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“Abnormal transient creep” in fine-grained Al-5356 alloy observed at low strain rates by high-resolution strain measurement 被引量:1
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作者 申俊杰 Kenichi IKEDA +1 位作者 Satoshi HATA Hideharu NAKASHIMA 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2013年第5期1209-1214,共6页
Transient creep at very low strain rates (less than 10-10 s-1) is still unclear. The traditional uniaxial creep testing is less useful due to unsatisfied resolution strain (~10-6). To study transient creep behavio... Transient creep at very low strain rates (less than 10-10 s-1) is still unclear. The traditional uniaxial creep testing is less useful due to unsatisfied resolution strain (~10-6). To study transient creep behavior at such low strain rates, a high-resolution strain measurement using the helicoid spring specimen technique was employed in a fine-grained Al-5356 alloy at temperatures ranging from 0.47Tm to 0.74Tm (Tm: melting point). To clarify transient creep mechanism at such low strain rates, transmission electron microscopy (TEM) was used in microstructure observation of crept specimens. The abnormal transient creep, high temperature strengthening at T〉Tp (Tp: the phase transformation temperature, 0.58Tm) or intermediate temperature softening at 0.4Tm〈T£Tp and double-normal type (creep curves including double work-hardening stages) at T=Tp, were firstly observed. The substructure observation in a crept specimen at T=0.58Tm and e=1×10-4 shows pile-up dislocations including many small jogs with equal interval, and dislocations emitted from grain boundaries. The b-Al3Mg2 phase dissolves under the condition of testing temperatures higher than 523 K, which causes solid-solution quantity of Mg atoms to increase. Therefore, the “abnormal transient creep” may be related to the difference of solid solution strengthening caused by phase change during the creep tests. 展开更多
关键词 Al-5356 alloy transient creep phase change low strain rate
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High-frequency interference waves in low strain dynamic testing of X-section concrete piles 被引量:1
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作者 Qu Liming Fan Yuming +2 位作者 Ding Xuanming Yang Changwei Zhang Yanling 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2021年第4期877-885,共9页
Stress waves propagate along vertical,radial and circumferential directions when a non-uniformly distributed load is applied at one end of a three-dimensional shaft.As a result,the receiving signals are usually mixed ... Stress waves propagate along vertical,radial and circumferential directions when a non-uniformly distributed load is applied at one end of a three-dimensional shaft.As a result,the receiving signals are usually mixed with undesired interference components,often featuring as high-frequency fluctuations.Previous studies have revealed that sectional geometry(shape and size)greatly affects the high-frequency interference.In this study,low strain dynamic testing on full-scale X-section concrete is conducted in order to investigate the influences of high-frequency interference on velocity responses at the pile head.Emphasis is placed on the frequency and peak value of interference waves at various receiving points.Additionally,the effects of the geometrical,and mechanical properties of the pile shaft on high-frequency interference are elaborated on through the three-dimensional finite element method.The results show that the measured wave is obscured by interference waves superposed by two types of high-frequency components.The modulus and cross-sectional area are contributing factors to the frequency and peak value of the interference waves.On the other hand,the position with the least interference is determined,to some extent,by the accurate shape of the X-section. 展开更多
关键词 low strain dynamic testing X-section concrete pile high-frequency interference full-scale model test finite element method
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Instantaneous Creep in Face-centered Cubic Metals at Ultra- low Strain Rates by a High-resolution Strain Measurement
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作者 SHEN Junjie Ikeda Kenichi +1 位作者 Hata Satoshi Nakashima Hideharu 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2013年第6期1096-1100,共5页
