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Effects of imperfect experimental conditions on stress waves in SHPB experiments 被引量:5
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作者 Xianqian Wu Qiuyun Yin +1 位作者 Yanpeng Wei Chenguang Huang 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2015年第6期827-836,共10页
Experimental and numerical simulations were undertaken to estimate the effects of imperfect conditions on stress waves in split Hopkinson pressure bar (SHPB) experiments. The photonic Doppler velocimetry (PDV) mea... Experimental and numerical simulations were undertaken to estimate the effects of imperfect conditions on stress waves in split Hopkinson pressure bar (SHPB) experiments. The photonic Doppler velocimetry (PDV) measurement results show that the rise and fall times of an incident wave increases with an increasing inclination angle; also, the fluctuations of the incident wave disappear gradually with the increase of inclination angle. The following characteristics for various defects in the SHPB were obtained by numerical simulation: (1) the influence of a curved bar was negligible; (2) misalignment modestly affects the fluctuation characteristics, and bending waves were generated at this condition; (3) inclination and indentation of the impact end- surface had a great impact on the incident waves, and both of them increase the rise time of the incident wave by increasing the degree of defects. In view of the results, misalignment, inclination, and indentation in SHPB experiments should be minimized. 展开更多
关键词 Imperfect experimental conditions SHPBexperiments stress waves PDV measurement. Numericalsimulation
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Response and energy dissipation of rock under stochastic stress waves 被引量:4
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作者 邓建 边利 《Journal of Central South University of Technology》 EI 2007年第1期111-114,共4页
The response and energy dissipation of rock under stochastic stress waves were analyzed based on dynamic fracture criterion of brittle materials integrating with Fourier transform methods of spectral analysis. When th... The response and energy dissipation of rock under stochastic stress waves were analyzed based on dynamic fracture criterion of brittle materials integrating with Fourier transform methods of spectral analysis. When the stochastic stress waves transmit through rocks, the frequency and energy ratio of harmonic components were calculated by analytical and discrete analysis methods. The stress waves in shale, malmstone and liparite were taken as examples to illustrate the proposed analysis methods. The results show the harder the rock, the less absorption of energy, the more the useless elastic waves transmitting through rock, and the narrower the cutoff frequency to fracture rock. When the whole stress energy doubles either by doubling the duration time or by increasing the amplitude of stress wave, ratio of the energy of elastic waves transmitting through rock to the whole stress energy (i.e. energy dissipation ratio) is decreased to 10%-15%. When doubling the duration time, the cutoff frequency to fracture rock remains constant. However, with the increase of the amplitude of stress wave, the cutoff frequency increases accordingly. 展开更多
关键词 stochastic stress waves dynamic fracture criterion Fourier transform energy dissipation ROCK
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Stress Waves in Polymeric Fluids
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作者 Karan S. Surana Michael D. Kitchen 《American Journal of Computational Mathematics》 2022年第1期87-118,共32页
This paper demonstrates the existence, propagation, transmission, reflection, and interaction of deviatoric stress waves in polymeric fluids for which the mathematical models are derived using conservation and balance... This paper demonstrates the existence, propagation, transmission, reflection, and interaction of deviatoric stress waves in polymeric fluids for which the mathematical models are derived using conservation and balance laws (CBL) of Classical Continuum Mechanics (CCM) and the constitutive theories are based on the entropy inequality and representation theorem. The physical mechanisms of deformation in polymeric liquids that enable the stress wave physics are identified and are demonstrated to be valid using Maxwell, Oldroyd-B, and Giesekus polymeric fluids, and are illustrated using model problem studies. We assume polymeric fluids to be isotropic and homogeneous at the macro scale so that the CBL of the CCM can be used to derive their mathematical models. For simplicity, we assume the polymeric fluids to be incompressible in the present work. 展开更多
关键词 Classical Continuum Theory Viscoelastic Fluids Polymeric Liquids stress waves MEMORY RHEOLOGY
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Physical simulation of rock burst induced by stress waves 被引量:16
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作者 LU Ai-hong MAO Xian-biao LIU Hai-shun 《Journal of China University of Mining and Technology》 EI 2008年第3期401-405,共5页
