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Water‑immersion softening mechanism of coal rock mass based on split hopkinson pressure bar experiment

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International Journal of Coal Science & Technology 2022年第4期9卷 122-134页

作者： Zhiyuan Liu Gang Wang Jinzhou Li Huaixing Li Haifeng Zhao Hongwei Shi Jianli Lan School of Petroleum Engineering China University of PetroleumBeijingBeijing 102249China Mine Disaster Prevention and Control-Ministry of State Key Laboratory Breeding Base Shandong University of Science and TechnologyQingdao 266590China College of Safety and Environmental Engineering Shandong University of Science and TechnologyQingdao 266590China

The coal mining process is afected by various water sources such as groundwater and coal seam water *** the dynamic mechanical parameters of water-immersed coal is helpful for coalmine safe *** impact compression tests were performed on coal with diferent moisture contents by using theϕ50 mm split hopkinson pressure bar(SHPB)experimental system,and the dynamic characteristics and energy loss laws of water-immersed coal with diferent compositions and water contents were *** analysis and discussion,it is found that:(1)When the moisture content of the coal sample is 0%,30%,60%,the stress,strain rate and energy frst increase and then decrease with time.(2)When the moisture content of the coal sample increases from 30%to 60%,the stress“plateau”of the coal sample becomes more obvious,resulting in an increase in the compressive stress stage and a decrease in the expansion stress stage.(3)The increase of moisture content of the coal sample will afect its impact deformation and failure *** the moisture content is 60%,the incident rod end and the transmission rod end of the coal sample will have obvious compression failure,and the middle part of the coal sample will also experience expansion and deformation.(4)The coal composition ratio suitable for the coal immersion softening impact experiment is optimized.

关键词： Coal immersion softening Dynamic compressive response split hopkinson pressure bar Softening mechanism model

Calibration of split hopkinson pressure bar system with special shape striker

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Journal of Central South University 2011年第4期18卷 1139-1143页

作者：周子龙洪亮李启月刘志祥 School of Resources and Safety Engineering Central South University Department of Civil Engineering Hunan City University

In order to present basic guidance for system calibration of split hopkinson pressure bar(SHPB) with the special shape striker,wave characteristics and dynamic responses of SHPB under striker impact were *** generated by the special shape striker tends to have a half-sine waveform and has little wave dispersion during its *** velocities of the special shape striker and peak values of generated stress still have linear relation but with a different coefficient from that of cylindrical *** stress histories on the surfaces of the input bar impacted by the special shape striker off-axially and obliquely,it is found that the misalignment impacts usually trigger wave distortion and amplitude decrease,which can be used to identify the poor system ***,the system calibration of SHPB with the special shape striker can be classified into four steps:system adjustment,wave distortion identification,measurement calibration and transmission calibration,where the measurement calibration factor and transmission calibration factor are elaborated and redefined.

关键词： split hopkinson pressure bar special shape striker system calibration misalignment impact

Experimental and numerical study of failure behavior and mechanism of coal under dynamic compressive loads

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International Journal of Mining Science and Technology 2020年第5期30卷 613-621页

作者： Junjun Feng Enyuan Wang Qisong Huang Houcheng Ding Xiangyang Zhang Civil Engineering and Architecture Anhui University of TechnologyMaanshanAnhui 243002China Key Laboratory of Safety and High-efficiency Coal Mining Ministry of EducationAnhui University of Science and TechnologyHuainanAnhui 232001China State Key Laboratory Cultivation Base for Gas Geology and Gas Control Henan Polytechnic UniversityJiaozuoHenan 454003China Key Laboratory of Gas and Fire Control for Coal Mines China University of Mining and TechnologyXuzhouJiangsu 221116China

A comprehensive understanding of the failure behavior and mechanism of coal is a prerequisite for dealing with dynamic problems in mining *** this study,the failure behavior and mechanism of coal under uniaxial dynamic compressive loads were experimentally and numerically *** experiments were conducted using a split hopkinson pressure bar(SHPB)*** results indicated that the typical failure of coal is lateral and axial at lower loading rates and totally smashed at higher loading *** further fractography analysis of lateral and axial fracture fragments indicated that the coal failure under dynamic compressive load is caused by tensile brittle *** addition,the typical failure modes of coal under dynamic load were numerically *** numerical results indicated that the axial fracture is caused directly by the incident compressive stress wave and the lateral fracture is caused by the tensile stress wave reflected from the interface between coal specimen and transmitted *** application was further conducted to interpret dynamic problems in underground coal mine and it manifested that the lateral and axial fractures of coal constitute the parallel cracks in the coal mass under roof fall and blasting in mining space.

