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Stress initialization methods for dynamic numerical simulation of rock mass with high in-situ stress 被引量:30
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作者 YANG Jia-cai LIU Ke-wei +1 位作者 LI Xu-dong LIU Zhi-xiang 《Journal of Central South University》 SCIE EI CAS CSCD 2020年第10期3149-3162,共14页
In the context of deep rock engineering,the in-situ stress state is of major importance as it plays an important role in rock dynamic response behavior.Thus,stress initialization becomes crucial and is the first step ... In the context of deep rock engineering,the in-situ stress state is of major importance as it plays an important role in rock dynamic response behavior.Thus,stress initialization becomes crucial and is the first step for the dynamic response simulation of rock mass in a high in-situ stress field.In this paper,stress initialization methods,including their principles and operating procedures for reproducing steady in-situ stress state in LS-DYNA,are first introduced.Then the most popular four methods,i.e.,explicit dynamic relaxation(DR)method,implicit-explicit sequence method,Dynain file method and quasi-static method,are exemplified through a case analysis by using the RHT and plastic hardening rock material models to simulate rock blasting under in-situ stress condition.Based on the simulations,it is concluded that the stress initialization results obtained by implicit-explicit sequence method and dynain file method are closely related to the rock material model,and the explicit DR method has an obvious advantage in solution time when compared to other methods.Besides that,it is recommended to adopt two separate analyses for the whole numerical simulation of rock mass under the combined action of in-situ stress and dynamic disturbance. 展开更多
关键词 in-situ stress stress initialization method dynamic disturbance numerical simulation rock mass
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Numerical simulation of intelligent compaction for subgrade construction 被引量:9
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作者 MA Yuan LUAN Ying-cheng +1 位作者 ZHANG Wei-guang ZHANG Yu-qing 《Journal of Central South University》 SCIE EI CAS CSCD 2020年第7期2173-2184,共12页
During the compaction of a road subgrade, the mechanical parameters of the soil mass change in real time, but current research assumes that these parameters remain unchanged. In order to address this discrepancy, this... During the compaction of a road subgrade, the mechanical parameters of the soil mass change in real time, but current research assumes that these parameters remain unchanged. In order to address this discrepancy, this paper establishes a relationship between the degree of compaction K and strain ε. The relationship between the compaction degree K and the shear strength of soil(cohesion c and frictional angle φ) was clearly established through indoor experiments. The subroutine UMAT in ABAQUS finite element numerical software was developed to realize an accurate calculation of the subgrade soil compaction quality. This value was compared and analyzed against the assumed compaction value of the model, thereby verifying the accuracy of the intelligent compaction calculation results for subgrade soil. On this basis, orthogonal tests of the influential factors(frequency, amplitude, and quality) for the degree of compaction and sensitivity analysis were carried out. Finally, the ‘acceleration intelligent compaction value’, which is based on the acceleration signal, is proposed for a compaction meter value that indicates poor accuracy. The research results can provide guidance and basis for further research into the accurate control of compaction quality for roadbeds and pavements. 展开更多
