期刊文献+
共找到15篇文章
< 1 >
每页显示 20 50 100
不同水力荷载路径下煤体微观渗流特征及宏观破坏研究 被引量:3
1
作者 马国良 陈曦 +1 位作者 范超男 葛少成 《岩土力学》 EI CAS CSCD 北大核心 2023年第6期1779-1788,共10页
为探究煤体在不同水力荷载路径下的微观渗流特征,通过CT三维重建技术,建立了基于煤体微观结构的双介质渗流模型,并设计了恒定速度加载(LP1)、常规脉动加载(LP2)和强加载缓卸载加载(LP3)3种水力荷载路径,进行了在不同循环荷载路径下的煤... 为探究煤体在不同水力荷载路径下的微观渗流特征,通过CT三维重建技术,建立了基于煤体微观结构的双介质渗流模型,并设计了恒定速度加载(LP1)、常规脉动加载(LP2)和强加载缓卸载加载(LP3)3种水力荷载路径,进行了在不同循环荷载路径下的煤体注水渗流数值模拟试验。另外利用自行搭建的煤体注水装置,探究了3种荷载路径下的宏观损伤情况。结果表明:联通裂隙占孔裂隙结构的73.49%,是影响煤体渗流的主要因素,而孔径为9~23μm的孔隙是孤立孔隙中的主要部分,数量和体积占比均超过了50%;煤体内部孔裂隙结构和荷载路径对渗流速度和压力的分布特征具有重要影响。LP1沿注入方向平均渗流速度的波动较大,LP3则抑制效果明显,且LP3路径较LP1和LP2随时间有较大跨度。LP3的荷载路径相对于LP1具有脉动荷载的疲劳损伤效果,并且造成的损伤程度强于LP2。该研究可为煤体微观结构研究和煤层注水技术参数优化提供方向。 展开更多
关键词 CT三维重建 渗流特征 煤层注水 孔裂隙结构 强加载缓卸
原文传递
Advances in the studies of the supported ruthenium catalysts for CO_(2) methanation
2
作者 Chenyang Shen Menghui Liu +2 位作者 Song He Haibo Zhao Chang-jun Liu 《Chinese Journal of Catalysis》 SCIE CAS CSCD 2024年第8期1-15,共15页
CO_(2) methanation has a potential in the large-scale utilization of carbon dioxide.It has also been considered to be useful for the renewable energy storage.The commercial pipeline for natural gas transportation can ... CO_(2) methanation has a potential in the large-scale utilization of carbon dioxide.It has also been considered to be useful for the renewable energy storage.The commercial pipeline for natural gas transportation can be directly applied for the methane product of CO_(2) methanation.The supported ruthenium(Ru)catalyst has been confirmed to be active and stable for CO_(2) methanation with its high ability in the dissociation of hydrogen and the strong binding of carbon monoxide.CO_(2) methanation over the supported Ru catalyst is structure sensitive.The size of the Ru catalyst and the support have significant effects on the activity and the mechanism.A significant challenge re-mained is the structural controllable preparation of the supported Ru catalyst toward a sufficiently high low-temperature activity.In this review,the recent progresses in the investigations of the supported Ru catalysts for CO_(2) methanation are summarized.The challenges and the future devel-opments are also discussed. 展开更多
关键词 RUTHENIUM Carbon dioxide METHANATION HYDROGENATION Catalyst and metal-support interaction
下载PDF
VHF频段大功率宽带滤波器的设计与实现 被引量:1
3
作者 贾建蕊 王烨 《无线电工程》 2015年第10期63-66,共4页
针对VHF频段大功率宽带带通滤波器设计中的问题,提出了一种梳状线滤波器设计的新方法——强加载电感耦合法。内导体采用T型带下拉结构,实现腔体小型化;合理布局腔体空间,实现了大功率的需要;内导体之间用导线连接,实现腔间强磁耦合达到... 针对VHF频段大功率宽带带通滤波器设计中的问题,提出了一种梳状线滤波器设计的新方法——强加载电感耦合法。内导体采用T型带下拉结构,实现腔体小型化;合理布局腔体空间,实现了大功率的需要;内导体之间用导线连接,实现腔间强磁耦合达到相对带宽19%的要求;基于部分模型与整体模型相结合的方法,通过HFSS(高频电磁仿真软件)建模进行了仿真和优化设计。论述了该滤波器的实现方式,并给出了测试结果,验证了该设计方法思路正确,设计效率较高。 展开更多
关键词 小型化 大功率 强磁耦合 强加载
下载PDF
Effects of aspect ratio and loading rate on room-temperature mechanical properties of Cu-based bulk metallic glasses 被引量:1
4
作者 蔡安辉 刘咏 +6 位作者 吴宏 丁大伟 安伟科 周果君 罗云 彭勇宜 李小松 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2016年第10期2617-2632,共16页
Room-temperature mechanical properties of Cu50Zr40Ti10-xNix(0≤x≤4,mole fraction,%) bulk metallic glasses (BMG) with aspect ratios in the range of 1:1-2.5:1 and loading rates in the range of1×10^-5-1×... Room-temperature mechanical properties of Cu50Zr40Ti10-xNix(0≤x≤4,mole fraction,%) bulk metallic glasses (BMG) with aspect ratios in the range of 1:1-2.5:1 and loading rates in the range of1×10^-5-1×10^-2s^-1were systematically investigated by room-temperatureuniaxialcompression test.In the condition of an aspect ratio of 1:1, the superplasticity can be clearly observed for Cu50Zr40Ti10BMG when the loading rate is1×10^-4s^-1, while for Cu50Zr40Ti10-xNix(x=1-3, mole fraction, %) BMGs when the loading rate is1×10^-2s^-1. The plastic strain (εp), yielding strength (σy) and fracture strength (σf) of the studied Cu-based BMGs significantly depend on the aspect ratio and the loading rate. In addition, theσyof the studied Cu-based BMGs with an aspect ratio of 1:1 is close to the σfof those with the other aspect ratios when the loading rate is1×10^-2s^-1. The mechanism for the mechanical response to the loading rate and the aspect ratiowas also discussed. 展开更多
关键词 Cu-based bulk metallic glasses aspect ratio loading rate PLASTICITY STRENGTH
下载PDF
Flexural strength of zirconia/stainless steel functionally graded materials 被引量:1