关键词： split hopkinson pressure bar Stress wave Failure mode Fracture mechanism Fractography

Ballistic tests on hot-rolled Ti-6Al-4V plates:Experiments and numerical approaches

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Defence Technology（防务技术） 2023年第8期26卷 39-53页

作者： Alexander Janda Benjamin James Ralph Yael Demarty Marcel Sorger Stefan Ebenbauer Aude Prestl Ingo Siller Martin Stockinger Helmut Clemens Department of Materials Science Montanuniversitat LeobenFranz Josef-Straße 188700 LeobenAustria Department Product Engineering Montanuniversitat LeobenFranz Josef-Straße 188700 LeobenAustria French-German Research Institute of Saint-Louis 5 Rue du General Cassagnou68300 Saint-LouisFrance voestalpine BOEHLER Bleche GmbH&Co KG Boehler-Gasse 18680MürzzuschlagAustria

Superior ballistic performance and the lightweight character of Ti alloys are considered as main reasons for their use in armour applications against a broad spectrum of ballistic threats,***,fragment or blast *** dynamic loading caused by typical penetrators is characterized by high strain rates,only specific test methods allow a closer investigation of the respective material *** the present study,quasi-static and dynamic compression tests as well as ballistic tests were conducted on a twophase a+βalloy Ti-6Al-4V(in m%)manufactured by ***-deformation heat treatments,influencing microstructure and mechanical properties were applied in order to compare three different microstructural configurations:as-rolled,mill-annealed and ***,on the one hand,ballistic tests were employed for the determination of the ballistic limit velocity v_(50),compression tests,on the other hand,delivered essential input parameters for the application of the Johnson-Cook constitutive model in a finite element simulation of the impact *** comparison of experimental results to simulation results was supplemented by means of microstructural characterization of tested samples with the focus set on the prevalently observed deformation and damage mechanisms,as for example adiabatic shearing.

关键词： Ti-6Al-4V Ballistic performance split hopkinson pressure bar FE simulation Adiabatic shear bands Intermetallic phase

Effect of dry-wet cycles on dynamic properties and microstructures of sandstone:Experiments and modelling

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International Journal of Mining Science and Technology 2024年第5期34卷 655-679页

作者： Hai Pu Qingyu Yi Andrey P.Jivkov Zhengfu Bian Weiqiang Chen Jiangyu Wu State Key Laboratory of Intelligent Construction and Healthy Operation and Maintenance of Deep Earth Engineering China University of Mining and TechnologyXuzhou 221116China Key Laboratory of Xinjiang Coal Resources Green Mining Ministry of EducationXinjiang Institute of EngineeringUrumqi 830023China Department of Solids and Structures School of EngineeringUniversity of ManchesterManchester M139PLUK School of Environment Science and Spatial Informatics China University of Mining and TechnologyXuzhou 221116China Department of Civil and Environmental Engineering Rice UniversityHouston 77005USA State Key Laboratory of High Performance Civil Engineering Materials Jiangsu Research Institute of Building Science Co.Ltd.Nanjing 210008China Department of Materials University of OxfordOxford OX13PHUK

