstructure of a broad range of natural and engineered materials. However, there are many unresearched or partly researched areas, such as, for example, the investigation of the shape of the indentation load–displacement curve, the associated mechanism in porous materials with clastic texture, and the influence of the texture on the constitutive behavior of the materials. In the present study, nanoindentation is employed in the analysis of the mechanical behavior of a benchmark material composed of plaster of Paris, which represents a brand of highly porous-clastic materials with a complex structure; such materials may find many applications in medicine, production industry, and energy sectors. The focus of the study is directed at the examination of the influence of the porous structure on the load–displacement response in loading and unloading phases based on nanoindentation experiments, as well as the variation with repeating the indentation in already indented locations. Events such as pop-in in the loading phase and bowing out and elbowing in the unloading phase of a given nanoindentation test are studied. Modulus, hardness, and the elastic stiffness values were additionally examined. The repeated indentation tests provided validations of various mechanisms in the loading and unloading phases of the indentation tests. The results from this study provide some fundamental insights into the interpretation of the nanoindentation behavior and the viscoelastic nature of porous-clastic materials. Some insights on the influence of indentation spacing to depth ratio were also obtained, providing scope for further studies.

scholarly journals Erratum: “Indentation responses of time-dependent films on stiff substrates” [J. Mater. Res. 19, 2487 (2004)]

2004 ◽  
Vol 19 (10) ◽  
pp. 3120-3121
Keyword(s):  
Power Law ◽  
Peak Load ◽  
Indentation Load ◽  
Small Peak ◽  
Peak Loads ◽  
Materials Research ◽  
Indentation Tests ◽  
Unloading Rate ◽  
Loading And Unloading ◽  
Load Displacement

This article appeared in the August 2004 issue of Journal of Materials Research. The following corrections are required.Section II. Experiments p. 2488The third paragraph in the Experiments section should appear as follows:One mechanism to explore changes in the shape of an indentation load-displacement response is to normalize the trace by its peak point. It has been demonstrated that the normalized [h/h(PMAX), P/PMAX] experimental responses for bulk polymers indented at constant loading- and unloading rate with the same rise time (but at different peak load levels) are identical. Figure 1(a) shows raw load-displacement data for indentation tests performed at small peak loads in the thickest polymer film (Epon) in the current study. The peak loads, 1 and 2 mN, were chosen to correspond to depths less than 10% of the film thickness in both cases. The responses normalize to the same shape [Fig. 1(b)]. When the 1-mN normalized response is compared with those from much greater load levels (50 and 500 mN), there are clear changes in the shape of the response, both loading and unloading [Fig. 1(c)]. In particular, the loading response shifts from slightly less than quadratic (power law fit with exponent 1.8) for the 1-mN response, as would be expected for a quadratic material with some creep effect; to a response between quadratic and cubic (power law fit with exponent 2.6) for the 500-mN response. The unloading response is also altered in shape, with a steeper unloading tangent at the larger load.

Uniqueness of reverse analysis from conical indentation tests

2004 ◽  
Vol 19 (8) ◽  
pp. 2498-2502 ◽  
Author(s):  
K.K. Tho ◽  
S. Swaddiwudhipong ◽  
Z.S. Liu ◽  
K. Zeng ◽  
J. Hua
Keyword(s):  
Material Properties ◽  
Plastic Material ◽  
Large Strain ◽  
Indentation Load ◽  
Initial Slope ◽  
Displacement Curve ◽  
Maximum Indentation Depth ◽  
Indentation Tests ◽  
Reverse Analysis ◽  
Load Displacement

The curvature of the loading curve, the initial slope of the unloading curve, and the ratio of the residual depth to maximum indentation depth are three main quantitiesthat can be established from an indentation load-displacement curve. A relationship among these three quantities was analytically derived. This relationship is valid for elasto-plastic material with power law strain hardening and indented by conical indenters of any geometry. The validity of this relationship is numerically verified through large strain, large deformation finite element analyses. The existence of an intrinsic relationship among the three quantities implies that only two independent quantities can be obtained from the load-displacement curve of a single conical indenter. The reverse analysis of a single load-displacement curve will yield non-unique combinations of elasto-plastic material properties due to the availability of only two independent quantities to solve for the three unknown material properties.

scholarly journals A Molecular Dynamics Investigation of the Temperature Effect on the Mechanical Properties of Selected Thin Films for Hydrogen Separation

Membranes ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 241
Author(s):  
Sunday Temitope Oyinbo ◽  
Tien-Chien Jen
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Mechanical Characteristics ◽  
Loading Rate ◽  
Indentation Load ◽  
Nanoindentation Test ◽  
Film Hardness ◽  
Loading And Unloading ◽  
Effects Of Temperature ◽  
The Impact

In this study, we performed nanoindentation test using the molecular dynamic (MD) approach on a selected thin film of palladium, vanadium, copper and niobium coated on the vanadium substrate at a loading rate of 0.5 Å/ps. The thermosetting control is applied with temperature variance from 300 to 700 K to study the mechanical characteristics of the selected thin films. The effects of temperature on the structure of the material, piling-up phenomena and sinking-in occurrence were considered. The simulation results of the analysis and the experimental results published in this literature were well correlated. The analysis of temperature demonstrated an understanding of the impact of the behaviour. As the temperature decreases, the indentation load increases for loading and unloading processes. Hence, this increases the strength of the material. In addition, the results demonstrate that the modulus of elasticity and thin-film hardness decreases in the order of niobium, vanadium, copper and palladium as the temperature increases.