Instantaneous creep in face-centered cubic metals, 5N Al(99.999%), 2N Al (99%) and 4N Cu (99.99%) with different grain sizes, was firstly investigated by sudden stress-change experiments at ultra- low strain rat... Instantaneous creep in face-centered cubic metals, 5N Al(99.999%), 2N Al (99%) and 4N Cu (99.99%) with different grain sizes, was firstly investigated by sudden stress-change experiments at ultra- low strain rates ε ≤10-10 s-1 and temperature T 〈 0.32 Tn. The experimental results indicate that the observed instantaneous creep is strongly dependent on grain size, the concentration of impurity, and stacking fault energy. Creep in high-purity aluminum, 5N Al, with a very large grain size, d 〉 1600μm, shows non-viscous behavior, and is controlled by the recovery of dislocations in the boundary of dislocation cells. On the other hand, for 5N A1 with a small grain size, d=30μm, and low-purity aluminum, 2N A1, with d8= 25μm, creep shows viscous behavior and may be related to 'low temperature grain boundary sliding'. For high-purity copper, 4N Cu, with d= 40 grn and lower stacking fault energy, creep shows a non-viscous behavior, and is controlled by the recovery process of dislocations. For all of the samples, creep shows anelastic behavior. 展开更多
关键词 face-centered cubic metals instantaneous creep ultra-low strain rate high strain resolution measurement
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High-frequency interference in low strain integrity testing of large-diameter pipe piles 被引量:19
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作者 DING XuanMing LIU HanLong ZHANG Bo 《Science China(Technological Sciences)》 SCIE EI CAS 2011年第2期420-430,共11页
The high-frequency interference exists obviously in low strain integrity testing of large-diameter pipe pile when a transientpoint load is applied. An analytical solution of vertical vibratory response of large-diamet... The high-frequency interference exists obviously in low strain integrity testing of large-diameter pipe pile when a transientpoint load is applied. An analytical solution of vertical vibratory response of large-diameter pipe piles in low strain testing isdeduced in this paper. The analytical solution is verified by both numerical simulation and model test results. The time-domainvelocity responses on pile top are analyzed. The calculation results indicate that the time-domain responses at various pointssuffer different high-frequency interferences, thus the peak values and phases of different points are different. The influence ofvibratory modes on high-frequency interference is analyzed. It is found that the high-frequency interference at 90° point main-ly derives from the second flexural mode, but for other points it mainly originates from the first flexural mode. The factors af-fecting the frequency and peak value of interference waves have been investigated in this study. The results indicate that thelarger radius angle between the receiving and 90° points leads to greater peak value of high frequency wave crest. The leasthigh-frequency interference is detected at the angle of 90°. The frequency of interference waves is decreased with the increaseof pile radius, while the peak value is almost constant. The frequency is also related to pile modulus, i.e. the larger pile modu-lus results in greater frequency. The peak value varies with impulse width and soil resistance, i.e., the wider impulse width andlarger soil resistance cause smaller peak value. In conclusion, the frequency of interference waves is dependent on the geomet-rical and mechanics characteristics of the piles such as pile radius and modulus, but independent of the external conditionssuch as impulse width and soil resistance. On the other hand, the peak value of interference waves is mainly dependent on theexternal conditions but independent of the geometrical and mechanics characteristics of the piles. In practice, some externalmeasures should be adopted to weaken high-frequency interference such as using soft hammer, hammer cushion and adoptingsuitable receiving point. 展开更多
关键词 large-diameter pipe pile low strain integrity testing high-frequency interference vibratory response analytic solution
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Low-S train and High-Energy KVPO_(4)F Cathode with Multifunctional Stabilizer for Advanced Potassium-Ion Batteries 被引量:1
