scholarly journals Design and Application of Simulating Cutting Experiment System for Drum Shearer

2021 ◽  
Vol 11 (13) ◽  
pp. 5917
Author(s):  
Tianhao Peng ◽  
Changpeng Li ◽  
Yanmin Zhu
Keyword(s):  
Compressive Strength ◽  
Coal Sample ◽  
Similarity Theory ◽  
Cutting Condition ◽  
Analysis Method ◽  
Similarity Coefficients ◽  
Range Analysis ◽  
Experiment System ◽  
Drum Shearer ◽  
Cutting Experiment

When the shearer cuts coal or rock with different hardness, it will produce corresponding cutting state information. This paper develops a simulation cutting experiment system for the drum shearer based on similarity theory. It took the spiral cutting drum of a shearer as the research target and derived the principal similarity coefficients through the dimensional analysis method. Meanwhile, this paper designed the structure of the cutting power system and hydraulic system. Then, it chose a certain amount of coal powder as an aggregate, cement 325# as cementing material, sand, and water as auxiliary materials to prepare simulated coal samples. The paper adopted the orthogonal experiment method and used a proportion of cement, sand, and water as the influencing factors in designing a simulated coal sample preparation plan. In addition, it utilized the range analysis method to research the influence of various factors on the density and compressive strength of simulated coal samples. Finally, it conducted simulated coal sample cutting tests. The results show that the density of the simulated coal samples is between 1192.59 Kg/m3–1483.51 Kg/m3, and the compressive strength range reaches 0.16 MPa–3.94 MPa. The density of the simulated coal sample is related to the mass proportion of cement and sand. When the ratio gradually increases, the influence of sand increases. Furthermore, the compressive strength is linearly proportional to the proportion of cement. The self-designed simulation cutting experiment system could effectively carry out the relevant experiments and obtain the corresponding cutting condition signals through the sensors. There are differences in vibration signals generated by cutting different strength materials. Extracting the kurtosis value as the characteristic value can distinguish various cutting modes, which can provide a reliable experimental solution for the research of coal-rock identification.

scholarly journals Experimental Analysis of the Mechanical Properties and Resistivity of Tectonic Coal Samples with Different Particle Sizes

Energies ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2303
Author(s):  
Congyu Zhong ◽  
Liwen Cao ◽  
Jishi Geng ◽  
Zhihao Jiang ◽  
Shuai Zhang
Keyword(s):  
Mechanical Properties ◽  
Particle Size ◽  
Compressive Strength ◽  
Elastic Modulus ◽  
Uniaxial Compressive Strength ◽  
Coalbed Methane ◽  
Coal Sample ◽  
Fine Particles ◽  
Particle Sizes ◽  
Tectonic Coal

Because of its weak cementation and abundant pores and cracks, it is difficult to obtain suitable samples of tectonic coal to test its mechanical properties. Therefore, the research and development of coalbed methane drilling and mining technology are restricted. In this study, tectonic coal samples are remodeled with different particle sizes to test the mechanical parameters and loading resistivity. The research results show that the particle size and gradation of tectonic coal significantly impact its uniaxial compressive strength and elastic modulus and affect changes in resistivity. As the converted particle size increases, the uniaxial compressive strength and elastic modulus decrease first and then tend to remain unchanged. The strength of the single-particle gradation coal sample decreases from 0.867 to 0.433 MPa and the elastic modulus decreases from 59.28 to 41.63 MPa with increasing particle size. The change in resistivity of the coal sample increases with increasing particle size, and the degree of resistivity variation decreases during the coal sample failure stage. In composite-particle gradation, the proportion of fine particles in the tectonic coal sample increases from 33% to 80%. Its strength and elastic modulus increase from 0.996 to 1.31 MPa and 83.96 to 125.4 MPa, respectively, and the resistivity change degree decreases. The proportion of medium particles or coarse particles increases, and the sample strength, elastic modulus, and resistivity changes all decrease.