关键词 intelligent compaction numerical simulation dynamic change control indicators orthogonal experiment
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Numerical simulation of dynamic fracture properties of rocks under different static stress conditions 被引量:7
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作者 LIANG Zheng-zhao QIAN Xi-kun +1 位作者 ZHANG Ya-fang LIAO Zhi-yi 《Journal of Central South University》 SCIE EI CAS CSCD 2022年第2期624-644,共21页
When underground cavities are subjected to explosive stress waves,a uniquely damaged zone may appear due to the combined effect of dynamic loading and static pre-load stress.In this study,a rate-dependent two-dimensio... When underground cavities are subjected to explosive stress waves,a uniquely damaged zone may appear due to the combined effect of dynamic loading and static pre-load stress.In this study,a rate-dependent two-dimensional rock dynamic constitutive model was established to investigate the dynamic fractures of rocks under different static stress conditions.The effects of the loading rate and peak amplitude of the blasting wave under different confining pressures and the vertical compressive coefficient(K_(0))were considered.The numerical simulated results reproduced the initiation and further propagation of primary radial crack fractures,which were in agreement with the experimental results.The dynamic loading rate,peak amplitude,static vertical compressive coefficient(K_(0))and confining pressure affected the evolution of fractures around the borehole.The heterogeneity parameter(m)plays an important role in the evolution of fractures around the borehole.The crack propagation path became more discontinuous and rougher in a smallerheterogeneity parameter case. 展开更多
关键词 rock mechanics coupled static and dynamic loading numerical simulation rate-dependent damage constitutive model
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Numerical simulation on behavior of pile foundations under cyclic axial loads 被引量:5
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作者 ZHAO Ming-hua HENG Shuai ZHENG Yue 《Journal of Central South University》 SCIE EI CAS CSCD 2017年第12期2906-2913,共8页
On the basis of the two dimensional finite element analysis model, the pile foundations' mechanical effect of the rigid pile composite foundation under the dynamic load was researched. Through the research, the de... On the basis of the two dimensional finite element analysis model, the pile foundations' mechanical effect of the rigid pile composite foundation under the dynamic load was researched. Through the research, the development law and deformation property of axial force of pile body, shaft resistance of pile, and cumulative settlement of pile head under vertical cyclic dynamic loads were concluded. Through the comparison and analysis of the test results of dynamic models, the test results of Poulos(1989) and cumulative settlement model of the single pile under cyclic loads were confirmed. Based on the above research, Fortran language was adopted to introduce the soil attenuation factor, the secondary development of relevant modules of ABAQUS was carried out, and the effect of soil attenuation factor on dynamic property of pile-soil was discussed further. 展开更多
关键词 PILE FOUNDATION ABAQUS CYCLIC dynamic load numerical simulation PILE-SOIL interaction SECONDARY development
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Numerical Simulation for Ventilated Supercavitation High Speed Underwater Vehicle