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作者 Yongli Heng Zhenyi Gu +6 位作者 Jinzhi Guo Haojie Liang Yan Liu Wei Guo Xinxin Zhao Xiaotong Wang Xinglong Wu 《Energy & Environmental Materials》 SCIE EI CAS CSCD 2024年第5期140-149,共10页
KVPO_(4)F with excellent structural stability and high operating voltage has been identified as a promising cathode for potassium-ion batteries(PIBs),but limits in sluggish ion transport and severe volume change cause... KVPO_(4)F with excellent structural stability and high operating voltage has been identified as a promising cathode for potassium-ion batteries(PIBs),but limits in sluggish ion transport and severe volume change cause insufficient potassium storage capability.Here,a high-energy and low-strain KVPO_(4)F composite cathode assisted by multifunctional K_(2)C_(4)O_(4)electrode stabilizer is exquisitely designed.Systematical electrochemical investigations demonstrate that this composite cathode can deliver a remarkable energy density up to 530 Wh kg^(-1)with 142.7 mAh g^(-1)of reversible capacity at 25 mA g^(-1),outstanding rate capability of 70.6 mAh g^(-1)at 1000 mA g^(-1),and decent cycling stability.Furthermore,slight volume change(~5%)and increased interfacial stability with thin and even cathode-electrolyte interphase can be observed through in situ and ex situ characterizations,which are attributed to the synergistic effect from in situ potassium compensation and carbon deposition through self-sacrificing K_(2)C_(4)O_(4)additive.Moreover,potassium-ion full cells manifest significant improvement in energy density and cycling stability.This work demonstrates a positive impact of K_(2)C_(4)O_(4)additive on the comprehensive electrochemical enhancement,especially the activation of high-voltage plateau capacity and provides an efficient strategy to enlighten the design of other high-voltage cathodes for advanced high-energy batteries. 展开更多
关键词 high energy density K_(2)C_(4)O_(4) KVPO_(4)F composite cathode low strain potassium-ion batteries
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Effect of ultraviolet mutagenesis on heterotrophic strain mutation and bioleaching of low grade copper ore 被引量:5
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作者 WU Ai-xiang HU Kai-jian +2 位作者 WANG Hong-jiang ZHANG Ai-qing YANG Ying 《Journal of Central South University》 SCIE EI CAS CSCD 2017年第10期2245-2252,共8页
The effect of ultraviolet mutagenesis on a heterotrophic strain(Providencia JAT-1) mutation was studied and bioleaching of low grade copper ore with mutant bacteria was investigated. The results show that the activity... The effect of ultraviolet mutagenesis on a heterotrophic strain(Providencia JAT-1) mutation was studied and bioleaching of low grade copper ore with mutant bacteria was investigated. The results show that the activity of bacteria was improved after ultraviolet mutagenesis; the best irradiation time was 120 s. Compared to the original bacteria, the cells density of mutant bacteria at stationary phase increased by 26% and ammonia produced by mutant bacteria increased by 12%. Higher activity of bacteria leads to a higher copper extraction rate. The bioleaching performance of Providencia JAT-1 was improved after UV mutagenesis. The copper extraction rate with mutant bacteria increased by 10.6% compared to the original bacteria. The ore surface was corroded and the fine particles were absent after bioleaching. Free copper oxide and copper silicates could be leached out easily by using JAT-1; a small part of the copper sulfide can also be leached out. Bioleaching using JAT-1 is more effective than ammonia leaching and copper extraction rate with mutant bacteria was 21.1% higher than that by ammonia leaching under the same condition. 展开更多
关键词 ULTRAVIOLET MUTAGENESIS BIOLEACHING HETEROTROPHIC strain ammonia low grade copper ORE
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EFFECT OF DYNAMIC STRAIN AGING ON LOW CYCLE FATIGUE BEHAVIOUR OF 18-8 AUSTENITIC STAINLESS STEEL 被引量:2
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作者 PENG Kaiping CHEN Wenzhe OIAN Kuangwu Fuzhou University,Fuzhou,China teaching assistant,Department of Mechanical Engineering,Fuzhou University,Fuzhou 350002,China 《Acta Metallurgica Sinica(English Letters)》 SCIE EI CAS CSCD 1993年第6期420-425,共6页