Research on Simulation Test of Coal Similar Material

2013 ◽  
Vol 850-851 ◽  
pp. 847-850 ◽  
Author(s):  
Lin Chao Dai
Keyword(s):  
Compressive Strength ◽  
Raw Materials ◽  
Similarity Theory ◽  
Design Method ◽  
Uniform Design ◽  
Physical And Mechanical Properties ◽  
Raw Material ◽  
Similar Material ◽  
Cement Ratio ◽  
Water Cement Ratio

In order to study the coal and gas outburst similar simulation experiment, coal similar material was made up based on the similarity theory. Based on the previous similar material study, the cement, sand, water, activated carbon and coal powder was selected as the raw material of similar material. Meanwhile similar material matching program with 5 factors and 6 levels was designed by using Uniform Design Method. And the physical and mechanical properties of the similar material compressive strength was measured under different proportions circumstances. The relationship between similar material and the raw materials was analyzed. The results show that choosing different materials can compound different similar materials with different requirements. And the water-cement ratio plays a decisive influence on the compressive strength of similar material. The compressive strength of similar material decreases linearly when the water-cement ratio increases.

Effects of Wet Activation Process Parameters on Surface Hydrophilicity in Silicon Direct Wafer Bonding

2012 ◽  
Vol 235 ◽  
pp. 250-253
Author(s):  
Lei Nie ◽  
Jun Xing Yu ◽  
Kun Zhang
Keyword(s):  
Wafer Bonding ◽  
Orthogonal Experiment ◽  
Volume Ratio ◽  
Holding Time ◽  
Activation Process ◽  
Analysis Method ◽  
Range Analysis ◽  
Surface Hydrophilicity ◽  
Direct Wafer Bonding ◽  
Value Range

Wet activation is a very important step in silicon direct wafer bonding process and a optimized activation process is desirable to improve the surface hydrophilicity. Therefore the pivotal parameters of activation process were investigated which were volume ratio, holding time and treat temperature. A orthogonal experiment array was designed to reveal the effects of these parameters and the experiment results were analyzed by range analysis method. The analysis results indicted among those three parameters, everyone had intimidate relationship with surface hydrophilicity, which was indexed by contact angle. And higher concentration, longer holding time and higher treating temperature in possible value range were more desirable. Based on these conclusions, optimized activation process was desigened using which void-free bonding was realized.

scholarly journals Experimental Development of Coal-Like Material with Solid-Gas Coupling for Quantitative Simulation Tests of Coal and Gas Outburst Occurred in Soft Coal Seams

Processes ◽  
2019 ◽  
Vol 7 (3) ◽  
pp. 155 ◽  
Author(s):  
Xingkai Wang ◽  
Wenbing Xie ◽  
Zhili Su ◽  
Qingteng Tang
Keyword(s):  
Compressive Strength ◽  
Elastic Modulus ◽  
Influencing Factors ◽  
Co2 Sequestration ◽  
Range Analysis ◽  
Coal Seams ◽  
Gas Outburst ◽  
Soft Coal ◽  
Coal Powder ◽  
Adsorption Desorption

Solid-gas coupling coal-like materials are essential for simulating coal and gas outbursts and the long-term safety study of CO2 sequestration in coal. However, reported materials still differ substantially from natural coal in mechanical, deformation and gaseous properties; the latter two aspects are common not considered. There is a lack of a definite and quantitative preparation method of coal-like materials with high similarity for future reference. Here, 25 groups of raw material ratios were designed in the orthogonal experiment using uniaxial compression, shearing and adsorption/desorption tests. Experiment results indicated that the coal-like materials were highly similar to soft coals in properties mentioned above. And range analysis revealed the key influencing factors of each mechanical index. The gypsum/petrolatum ratio controls the density, compressive strength, elastic modulus, cohesion and deformation characteristic. The coarse/fine coal powder (1–2 and 0–0.5 mm) controls the internal friction angle and is the secondary controlling factor for compressive strength and elastic modulus. The effect of coal particle size on the sample strength was studied using scanning electron microscope (SEM). When the gypsum/petrolatum ratio increased, the deformation characteristics changed from ductile to brittle. The different failure modes in the samples were revealed. The coal powder content is a key in the gas adsorption/desorption properties and an empirical formula for estimating the adsorption capacity was established. Based on the range analysis of experimental results, a multiple linear regression model of the mechanical parameters and their key influencing factors was obtained. Finally, a composition closely resembling the natural coal was determined, which differs by only 0.47–7.41% in all parameters except porosity (11.76%). Possible improvements and extension to similar materials are discussed. The findings of this study can help for better understanding of coal and gas outburst mechanism and stability of CO2 sequestration in soft coal seams.