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作者 杨武刚 杨振才 +3 位作者 楚岩 邓秋霞 李亚绒 张宇文 《Defence Technology(防务技术)》 SCIE EI CAS 2009年第2期112-118,共7页
Supercavitation is a revolutionary technique to achieve high drag reduction for underwater vehicle.It can help us to break through the conventional speed barrier.This article presents a numerical algorithm for ventila... Supercavitation is a revolutionary technique to achieve high drag reduction for underwater vehicle.It can help us to break through the conventional speed barrier.This article presents a numerical algorithm for ventilated supercavitation flow field based on mixture multiphase flow model,briefs the calculation results and compares them with that tested in high-speed water tunnel and towing tank.The mathematical model,its numerical calculation method,computational region and boundary conditions are discussed in detail.Some pertinent nondimensional parameters about the ventilated supercavitation,such as geometrical configuration of supercavity,drag coefficient and ventilation rate are investigated.Reynolds number is selected to predict gas ventilation rate instead of Froude number.Finally,based on the test and simulation results,a semi-empirical formula of the ventilation rate estimation suitable for different conical angle caritators is proposed. 展开更多
关键词 水下航行器 数值模拟 通风量 Froude数 数值计算方法 计算结果 多相流模型 无量纲参数
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Review of numerical simulation on the dy-namics of Qinghai-Xizang plateau
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作者 陆诗阔 蔡永恩 《地震学报》 CSCD 北大核心 2004年第5期547-559,共13页
In recent twenty years, much numerical simulation work has been done on the evolution of Qinghai-Xizang (Tibetan) plateau. In this paper some principal numerical models and results are reviewed and analyzed. The earli... In recent twenty years, much numerical simulation work has been done on the evolution of Qinghai-Xizang (Tibetan) plateau. In this paper some principal numerical models and results are reviewed and analyzed. The earlier plane stress or plane strain model has much discrepancy with the actual deformation of Qinghai-Xizang plateau, such as the thickening of Tibetan crust and the lateral extrusion of Tibet along strike-slip faults. The thin viscous sheet model and the thin-plate model may simulate the change of the crustal thickness and the deformation pro-duced by gravitational force. It is suitable for studying the large-scale and long-time deformation. The influence of faults on the deformation of Tibetan plateau should be further studied. 展开更多
关键词 青藏高原 动力学过程 数值模型
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A Class of Fast Algorithms in Real-Time Simulation 被引量:4
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作者 Zhu Zhenmin & Liu Degui(Beijing Institute of Computer Application and Simulation Technology, 100854, P. R. China)Li Shoufu(Mathematics Department of Xiangtan University, 411105, P. R. China) 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 1999年第4期10-20,共11页
A class of hybrid algorithms of real-time simulation based on evaluation of non-integerstep right-hand side function are presented in this paper. And some results of the convergence and stability of the algorithms are... A class of hybrid algorithms of real-time simulation based on evaluation of non-integerstep right-hand side function are presented in this paper. And some results of the convergence and stability of the algorithms are given. Using the class of algorithms, evaluation for the right-hand side function is needed once in every integration-step. Moreover, comparing with the other methods with the same amount of work, their numerical stability regions are larger and the method errors are smaller, and the numerical experiments show that the algorithms are very effective. 展开更多
