Elastic recovery in the unloading process of pyramidal microindentation

2003 ◽  
Vol 18 (7) ◽  
pp. 1631-1640 ◽  
Author(s):  
M. Sakai
Keyword(s):  
Penetration Depth ◽  
Elastic Recovery ◽  
Elastic Half Space ◽  
Indentation Load ◽  
Test Results ◽  
Depth Of Penetration ◽  
Extensive Test ◽  
Novel Method ◽  
Loading And Unloading ◽  
Theoretical Considerations

It is confirmed on the basis of extensive test results for various ceramic and metallic materials that the indentation load P versus penetration depth h curves (P–h curves) both in loading and unloading processes are well approximated with the quadratic formulas of P = k1h2 and P = k2(h – hr)2, respectively, and unloading parameter k2 is quantitatively related to the elastic modulus E′ of the material indented, where hr is the residual penetration depth after a complete unload. The unloading/reloading indentation processes for a locally deformed conical/pyramidal impression are well represented by the equivalent mechanical process of a conical/pyramidal indenter with the effective face angle of βeff = (β – βr) on a flat elastic half-space, in terms of the inclined face angles β and βr of the indenter used and of the residual impression formed, respectively. With utilization of the unloading parameter k2 and the relative residual depth of penetration ξr, a novel method is proposed for estimating E′. Theoretical considerations for a nonquadratic P–h unloading behavior are also made.

The Indentation Load-depth Curve of Ceramics

1999 ◽  
Vol 14 (4) ◽  
pp. 1471-1484 ◽  
Author(s):  
M. Sakai ◽  
S. Shimizu ◽  
T. Ishikawa
Keyword(s):  
Surface Deformation ◽  
Test System ◽  
Indentation Load ◽  
Quadratic Functions ◽  
Test Results ◽  
Extensive Test ◽  
Physical Insight ◽  
Loading And Unloading ◽  
Material Measure

The pyramidal indentation-induced surface deformation of brittle ceramics is examined on the basis of extensive test results for indentation load (P)-depth (h) curves during loading/unloading cycle. A mechanically stiff test system is essential for obtaining P-h curves acceptable and reliable for subsequent analyses. Both the loading and unloading P-h curves are expressed by quadratic functions within experimental variations for all the indenters used (Vickers, Berkovich, and Knoop). The loading curve is then related to the Meyer hardness and the unloading curve to Young's modulus by the use of semiempirical equations which enable one to estimate these moduli from the observed loading/unloading parameters. An elastoplastic constitutive equation for indentation surface deformation is theoretically derived. This equation not only predicts well the experimental observations but also gains an important physical insight into the Meyer hardness. The Meyer hardness of brittle materials is not a measure for plasticity, but an elastic/plastic parameter which significantly depends on the geometry of indenter. The concept and experimental determination of “true” hardness as a characteristic material measure for plasticity are proposed.

The Conception of the Segmented Kinetic Energy Penetrators for Tank Guns

2010 ◽  
Vol 77 (5) ◽  
Author(s):  
Mariusz Magier
Keyword(s):  
Kinetic Energy ◽  
Penetration Depth ◽  
Steel Plate ◽  
Tungsten Alloy ◽  
Test Results ◽  
Axial Deformation ◽  
Review Of The Literature ◽  
Depth Of Penetration ◽  
Penetration Process ◽  
Firing Test

In this paper we present possibilities of increasing the depth of penetration through a steel plate by using segmented kinetic energy penetrators. Conclusions about the possibilities of increasing the penetration depth were formulated based on the critical review of the literature, simulations, and firing test results. A new concept called “forced segmented penetration,” where applied penetrator is composed of two tungsten alloy pieces connected by a screwed steel muff, is presented in this paper. The axial deformation of the connecting muff during the penetration process results in a decrease in the distance between tungsten segments. For this reason the rear segment can hit the front segment to give it some additional kinetic energy, enhancing the penetration depth. Such type of segmented penetration phenomena was not presented earlier. The numerical analyses of the segmented penetrator of the new design are presented in this paper.