Underground pumped storage power plant(UPSP)is an innovative concept for space recycling of abandoned *** realization requires better understanding of the dynamic performance and durability of reservoir *** paper conducted ultrasonic detection,split hopkinson pressure bar(SHPB)impact,mercury intrusion porosimetry(MIP),and backscatter electron observation(BSE)tests to investigate the dynamical behaviour and microstructure of sandstone with cyclical dry-wet damage.A coupling FEM-DEM model was constructed for reappearing mesoscopic structure *** results show that dry-wet cycles decrease the dynamic compressive strength(DCS)with a maximum reduction of 39.40%,the elastic limit strength is reduced from 41.75 to 25.62 *** sieved fragments obtain the highest crack growth rate during the 23rd dry-wet cycle with a predictable life of 25 cycles for each rock *** pore fractal features of the macropores and micro-meso pores show great differences between the early and late cycles,which verifies the computational statistics analysis of particle *** numerical results show that the failure patterns are governed by the strain in pre-peak stage and the shear cracks are *** dry-wet cycles reduce the energy transfer efficiency and lead to the discretization of force chain and crack fields.

关键词： Underground pumped storage power plant Dry-wet cycles split hopkinson pressure bar Macro and micro properties FEM-DEM coupling model Damage characterization

Effects of Craddition on Charpy impact energy in austenitic 0.45C-24Mn-(0,3,6)Cr steels

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Journal of Materials Science & Technology 2020年第15期47卷 21-30页

作者： Seok Gyu Lee Bohee Kim Min Cheol Jo Kyeong-Min Kim Junghoon Lee Jinho Bae Byeong-Joo Lee Seok Su Sohn Sunghak Lee Center for Advanced Aerospace Materials Pohang University of Science and TechnologyPohang37673South Korea Steel Products Design Team Hyundai SteelDangjin31779South Korea Steel Products Research Group 1 Technical Research LaboratoriesPOSCOGwangyang57807South Korea Department of Materials Science and Engineering Korea UniversitySeoul02841South Korea

Effects of Cr addition(0,3,and 6 wt%) on Charpy impact properties of Fe-C-Mn-Cr-based steels were studied by conducting dynamic compression tests at room and cryogenic *** room temperature,deformation mechanisms of Charpy impacted specimens were observed as twinning induced plasticity(TWIP) without any transfo rmation induced plasticity(TRIP) in all the *** cryogenic temperature,many twins were populated in the Cr-added steels,but,interestingly,fine ε-martensite was found in the OCr steel,satisfying the Shoji-Nishiyama(S-N) orientation relationship,{111}γ//{0002}ε and γ//ε.Even though the cryogenic-temperature staking fault energies(SFEs) of the three steel were situated in the TWIP regime,the martensitic transformation was induced by Mn-and Cr-segregated *** the OCr steel,SFEs of low-(Mn,Cr) bands lay between the TWIP and TRIP regimes which were sensitively affected by a small change of *** dynamic compressive test results well showed the relation between segregation bands and the *** of Cr were known as not only increasing the SFE but also promoting the carbide *** order to identify the possibility of carbide formation,a precipitation kinetics simulation was conducted,and the predicted fractions of precipitated M23C6 were negligible,0.4-1.1×10-5,even at the low cooling rate of 10℃/s.

关键词： Austenitic high-Mn steels Charpy impact energy split hopkinson pressure bar Twinning induced plasticity(TWIP) Transformation induced plasticity(TRIP) Stacking fault energy(SFE)

Damage constitutive model of different age concretes under impact load

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Journal of Central South University 2015年第2期22卷 693-700页

作者：李夕兵王世鸣翁磊黄麟淇周韬周健 School of Resources and Safety Engineering Central South University Hunan Key Lab of Resources Exploitation and Hazard Control for Deep Metal Mines

In order to investigate the mechanical properties and stress-strain curves of concrete at different ages under impact load,the impact compression tests of concrete at age of 1, 3, 7, 14 and 28 d were conducted with a large diameter split hopkinson pressure bar, respectively. Based on statistical damage theory and Weibull distribution, combining the analysis of the change laws of stressstrain curves and viscosity coefficient of concrete with age, a damage constitutive model that can reflect the variation in dynamic mechanical properties with age was proposed. The stress-strain curves calculated from the proposed model are in good agreement with those from experimental data directly.

