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Modeling wave propagation across rock masses using an enriched 3D numerical manifold method

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Science China(Technological Sciences) 2024年第3期67卷 835-852页

作者： YANG YongTao LI JunFeng WU WenAn State Key Laboratory of Geomechanics and Geotechnical Engineering Institute of Rock and Soil MechanicsChinese Academy of SciencesWuhan 430071China Key Laboratory of Urban Security and Disaster Engineering Ministry of EducationBeijing University of TechnologyBeijing 100124China University of Chinese Academy of Sciences Beijing 100049China

The three-dimensional numerical manifold method(3DNMM) method is further enriched to simulate wave propagation across homogeneous/jointed rock masses. For the purpose of minimizing negative effects from artificial boundaries, a viscous nonreflecting boundary, which can effectively absorb the energy of a wave, is firstly adopted to enrich 3DNMM. Then, to simulate the elastic recovery property of an infinite problem domain, a viscoelastic boundary, which is developed from the viscous nonreflecting boundary, is further adopted to enrich 3DNMM. Finally, to eliminate the noise caused by scattered waves, a force input method which can input the incident wave correctly is incorporated into 3DNMM. Five typical numerical tests on P/S-wave propagation across jointed/homogeneous rock masses are conducted to validate the enriched 3DNMM. Numerical results indicate that wave propagation problems within homogeneous and jointed rock masses can be correctly and reliably modeled with the enriched 3DNMM.

关键词： 3D numerical manifold method viscous nonreflecting boundary rock masses force input method wave propagation

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wave propagation in Viscoelastic Functionally Graded Nanoplates:Comparison of the Integral and Differential Nonlocal Models

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Acta Mechanica Solida Sinica 2023年第5期36卷 724-733页

作者： Xianhui Wang Yaohui Chen Jiangong Yu School of Mechanical and Power Engineering Henan Polytechnic UniversityJiaozuo 454003China

As one of the popular non-classical continuum theories in functionally graded material(FGM)nanostructures,the modified nonlocal theory(MNT)has been applied in various mechanical ***,due to the difficult solution process,the original integral formulation of MNT(IMNT)is transformed into a differential formulation of MNT(DMNT),which results in an inevitable approximation *** clarify the consistency and difference between two formulations,the Lamb wave characteristics in viscoelastic FGM nanoplates are *** mathematical models are established based on the IMNT and DMNT,and solved by the proposed displacement-based and strain-based Legendre polynomial series approaches(LPSAs),*** with the available data verify the validates of the presented *** examples indicate that the results from the DMNT and IMNT are significantly different at high *** important differences are *** example,the escape frequency only appears in the results from DMNT,but not in *** addition to comparing with classical structures,more attention should be paid to the attenuation characteristics of nonlocal nanostructures.

关键词： Modiﬁed nonlocal theory Viscoelasticity wave propagation Legendre polynomial Phase velocity Attenuation

wave propagation responses of porous bi-directional functionally graded magneto-electro-elastic nanoshells via nonlocal strain gradient theory

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应用数学和力学:英文版 2023年第10期44卷 1821-1840页

作者： Xinte WANG Juan LIU Biao HU Bo ZHANG Huoming SHEN School of Mechanics and Aerospace Engineering Southwest Jiaotong UniversityChengdu 610031China School of Civil Engineering Guizhou University of Engineering ScienceBijie 551700Guizhou ProvinceChina

This study examines the wave propagation characteristics for a bi-directional functional grading of barium titanate(BaTiO_(3)) and cobalt ferrite(CoFe_(2)O_(4)) porous nanoshells,the porosity distribution of which is simulated by the honeycomb-shaped symmetrical and asymmetrical distribution *** nonlocal strain gradient theory(NSGT) and first-order shear deformation theory are used to determine the size effect and shear deformation,*** governing equations are derived for the nanoshells by Hamilton's *** resulting dimensionless differential equations are solved by means of an analytical solution of the combined exponential function after dimensionless ***,extensive parametric surveys are conducted to investigate the influence of diverse parameters,such as dimensionless scale parameters,radiusto-thickness ratios,bi-directional functionally graded(FG) indices,porosity coefficients,and dimensionless electromagnetic potentials on the wave propagation *** on the analysis results,the effect of the dimensionless scale parameters on the dispersion relationship is found to be related to the ratio of the scale *** wave propagation characteristics of nanoshells in the presence of a magnetoelectric field depend on the bi-directional FG indices.