scholarly journals LiDAR-Based Glass Detection for Improved Occupancy Grid Mapping

Sensors ◽  
2021 ◽  
Vol 21 (7) ◽  
pp. 2263
Author(s):  
Haileleol Tibebu ◽  
Jamie Roche ◽  
Varuna De Silva ◽  
Ahmet Kondoz
Keyword(s):  
Laser Scanner ◽  
Point Clouds ◽  
Light Detection And Ranging ◽  
Test Results ◽  
New Approach ◽  
Occupancy Grid ◽  
Laser Scanners ◽  
Novel Method ◽  
Occupancy Grid Mapping ◽  
Cartesian Coordinate

Creating an accurate awareness of the environment using laser scanners is a major challenge in robotics and auto industries. LiDAR (light detection and ranging) is a powerful laser scanner that provides a detailed map of the environment. However, efficient and accurate mapping of the environment is yet to be obtained, as most modern environments contain glass, which is invisible to LiDAR. In this paper, a method to effectively detect and localise glass using LiDAR sensors is proposed. This new approach is based on the variation of range measurements between neighbouring point clouds, using a two-step filter. The first filter examines the change in the standard deviation of neighbouring clouds. The second filter uses a change in distance and intensity between neighbouring pules to refine the results from the first filter and estimate the glass profile width before updating the cartesian coordinate and range measurement by the instrument. Test results demonstrate the detection and localisation of glass and the elimination of errors caused by glass in occupancy grid maps. This novel method detects frameless glass from a long range and does not depend on intensity peak with an accuracy of 96.2%.

Selective Leaching Nickel from the Pre-Reduced Limonitic Laterite Ore at Atmospheric Pressure

2012 ◽  
Vol 560-561 ◽  
pp. 494-498
Author(s):  
Yong Feng Chang ◽  
Chuan Lin Fan ◽  
Bin Chuan Li ◽  
Xiu Jing Zhai ◽  
Ting An Zhang
Keyword(s):  
Atmospheric Pressure ◽  
Ph Value ◽  
Test Results ◽  
Selective Leaching ◽  
Nickel Extraction ◽  
Extraction Degree ◽  
Leaching Solution ◽  
Novel Method ◽  
Leaching Condition ◽  
Laterite Ore

In this paper a novel method for selective leaching nickel from pre-reduced laterite ore at atmospheric pressure was reported. The reduced calcine was leached in thin acid liquor to liberate the nickel and iron together firstly. By properly controlling the leaching condition, the leached iron ion could hydrolyze as goethite precipitate and regenerate the acid consumed in the leaching procedure. Finally, the nickel is selectively extracted into the leaching solution. The main factors in the leaching process, such as reduction degree of the laterite ore, acidity of the leaching solution were investigated as influence on the nickel extraction. The test results showed that selectively leaching of nickel could be achieved with an extraction degree up to 90% by reducing most of the iron in the lateritic ore to wuestite and controlling the pH value of the leaching solution below 2.5.

A Four Novel Energy Pattern Factor Method for Computation of Weibull Parameter in Impact Strength Reliability of Fibre-Reinforced Concrete

2018 ◽  
Vol 7 (3.12) ◽  
pp. 272
Author(s):  
Gayathri R ◽  
Murali. G ◽  
Parthiban Kathirvel ◽  
Haridharan M.K ◽  
Karthikeyan. K
Keyword(s):  
Reinforced Concrete ◽  
Impact Strength ◽  
Shape Parameter ◽  
Failure Strength ◽  
Fibre Reinforced Concrete ◽  
Test Results ◽  
Weibull Parameter ◽  
Impact Failure ◽  
Novel Method ◽  
The Impact