Studies were made of the symmetric tensile-compressive low cycle fatigue behaviour and the influence of dynamic strain aging(DSA)pre-treatment of 18-8 austenitic stainless steel. Within the testing amplitude range of ... Studies were made of the symmetric tensile-compressive low cycle fatigue behaviour and the influence of dynamic strain aging(DSA)pre-treatment of 18-8 austenitic stainless steel. Within the testing amplitude range of strain.±0.5 % to±1.5 %,the three processes of cyclic hardening,cyclic saturation and cyclic softening were observed.In the same amplitude of strain,the peak stress of the samples pre-treated by DSA is higher than that of solid-solu- tion and cold working pre-treatment,but no remarkable differences of the fatigue lives of them were found.TEM observation shows that the uniform and stable dislocation networks with high density form after DSA pre-treatment,which increases the cyclic peak stress.The cyclic softening results from the low dislocation density and elongated cell structure with low energy. 展开更多
关键词 18-8 austenitic stainless steel dynamic strain aging low cycle fatigue
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Effect of Strain Rate on the Ferrite Grain Refinement in a Low Carbon Nb-Ti Microalloyed Steel during Low Temperature Deformation 被引量:4
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作者 B.Eghbali A.Abdollah-zadeh 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 2005年第6期851-855,共5页
Grain refinement is one of the effective methods to develop new generation low carbon microalloyed steels possessing excellent combination of mechanical properties. The microstructural evolution and ferrite grain refi... Grain refinement is one of the effective methods to develop new generation low carbon microalloyed steels possessing excellent combination of mechanical properties. The microstructural evolution and ferrite grain refinement at the deformation temperature of 865℃, above Ar3, with different strain rates were investigated using single pass isothermal hot compression experiments for a low carbon Nb-Ti microalloyed steel. The physical processes that occurred during deformation were discussed by observing the optical microstructure and analyzing the true stress-true strain responses. At strain rates of 0.001 and 0.01s^-1, there is no evidence of work hardening behavior during hot deformation and strain-induced transformation (SIT) leads to dynamic flow softening in flow curves. Optical microscopy observation shows that ultrafine and equiaxed ferrite with grain sizes of 2μm can be obtained by applying deformation with strain rate of 0.1 s^-1 due to SIT just after deformation. Furthermore, increasing the strain rate from 0.001 to 0.1 s^-1 reduces both the grain size of the equiaxed ferrite and the amount of deformed ferrite. 展开更多
关键词 low carbon microalloyed steel Hot compression Grain refinement strain induced transformation
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Characteristics of Strain-Induced Ferrite in Low Carbon Steel
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作者 LIWei-juan LIUCui-qin +1 位作者 WANGGuo-dong LIUXiang-hua 《Journal of Iron and Steel Research International》 SCIE EI CAS CSCD 2003年第4期54-58,共5页
The strain-induced ferrite formed under different conditions was observed with SEM and optical microscope.The nucleation sites of strain-induced ferrite include grain boundary,grain inside,deformed band and annealing ... The strain-induced ferrite formed under different conditions was observed with SEM and optical microscope.The nucleation sites of strain-induced ferrite include grain boundary,grain inside,deformed band and annealing twin boundary.The shapes of the ferrite accordingly are equiaxed irregular polygonal,strip-shaped and acicular. 展开更多
关键词 low carbon steel strain-induced ferrite grain boundary formed band annealing twin boundary
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ISOCHRONOUS STRESS-STRAIN CURVES OF LOW ALLOY STEEL CROSS-WELD-SPECIMEN AT HIGH TEMPERATURE 被引量:4
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作者 C.W.Ma F.Z.Xuan +1 位作者 Z.D.Wang S.T.Tu 《Acta Metallurgica Sinica(English Letters)》 SCIE EI CAS CSCD 2004年第4期612-617,共6页