关键词： bi-directional functionally graded(FG) wave propagation dimensionless magneto-electro-elastic(MEE)nanoshell nonlocal strain gradient theory(NSGT) porosity

Dynamic mechanical properties and wave propagation of composite rock-mortar specimens based on SHPB tests

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International Journal of Mining Science and Technology 2022年第4期32卷 793-806页

作者： Zhenyu Han Diyuan Li Xibing Li School of Resources and Safety Engineering Central South UniversityChangsha 410083China School of Civil Engineering Southeast UniversityNanjing 210096China Department of Civil Engineering Monash UniversityMelbourneVictoria 3800Australia

Filled inclusions in rock discontinuities play a key role in the mechanical characteristics of the rock and thereby influence the stability of rock engineering. In this study, a series of impact tests were performed using a split Hopkinson pressure bar system with high-speed photography to investigate the effect of interlayer strength on the wave propagation and fracturing process in composite rock-mortar *** results indicate that the transmission coefficient, nominal dynamic strength, interlayer closure, and specific normal stiffness generally increase linearly with increasing interlayer stiffness. The cement mortar layer can serve as a buffer during the deformation of composite specimens. The digital images show that tensile cracks are typically initiated at the rock-mortar interface, propagate along the loading direction, and eventually result in a tensile failure regardless of the interlayer properties. However, when a relatively weaker layer is sandwiched between the rock matrix, an increasing amount of cement mortar is violently ejected and slight slabbing occurs near the rock-mortar interface.

关键词： Rock dynamics wave propagation Rock-mortar Stiffness Energy Fracturing

Guided wave propagation analysis in stiffened panel using time-domain spectral finite element method

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Chinese Journal of Aeronautics 2022年第10期35卷 208-221页

作者： Zexing YU Chao XU Jiaying SUN Fei DU School of Astronautics Northwestern Polytechnical UniversityXi'an 710072China Qingdao R&D Institute Northwestern Polytechnical UniversityQingdao 266200China

Stiffened panels have been widely utilized in fuselages and wings as critical load-bearing components. These structures are prone to be damaged under long-term and extreme loads, and their health monitoring has been a common concern. The guided wave-based monitoring method is regarded as an efficient approach to detect the damage in stiffened plates because of its wide monitoring range and high sensitivity to micro-damage. Efficient simulation of wave propagation can theoretically demonstrate the detection mechanism of the method. In this study, a Time-Domain Spectral Finite Element Method(TD-SFEM) is adopted to study the wavefield in stiffened plates,where continuous Absorbing Layers with Increasing Damping(ALID) strategy is proposed to circumvent the disturbance of reflected waves on boundaries. After the convergence analysis, the developed TD-SFEM with ALID is validated by the finite element method first. Then, wave scattering and the influence of the stiffener are investigated in detail by comparing the results with the non-stiffened structure. Finally, the effects of the parameters of the stiffener, such as the height and width, on wave propagation are studied, respectively. The results illustrate that the proposed TDSFEM with ALID is an efficient approach to study the wave propagation in the stiffened plate and can reveal the mechanism of influence of the stiffener. It is found that the height of the stiffener changes the interference of wavefield in the plate, while the effects of the width are mainly in wave scattering and mode conversion.

关键词： Absorbing layers with increasing damping Guided waves Stiffened Panel Time-domain spectral finite element wave propagation

Difference analysis in terahertz wave propagation in thermochemical nonequilibrium plasma sheath under different hypersonic vehicle shapes

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Chinese Journal of Aeronautics 2023年第10期36卷 137-151页

作者： Wenchong OUYANG Qi LIU Zhengwei WU School of Nuclear Science and Technology University of Science and Technology of ChinaHefei 230026China Joint Laboratory of Plasma Application Technology Institute of Advanced TechnologyUniversity of Science and Technology of ChinaHefei 230031China CAS Key Laboratory of Geospace Environment University of Science and Technology of ChinaHefei 230026China

Research on terahertz communication under different vehicles has important guiding significance for the design of future hypersonic vehicle and Radio Frequency(RF)*** this paper,a joint simulation model of plasma flow under thermochemical nonequilibrium state and terahertz transmission is developed to investigate the differences in terahertz wave transmission characteristics under different vehicle shapes and the related *** comparing the plasma sheath characteristics and terahertz transmission among HIFIRE-5b(Hypersonic International Flight Research Experimentation-5b),RAM C(Radio Attenuation Measurement C)and ARD(Atmospheric Reentry Demonstrator)vehicles,it is found that the sheath thickness and electron density of ARD vehicles is significantly larger than that of HIFIRE-5b and RAM C vehicles,resulting in greater terahertz wave *** absorption plays a major role in the terahertz attenuation of vehicles,and the contribution of reflection effects is only observed in the ARD vehicle due to its larger plasma sheath thickness and spatial structure *** on the above comparison results,a shape design scheme of reducing the vehicle head and tail for mitigating RF blackout is proposed,and the scheme is proved by further analyzing the effects of different vehicle heads and tails on the terahertz *** the decrease of the head radius and tail width of hypersonic vehicle,the wave attenuation at the same terahertz frequency decreases,and the contribution of reflection effect to wave attenuation gradually ***,the shape design scheme of reducing the vehicle head and tail can effectively alleviate the RF blackout problem,which provides an important reference value for future hypersonic vehicle design.