Impact strength data is a noteworthy factor for designing airport pavements, civilian and military structures etc and it is ought to be modelled precisely. In order to achieve an appropriate modelling data, it is important to select a suitable estimation method. One such commonly used statistical tool is the two parameter Weibull distribution for modelling impact failure strength accurately besides the variations in test results. This study statistically commandsthe variations in the impact failure strength (number of blows to induce failure) of fibre reinforced concrete (FRC) subjected to drop hammer test. Subsequently, a four-different novel method for the computation of Weibull parameter (Shape parameter) based on the earlier researchers test results has been proposed. The accuracy of the proposed four novel method is demonstrated by comparing with power density method and verified with goodness of fit test. Finally, the impact failure strength of FRC is offered in terms of reliability. The proposed four NEPFM is very suitable and efficient to compute the shape parameter in impact failure strength applications. 

A New Method Developed for Brittle and Ductile Materials to Evaluate Mechanical Properties of a Lump Specimen in the Use of Indentation Test

2006 ◽  
Vol 129 (2) ◽  
pp. 284-292 ◽  
Author(s):  
Pal Jen Wei ◽  
Jen Fin Lin
Keyword(s):  
Yield Strength ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Elastic Recovery ◽  
Indentation Test ◽  
New Method ◽  
Ductile Materials ◽  
Conventional Material ◽  
Loading And Unloading ◽  
Logarithm Function

In this study, the load-depth (P‐h) relationships matching the experimental results of the nanoindentation tests exhibited at the subregions of small and large depths are obtained, respectively. The relationships associated with these two subregions are then linked by the hyperbolic logarithm function to attain a single expression that is applied in the evaluation of the specimen’s elastic recovery ability, as shown in the unloading process. A new method is developed in the present study to evaluate both Young’s modulus and the yield strength of either a ductile or brittle material through the uses of the appropriate P‐h relationships developed in the load and unloading processes. The results of the Young’s modulus and the yield strength achieved by the present method are compared to those obtained from the conventional material tests for a lump material. The scattering of the experimental data shown in the loading and unloading processes are also interpreted by different causes.

Simulation Analysis of the Working Process of the Corn Seed Metering Device with Combination Inner-Cell

2012 ◽  
Vol 215-216 ◽  
pp. 160-167 ◽  
Author(s):  
Qing Long Li ◽  
Ji Yang Yu ◽  
Qiang Qiang Zhang ◽  
Jian Qun Yu ◽  
Hong Fu
Keyword(s):  
Simulation Analysis ◽  
Three Dimensional ◽  
Bench Test ◽  
Particle Model ◽  
Test Results ◽  
Working Process ◽  
Corn Seed ◽  
3D Cad ◽  
Novel Method ◽  
Seed Metering Device

A three-dimensional discrete element method analytic model of the corn seed metering device with combination inner-cell was established based on its 3D CAD model, and the three-dimensional particle model of corn seeds was built by using the method of combination spherical particle. The working process of the corn seed metering device was simulated and analyzed by self-developed three-dimensional CAE software. It was observed that the simulative results of the seeding performance, clearing angles and dropping angles of the corn seeds well agreed with the bench test results. A novel method for studying and designing of the corn seed metering device was put forward.

Field testing and probabilistic assessment of ballistic penetration of steel plates for small calibre military ammunition

2018 ◽  
Vol 10 (4) ◽  
pp. 421-438 ◽  
Author(s):  
Mark G Stewart ◽  
Brianna Dorrough ◽  
Michael D Netherton
Keyword(s):  
Penetration Depth ◽  
Field Test ◽  
Predictive Models ◽  
High Strength ◽  
Field Testing ◽  
Hardened Steel ◽  
Steel Plates ◽  
Probabilistic Assessment ◽  
Test Results ◽  
Terminal Ballistics