The behavior of stress wave propagation in rock walls and the process of rock bursts were simulated by application tests of material similar to rock. Results show that 1) the attenuation characteristics of stress wave... The behavior of stress wave propagation in rock walls and the process of rock bursts were simulated by application tests of material similar to rock. Results show that 1) the attenuation characteristics of stress waves were related to the material proper-ties, stress waves attenuate more quickly in soft material and 2) when the explosion load was applied at the top of the roadway, the number and the length of the cracks increased with a decrease in the distance between the explosive point and roof of the roadway. When the distance was 280 mm, only some chips appeared near the source, when the distance was 210 mm, some small cracks started to appear near the road-rib and when the distance was reduced to 140 mm, larger cracks appeared at the road-rib. It can be concluded that, under a given stress the number of cracks is closely related to the intensity of stress waves. The cracks in the sur-rounding rock can be reduced by controlling the intensity of the stress waves and rock bursts can be avoided to some extent by pre-venting the formation of layered crack structures. A new experimental approach has been provided for studying rock bursts by using physical simulation. 展开更多
关键词 similar material stress wave physical simulation rock burst
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Experimental Investigation on Transmission of Stress Waves in Sandwich Samples Made of Foam Concrete 被引量:4
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作者 SHEN Jun REN Xinjian 《Defence Technology(防务技术)》 SCIE EI CAS 2013年第2期139-144,共6页
A series of impact tests of sandwich samples were completed using a large-diameter split Hopkinson pressure bar (SHPB)device at different velocities. The interlayer is made of foam concrete, loess or sand. The stress ... A series of impact tests of sandwich samples were completed using a large-diameter split Hopkinson pressure bar (SHPB)device at different velocities. The interlayer is made of foam concrete, loess or sand. The stress peak value decay, energy decay and waveform dispersion characters are studied by comparing the incident waves with the transmission waves. The tests indicate that the foam concrete has the best capabilities of shock resistance and energy absorption, the loess comes second, and the sand takes third place. 展开更多
关键词 non-metallic inorganic material foam concrete SHPB stress wave energy absorption
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SCATTERING OF HARMONIC ANTI-PLANE SHEAR STRESS WAVES BY A CRACK IN FUNCTIONALLY GRADED PIEZOELECTRIC/PIEZOMAGNETIC MATERIALS 被引量:6
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作者 Liang Jun 《Acta Mechanica Solida Sinica》 SCIE EI 2007年第1期75-86,共12页
In this paper, the dynamic behavior of a permeable crack in functionally graded piezoelectric/piezomagnetic materials is investigated. To make the analysis tractable, it is assumed that the material properties vary ex... In this paper, the dynamic behavior of a permeable crack in functionally graded piezoelectric/piezomagnetic materials is investigated. To make the analysis tractable, it is assumed that the material properties vary exponentially with the coordinate parallel to the crack. By using the Fourier transform, the problem can be solved with the help of a pair of dual integral equations in which the unknown is the jump of displacements across the crack surfaces. These equations are solved to obtain the relations between the electric filed, the magnetic flux field and the dynamic stress field near the crack tips using the Schmidt method. Numerical examples are provided to show the effect of the functionally graded parameter and the circular frequency of the incident waves upon the stress, the electric displacement and the magnetic flux intensity factors of the crack. 展开更多
关键词 functionally graded piezoelectric/piezomagnetic materials CRACK stress wave
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Propagation of combined longitudinal and torsional stress waves in a functionally graded thin-walled tube 被引量:2
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作者 Shitang CUI Xiaojun NI 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI CSCD 2021年第12期1717-1732,共16页
An analytical model for the propagation of combined stress waves in a functionally graded thin-walled tube subjected to combined longitudinal and torsional impact loading is established.The material properties of the ... An analytical model for the propagation of combined stress waves in a functionally graded thin-walled tube subjected to combined longitudinal and torsional impact loading is established.The material properties of the tube are assumed to be continuously graded along the length according to a power law function with respect to the volume fractions of the constituents.The generalized characteristic theory is used to analyze the main features of the characteristic wave speeds and simple wave solutions in the functionally graded thin-walled tube.The finite difference method is used to discretize the governing equations.Two types of typical solutions are obtained for the functionally graded tube and the homogeneous tube subjected to combined longitudinal and torsional step loading.The numerical results reveal some abnormal phenomena in the stress path and wave process of the functionally graded thin-walled tube. 展开更多
关键词 elastoplastic behavior combined stress wave finite difference scheme thinwalled tube
