scholarly journals Experimental research on cyclic impact load of concrete during curing period

2021 ◽  
Vol 1972 (1) ◽  
pp. 012088
Author(s):  
Chen Chen ◽  
Liu Xiaoyi ◽  
Yu Jianxin ◽  
Liu Pan ◽  
Guo Min
Keyword(s):  
Experimental Research ◽  
Impact Load ◽  
Curing Period ◽  
Cyclic Impact

Experimental Research on Abrasion Resistance of Alkaline Residue Concrete

2014 ◽  
Vol 1051 ◽  
pp. 687-691
Author(s):  
Yuan Zhang ◽  
Jun Cao ◽  
Yun Dong
Keyword(s):  
Image Analysis ◽  
Experimental Research ◽  
Abrasion Resistance ◽  
Cement Material ◽  
Sem Image ◽  
Curing Period ◽  
The Law ◽  
Sem Image Analysis ◽  
Curing Age

The abrasion resistance of the alkaline residue admixture concrete was observed in the experiment under different conditions, the results showed that: the abrasion resistance of the alkaline residue concrete first increased and then decreased in the law with the increase of alkaline content. The abrasion resistance of concrete is best when the content of alkaline residue is 10% of cement material, combined with SEM image analysis, the microstructure of concrete that alkaline residue accounted for cement material 10% is more dense than others proportions concrete, and the abrasion resistance of concrete will decrease with the increasing the amount of alkaline residue. The experiment also observed the abrasion resistance of the different curing period of the alkaline residue admixture concrete. We could find that the abrasion resistance of concrete increases with the growth of curing age.

scholarly journals Influence of Cyclic Impact Loading and Axial Stress on Dynamic Mechanical Properties of Burst-Prone Coal

2021 ◽  
Vol 2021 ◽  
pp. 1-10 ◽  
Author(s):  
Shuang Gong ◽  
Zhen Wang ◽  
Lei Zhou ◽  
Wen Wang
Keyword(s):  
Mechanical Properties ◽  
Impact Loading ◽  
Coal Sample ◽  
Impact Load ◽  
Axial Stress ◽  
Dynamic Mechanical Properties ◽  
Dynamic Mechanical ◽  
Cyclic Impact Loading ◽  
Cyclic Impact ◽  
The Impact

High in-situ stress and frequent dynamic disturbances caused by the mining process in deep coal mines can easily induce dynamic disasters such as coal burst. We conducted laboratory experiments to assess the effects of the axial stress loading and dynamic cyclic impact loading on the dynamic mechanical properties of burst-prone coals by using a modified split Hopkinson pressure bar (SHPB). Comparisons were made using two types of burst-prone and burst-resistant coal samples. The mineral components, organic macerals, and dynamic mechanical features of both burst-prone and burst-resistant coal samples were comparatively analyzed based on the obtained X-ray diffraction (XRD), optical microscope observations, and dynamic compressive stress-strain curves, respectively. The results of the microstructure analysis indicated a larger difference between the minimum and maximum reflectances of vitrinite for burst-prone coal. Compared to the burst-resistant coal samples, the burst-prone coals contained less corpocollinite and fusinite. While applying a high axial static load combined with cyclic impact load, the coal samples showed the characteristics of fatigue damage. The results also demonstrated that preaxial stress affected the burst resistance of coal samples. The greater the preaxial stress was, the less the coal samples could withstand the dynamic cyclic impact load. In comparison to the burst-resistant coal sample, the burst-prone coal sample showed a larger dynamic compressive strength and a lower deformation. They were also more positively capable of the propagation and activation of the coal burst. We believe that the results of the study are conducive to further understanding of the distribution of microcomponents of burst-prone coals. The results are also beneficial for realizing the dynamic mechanical characteristics of burst-prone coals under the impact of cyclic dynamic load.

scholarly journals METHODOLOGICAL APPROACHES TO ACCELERATED TESTS OF CRUSHING KNIVES OF GRINDING CATS. COMPARATIVE TESTS OF LOSS OF CUTTING CAPACITY

2021 ◽  
Author(s):  
L. Shustik ◽  
◽  
V. Pogoriliy ◽  
T. Gaidai ◽  
S. Stepchenko ◽  
...  
Keyword(s):  
Impact Load ◽  
Operating Time ◽  
Accelerated Tests ◽  
Plant Debris ◽  
Design Features ◽  
Comparative Tests ◽  
Low Intensity ◽  
Methodological Approaches ◽  
Cyclic Impact ◽  
Cutting Capacity

Abstract. The purpose of the research is to analyze the design features and parameters of grinding knives to compare the intensity of loss of cutting ability of each of the models of knives depending on the load cycles. Methods and materials. Conduct an analytical inspection and instrumental studies of the blades of grinding rollers type KR with different design features. Carry out bench accelerated tests based on the cyclic impact load of the knife fragment due to falling on the simulator of wear cycles and check the residual cutting capacity on the cutting simulator. Justify the coefficient of acceleration of tests as a derivative of hardness and density of the simulator, as well as the ratio of the energy of the fall of the knife fragment on the stand and its rotational motion in the field. Statistical analysis of experimental data was performed by analysis of variance and interpreted by standard computer programs Excel in the form of graphs. Results. Analyzing the proposed method for determining the intensity of loss of cutting ability of the knife when it falls on the simulator of plant debris allowed to rank different models and establish their relative resource. Unhardened models of both 45 and 30MnB5 Steel provide low life and their residual cutting ability is only 15-25% compared to hardened models. Analyzing the research results, the hardened model of a knife made of 45 Steel withstands 4 times more load cycles compared to unhardened models, but is inferior to the hardened model of Steel 30MnB5 (borista), which has the highest resource. Even after 150 load cycles (in terms of the work of a roller with a width of 12.5 m - operating time of more than 1000 ha), it retains more than 55% of the initial cutting ability, which is characterized by low intensity of its loss. Conclusions. According to the tests of the intensity of loss of cutting ability of knives, the most acceptable option for the equipment of roller-shredders is a hardened model made of 30MnB5 Steel (borista), which has the highest resource.