关键词 Real-time simulation algorithm numerical stability CONVERGENCE Dynamic system
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Dynamic simulation and experimental study of inspection robot for high-voltage transmission-line 被引量:6
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作者 肖晓晖 吴功平 +1 位作者 杜娥 史铁林 《Journal of Central South University of Technology》 EI 2005年第6期726-731,共6页
A mobile robot developed by Wuhan University for full-path hotline inspection on 220 kV transmission lines was presented. With 4 rotating joints and 2 translational ones, such robot is capable of traveling along non- ... A mobile robot developed by Wuhan University for full-path hotline inspection on 220 kV transmission lines was presented. With 4 rotating joints and 2 translational ones, such robot is capable of traveling along non- obstaclestraight-line segment and surmounting straight-line segment obstacles as well as transferring between two spans automatically. Lagrange’s equations were utilized to derive dynamic equations of all the links, including items of inertia, coupling inertia, Coriolis acceleration, centripetal acceleration and gravity. And a dynamic response experiment on elemental motions of robot prototype’s travelling along non-obstacle straight-line segment and surmounting obstacles was performed on 220 kV 1∶1 simulative overhanging transmission-line in laboratory. In addition, dynamic numerical simulation was conducted in the corresponding condition. Comparison and analysis on results of experiment and numerical simulation have validated theoretical model and simulation resolution. Therefore, the dynamic model formed hereunder can be used for the study of robot control. 展开更多
关键词 inspection robot TRANSMISSION-LINE dynamic modeling numerical simulation dynamic experiment
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Experimental and numerical analysis of submerged floating tunnel 被引量:2
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作者 陈健云 李静 +1 位作者 孙胜男 苏志斌 《Journal of Central South University》 SCIE EI CAS 2012年第10期2949-2957,共9页
As a new type of structure which has never been built, submerged floating tunnel was studied mainly by numerical simulations. To further study the seismic response of a submerged floating tunnel, the first model exper... As a new type of structure which has never been built, submerged floating tunnel was studied mainly by numerical simulations. To further study the seismic response of a submerged floating tunnel, the first model experiment of submerged floating tunnel (SFT) under the earthquake was carried out on the unique underwater shaking table in China. The experimental results show that vertical excitation induces larger response than horizontal and different inclination degrees of the tether also cause different seismic responses. Subsequently, based on the fluid-structure interaction theory, the corresponding numerical model is established. And comparing the numerical results with the experimental results, those of shaking table test. Numerical model adopted is effective for it is shown that the numerical results are basically identical with dynamic response of SFT. 展开更多
关键词 submerged floating tunnel seismic response dynamic response shaking table test numerical simulation
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Numerical study on dynamic properties of rubberised concrete with different rubber contents 被引量:1