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Numerical analysis of tunnel reinforcing influences on failure process of surrounding rock under explosive stress waves 被引量:3
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作者 左宇军 唐春安 +2 位作者 朱万成 李地元 李术才 《Journal of Central South University of Technology》 2008年第5期632-638,共7页
Based on mesoscopic damage mechanics, numerical code RFPA2D (dynamic edition) was developed to analyze the influence of tunnel reinforcing on failure process of surrounding rock under explosive stress waves. The res... Based on mesoscopic damage mechanics, numerical code RFPA2D (dynamic edition) was developed to analyze the influence of tunnel reinforcing on failure process of surrounding rock under explosive stress waves. The results show that the propagation phenomenon of stress wave in the surrounding rock of tunnel and the failure process of surrounding rock under explosive stress waves are reproduced realistically by using numerical code RFPA2O; from the failure process of surrounding rock, the place at which surrounding rock fractures is transferred because of tunnel reinforcing, and the rockfall and collapse caused by failure of surrounding rock are restrained by tunnel reinforcing; furthermore, the absolute values of peak values of major principal stress, and the minimal principal stress and shear stress at center point of tunnel roof are reduced because of tunnel reinforcing, and the displacement at center point of runnel roof is reduced as well, consequently the stability of tunnel increases. 展开更多
关键词 tunnel reinforcing numerical simulation explosive stress wave failure process INHOMOGENEITY
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THE INVESTIGATION ON DYNAMIC FRACTURE BEHAVOUR OF MATERIALS UNDER COMPRESSIVE-SHEAR COMBINED STRESS WAVES
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作者 马维 段祝平 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2000年第4期335-346,共12页
In this paper,an improved plate impact experimental technique is presented for studying dynamic fracture mechanism of materials,under the conditions that the impacting loading is provided by a single pulse and the loa... In this paper,an improved plate impact experimental technique is presented for studying dynamic fracture mechanism of materials,under the conditions that the impacting loading is provided by a single pulse and the loading time is in the sub-microsecond range.The impacting tests are carried out on the pressure-shear gas gun.The loading rate achieved is dK/dt~10~8 MPam^(1/2)s^(-1).With the elimination of influence of the specimen boundary,the plane strain state of a semi-infinite crack in an infinite elastic plate is used to simulate the deformation fields of crack tip. The single pulses are obtained by using the 'momentum trap'technique.Therefore, the one-time actions of the single pulse are achieved by eradicating the stress waves reflected from the specimen boundary or diffracted from the crack surfaces.In the current study,some important phenomena have been observed.The special loading of the single pulse can bring about material damage around crack tip,and affect the material behavior,such as kinking and branching of the crack propagation.Failure mode transitions from mode Ⅰ to mode Ⅱ crack are observed under asymmetrical impact conditions.The mechanisms of the dynamic crack propagation are consistent with the damage failure model. 展开更多
关键词 single pulse compressive-shear combined stress wave pressureshear gas gun
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Influence of the Radial Inertia Effect on the Propagation Law of Stress Waves in Thin-Walled Tubes
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作者 Shitang Cui Yongliang Zhang 《Advances in Applied Mathematics and Mechanics》 SCIE 2023年第5期1216-1232,共17页
This investigation focused on the influence of the radial inertia effect on the propagation behavior of stress waves in thin-walled tubes subjected to combined longitudinal and torsional impact loads.Generalized chara... This investigation focused on the influence of the radial inertia effect on the propagation behavior of stress waves in thin-walled tubes subjected to combined longitudinal and torsional impact loads.Generalized characteristics theory was used to analyze the main features of the characteristic wave speeds and simple wave solutions in thin-walled tubes.The incremental elastic-plastic constitutive relations described by the rate-independent plasticity were adopted,and the finite difference method was used to investigate the evolution and propagation behaviors of combined elasticplastic stress waves in thin-walled tubes when the radial inertial effect was considered.The numerical results were compared with those obtained when the radial inertia effect was not considered.The results showed that the speed of the coupled stress wave increased when the radial inertia effect was considered.The hardening modulus of the material in the plastic stage had a greater impact on the coupled slow waves than on the coupled fast waves. 展开更多
关键词 Radial inertia effect thin-walled tube stress waves finite difference method characteristic theory
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Macro Meso Response and Stress Wave Propagation Characteristics of MCT High-Voltage Switch Under Shock load
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作者 Yuyang Guo Chuang Chen +1 位作者 Ruizhi Wang Enling Tang 《Defence Technology(防务技术)》 SCIE EI CAS CSCD 2024年第2期317-335,共19页