5
作者 李军 赵康 +1 位作者 汤玉斐 李大玉 《Journal of Central South University》 SCIE EI CAS 2009年第6期892-896,共5页
Zirconia/stainless steel (ZrO2/SUS316L) functionally graded materials (FGMs) were fabricated by tape casting and laminating. Microstructures of FGMs were observed by optical microscope. Fracture behavior of FGMs in di... Zirconia/stainless steel (ZrO2/SUS316L) functionally graded materials (FGMs) were fabricated by tape casting and laminating. Microstructures of FGMs were observed by optical microscope. Fracture behavior of FGMs in different loading modes and influences of different gradient changes on flexural strength were investigated. The results show that ZrO2/ SUS316L FGMs with graded components at interlayers are obtained after they are sintered in vacuum and pressureless condition at 1 350 ℃. TheⅠ?Ⅱ mixed mode crack creates in composite layer and grows to both sides zigzag while loading on ZrO2 layer. Flexural strengths are 496.4,421.7 and 387.5 MPa when gradient changes are 10%,15% and 20%,but flexural strengths of the corresponding fracture layers are 387.1,334.6 and 282.3 MPa since cracks of FGMs are affected by three-dimensional stress,respectively. The cracks are generated in ZrO2 layer and extend to SUS316L layer while loading is added on SUS316L layer,flexural strength does not change with the graded components and keeps consistent basically. 展开更多
关键词 ZRO2 functionally graded materials flexural strength FRACTURE tape casting
下载PDF
Relationship between diameter of split Hopkinson pressure bar and minimum loading rate under rock failure 被引量:6
6
作者 李夕兵 洪亮 +2 位作者 尹土兵 周子龙 叶洲元 《Journal of Central South University of Technology》 EI 2008年第2期218-223,共6页
In order to investigate the relationship between bar diameter and loading rate of the split Hopkinson pressure bar(SHPB) setup under the failure of rock specimen and realize the medium strain rate loading of specimen,... In order to investigate the relationship between bar diameter and loading rate of the split Hopkinson pressure bar(SHPB) setup under the failure of rock specimen and realize the medium strain rate loading of specimen,new SHPB setups with different elastic bar's diameters of 22,36,50 and 75 mm were constructed.The tests were carried out on these setups at different loading rates,and the specimens had the same diameter of elastic bars and same ratio of length to diameter.The test results show that the larger the elastic bar's diameter is,the less the loading rate is needed to cause specimen failure,they show good power relationship,and that under the same strain rate loading,specimens are broken more seriously with larger diameter SHPB setup than with smaller one. 展开更多
关键词 rock failure Hopkinson pressure bar DIAMETER minimum loading rate medium strain rate
下载PDF
Normalization method for asphalt mixture fatigue equation under different loading frequencies 被引量:2
7
作者 吕松涛 郑健龙 《Journal of Central South University》 SCIE EI CAS CSCD 2015年第7期2761-2767,共7页
In order to analyze the effect of different loading frequencies on the fatigue performance for asphalt mixture,the changing law of asphalt mixture strengths with loading speed was revealed by strength tests under diff... In order to analyze the effect of different loading frequencies on the fatigue performance for asphalt mixture,the changing law of asphalt mixture strengths with loading speed was revealed by strength tests under different loading speeds.Fatigue equations of asphalt mixtures based on the nominal stress ratio and real stress ratio were established using fatigue tests under different loading frequencies.It was revealed that the strength of the asphalt mixture is affected by the loading speed greatly.It was also discovered that the fatigue equation based on the nominal stress ratio will change with the change of the fatigue loading speed.There is no uniqueness.But the fatigue equation based on the real stress ratio doesn't change with the loading frequency.It has the uniqueness.The results indicate the fatigue equation based on the real stress ratio can realize the normalization of the asphalt mixture fatigue equation under different loading frequencies.It can greatly benefit the analysis of the fatigue characteristics under different vehicle speeds for asphalt pavement. 展开更多