In this work, a parametric approach is presented and utilized to determine the creep properties of weldments; then the model of creep strain for cross weld specimen is given. On the basis of the experimental results, ... In this work, a parametric approach is presented and utilized to determine the creep properties of weldments; then the model of creep strain for cross weld specimen is given. On the basis of the experimental results, attempt has been made to establish equations of the isochronous stress-strain for weld joint that can predict the function of loading and service time in use of the creep data of base metal and weld metal. 展开更多
关键词 isochronous stress-strain curve creep deformation high temperature welded joint low alloy steel
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Investigation into the stress-strain curves of deformation-induced ferrite transformation in a low carbon steel
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作者 ZHAO Shengsheng ZHAO Heshan 《Baosteel Technical Research》 CAS 2012年第2期49-54,共6页
A series of tests of deformation-induced ferrite transformation (DIP-T) in a low carbon steel were carried out by the Gleeble-3500 hot simulation machine at a temperature range of Ae3-Ar3. The overall stress-strain ... A series of tests of deformation-induced ferrite transformation (DIP-T) in a low carbon steel were carried out by the Gleeble-3500 hot simulation machine at a temperature range of Ae3-Ar3. The overall stress-strain curves during DIFT can be divided into three typical types: "double-humped"," single-humped" and "transitional". The peaks exhibited in the curve are involved with deformation-induced transformation which happened in grains or at the grain boundaries. According to the stress-time curve and strain-time curve, strain capacity dramatically postponed the strain-induced transformation, which leads to the start of the transformation right ahead of the finish of deformation and the majority of the ferrite transformation process mainly happened after the deformation. Deformation-induced transformation is a metadynamic transformation process with dynamic nucleation. 展开更多
关键词 low carbon steel deformation-induced ferrite transformation stress-strain curve metadynamic transformation
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Austenite Recrystallization and Controlled Rolling of Low Carbon Steels 被引量:4
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作者 DU Lin-xiu ZHANG Zhong-ping SHE Guang-fu LIU Xiang-hua WANG Guo-dong 《Journal of Iron and Steel Research International》 SCIE EI CAS CSCD 2006年第3期31-35,50,共6页
The dynamic recrystallization and static recrystallization in a low carbon steel were investigated through single-pass and double-pass experiments. The results indicate that as the deformation temperature increases an... The dynamic recrystallization and static recrystallization in a low carbon steel were investigated through single-pass and double-pass experiments. The results indicate that as the deformation temperature increases and the strain rate decreases, the shape of the stress-strain curve is changed from dynamic recovery shape to dynamic recrystallization shape. The austenite could not recrystallize within a few seconds after deformation at temperature below 900 ℃. According to the change in microstructure during deformation, the controlled rolling of low carbon steel can be divided into four stages: dynamic recrystallization, dynamic recovery, strain-induced ferrite transformation, and rolling in two-phase region. According to the microstructure after deformation, the controlled rolling of low carbon steel can be divided into five regions: non-recrystallized austenite, partly-recrystallized austenite, fully-recrystallized austenite, austenite to ferrite transformation, and dual phase. 展开更多
关键词 RECRYSTALLIZATION low carbon steel AUSTENITE strain-induced transformation controlled rolling
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PROBABILISTIC METHODOLOGY OF LOW CYCLE FATIGUE ANALYSIS 被引量:1
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作者 JinHui WangJinnuo WangLibin 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2003年第4期356-358,366,共4页