关键词： Hypersonic vehicles Plasma flow Plasma sheaths Shape optimization Terahertz waves wave propagation

Guided wave propagation in Multilayered Two-dimensional Quasicrystal Plates with Imperfect Interfaces

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Acta Mechanica Solida Sinica 2022年第4期35卷 694-704页

作者： Xin Feng Liangliang Zhang Zhiming Hu Han Zhang Yang Gao College of Science China Agricultural UniversityBeijing 100083China College of Engineering China Agricultural UniversityBeijing 100083China China State Key Laboratory of Acoustics Institute of AcousticsChinese Academy of SciencesBeijing 100190China

An analytical solution of the guided wave propagation in a multilayered twodimensional decagonal quasicrystal plate with imperfect interfaces is *** to the elastodynamic equations of quasicrystals(QCs),the wave propagating problem in the plate is converted into a linear control system by employing the state-vector approach,from which the general solutions of the extended displacements and stresses can be obtained,These solutions along the thickness direction are utilized to derive the propagator matrix which connects the physical variables on the lower and upper interfaces of each *** special spring model,which describes the discontinuity of the physical quantities across the interface,is introduced into the propagator relationship of the multilayered *** total propagator matrix can be used to propagate the solutions in each interface and each layer about the multilayered *** addition,the traction-free boundary condition on the top and bottom surfaces of the laminate is considered to obtain the dispersion equation of wave propagation,Finally,typical numerical examples are presented to illustrate the marked influences of stacking sequence and interface coeficients on the dispersion curves and displacement mode shapes of the QC laminates.

关键词： Two-dimensional QC materials wave propagation Dispersion curve State vector approach Propagator matrix Imperfect interface

The theory of compression–shear coupled composite wave propagation in rock

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Deep Underground Science and Engineering 2022年第1期1卷 77-86页

作者： Jianhua Lu Songlin Xu Chunhe Miao Yushan Xie Liangzhu Yuan Hao Ma Meiduo Chen Pengfei Wang CAS Key Laboratory for Mechanical Behavior and Design of Materials Department of Modern MechanicsUniversity of Science and Technology of ChinaHefeiAnhuiChina

The wave velocity analysis of rock medium is the main method used to explore the internal compositions in the crust and research *** this paper,a compression–shear coupled nonlinear elastic constitutive relation is established,which is consistent with the mechanical properties of rock and mineral medium under high *** this basis,numerical solutions of the wave equation and plane wave analytical solutions for the primary and secondary wave velocities are *** is indicated by the comparison with the linear elastic constitutive theory,the results reflect the compression–shear coupling characteristics of the rock,including the stress path effect and the compression–shear coupling wave *** different parameter values,the velocity of the secondary wave changes from lower than that of the elastic shear wave,to higher than that of the elastic shear *** research results are expected to provide meaningful explanations for the physical mechanisms of the supershear wave and sub-Rayleigh wave,and guidance for the detection of rock and soil composition and the observation of seismic waves.

关键词： compression-shear coupling high pressure constitutive relation rock dynamic wave propagation wave velocity

High-performance computing of 3D blasting wave propagation in underground rock cavern by using 4D-LSM on TianHe-3 prototype E class supercomputer

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Deep Underground Science and Engineering 2022年第1期1卷 87-100页

作者： Meng Fu Gaofeng Zhao State Key Laboratory of Hydraulic Engineering Simulation and Safety School of Civil EngineeringTianjin UniversityTianjinChina

Parallel computing assigns the computing model to different processors on different devices and implements it ***,it has broad applications in the numerical simulation of geotechnical engineering and underground engineering,of which models are always *** parallel computing,the computing time or the memory requirements will be reduced by splitting the original domain of the numerical model into many subdomains,which is thus named as the domain decomposition *** this study,a cubic and equal volume domain decomposition strategy was utilized to realize the parallel computing on the distributed memory system of four-dimensional lattice spring model(4D-LSM)based on the message passing *** a more efficient communication strategy introduced,this study aimed at operating an one-billion-particle model on a supercomputer *** preprocessing procedure of the parallelized 4D-LSM was restructured and the particle generation strategy suitable for the supercomputer platform was employed to minimize the time consumption in preprocessing and *** this basis,numerical calculations were performed on TianHe-3 prototype E class supercomputer at the National Supercomputer Center in *** fieldscale three-dimensional blasting wave propagation models were carried out,of which the numerical results verify the computing power and the advantage of the parallelized 4D-LSM in the simulation of large-scale three-dimension ***,the time complexity and spatial complexity of 4D-LSM and other particle discrete element methods were analyzed.

关键词： domain decomposition method lattice spring model parallel computing wave propagation