scholarly journals Investigating the Influences of Indentation Hardness and Brittleness of Rock-Like Material on Its Mechanical Crushing Behaviors

2020 ◽  
Vol 2020 ◽  
pp. 1-16
Author(s):  
Jiuqun Zou ◽  
Jihuan Han ◽  
Weihao Yang
Keyword(s):  
Mechanical Properties ◽  
Correlation Coefficient ◽  
Specific Energy ◽  
Indentation Test ◽  
Experimental Results ◽  
Indentation Hardness ◽  
Conical Pick ◽  
Artificial Rock ◽  
Structure Plane ◽  
Mechanical Crushing

Indentation hardness and brittleness are the important factors to be considered in the study of rock-like materials’ mechanical crushing behaviors. The brittleness of rock-like materials is defined as the ratio of uniaxial compressive strength to tensile strength in this paper. In order to investigate the influences of hardness and brittleness on rock-like materials’ crushing behaviors, quartz sand and high strength α-hemi-hydrated gypsum were used to prepare rock-like materials with different hardness and brittleness through different mass ratios. The artificial rock-like materials can eliminate the effects of natural rock’s weak structure plane on experimental results. The indentation test, Uniaxial compressive test, and Brazilian tensile test were conducted for characterizing the indentation hardness and brittleness of this artificial rock-like materials. The experimental results showed that brittleness increased with the increase of indentation hardness with high correlation coefficient. The confining stress presented a positive impact on the indentation hardness of the rock-like materials. Based on those mechanical properties, the numerical rock models were calculated to study rock crushing behaviors using discrete element method (DEM). A series of rock crushing tests were conducted to investigate the influences of hardness and brittleness of rock-like materials on rock crushing behaviors using a conical pick cutter. The numerical results showed that the normalized specific energy was negatively correlated with indentation hardness index (IHI). The normalized specific energy decreased with the increase of brittleness index (BI) with a high correlation coefficient. This study is beneficial in utilizing IHI and BI to evaluate the mechanical properties, failure patterns, and mechanical crushing efficiency of rock-like materials.

Improving Surface Properties of Linear Polyethylene by Radiation Measured by Ultra-Nano Indentation Test

2019 ◽  
Vol 952 ◽  
pp. 172-179
Author(s):  
Martin Ovsik ◽  
Michal Stanek ◽  
Adam Dockal ◽  
Martin Reznicek ◽  
Lenka Hylova
Keyword(s):  
Mechanical Properties ◽  
Surface Properties ◽  
Three Dimensional ◽  
Indentation Test ◽  
Optimal Dose ◽  
Indentation Hardness ◽  
Indentation Modulus ◽  
Deformation Work ◽  
Correct Function ◽  
Economical Aspect

Surface properties are important aspect for correct function of construction (technical) parts. By improving mechanical properties of surface, an increase of abrasion resistance and wear resistance is reached. Longevity and economical aspect have an important role in final useful properties of product. Measurement of surface properties was done by ultra-nanoindentation technique (UNHT3), this is the best tool available right now, this technique is based on instrumented testing. Surface properties were modified by ionized radiation, that caused the creation of crosslinked structure in polyethylene. During radiation a three dimensional network is created, that improves final properties of product such as: hardness, elasticity modulus, thermal stability, etc. During ionized radiation there are two actions that take place at the same time, crosslinking and degradation. Goal of this paper is to consider how radiation intensity affects surface properties (indentation hardness, indentation modulus, deformation work, etc.) Another goal of this paper is to find out the optimal dose of radiation, that will cause more three dimensional crosslinking and less degradation as degradation causes decrease in mechanical properties.

The Behaviour of Cross-Linking Filled PA66 by Micro-Indentation Test

2016 ◽  
Vol 699 ◽  
pp. 43-48
Author(s):  
Martin Ovsik ◽  
David Manas ◽  
Miroslav Manas ◽  
Michal Stanek ◽  
Vojtech Senkerik
Keyword(s):  
Mechanical Properties ◽  
Surface Layer ◽  
Glass Fiber ◽  
Indentation Test ◽  
Polymer Materials ◽  
Beta Radiation ◽  
Indentation Hardness ◽  
Indentation Modulus ◽  
Polyamide 66 ◽  
Depth Sensing

The process of radiation crosslinking helps to improve some mechanical properties of polymer materials. Micro-mechanical changes in the surface layer of glass-fiber filled PA 66 modified by beta radiation were measured by the Depth Sensing Indentation - DSI method on samples which were non-irradiated and irradiated by different doses of the β - radiation. The specimens were prepared by injection technology and subjected to radiation doses of 0, 33, 66 nad 99 kGy. The change of micro-mechanical properties is greatly manifested mainly in the surface layer of the modified polypropylene where a significant growth of micro-hardness values can be observed. Indentation modulus increased from 1.8 to 3.0 GPa (increasing about 66%) and indentation hardness increased from 87 to 157 MPa (increasing about 80%). This research paper studies the influence of the dose of irradiation on the micro-mechanical properties of semi-crystalline polyamide 66 filled by 30% glass fiber at room temperature. The study is carried out due to the ever-growing employment of this type of polymer.