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作者 Lei Pan Hong Hao +1 位作者 Jian Cui Thong M.Pham 《Defence Technology(防务技术)》 SCIE EI CAS CSCD 2023年第6期228-240,共13页
As a green environmentally-friendly material,rubberised concrete(Ru C),which has the characteristics of low elastic modulus,large deformation capacity,high damping,good energy dissipation and good crack resistance,has... As a green environmentally-friendly material,rubberised concrete(Ru C),which has the characteristics of low elastic modulus,large deformation capacity,high damping,good energy dissipation and good crack resistance,has attracted extensive attention and research in the civil engineering discipline.However,most of existing studies are based on experimental tests on Ru C material properties,and there has been no numerical study based on meso-scale modelling of Ru C yet.To more comprehensively investigate the Ru C dynamic material properties without conducting intensive experimental tests,this study developed a high-fidelity meso-scale model considering coarse and fine aggregates and rubber crumbs to numerically investigate the mechanical properties of rubberised concrete under different strain rates.The meso-scale model was verified against both quasi-static compressive testing data and Split Hopkinson Pressure Bar(SHPB)dynamic testing data.Using the verified numerical model,the dynamic properties of rubberised concrete with various rubber content(0%-30%)under different strain rates were studied.The numerical results show that the developed meso-scale model can use to predict the static and dynamic properties of rubberised concrete with high accuracy.The dynamic compressive strength of the rubberised concrete increases with the increment of the strain rate,and the strain rate sensitivity increases with the rubber content ranging from 0 to 30%.Based on intensive numerical simulation data,empirical DIFs is used as a function of strain rate and rubber content to predict the dynamic strength of rubberised concrete. 展开更多
关键词 Rubberised concrete Meso-scale model numerical simulation Strain rate effect Dynamic increase factor
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Mechanism on simulation and experiment of pre-crack seam formation in stope roof 被引量:1
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作者 胡建华 雷涛 +2 位作者 周科平 刘浪 劳德正 《Journal of Central South University》 SCIE EI CAS 2014年第4期1526-1533,共8页
The pre-crack blast technology has been used to control the induction caving area in the roof. The key is to form the pre-crack seam and predict the effect of the seam. The H-J-C blast model was built in the roof. Bas... The pre-crack blast technology has been used to control the induction caving area in the roof. The key is to form the pre-crack seam and predict the effect of the seam. The H-J-C blast model was built in the roof. Based on the theories of dynamic strength and failure criterion of dynamic rock, the rock dynamic damage and the evolution of pre-crack seam were simulated by the tensile damage and shear failure of the model. According to the actual situation of No. 92 ore body test stope at Tongkeng Mine, the formation process of the pre-crack blast seam was simulated by Ansys/Ls-dyna software, the pre-crack seam was inspected by a system of digital panoramic borehole camera. The pre-crack seam was inspected by the system of digital panoramic borehole in the roof. The results of the numerical simulation and inspection show that in the line of centers of pre-hole, the minimum of the tensile stress reaches 20 MPa, which is much larger than 13.7 MPa of the dynamic tensile strength of rock. The minimum particle vibration velocity reaches 50 cm/s, which is greater than 30-40 cm/s of the allowable vibration velocity. It is demonstrated that the rock is destroyed near the center line and the pre-crack is successfully formed by the large diameters and large distances pre-crack holes in the roof. 展开更多