Nanoindentation Test and Stress Fields Simulation of Hot-Pressed Silicon Nitride Ceramic

2012 ◽  
Vol 472-475 ◽  
pp. 2207-2210
Author(s):  
Guo Chao Qiao ◽  
Ming Zhou ◽  
Ming Wang
Keyword(s):  
Silicon Nitride ◽  
Material Removal ◽  
Stress Fields ◽  
Nanoindentation Test ◽  
Displacement Curve ◽  
Hot Press ◽  
Silicon Nitride Ceramic ◽  
Whole Process ◽  
Loading And Unloading ◽  
Distribution Of Stress

In order to investigate material properties of silicon nitride ceramic, nanoindentation tests are carried out on Hot-press silicon nitride specimen. The micro-hardness and elastic modulus are obtained. simultaneously, load-displacement curve is acquired. The whole process is simulated in ansys. Through comparing, there are satisfactory consistency between experimental curve and simulation curve. In addition, simulation can also indicate the distribution of stress fields during loading and unloading process. Base on these informations, the mode of cracks development and mechanism of material removal can be known.

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.

Fracture Toughness Measurement of Asphalt Concrete by Nanoindentation

2017 ◽  
Author(s):  
Zafrul Khan ◽  
Hasan M. Faisal ◽  
Rafiqul Tarefder
Keyword(s):  
Fracture Toughness ◽  
Energy Release Rate ◽  
Fracture Energy ◽  
Energy Release ◽  
Release Rate ◽  
Asphalt Concrete ◽  
Nanoindentation Test ◽  
Displacement Curve ◽  
Macro Scale ◽  
Load Displacement

Fracture toughness and fracture energy release rate are two important parameters to understand the crack propagation within any material. Fracture toughness of asphalt concrete (AC) is vital to explain the fatigue cracking and low temperature cracking of asphalt pavement. These two types of distresses are still unsolved issues for asphalt researchers. Measuring fracture toughness of AC is not a new phenomenon. Recently, researchers have used several techniques to measure the fracture toughness of AC. Tests like semi-circular bending (SCB) and disk-shaped compact specimen (DCT) testing have been used to measure the fracture toughness of the AC. From the SCB or DCT tests, past researchers have shown that crack in AC propagates through mainly binder and mastic phase. All these conventional tests are carried out in macro scale. It is important to understand that before propagation of these macro scale cracks, the cracks initiates at the nano/micro scale level. With the increment of the loads these nanoscale cracks become macro scale cracks and propagates through the sample. Therefore, it is important to understand the cracks at nanoscale. In this study, nanoindentation test was introduced to measure the fracture toughness of the asphalt concrete. In a nanoindentation test, the sample surface is indented with a loaded indenter. For this test, Berkovich indenter with load control method was used. A field cored asphalt concrete sample was used for this study. The sample was collected by coring at interstate 40 (I-40) near Albuquerque, New Mexico. The sample was field aged for four years. The maximum load applied in this study was 5-mn and the unloading was done at a faster rate than the loading rate. From the load-displacement curves of the nanoindentation tests, fracture toughness of the samples was measured. The unloading curve of the nanoindentation test was further used to obtain reduced modulus of the asphalt concrete using Oliver-Pharr method. In this study, fracture energy is thought of as a portion of irreversible energy. This irreversible energy is comprised of plastic energy and energy required for propagation of crack. By analyzing the load displacement curve along with the maximum indentation depth, energy release rate and mode I fracture toughness of asphalt concrete was measured.

THE PLASTICITY OF MONOCRYSTALLINE SILICON UNDER NANOINDENTATION

2008 ◽  
Vol 22 (31n32) ◽  
pp. 6022-6028 ◽  
Author(s):  
LI CHANG ◽  
L. C. ZHANG
Keyword(s):  
Plastic Deformation ◽  
Shape Change ◽  
Indentation Load ◽  
Monocrystalline Silicon ◽  
Displacement Curve ◽  
Wide Range ◽  
Rapid Loading ◽  
Load Displacement ◽  
The Difference ◽  
Critical Contact

This paper focuses on a fundamental understanding of the plastic deformation mechanism in monocrystalline silicon subjected to nanoindentation. It was found that over a wide range of indentation loads from 100 μN to 30 mN and loading/unloading rates from 3.3 μN/s to 10 mN/s, the plasticity of silicon is mainly caused by stress-induced phase transitions. The results indicate that the critical contact pressure for phase transition at unloading is almost constant, independent of the maximum indentation load ( P max ) and loading/unloading rates. However, the shape of the load-displacement curves greatly relies on the loading/unloading conditions. In general, higher P max and lower unloading/loading rates favor an abrupt volume change and thus a discontinuity in the load-displacement curve, commonly referred to as pop-in and/or pop-out events; whereas smaller P max and rapid loading/loading processes tend to generate gradual slope changes of the curves. This study concludes that the difference in the curve shape change does not indicate the mechanism change of plastic deformation in silicon.

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