scholarly journals Strength, Permeability, and Freeze-Thaw Durability of Pervious Concrete with Different Aggregate Sizes, Porosities, and Water-Binder Ratios

2018 ◽  
Vol 8 (8) ◽  
pp. 1217 ◽  
Author(s):  
Hanbing Liu ◽  
Guobao Luo ◽  
Haibin Wei ◽  
Han Yu
Keyword(s):  
Compressive Strength ◽  
Mechanical Strength ◽  
Aggregate Size ◽  
Pervious Concrete ◽  
High Porosity ◽  
Range Analysis ◽  
Freeze Thaw ◽  
Binder Ratio ◽  
The Impact ◽  
Water Binder Ratio

Pervious concrete (PC), as an environmental friendly material, can be very important in solving urban problems and mitigating the impact of climate change; i.e., flooding, urban heat island phenomena, and groundwater decline. The objective of this research is to evaluate the strength, permeability, and freeze-thaw durability of PC with different aggregate sizes, porosities, and water-binder ratios. The orthogonal experiment method is employed in the study and nine experiments are conducted. The compressive strength, flexural strength, permeability coefficient, porosity, density, and freeze-thaw durability of PC mixtures are tested. Range analysis and variance analysis are carried out to analyze the collected data and estimate the influence of aggregate size, porosity, and water-binder ratio on PC properties. The results indicate that porosity is the most important factor determining the properties of PC. High porosity results in better permeability, but negatively affects the mechanical strength and freeze-thaw durability. PC of 15% porosity can obtain high compressive strength in excess of 20 MPa and favorable freeze-thaw durability of 80 cycles without sacrificing excessive permeability. Aggregate size also has a significant effect on freeze-thaw durability and mechanical strength. Small aggregate size is advantageous for PC properties. PC with 4.75–9.5 mm coarse aggregate presents excellent freeze-thaw durability. The influence of the water-binder ratio on PC properties is not as significant as that of aggregate size and porosity. An optimal mix ratio is required to trade-off between permeability, mechanical strength, and freeze-thaw durability.

MECHANICAL PROPERTIES OF FLY ASH-BASED ALKALI-ACTIVATED CEMENT USING A STATISTICAL ANALYSIS TECHNIQUE

2014 ◽  
Vol 1 (1) ◽  
Author(s):  
Hyuk Lee ◽  
Vanissorn Vimonsatit
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Statistical Analysis ◽  
Fly Ash ◽  
Silica Fume ◽  
Dry Density ◽  
Analysis Method ◽  
Solid Ratio ◽  
Alkali Activated ◽  
Alkali Activated Cement

This paper presents the mechanical properties of fly ash-based alkali-activated cement (AAC). A statistical analysis method was used to determine the effect of mix proportion parameters on the dry density and compressive strength of fly ash-based AAC pastes and mortars. For that purpose, sample mixtures were designed according to Taguchi’s experimental design method, i.e., in a L9 orthogonal array. Four factors were selected: “silica fume content” (SF), “sand to solid ratio” (s/c), “liquid to solid ratio” (l/s), and “superplasticiser content” (SP). The experimental results were analysed by using signal to noise for quality control of each mixture, and analysis of variance (ANOVA) was used to determine the significant effect on the compressive strength of fly ash-based AAC. Furthermore, a regression-analysis method was used to predict the compressive strength according to the variation of the four factors. Results indicated that silica fume is the most influencing parameter on compressive strength, which could be decreased by superplasticiser and l/s ratio. There is no significant effect of sand-to-cementitious ratio on compressive strength of fly ash-based AAC. The dry density decreases as the sand-to-cementitious ratio is decreased. The increasing l/s ratio and superplasticiser dosage could further decrease the dry density of fly ash-based AAC.