The penetration of projectiles into semi-infinite targets helps in the understanding and modelling of terminal ballistics. The article describes field test results of 5.56×45 mm F1 Ball and 7.62×51 mm M80 Ball ammunition. The targets were 25-mm-thick mild and high strength steel plates of Grade 250 MPa and 350 MPa, respectively. The tests recorded penetration depth, muzzle and impact velocities, and bullet mass. Despite its smaller calibre, the 5.56 mm × 45 mm F1 Ball ammunition recorded deeper penetrations than the larger calibre 7.62 mm × 51 mm M80 Ball ammunition. This is due to the 5.56 mm ammunition comprising a hardened steel penetrator and lead core, whereas the 7.62 mm ammunition comprised only a lead core. Multiple shots were fired for each type of munition. The coefficient of variation of steel penetration is approximately 0.10 and 0.03 for 5.56 mm and 7.62 mm rounds, respectively. The article also presents predictive models of steel penetration depth and compares these to the field test results.

scholarly journals SYNTHESIS AND STABILITY OF RESVERATROL-CONJUGATED GOLD NANOPARTICLES MODIFIED WITH POLYETHYLENE GLYCOL

2020 ◽  
pp. 230-236
Author(s):  
RADITYA ISWANDANA ◽  
RICHA NURSELVIANA ◽  
SUTRIYO SUTRIYO
Keyword(s):  
Particle Size ◽  
Gold Nanoparticles ◽  
Polyethylene Glycol ◽  
Zeta Potential ◽  
High Performance ◽  
Entrapment Efficiency ◽  
Test Results ◽  
Novel Method ◽  
The Stability ◽  
Phosphate Buffered Saline

Objective: Gold nanoparticles (AuNPs) are highly useful for drug delivery, but their application is limited by their stability as they readily aggregate.This issue can be prevented by adding a stabilizing agent such as resveratrol (RSV), which is a polyphenol derived from plants, that is used to preventcancer. Therefore, we propose a novel method to prepare stable RSV-conjugated nanoparticles modified with polyethylene glycol (RSV-AuNP-PEG).Methods: In the first step, the Turkevich method was used to synthesize the AuNPs. Then, PEG was added as stabilizer agent and conjugated with RSV.The synthesized conjugates were characterized using ultraviolet-visible spectrophotometry, Fourier transform infrared spectroscopy, particle sizeanalysis, and high-performance liquid chromatography.Results: The obtained RSV-AuNP-PEG had a particle size of 83.93 nm with a polydispersity index (PDI) of 0.562 and formed a translucent purple-redfluid in solution. The zeta potential was −22.9 mV, and the highest entrapment efficiency was 75.86±0.66%. For comparison, the RSV-AuNP solutionwas purple and turbid, the particle size was 51.97 nm with a PDI of 0.694, and the zeta potential was −24.6 mV. The stability test results showed thatthe storage stability of RSV-AuNP-PEG was better than that of AuNP-RSV. Further, the RSV-AuNP-PEG was shown to be most stable in 2% bovine serumalbumin (BSA) while the AuNP-RSV was most stable in 2% BSA in phosphate-buffered saline pH 7.4.Conclusion: These results show that modification of RSV-conjugated AuNPs with PEG effectively prevents their aggregation in storage, but only incertain mediums.

A Novel Method to Qualify the Status of Printing Process Rapidly

2010 ◽  
Vol 174 ◽  
pp. 203-206 ◽  
Author(s):  
Ying Wang ◽  
Hao Xue Liu ◽  
Min Huang
Keyword(s):  
Test Results ◽  
Single Test ◽  
Test Sheet ◽  
Solid Density ◽  
Printing Quality ◽  
Dot Gain ◽  
The Status ◽  
Density Values ◽  
Novel Method ◽  
Printing Ink

According to the characteristics of ink feeding and printing quality control principles, a new test sheet was designed for qualifying press state and the test results were discussed in this paper. This test sheet was printed under the condition that printing ink volume for different ink zone is identical. Solid density, dot gain and print contrast of different printing ink volume were simulated on a single test sheet, and thus the optimal printing status can be determined quickly. Experiment results show that this method is accessible, economic, and rapid. The optimum solid density values can be got easily for all primary colors on a single test sheet. This method is suit for the adjustment of printing status.

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