关键词 road engineering asphalt pavement fatigue equation loading speed loading frequency strength stress ratio
下载PDF
Analysis of Contact Stress Distribution and Strength in Pin-Loaded Orthotropic Plates 被引量:1
8
作者 Olanrewaju A luko 《Journal of Mechanics Engineering and Automation》 2012年第11期647-655,共9页
The development of an analytic solution in terms of laminate parameters is presented for contact stresses and joint strength in pin-loaded orthotropic plates. This involved the determination of complex stress function... The development of an analytic solution in terms of laminate parameters is presented for contact stresses and joint strength in pin-loaded orthotropic plates. This involved the determination of complex stress functions required to compute stresses in terms of a set of unknown coefficients for the specified displacement expressions satisfying the prescribed boundary conditions. The assumed Coulomb friction between the plate and the pin was used to provide the solution and iteration was also used to determine the extent of contact region. The results from present study showed good agreement with the available results in literature for all the joint configurations evaluated. 展开更多
关键词 Laminate parameters stress functions FRICTION orthotropic.
下载PDF
Effects of curing under step-by-step load on mechanical and deformation properties of cemented gangue backfill column 被引量:9
9
作者 GUO Yu-xia RAN Hong-yu +3 位作者 FENG Guo-rui DU Xian-jie QI Ting-ye WANG Ze-hua 《Journal of Central South University》 SCIE EI CAS CSCD 2020年第11期3417-3435,共19页
A step-by-step load was utilized to mimic the load history of the backfill column in the in-situ curing process.The inner damage of the specimen during curing and uniaxial compressive testing was monitored by electric... A step-by-step load was utilized to mimic the load history of the backfill column in the in-situ curing process.The inner damage of the specimen during curing and uniaxial compressive testing was monitored by electrical resistivity and ultrasonic equipment.Results show that:1)Uniaxial compressive strength(UCS)and elastic modulus(EM)of the samples curing under pressure are higher than those of the control samples without pressure,ranging in ratio from 0.5%to 20.2%and 7.1%to 52.3%,respectively,and are influenced by the initial loading age(ILA)and stress strength ratio(SSR).The SSR during curing should not exceed 80%.2)The earlier the ILA is,the higher the total strain becomes.The higher the SSR applies,the larger the total strain gets.The creep strain increases with the increase of SSR and can be described by Burger’s viscoelastic creep model.When SSR is less than 80%,the earlier the ILA is,the smaller the creep strain becomes after the last step-loading.3)The stability of the early age backfill column under pressure can be monitored based on the change of ultrasonic pulse velocity(UPV)and electrical resistivity. 展开更多
关键词 cemented gangue backfill column curing under step-by-step load compressive strength elastic modulus deformation electrical resistivity
下载PDF
Dynamic tensile strength and failure mechanisms of thermally treated sandstone under dry and water-saturated conditions 被引量:8
10
作者 Pin WANG Tu-bing YIN Bi-wei HU 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2020年第8期2217-2238,共22页
To study the tensile strength and failure mechanisms of rock with hydro-thermal coupling damage under different loading rates,a series of static and dynamic splitting tests were conducted on thermally treated sandston... To study the tensile strength and failure mechanisms of rock with hydro-thermal coupling damage under different loading rates,a series of static and dynamic splitting tests were conducted on thermally treated sandstone under dry and water-saturated conditions.Experimental results showed that high temperatures effectively weakened the tensile strength of sandstone specimens,and the P-wave velocity declined with increasing temperature.Overall,thermal damage of rock increased gradually with increasing temperature,but obvious negative damage appeared at the temperature of 100℃.The water-saturated sandstone specimens had lower indirect tensile strength than the dry ones,which indicated that water-rock interaction led to secondary damage in heat-treated rock.Under both dry and water-saturated conditions,the dynamic tensile strength of sandstone increased with the increase of strain rate.The water-saturated rock specimens showed stronger rate dependence than the dry ones,but the loading rate sensitivity of thermally treated rock decreased with increasing treatment temperature.With the help of scanning electron microscopy technology,the thermal fractures of rock,caused by extreme temperature,were analyzed.Hydro-physical mechanisms of sandstone under different loading rate conditions after heat treatment were further discussed. 展开更多