scholarly journals Mechanical Properties and Durability of Recycled Aggregate Permeable Concrete

2021 ◽  
Vol 31 (3) ◽  
pp. 159-167
Author(s):  
Lifang Liu ◽  
Bo Dong
Keyword(s):  
Mechanical Properties ◽  
Target Material ◽  
Orthogonal Test ◽  
Recycled Aggregate ◽  
Analysis Method ◽  
Range Analysis ◽  
The Sustainable Development ◽  
Island Effect ◽  
Water Permeability Coefficient ◽  
Urban Heat

The recycled aggregate permeable concrete made of reused construction wastes is very important for realizing the sustainable development of the construction industry, it can alleviate the adverse impact of surface runoff during storm and the urban heat island effect. Therefore, this paper studied the mechanical properties and durability of recycled aggregate permeable concrete. At first, a few properties of the target material, including bulk density, moisture content, water absorption, compressive strength, and water permeability coefficient, were tested respectively. Then, based on the orthogonal test, the performance of the target material was analyzed, and the analysis steps of the range analysis method and the variance analysis method in the orthogonal test were given. At last, the mechanical properties and durability of the target material were tested via experiments, and the relevant test results and analysis were elaborated.

Design and Optimization of Conformal Cooling System of an Injection Molding Chimney

2016 ◽  
Vol 850 ◽  
pp. 679-686
Author(s):  
He Li ◽  
Yi Mei ◽  
Bo Lin ◽  
Hua Qiang Xiao
Keyword(s):  
Temperature Field ◽  
Cooling System ◽  
Transfer Model ◽  
Analysis Method ◽  
Range Analysis ◽  
Straight Pipe ◽  
Cooling Systems ◽  
Conformal Cooling ◽  
Design And Optimization ◽  
Plastic Parts

Cooling system is important in the quality and the efficiency of forming plastic parts. The heat transfer model for conformal chimney cavity and straight pipe cooling system was developed employing thermal analysis module of UG software. The temperature field distributions of two cavities were analyzed. The differences in chimney forming warping deformations, shrinkage and freeze times for the two types of cooling systems were analyzed quantitatively by Moldflow software. The results showed that the temperature field distribution of the conformal cooling system was more homogeneous and the forming quality and efficiency of molding for the plastic parts was better. Finally, the cooling system parameters were optimized through orthogonal test and range analysis method.

Estimation of Chatter Vibration Under End-Milling Process With a Wavelet Transform

2021 ◽  
Author(s):  
Haruki Minetaka ◽  
Nobutoshi Ozaki ◽  
Toshiki Hirogaki ◽  
Eiichi Aoyama
Keyword(s):  
Fourier Transform ◽  
Wavelet Transform ◽  
End Milling ◽  
Early Stage ◽  
Milling Process ◽  
Frequency Resolution ◽  
Cutting Condition ◽  
Analysis Method ◽  
Chatter Vibration ◽  
Machined Surface

Abstract In this study, a new analysis method using a wavelet transform was considered to evaluate the chatter vibration generated during end milling. End milling often generates vibrations between the tool and work material, called chatter vibration, which causes deterioration of the finished surface and breakage of the tool. Therefore, countermeasures to detect chatter vibration at an early stage have been attempted in the past by using fast Fourier transform (FFT) and short-time Fourier transform (STFT) methods and monitoring the dynamic stability of the cutting process. However, the FFT analysis method assumes steady-state vibration, and the STFT method does not have sufficient frequency resolution. In contrast, the wavelet transform is excellent for analyzing non-stationary vibrations and has a high noise separation capability. To fully validate the analysis method, a groove was added to the machined surface, so that the cutting condition changed with time, and the cutting vibration under the condition where the disturbance was involuntary was analyzed. As a result, it was possible to identify minute fluctuations in chatter vibration, which could not be obtained using the STFT method.

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