关键词 induction caving dynamic damage model pre-crack seam numerical simulation digital borehole camera
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THE NUMERICAL SIMULATE OF THE UPLIFT PROCESS OF THE QINGHAI—TIBET PLATEAU
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作者 Cui Junwen 1, Shi Jinsong 2,Li Pengwu 1,Li Li 1 2 Hoha University, Nanjing 210098,China) 《地学前缘》 EI CAS CSCD 2000年第S1期359-361,共3页
The quantitative analysis of uplift process of the Qinghai—Tibet plateau is a key to deepen the study of uplift mechanism and dynamic model, for this, numerical simulate was done to the whole process of uplift of the... The quantitative analysis of uplift process of the Qinghai—Tibet plateau is a key to deepen the study of uplift mechanism and dynamic model, for this, numerical simulate was done to the whole process of uplift of the Qinghai—Tibet plateau.1 Geological model According to the tectonic evolution and lithospheric structure, continental crust in the Qinghai—Tibet plateau in profile is divided into sedimentary cover, crystalline rock formation and lower crust and composed of Kunlun, Bayan Har, Qiangtang, Gangdise and Himalaya blocks on the plane. Layer or block is bounded the detachment layer or large fault. On the basis of the uplift characteristics, the calculated time limit is in the Cenozoic since 65Ma, roughly four stages, i.e., 65 to 40Ma, 40 to 20Ma, 20 to 3Ma and 3Ma to now. Mesh profile used Yadong—Golmud Geoscience transect. 展开更多
关键词 Uplift dynamic process numerical simulate shortening thickening stress strain rate of increasing temperature(RIT)
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基于刚柔耦合模型的地铁啸叫研究 被引量:1
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作者 刘洋 李午垚 江晓禹 《铁道标准设计》 北大核心 2025年第4期205-213,共9页
地铁在通过狭窄的曲线轨道时经常会产生严重的啸叫噪声,严重影响人们的出行体验,故建立动力学模型研究地铁车辆在曲线段产生啸叫现象的机理。为使高频范围内的动力学仿真结果更加准确,在动力学模型中引入柔性轮对组成动力学刚柔耦合系统... 地铁在通过狭窄的曲线轨道时经常会产生严重的啸叫噪声,严重影响人们的出行体验,故建立动力学模型研究地铁车辆在曲线段产生啸叫现象的机理。为使高频范围内的动力学仿真结果更加准确,在动力学模型中引入柔性轮对组成动力学刚柔耦合系统,模型采用三维滚动接触方法模拟轮轨间的弹性接触,在计算切向力时使用迭代算法并在此基础上引入下落摩擦机制。针对我国地铁运行的速度和曲线半径,设计了5个研究工况,在动力学系统中对不同工况下车辆通过曲线时的蠕滑率和接触力进行研究,并将接触力的计算结果导入边界元模型中,分析不同工况下车轮的振动响应和约束阻尼层的降噪效果。研究结果表明:由弹性轮对组成的动力学刚柔耦合系统在曲线段的垂向振动加速度和垂向力均大于刚性轮对;引入下落摩擦机制后,当曲线半径分别为200 m和300 m时,轮轨接触力会出现振荡且轮轨间发生两点接触,容易产生啸叫噪声,当曲线半径为400 m时,接触力没有出现振荡且轮轨间主要是踏面接触;车轮在曲线段的振动主要是轴向振动;在相同曲线半径下,列车通过曲线时轮轨间产生的接触力会随列车速度的增大而增大,且当速度较大时轮轨间更容易发生两点接触;车轮添加约束阻尼层后,在相同激振力的作用下,阻尼车轮在测点的总声压级均小于标准车轮的总声压级,最大声压级下降21 dB。 展开更多
关键词 地铁 啸叫 数值模拟 刚柔耦合 降噪 动力学系统
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Complete geometric nonlinear formulation for rigid-flexible coupling dynamics 被引量:4
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作者 刘铸永 洪嘉振 刘锦阳 《Journal of Central South University》 SCIE EI CAS 2009年第1期119-124,共6页
A complete geometric nonlinear formulation for rigid-flexible coupling dynamics of a flexible beam undergoing large overall motion was proposed based on virtual work principle, in which all the high-order terms relate... A complete geometric nonlinear formulation for rigid-flexible coupling dynamics of a flexible beam undergoing large overall motion was proposed based on virtual work principle, in which all the high-order terms related to coupling deformation were included in dynamic equations. Simulation examples of the flexible beam with prescribed rotation and free rotation were investigated. Numerical results show that the use of the first-order approximation coupling (FOAC) model