Irradiation of Polyamide Measured by Micro-Indentation Test

2015 ◽  
Vol 1120-1121 ◽  
pp. 1179-1182
Author(s):  
Martin Ovsik ◽  
David Manas ◽  
Miroslav Manas ◽  
Michal Stanek ◽  
Adam Skrobak ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Surface Layer ◽  
Material Properties ◽  
Indentation Test ◽  
Polymer Chains ◽  
Cross Linking ◽  
Indentation Hardness ◽  
Chemical Bonds ◽  
Depth Sensing ◽  
Micro Indentation

Cross-linking is a process in which polymer chains are associated through chemical bonds. This research paper deals with the possible utilization of irradiated polyamide. Influence of the intensity of irradiation on micro-indentation hardness was investigated. Material properties created by β – radiation are measured by micro-indentation test using the DSI method (Depth Sensing Indentation). Hardness increased with increasing dose of irradiation at everything samples; however results of micro-indentation test shows increasing in micro-mechanical properties of surface layer. The highest values of micro-mechanical properties were reached radiation dose of 99 kGy, when the micro-mechanical values increased by about 18%.

A Study on the Nondestructive Evaluation of Material Degradation

2006 ◽  
Vol 326-328 ◽  
pp. 685-688
Author(s):  
Hyung Ick Kim ◽  
Yong Huh ◽  
Jeong Pyo Kim ◽  
Chang Sung Seok
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Yield Strength ◽  
Nondestructive Evaluation ◽  
Evaluation System ◽  
Ultrasonic Method ◽  
Indentation Test ◽  
Experimental Results ◽  
Material Degradation ◽  
Ultrasonic Parameters

The mechanical properties of in-service facilities under harsh environment a decrease as materials of the facilities degrade. This decrease of mechanical properties can affect the safety operation of the facilities. Therefore, the extent of degradation due to prolonged service exposure must be estimated. Nondestructive evaluation method is a good technique for monitoring the change of mechanical properties of in-service facilities. The most widely used nondestructive methods are the ultrasonic method and the indentation test, which is advantageous with respect of applicability to in-service facilities. The modified theoretical Vary's equation, considering nonlinear response due to material degradation, was proposed for obtaining the correlations between ultrasonic parameters and fracture toughness. Experimental results showed that ultrasonic attenuation, velocity, and nonlinear parameters have significant correlation with fracture toughness and yield strength. The nondestructive evaluation system can be used to obtain the yield strength and ultrasonic parameters simultaneously, and this information can be used to predict the fracture toughness. The predicted results produced good correlations with the experimental results, indicating that the nondestructive evaluation system can be effective in evaluating material properties and degradation, and the life time of facilities.

Micro-Indentation Test of Cross-Linking Polyethylene

2015 ◽  
Vol 1120-1121 ◽  
pp. 1175-1178
Author(s):  
Martin Ovsik ◽  
David Manas ◽  
Miroslav Manas ◽  
Michal Stanek ◽  
Martin Reznicek
Keyword(s):  
Mechanical Properties ◽  
Mechanical Behavior ◽  
Indentation Test ◽  
Basic Material ◽  
Cross Linking ◽  
Indentation Hardness ◽  
Indentation Modulus ◽  
Linear Polyethylene ◽  
Radiation Crosslinking ◽  
Micro Indentation

Radiation crosslinking of linear polyethylene (LLDPE) is a well-recognized modification of improving basic material characteristics. This research paper deals with the utilization of electron beam irradiated LLDPE on the micro-indentation test. The effect of the irradiation on mechanical behavior of the tested polyethylene was investigated. The results indicate that the mechanical behavior, highly depends on the intensity of irradiation. Toughness and hardness grew with increasing dose of the irradiation LLDPE. Indentation modulus increased from 0.25 to 0.28 GPa and indentation hardness increased from 21.89 to 26.25 MPa. These results indicate advantage crosslinking of the improved mechanical properties.

scholarly journals Nano-indentation test of electron beam irradiated polyamide 11

2018 ◽  
Vol 210 ◽  
pp. 02037
Author(s):  
Martin Ovsik ◽  
Lenka Hylova ◽  
Ivan Hudec ◽  
Adam Dockal
Keyword(s):  
Mechanical Properties ◽  
Electron Beam ◽  
Indentation Test ◽  
Polymeric Materials ◽  
Beta Radiation ◽  
High Tech ◽  
Indentation Hardness ◽  
Indentation Modulus ◽  
Beam Radiation ◽  
Polyamide 11

This article deals with the influence of electron beam radiation on nano-mechanical properties and the structure of polyamide 11. Crosslinking of polymers is a process, during which macromolecular chains start to connect to each other and the spatial network creates in the structure. During the action of the ionizing radiation two actions can occur: crosslinking and scission of macromolecules – degradation. Both these processes run parallel. Using the crosslinking technology the standard and construction polymer can obtain the more “expensive” high-tech polymeric materials properties and thus replace these materials in many applications. Tested material was irradiated by different doses of beta radiation (33, 66 and 99 kGy). The nano-mechanical properties were measured using DSI method, which fluently records the change of the indentation in time. From this dependence it is possible to determine nano-mechanical properties such as indentation hardness, indentation modulus etc. During results consideration it is obvious that irradiation acts on each polymer differently, but always when the optimal dose was found, nano-mechanical properties increased up to 34 %. The changes of nano-mechanical properties were confirmed by structural measurement when the change of hardness and modulus corresponded to gel content.