The cyclic stress-strain responses (CSSR), Neuber's rule (NR) and cyclic strain-life relation (CSLR) are treated as probabilistic curves in local stress and strain method of low cycle fatigue analysis. The randomn... The cyclic stress-strain responses (CSSR), Neuber's rule (NR) and cyclic strain-life relation (CSLR) are treated as probabilistic curves in local stress and strain method of low cycle fatigue analysis. The randomness of loading and the theory of fatigue damage accumulation (TOFDA) are considered. The probabilistic analysis of local stress, local strain and fatigue life are constructed based on the first-order Taylor's series expansions. Through this method proposed fatigue reliability analysis can be accomplished. 展开更多
关键词 low cycle fatigue Local stress and strain method Probabilistic analysis Fatigue reliability
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Similarity model tests of movement and deformation of coal-rock mass below stopes 被引量:6
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作者 WANG, Haifeng CHENG, Yuanping +1 位作者 YUAN, Liang WANG, Liang 《Mining Science and Technology》 EI CAS 2010年第2期188-192,共5页
For a study of the movement and deformation of coal-rock mass and low protected seams below a stope,as well as for fracture developments and rules of evolution of permeability,we designed a plane strain model test sta... For a study of the movement and deformation of coal-rock mass and low protected seams below a stope,as well as for fracture developments and rules of evolution of permeability,we designed a plane strain model test stand to carry out model tests of similar materials in order to improve the effect of gas drainage from low protected seams and to measure the movement and deformation of coal-rock mass using a method of non-contact close-range photogrammetry.Our results show that 1) using paraffin melting to take the place of coal seam mining can satisfy the mining conditions of a protective seam;2) coal-rock mass under goafs has an upward movement after the protective seam has been mined,causing floor heaving;3) low protected seams become swollen and deformed,providing a good pressure-relief effect and causing the coal-rock mass under both sides of coal pillars to become deformed by compression and 4) the evolution of permeability of low protected seams follows the way of initial values→a slight decrease→a great increase→stability→final decrease.Simultaneously,the coefficient of air permeability increased at a decreasing rate with an increase in interlayer spacing. 展开更多
关键词 coal-rock mass below stope low protected seam plane strain similar model test
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Strain-modulated excitonic gaps in mono-and bi-layer MoSe_2
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作者 籍建葶 张安民 +4 位作者 夏天龙 高坡 揭英昊 张倩 张清明 《Chinese Physics B》 SCIE EI CAS CSCD 2016年第7期455-458,共4页
Photoluminescence(PL) and Raman spectra under uniaxial strain were measured in mono- and bi-layer MoSe;to comparatively investigate the evolution of excitonic gaps and Raman phonons with strain. We observed that the... Photoluminescence(PL) and Raman spectra under uniaxial strain were measured in mono- and bi-layer MoSe;to comparatively investigate the evolution of excitonic gaps and Raman phonons with strain. We observed that the strain dependence of excitonic gaps shows a nearly linear behavior in both flakes. One percent of strain increase gives a reduction of;2 meV(;5 me V) in A-exciton gap in monolayer(bilayer) MoSe;. The PL width remains little changed in monolayer MoSe;while it increases rapidly with strain in the bilayer case. We have made detailed discussions on the observed strain-modulated results and compared the difference between monolayer and bilayer cases. The hybridization between 4d orbits of Mo and 4p orbits of Se, which is controlled by the Se–Mo–Se bond angle under strain, can be employed to consistently explain the observations. The study may shed light into exciton physics in few-layer MoSe;and provides a basis for their applications. 展开更多
关键词 photoluminescence strain low-dimensional semiconductors
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Investigation on experimental method of low-impedance materials using modified Hopkinson pressure bar 被引量:4
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作者 苗应刚 李玉龙 +3 位作者 邓琼 汤忠斌 胡海涛 索涛 《Journal of Beijing Institute of Technology》 EI CAS 2015年第2期269-276,共8页