Experimental Research on Alkaline Residue Concrete Dry Shrinkage Performance

2015 ◽  
Vol 1088 ◽  
pp. 603-607
Author(s):  
Yuan Zhang ◽  
Jun Cao
Keyword(s):  
Experimental Research ◽  
Plain Concrete ◽  
Shrinkage Rate ◽  
Curing Time ◽  
Shrinkage Curve ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Curing Period ◽  
Dry Shrinkage ◽  
High Incorporation

Shrinkage performance of alkaline residue concrete is researched in different conditions, it found that different alkaline residue proportions concrete dry shrinkage increases with the growth of the curing time increasing, but the dry shrinkage changes of different alkaline residue proportions are different, the dry shrinkage of low proportions of 8-12% concrete is similar with that of plain concrete, therefore, to the high content of concrete, its dry shrinkage significantly increase. The dry shrinkage of low incorporation proportion (8-12%) concrete increases quickly in the initial curing period (3-7 days), its shrinkage rate changes stabilized in the subsequent conservation period; to high incorporation proportion (20-30%) concrete, its dry shrinkage increases rapidly in the curing period of 7-14 days, then it stabilized. compared with the low proportion of concrete, its growth is faster in the late curing period. Water-cement ratio is very important factor of the shrinkage performance of concrete, dry shrinkage curve of alkaline residue concrete present concave, when water-cement ratio are in 0.52-0.57, the shrinkage of alkaline residue concrete is minimum.

Experimental research on dynamic response of PZT-5H under impact load

2020 ◽  
Vol 46 (3) ◽  
pp. 2868-2876 ◽  
Author(s):  
Ruizhi Wang ◽  
Enling Tang ◽  
Guolai Yang ◽  
Yafei Han
Keyword(s):  
Dynamic Response ◽  
Experimental Research ◽  
Impact Load

scholarly journals Experimental Research on Enhanced Denitrification by Biological Agents

2019 ◽  
Vol 136 ◽  
pp. 07022
Author(s):  
Xiaoyu Liu ◽  
Ruozheng Li ◽  
Zhengkun Li ◽  
Can Wang
Keyword(s):  
Experimental Research ◽  
Significant Role ◽  
Impact Load ◽  
Sewage Treatment ◽  
Load Resistance ◽  
Biological Agents ◽  
Removal Rates ◽  
Urban Sewage ◽  
Start Up

Biological agents play a significant role in sewage treatment, with good removal effect, low sludge yield, good performance, and shorten the system start-up time, impact load resistance and stability enhancement.This paper describes the characteristics ofbiological agents and the effect of biological agents on wastewater denitrification was investigated through experiments, so as to provide effective basis support for the wide application of biological agents in the field of urban sewage treatment.The experiment showed that through reasonable addition of biological agents,the removal rates of COD,NH3-N and TNinlowpollutantsewage treatmentwere increased by 41%, 15% and 62% respectively.

scholarly journals An Impact Vibration Experimental Research on the Pretension Rectangular Membrane Structure

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Jianjun Guo ◽  
Zhoulian Zheng ◽  
Song Wu
Keyword(s):  
Experimental Research ◽  
Impact Load ◽  
Biaxial Tension ◽  
Membrane Surface ◽  
Spectral Density Function ◽  
Theoretical Research ◽  
Displacement Sensor ◽  
Theoretical Formula ◽  
Time Curve ◽  
Vibration Displacement

The pretension of the membrane is applied with biaxial tension bracket; the digital dynamometer is used for measuring the change of the tension; the concentrated impact load is applied on the surface of rectangular membrane; the displacement change of each feature point on the membrane surface is measured by noncontact laser displacement sensor. Through this experiment, the vibration displacement-time curve of the rectangular membrane under the fixed boundary condition is obtained. Further, the vibration frequency is given, according to the power spectral density function. The results of the experimental research are used to verify and correct theoretical formula and make the foundation for further theoretical research.

Experimental Research and Simulation Analysis on Composite Structure Embedded Optical Fiber Sensor under Impact Load

2014 ◽  
Vol 912-914 ◽  
pp. 27-31
Author(s):  
Fei Gao ◽  
Hao Song ◽  
Wen Juan Wang
Keyword(s):  
Experimental Research ◽  
Composite Laminates ◽  
Simulation Analysis ◽  
Impact Load ◽  
Optical Fiber Sensor ◽  
High Energy ◽  
Experimental Models ◽  
Failure Behavior ◽  
Energy Impact ◽  
The Impact

The low-energy impact experimental research and monitoring the response of composites structure at different impact positions was conducted by embedding fiber bragg grating strain sensor into composite laminates. Simulation work on the experimental models was conducted and compared to the results of the experiment. According to the Hashin failure criteria, a suitable calculation model was established to investigate the action of the laminates under high energy impact load. The spreading of the fiber damage areas could be observed in the structure until the macroscopic cracks appear. It was indicated that a proper model can be used to simulate the damage evolution and failure behavior of composites structure under the impact load.

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