may lead to a significant error when the flexible beam experiences large deformation or large deformation velocity. However, the correct solutions can always be obtained by using the present complete model. The difference in essence between this model and the FOAC model is revealed. These coupling high-order terms, which are ignored in FOAC model, have a remarkable effect on the dynamic behavior of the flexible body. Therefore, these terms should be included for the rigid-flexible dynamic modeling and analysis of flexible body undergoing motions with high speed. 展开更多
关键词 flexible beam rigid-flexible coupling dynamic modeling numerical simulation
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高速铁路箱型路基动力响应分析 被引量:1
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作者 刘晶磊 周玮浩 +2 位作者 张伯扬 刘佳凡 张业荣 《铁道标准设计》 北大核心 2025年第1期57-66,共10页
为研究高速铁路箱型路基在列车荷载作用下的动力响应问题,采用数值模拟方法建立轨道-路基-地基三维有限元模型,分析箱型路基的动应力、动位移和加速度的分布规律,并与常规填土路基进行对比。结果表明,列车荷载作用下的动力响应时程曲线... 为研究高速铁路箱型路基在列车荷载作用下的动力响应问题,采用数值模拟方法建立轨道-路基-地基三维有限元模型,分析箱型路基的动应力、动位移和加速度的分布规律,并与常规填土路基进行对比。结果表明,列车荷载作用下的动力响应时程曲线周期性变化明显,不同车厢相邻2个转向架产生叠加效应,随深度增加叠加效应减弱,且发生时间滞后约0.1 s。动力响应沿深度分布,主要呈递减趋势。箱型路基内,竖向动应力和加速度衰减率分别可达60%、75%以上。动力响应沿横向分布,在支承层范围内,横向分布差异较小,顶板竖向动位移最大差值仅为0.008 mm,而范围外则变化迅速。动力响应沿横向分布,主要呈“马鞍”形和“U”形分布,在支承层边缘下方、竖板和顶、底板连接处以及底板边缘均出现峰值,存在应力集中效应。路基表面最大动应力为39.6 kPa,最大动位移为0.165 mm,路基内最大动应力为100.6 kPa,满足设计要求。与常规填土路基相比,箱型路基竖向动应力的衰减率更大,可达到95%,且加速度较小,对动荷载的吸收和耗散作用更显著。箱型路基与常规路基表面竖向动位移幅值分别为0.165 mm、0.329 mm,最大差值为0.036 mm、0.189 mm。箱型路基动位移更小,横向分布更均匀,整体性更好。 展开更多
关键词 高速铁路 箱型路基 数值模拟 动应力 动位移 加速度
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A simplified approach to modelling blasts in computational fluid dynamics (CFD) 被引量:2
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作者 D.Mohotti K.Wijesooriya S.Weckert 《Defence Technology(防务技术)》 SCIE EI CAS CSCD 2023年第5期19-34,共16页
This paper presents a time-efficient numerical approach to modelling high explosive(HE)blastwave propagation using Computational Fluid Dynamics(CFD).One of the main issues of using conventional CFD modelling in high e... This paper presents a time-efficient numerical approach to modelling high explosive(HE)blastwave propagation using Computational Fluid Dynamics(CFD).One of the main issues of using conventional CFD modelling in high explosive simulations is the ability to accurately define the initial blastwave properties that arise from the ignition and consequent explosion.Specialised codes often employ Jones-Wilkins-Lee(JWL)or similar equation of state(EOS)to simulate blasts.However,most available CFD codes are limited in terms of EOS modelling.They are restrictive to the Ideal Gas Law(IGL)for compressible flows,which is generally unsuitable for blast simulations.To this end,this paper presents a numerical approach to simulate blastwave propagation for any generic CFD code using the IGL EOS.A new method known as the Input Cavity Method(ICM)is defined where input conditions of the high explosives are given in the form of pressure,velocity and temperature time-history curves.These time history curves are input at a certain distance from the centre of the charge.It is shown that the ICM numerical method can accurately predict over-pressure and impulse time history at measured locations for the incident,reflective and complex multiple reflection scenarios with high numerical accuracy compared to experimental measurements.The ICM is compared to the Pressure Bubble Method(PBM),a common approach to replicating initial conditions for a high explosive in Finite Volume modelling.It is shown that the ICM outperforms the PBM on multiple fronts,such as peak values and overall overpressure curve shape.Finally,the paper also presents the importance of choosing an appropriate solver between the Pressure Based Solver(PBS)and Density-Based Solver(DBS)and provides the advantages and disadvantages of either choice.In general,it is shown that the PBS can resolve and capture the interactions of blastwaves to a higher degree of resolution than the DBS.This is achieved at a much higher computational cost,showing that the DBS is much preferred for quick turnarounds. 展开更多