Indentation Measurement of CuZnAl Dual Phase Shape Memory Alloy

2018 ◽  
Vol 784 ◽  
pp. 38-43
Author(s):  
Marek Vojtko ◽  
Ján Balko ◽  
Martin Fides ◽  
Liudmila Vojtkova
Keyword(s):  
Mechanical Properties ◽  
Shape Memory ◽  
Indentation Test ◽  
Phase Region ◽  
Indentation Hardness ◽  
Indentation Modulus ◽  
Dual Phase ◽  
Quenching Temperature ◽  
Β Phase ◽  
Α Phase

The aim of this work is indentation study of local mechanical properties of Cu-22Zn-4.6Al alloy, which has significant shape memory effect after quenching from dual α + β phase region. The study was carried out on the samples with thermoelastic and non-thermoelastic martensite in the structure, which were obtained by quenching from various temperatures. A different behavior concerning mechanical properties measurements of α phase and β phase transformed to martensite after quenching from various temperatures was found out. It was observed almost no change of mechanical properties of α phase, whereas indentation hardness HIT and indentation modulus EIT raised with increasing quenching temperature. Also some serious differences were observed at indentation test of thermoelastic and non-thermoelastic martensite.

scholarly journals Conventional Vickers and true instrumented indentation hardness determined by instrumented indentation tests

2010 ◽  
Vol 25 (2) ◽  
pp. 337-343 ◽  
Author(s):  
Seung-Kyun Kang ◽  
Ju-Young Kim ◽  
Chan-Pyoung Park ◽  
Hyun-Uk Kim ◽  
Dongil Kwon
Keyword(s):  
Mechanical Properties ◽  
Vickers Hardness ◽  
Material Properties ◽  
Indentation Test ◽  
Indentation Hardness ◽  
Instrumented Indentation ◽  
Real Contact ◽  
Wide Range ◽  
Indentation Tests ◽  
Instrumented Indentation Test

We evaluate Vickers hardness and true instrumented indentation test (IIT) hardness of 24 metals over a wide range of mechanical properties using just IIT parameters by taking into account the real contact morphology beneath the Vickers indenter. Correlating the conventional Vickers hardness, indentation contact morphology, and IIT parameters for the 24 metals reveals relationships between contact depths and apparent material properties. We report the conventional Vickers and true IIT hardnesses measured only from IIT contact depths; these agree well with directly measured hardnesses within ±6% for Vickers hardness and ±10% for true IIT hardness.

Mechanical Properties of Polypropylene/Carbon Nanotube Composites by Indentation Technique

2015 ◽  
Vol 1128 ◽  
pp. 115-122
Author(s):  
Alina Mihaela Cantaragiu ◽  
Catalin Fetecau
Keyword(s):  
Mechanical Properties ◽  
Indentation Test ◽  
Indentation Hardness ◽  
Instrumented Indentation ◽  
Plastic Deformations ◽  
Indentation Technique ◽  
Nanotube Composites ◽  
Multi Walled Carbon Nanotubes ◽  
Carbon Nanotube Composites ◽  
Walled Carbon Nanotubes

The Instrumented Indentation Technique (IIT) is used to measure the local mechanical properties of different materials. The mechanical parameters (indentation hardness and modulus) of multi-walled carbon nanotubes filled polypropylene (PP/MWCNTs) nanocomposites derived from the load-displacement indentation curve are investigated by sharp indentation. The effect of the visco-elastic-plastic deformations on the mechanical properties is studied considering a 5-step indentation test. The mechanical properties calculated based on the traditional Oliver and Pharr method are compared with those extracted from the new indentation methodology. During the 5-step indentation test, the viscoelastic deformations during the reloading-holding phases are reduced due to the decrease in the indentation displacement with the increase in the concentration.

Mechanical Properties of High Strength Desert Sand Concrete

2015 ◽  
Vol 1095 ◽  
pp. 263-266
Author(s):  
Hai Feng Liu ◽  
Ju Rong Ma ◽  
Yun Long Chen ◽  
Deng Yang
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Energy Absorption ◽  
Specific Energy ◽  
High Strength ◽  
Experimental Results ◽  
Replacement Ratio ◽  
Specific Energy Absorption ◽  
Desert Sand

In order to research on the mechanical properties of high strength desert sand concrete, the compressive experiment of high strength desert sand concrete with different desert sand replacement ratio was carried out. The influence of desert sand replacement ratio on the compressive strength and specific energy absorption of high strength desert sand concrete was analyzed. Experimental results shows that the optimum desert sand replacement ratio is from 0 to 40%, which provides advice and guidance to the utility of high strength desert sand concrete in practice.

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