To increase the detectability of split Hopkinson pressure bar (SHPB) of low-impedance materials, modifications were conducted on traditional SHPB apparatus with a PMMA tube to output transmitted signal, and weak sig... To increase the detectability of split Hopkinson pressure bar (SHPB) of low-impedance materials, modifications were conducted on traditional SHPB apparatus with a PMMA tube to output transmitted signal, and weak signals were further amplified by semiconductor strain gauges. Experiments on soft rubbers and cushioning foam materials were carried out. In order to analyze the accuracy of the experimental results, the stress equilibrium issues involved in the assumptions of SHPB were investigated. First, by way of re-constructing loading process of incident wave, the stress- strain curve was obtained, along with the stress equilibrium ratio of specimen. Secondly, the influences on the accuracy of stress-strain curves were investigated through the elastic modulus comparisons. And the results illustrate that the bilinear incident wave from experiments can ensure the stress equilibrium deformation of specimen after 2 normalized times, much sooner than ramp incident waves. Moreover, it even facilitates specimen deformation with a constant strain rate. The results confirm that the detectability of the modified SHPB can be down to tens kPa with enough accuracy level. 展开更多
关键词 SHPB low-impedance materials bilinear wave stress equilibrium constant strain rate
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含钪超高强铝合金在应变速率10^(-3)s^(-1)下的热流变及动态再结晶行为
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作者 李昂 张毅 +2 位作者 陈开媛 吴福 高蔚 《材料工程》 EI CAS CSCD 北大核心 2024年第8期169-177,共9页
采用等温热压缩实验和电子背散射衍射分析技术,研究了Al-11.1Zn-2.3Mg-2.0Cu-0.05Sc合金在应变速率10^(-3)s^(-1),变形温度653~733 K条件下的热流变及动态再结晶行为,建立动态再结晶临界应力、临界应变、相对含量、晶粒平均尺寸的拟合... 采用等温热压缩实验和电子背散射衍射分析技术,研究了Al-11.1Zn-2.3Mg-2.0Cu-0.05Sc合金在应变速率10^(-3)s^(-1),变形温度653~733 K条件下的热流变及动态再结晶行为,建立动态再结晶临界应力、临界应变、相对含量、晶粒平均尺寸的拟合方程。结果表明:相关特征参数的拟合方程可以较好地描述含钪铝合金在实验条件范围内的动态再结晶行为。变形温度的升高会增加晶粒内部的取向差,减弱晶粒沿法向的择优取向,有助于动态再结晶的发生。动态回复是含钪铝合金的主要软化机制。随着温度的变化,铝合金微观组织存在不连续动态、连续动态及几何动态三种再结晶机制。 展开更多
关键词 含钪铝合金 动态再结晶 热流变行为 低应变速率 微观组织演化
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低应变率冲击荷载下节理花岗岩的动力响应规律
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作者 王智德 司莹莹 +2 位作者 李杰 钱梦凡 安佳兴 《岩土力学》 EI CAS CSCD 北大核心 2024年第6期1755-1762,1777,共9页
岩体中节理面的存在是引起冲击应力波衰减的主要原因,会造成爆炸能量的衰减及降低爆破效果。为探讨低应变率下不同节理倾角花岗岩在冲击荷载作用下的动态力学性质、应力波传递规律和能量传递规律,利用分离式霍普金森压杆(split Hopkinso... 岩体中节理面的存在是引起冲击应力波衰减的主要原因,会造成爆炸能量的衰减及降低爆破效果。为探讨低应变率下不同节理倾角花岗岩在冲击荷载作用下的动态力学性质、应力波传递规律和能量传递规律,利用分离式霍普金森压杆(split Hopkinson pressure bar,简称SHPB)试验装置对低应变率下3种不同冲击气压、4种不同倾角的节理花岗岩进行冲击试验。结果表明:(1)在含节理的岩样中,其峰值应力随节理倾角的增大呈下降趋势,随冲击荷载的增大呈上升趋势;(2)透射系数随节理倾角的增加先增大后减小,随冲击荷载的增大先减小后增大;(3)能量传递系数随节理倾角的增加先增高后降低,完整岩样、节理倾角θ=0º和45º的岩样,其能量传递系数都随着冲击荷载的增大而减小,而节理倾角θ=15º和30º的岩样,其能量传递系数随着冲击荷载的增大先减小后增大。 展开更多
关键词 倾角 节理花岗岩 SHPB冲击试验 动力响应 低应变率
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羊肚菌栽培方法优化研究
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作者 武彬 韩建东 +8 位作者 张元祺 李文刚 黄春燕 李兆荣 杨鹏 景文婷 谢业水 张振宇 姚强 《安徽农业科学》 CAS 2024年第16期43-46,56,共5页
为了探究不同环境条件对羊肚菌产量和品质的影响,分别研究了品种、单播混播、菌种形态、低畦、腐殖质添加量等因素对羊肚菌生产性能的影响。选取ZHS-3、ZHS-5、四川-6和MZ-8等品种,在冬春季节分别做了品比试验、单一菌种和混合菌种栽培... 为了探究不同环境条件对羊肚菌产量和品质的影响,分别研究了品种、单播混播、菌种形态、低畦、腐殖质添加量等因素对羊肚菌生产性能的影响。选取ZHS-3、ZHS-5、四川-6和MZ-8等品种,在冬春季节分别做了品比试验、单一菌种和混合菌种栽培试验、固体菌种和液体原种栽培试验、低畦栽培试验和土壤基质栽培试验。结果表明,品比试验中四川-6的栽培效果更好,较ZHS-3、ZHS-5和MZ-8产量分别高22.27%、32.17%和19.74%;单一菌种和混合菌种栽培试验中单一菌种的栽培效果更好,产量较混合菌种高22.72%,说明若早发菌种和晚发菌种同时存在则无协同作用;液体原种和固体菌种栽培试验中固体菌种的栽培效果更好,产量较液体菌种高28.78%,液体菌种虽然发菌快但个体小;低畦栽培试验中平栽的栽培效果更好,产量较下挖组高53.24%,说明通风不足会影响产量;腐殖质添加试验中添加腐殖质含量在5%时栽培效果更好,产量较添加10%腐殖质区域高20.10%,较对照组高31.12%,说明腐殖质添加不宜过量。 展开更多
关键词 羊肚菌 液体菌种 混合菌种 低畦 腐殖质
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低应变率下NEPE推进剂“双屈服”特性及其粘-弹-塑性屈服模型
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作者 申志彬 张宇轩 邓旷威 《推进技术》 EI CAS CSCD 北大核心 2024年第12期262-268,共7页
固体发动机全寿命周期中,推进剂药柱长期处于低应变率状态。为了分析硝酸酯增塑聚醚(NEPE)推进剂在低应变率下的屈服与损伤特性,开展了NEPE推进剂在低应变率(1.190×10^(-5)~2.381×10^(-2)s^(-1))下的单轴拉伸试验。研究表明,N... 固体发动机全寿命周期中,推进剂药柱长期处于低应变率状态。为了分析硝酸酯增塑聚醚(NEPE)推进剂在低应变率下的屈服与损伤特性,开展了NEPE推进剂在低应变率(1.190×10^(-5)~2.381×10^(-2)s^(-1))下的单轴拉伸试验。研究表明,NEPE推进剂的应力-应变曲线呈“双屈服”态,最大抗拉强度、断裂强度随拉伸速率的下降而明显下降,但初始屈服点(“脱湿点”)与后继屈服点不受应变率的影响,两级屈服点应变近似保持一个稳定值,分别为13.5%和55.4%。因此,可将“脱湿点”应力视为推进剂的屈服强度。在此基础上,构建了NEPE推进剂粘-弹-塑性屈服模型,通过引入动屈服函数,建立了动屈服强度、粘塑性应变率与静屈服强度之间的关系。结合试验数据,NEPE推进剂静屈服强度为0.22 MPa。 展开更多
关键词 NEPE推进剂 低应变率 屈服 “脱湿”损伤 粘-弹-塑性
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