关键词 Blast loads Computational fluid dynamics Explosions numerical simulations
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足地接触对被动行走机器人步态动力学行为的影响
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作者 高建设 郑子怡 +2 位作者 宛磊 李奎 吴广良 《郑州大学学报(工学版)》 北大核心 2025年第3期1-10,共10页
为解决被动行走机器人步态研究中难以分析滑移、弹起等复杂步态的动力学行为的问题,搭建了一种考虑足地接触的圆弧足被动行走机器人模型,分析其在路面材料变化的复杂行走路况下表现出的多种行走模式,并揭示了多参数协同演化下的步态失... 为解决被动行走机器人步态研究中难以分析滑移、弹起等复杂步态的动力学行为的问题,搭建了一种考虑足地接触的圆弧足被动行走机器人模型,分析其在路面材料变化的复杂行走路况下表现出的多种行走模式,并揭示了多参数协同演化下的步态失稳机制。首先,引入赫兹接触模型与库仑摩擦模型描述足地间的法向接触力与切向摩擦力,使用第二类拉格朗日方程进行动力学建模;其次,通过改变接触参数模拟不同弹性与摩擦特性的行走路面,采用数值仿真对行走中的滑移、弹起、跌倒等现象进行研究,获得使机器人行走性能较好的足地接触条件;最后,使用分岔图、时间响应图等工具对机器人各结构参数协同演化时的行走步态进行分析。研究结果表明:摩擦系数大于0.24且阻尼系数大于4.37×10^(6) kg/(m^(1.5)·s)的足地接触环境是机器人稳定行走的必要条件,摩擦系数和阻尼系数的减小将分别使步态出现滑移和弹起,且摩擦系数对步态的影响占主导地位,两接触参数持续减小将使机器人摔倒;在结构参数中,髋关节质量及转动惯量的减小、足半径增大都更有利于机器人适应大范围的行走斜面角度;同时观察到,无论结构参数如何演化,机器人都将随着斜面角度的增大通过滑移而引发步态失稳。 展开更多
关键词 被动行走机器人 滑移 弹起 动力学分析 数值模拟
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气泡动力学研究进展
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作者 张阿漫 李世民 +1 位作者 李帅 刘云龙 《力学学报》 北大核心 2025年第1期1-16,共16页
只要有流体的地方,就可能会产生气泡,气泡是气体在液体中一种常见的呈现形式,在自然界和工程界中广泛存在,在船舶与海洋、先进制造、环境与化工、生命科学和医学等许多领域均有重要应用价值,同时,在水中结构抗爆和空蚀等很多领域气泡也... 只要有流体的地方,就可能会产生气泡,气泡是气体在液体中一种常见的呈现形式,在自然界和工程界中广泛存在,在船舶与海洋、先进制造、环境与化工、生命科学和医学等许多领域均有重要应用价值,同时,在水中结构抗爆和空蚀等很多领域气泡也是导致危害产生的根源,因此,气泡动力学是诸多领域共同关心的基础科学问题.然而,由于气泡动力学行为的复杂性,涉及边界、多气泡、流场环境、流体可压缩性、黏性和表面张力等多物理因素和环境条件的显著影响,迄今为止,仍存在复杂条件下气泡动力学理论、气泡群相互作用、气液固耦合效应和气泡损伤及防护机制等难题亟待解决.为此,从气泡动力学的基本物理现象入手,深入剖析了该领域所面临的挑战,给出了存在的力学难题,综述了气泡动力学理论、数值和实验技术的研究进展与最新动态,通过对现有研究成果的系统梳理和详细分析,最后总结了气泡动力学领域未来发展趋势,并提出了潜在的研究方向和课题,旨在为气泡动力学相关研究提供基础和依据. 展开更多
关键词 气泡动力学 理论研究 数值模拟 实验技术
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考虑颗粒形态的滑坡体运移特征研究
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作者 韩长玉 陈文超 +3 位作者 张敏 金莉 王喆 杨振兴 《水文地质工程地质》 北大核心 2025年第3期234-244,共11页
岩土材料的颗粒形态对评估边坡稳定性和滑坡运移范围的准确性至关重要,但目前颗粒形态对大尺度边坡相关问题的影响研究尚不明确。为探究颗粒形态与边坡稳定性及滑坡体运移特征的关系,基于实际工程滑坡,采用颗粒离散单元法,构建不同颗粒... 岩土材料的颗粒形态对评估边坡稳定性和滑坡运移范围的准确性至关重要,但目前颗粒形态对大尺度边坡相关问题的影响研究尚不明确。为探究颗粒形态与边坡稳定性及滑坡体运移特征的关系,基于实际工程滑坡,采用颗粒离散单元法,构建不同颗粒形态构成的二维边坡。使用球形度和棱角度两个颗粒形态参数分别反映颗粒的整体轮廓特征和棱角数目,研究粒径缩放和颗粒形态对边坡稳定系数的影响。通过强度折减法使边坡破坏,进一步分析滑坡体的运移特征。研究结果表明:对于工程尺度滑坡,粒径缩放对边坡稳定系数预测有一定的影响阈值;颗粒球形度与边坡稳定系数成反比,棱角度与边坡稳定系数成正比,且颗粒球形度与滑坡体的平均滑动速率成正比;滑坡体运移范围受颗粒形态影响,颗粒球形度越高,运移范围越大。研究结果进一步揭示,颗粒形态导致的能量耗散特征差异,是滑坡体运移距离与堆积状态变化的主要内因。该研究可为滑坡致灾范围预测和防灾减灾工程提供参考。 展开更多
关键词 边坡 数值模拟 颗粒形态 稳定系数 运移特征
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切变和变风向入流对偏航风力机气动特性的影响研究
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作者 汪建文 赵爽 +4 位作者 白叶飞 张立茹 马剑龙 张建伟 闫思佳 《中国电机工程学报》 北大核心 2025年第8期3079-3091,I0019,共14页
自然风况与偏航工况结合使风力机气动特性变得十分复杂,进而影响风力机输出稳定性及结构安全。该文选择切变和变风向两种入流工况,利用双重嵌套滑移网格方法建立风力机整机动态入流计算流体力学(computational fluid dynamics,CFD)仿真... 自然风况与偏航工况结合使风力机气动特性变得十分复杂,进而影响风力机输出稳定性及结构安全。该文选择切变和变风向两种入流工况,利用双重嵌套滑移网格方法建立风力机整机动态入流计算流体力学(computational fluid dynamics,CFD)仿真计算模型,分析偏航风力机的气动特性。研究表明,风切变几乎不改变风力机扭矩和轴向推力的均值,但使相对波幅增加,偏航工况下增加更多。基于实测风轮转速进行匀速变风向计算,风向变化结束/转速稳定时的扭矩均值比静态偏航时更大/更小,相对波幅正好相反。偏航使轴向高/低载荷区呈“C”形,切向高/低载荷区呈扇形/豌豆形,切变入流趋使高/低载荷区向风轮上/下半平面移动。变风向入流时叶根区域载荷均值和波动频率更大,其他区域的均值虽然较少,但波幅更高。结果可为运行在自然风况下的风力机的疲劳设计提供理论参考。 展开更多
关键词 风力机 自然风况 气动特性 偏航 计算流体力学数值模拟
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