关键词 SANDSTONE dynamic tensile strength hydro-thermal coupling damage loading rate dependence failure mechanism
下载PDF
Behaviour of Concrete Elements under the Shear Forces and Strengthening with the Fibre Reinforcement Polymers
11
作者 NaserKabashi Cene Krasniqi Burim Hajrizi 《Journal of Civil Engineering and Architecture》 2014年第5期581-587,共7页
The paper presents the behaviour of concrete elements, in this case the beams under the different loadings result with the capacity of section. In analyzing process, results are followed with the deflections of beams ... The paper presents the behaviour of concrete elements, in this case the beams under the different loadings result with the capacity of section. In analyzing process, results are followed with the deflections of beams and the cracks. In this paper, we analyse the type, form and dimensions of cracks under the third point load method of applied loads in simple concrete beam. To improve the capacity, the authors use the different types of FRP (fibre reinforcement polymers), including the glass fibre reinforcement polymers and carbon fibre reinforcement polymers, comparing the deflections and cracks. The focused parameters are in using the different methods for transversal force, including the primary forms with steel stirrups and the new proposal for using the outside stirrups from FRP. The all analyses presented in this paper are based on the analytical model and experimental results. The behaviour of beams under the mixed form with ordinary steel stirrups and proposal stirrups from FRP, successfully increase the energetic capacity of sections. 展开更多
关键词 Concrete elements FRP cracks DEFLECTIONS strengthening.
下载PDF
Molecular dynamics analysis on bending mechanical behavior of alumina nanowires at different loading rates 被引量:3
12
作者 Yuxiao James HE Bin MA 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2022年第11期3687-3698,共12页
The molecular dynamics(MD)model ofα-Al_(2)O_(3) nanowires in bending is established by using LAMMPS to calculate the atomic stress and strain at different loading rates in order to study the effect of loading rate on... The molecular dynamics(MD)model ofα-Al_(2)O_(3) nanowires in bending is established by using LAMMPS to calculate the atomic stress and strain at different loading rates in order to study the effect of loading rate on the bending mechanical behaviors of theα-Al_(2)O_(3) nanowires.Research results show that the maximum surface stress−rotation angle curves ofα-Al_(2)O_(3) nanowires at different loading rates are all divided into three stages of elastic deformation,plastic deformation and failure,where the elastic limit point can be determined by the curve symmetry during loading and unloading cycle.The loading rate has great influence on the plastic deformation but little on the elastic modulus ofα-Al_(2)O_(3) nanowires.When the loading rate is increased,the plastic deformation stage is shortened and the material is easier to fail in brittle fracture.Therefore,the elastic limit and the strength limit(determined by the direct and indirect MD simulation methods)are closer to each other.The MD simulation result ofα-Al_(2)O_(3) nanowires is verified to be valid by the good agreement with the improved loop test results.The direct MD method becomes an effective way to determine the elastic limit and the strength limit of nanoscale whiskers failed in brittle or ductile fracture at arbitrary loading rate. 展开更多
关键词 alumina nanowires bending behavior loading rate elastic limit strength limit molecular dynamics
下载PDF
Numerical Simulation of Mechanical Behaviors of Degradable Porous Bioceramics with Cracks
13