关键词： concrete constitutive model age split hopkinson pressure bar

Effects of strain rates on dynamic deformation behavior of Cu-20Ag alloy

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Journal of Materials Science & Technology 2021年第20期79卷 75-87页

作者： Kexing Song Yongfeng Geng Yijie Ban Yi Zhang Zhou Li Xujun Mi Jun Cao Yanjun Zhou Xuebin Zhang School of Materials Science and Engineering Henan University of Science and TechnologyLuoyang471023China Provincial and Ministerial Co-Construction of Collaborative Innovation Center for Non-Ferrous Metal New Materials and Advanced Processing Technology Henan ProvinceLuoyang471023China Henan Province Key Laboratory of Nonferrous Materials Science and Processing Technology Luoyang471023China School of Materials Science and Engineering Central South UniversityChangsha410083China General Research Institute for Nonferrous Metals Beijing100088China Henan Polytechnic University Henan ProvinceJiaozuo454010China

Copper alloy is widely used in high-speed railway,aerospace and other fields due to its excellent electrical conductivity and mechanical *** speed deformation and dynamic loading under impact load is a complex service condition,which widely exists in the field of national defense,military and industrial ***,the dynamic deformation behavior of the Cu-20Ag alloy was investigated by split hopkinson pressure bar(SHPB)with the strain rates of 1000-25000 s^(-1),high-speed hydraulic servo material testing machine with the strain rates of 1-500 s^(-1).The effect of strain rate on flow stress and adiabatic shear sensitivity was *** results show that the increase of strain rate will increase the flow stress and critical strain,that is to say,the increase of strain rate will reduce the adiabatic shear sensitivity of the Cu-20Ag *** Cu-Ag interface has obvious orientation relationship with;(111)_(Cu)//(111)_(Ag):(^(-)111)_(Cu)//(^(-)111)_(Ag):(^(-)200)_(Cu)//(^(-)200)_(Ag) and [0^(-)11]_(Cu)//[0^(-)11]_(Ag) with the increase of strain *** increase of strain rate promotes the precipitation of Ag and increases the number of interfaces in the microstructure,which hinders the movement of dislocations and improves the stress and yield strength of the Cu-20Ag *** concentration and distribution density of dislocations and the precipitation of Ag were the main reasons improve the flow stress and yield strength of the Cu-20Ag alloy.

关键词： Cu-20Ag alloy Dynamic deformation split hopkinson pressure bar Adiabatic shear sensitivity

Dynamic Mechanical Properties and Energy Dissipation Characteristics of Frozen Soil Under Passive Confined pressure

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Acta Mechanica Solida Sinica 2021年第2期34卷 184-203页

作者： Jinxuan Jia Huaiping Tang Huijian Chen Applied Mechanics and Structure Safety Key Laboratory of Sichuan Province School of Mechanics and EngineeringSouthwest Jiaotong UniversityChengdu 610031China

Impact compression tests on frozen soil samples with different freezing temperatures and subjected to passive confined pressure were performed using a split hopkinson pressure bar at different loading strain *** three-dimensional stress-strain curves of the frozen soil samples under the corresponding conditions were *** experimental results showed that,when the frozen soil was loaded to its elastic limit,shear failure occurred,the bearing capacity of pore ice was lost,and the thawed soil functioned as the main stress-bearing ***,the capacity of frozen soil to withstand hydrostatic pressure continued to *** dynamic mechanical properties of the frozen soil under passive confined pressure were observed to be strongly related to the loading strain rate and freezing *** the loading strain rate increased,the secant modulus,elastic modulus,and strength(including the shear strength)of the frozen soil increased,whereas its Poisson^ratio and coefficient of lateral pressure *** the freezing temperature decreased,the secant modulus,elastic modulus,and shear strength of the frozen soil increased;however,its Poisson5s ratio and coefficient of lateral pressure *** the frozen soil was subjected to impact loading under passive confined pressure,energy dissipation occurred due to plastic deformation,mesoscopic damage evolution,and ice-water phase *** shear failure occurred,the absorption energy per unit volume of frozen soil increased as the freezing temperature decreased and the loading strain rate increased.

关键词： Frozen soil split hopkinson pressure bar Passive confined pressure Dynamic mechanical properties Energy dissipation