作者 CHEN Jinlong LIU Qian ZHAN Nan 《Transactions of Tianjin University》 EI CAS 2012年第1期21-25,共5页
Hydroxyapatite bioceramics is simulated by using finite element method (FEM). The influences of porosity, hole shape, angle of crack and other parameters on the ceramics are analyzed. The results show that with the ... Hydroxyapatite bioceramics is simulated by using finite element method (FEM). The influences of porosity, hole shape, angle of crack and other parameters on the ceramics are analyzed. The results show that with the increase of the angle between crack and horizontal direction, the stress intensity factor KⅠ decreases gradually, but stress intensity factor KⅡ increases at first and then it decreases. The value of KⅡ reaches maximum when the angle between crack and horizontal direction is 45°. KⅠ and KⅡ rise with the increase of porosity, and they are almost the same for the circular and hexagonal holes. For elliptical holes, KⅠ and KⅡ reach maximum when the long axis of ellipse is perpendicular to the loading direction and they reach minimum when the same axis is parallel to the loading direction. Moreover, with the increase of the angle between the long axis and loading direction, KⅠ and KⅡ increase gradually. 展开更多
关键词 porous bioceramics DEGRADATION finite element method (FEM) POROSITY stress intensity factor
下载PDF
A Quadrature Approach for N-Collinear Crack Problem in an Orthotropic Strip
14
作者 Elcin YUSUFOGLU Ilkem TURHAN CETINKAYA 《Journal of Mathematics and System Science》 2017年第8期213-224,共12页
This study presents the determination of the stress intensity factors (SIFs) at the edges of the cracks in an elastic strip weakened by N-collinear cracks. The problem of an orthotropic elastic strip is reduced to a... This study presents the determination of the stress intensity factors (SIFs) at the edges of the cracks in an elastic strip weakened by N-collinear cracks. The problem of an orthotropic elastic strip is reduced to a system of Cauchy type singular integral equations. The system of singular integral equations is approached by a Quadrature technique. Under two different loading conditions, the results are obtained for the different cases of crack numbers. The resistance of the strip is examined by considering the orthotropic properties of the strip material. Finally, the crack interactions are clarified during the analysis. 展开更多
关键词 CRACK Theory of Elasticity System of Singular Integral Equations Quadrature Approach
下载PDF
Shear Behavior of Novel Prestressed Concrete Beam Subjected to Monotonic and Cyclic Loading
15
作者 余芳 姚大立 +1 位作者 贾金青 吴锋 《Transactions of Tianjin University》 EI CAS 2014年第4期257-265,共9页
Prestressed steel ultrahigh-strength reinforced concrete(PSURC) beam is a new type of prestressed concrete beam, which not only has a considerable compressive strength attributed to the ultrahigh strength concrete, bu... Prestressed steel ultrahigh-strength reinforced concrete(PSURC) beam is a new type of prestressed concrete beam, which not only has a considerable compressive strength attributed to the ultrahigh strength concrete, but also ensures a certain degree of ductility at failure due to the existence of structural steel. Five of these beams were monotonically tested until shear failure to investigate the static shear performance including the failure pattern, loaddeflection behavior, shear capacity, shear crack width and shear ductility. The experimental results show that these beams have superior shear capacity, crack control ability and shear ductility. To study the shear performance under repeated overloading, seven PSURC beams were loaded in cyclic test simultaneously. The overall shear performance of cycled beams is similar to that of uncycled beams at low load level but different at high load level. The shear capacity and crack control ability of cycled beams at high load level are reduced, whereas the shear ductility is improved. In addition, the influences of variables including the degree of prestress, stirrup ratio and load level on the shear performance of both uncycled and cycled beams were also discussed and compared, respectively. 展开更多
关键词 prestressed concrete beam structural steel ultrahigh strength concrete shear behavior cyclic loading
下载PDF
上一页 1 下一页 到第
使用帮助 返回顶部