In order to study the dynamic and electrical coupling response characteristics of Metal Oxide Semiconductor Controlled Thyristor(MCT)high-voltage switch under the synergic action of mechanical load and high voltage,th... In order to study the dynamic and electrical coupling response characteristics of Metal Oxide Semiconductor Controlled Thyristor(MCT)high-voltage switch under the synergic action of mechanical load and high voltage,the separated Hopkinson pressure bar(SHPB)test system was used to simulate different impact load environments,and combined with the multi-layer high-voltage ceramic capacitor charging and discharging system,the instantaneous electrical signals of MCT high-voltage switch were collected.Combined with numerical simulation and theoretical analysis,the failure mode and stress wave propagation characteristics of MCT high voltage switch were determined.The mechanical and electrical coupling response characteristics and failure mechanism of MCT high voltage switch under dynamic load were revealed from macroscopic and microscopic levels.The results show that the damage modes of MCT high-voltage switches can be divided into non-functional damage,recoverable functional damage,non-recoverable damage and structural damage.Due to the gap between the metal gate and the oxide layer,the insulating oxide layer was charged.After placing for a period of time,the elastic deformation of the metal gate partially recovered and the accumulated charge disappeared,which induced the recoverable functional damage failure of the device.In addition,obvious cracks appeared on both sides of the monocrystalline silicon inside the MCT high-voltage switch,leading to unrecoverable damage of the device. 展开更多
关键词 MCT Impact load Failure analysis stress wave Numerical simulation
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Blasting induced dynamic stress concentration and failure characteristics of deep-buried rock tunnel
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作者 ZHAO Rui TAO Ming +2 位作者 XIANG Gong-liang WANG Shao-feng ZHAO Hua-tao 《Journal of Central South University》 SCIE EI CAS CSCD 2024年第7期2321-2340,共20页
In this study,the dynamic stress concentration factors(DSCF)around a straight-wall arch tunnel(SWAT)were solved analytically utilizing the complex variable function methods and Duhamel’s integral.The effects of wavel... In this study,the dynamic stress concentration factors(DSCF)around a straight-wall arch tunnel(SWAT)were solved analytically utilizing the complex variable function methods and Duhamel’s integral.The effects of wavelength,incident angle,and blasting rising time on the DSCF distribution were analyzed.Theoretical results pointed out dynamic disturbances resulting in compressive stress concentration in the vertical direction and tensile stress in the incident direction.As the wavelength and rising time increased,there was a tendency for the amplitude of stress concentration to initially rise and then converge.Moreover,a series of 3D FEM models were established to evaluate the effect of different initial stress states on the dynamic failure of the tunnel surrounding rock.The results indicated that the failure of the surrounding rock was significantly influenced by the direction of the static maximum principal stress and the direction of the dynamic disturbance.Under the coupling of static and blasting loading,damage around the tunnel was more prone to occur in the dynamic and static stress concentration coincidence zone.Finally,the damage modes of rock tunnel under static stress and blasting disturbance from different directions were summarized and a proposed support system was presented.The results reveal the mechanisms of deep-buried rock tunnel destruction and dynamically triggered rockburst. 展开更多
关键词 stress wave scattering dynamic stress analysis rock tunnel dynamic failure analysis
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Effect of Blasting Stress Wave on Dynamic Crack Propagation
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作者 Huizhen Liu Duanying Wan +2 位作者 Meng Wang Zheming Zhu Liyun Yang 《Computer Modeling in Engineering & Sciences》 SCIE EI 2024年第1期349-368,共20页
Stress waves affect the stress field at the crack tip and dominate the dynamic crack propagation.Therefore,evaluating the influence of blasting stress waves on the crack propagation behavior and the mechanical charact... Stress waves affect the stress field at the crack tip and dominate the dynamic crack propagation.Therefore,evaluating the influence of blasting stress waves on the crack propagation behavior and the mechanical characteristics of crack propagation is of great significance for engineering blasting.In this study,ANSYS/LS-DYNA was used for blasting numerical simulation,in which the propagation characteristics of blasting stress waves and stress field distribution at the crack tip were closely observed.Moreover,ABAQUS was applied for simulating the crack propagation path and calculating dynamic stress intensity factors(DSIFs).The universal function was calculated by the fractalmethod.The results show that:the compressive wave causes the crack to close and the reflected tensile wave drives the crack to initiate and propagate,and failure mode is mainly tensile failure.The crack propagation velocity varies with time,which increases at first and then decreases,and the crack arrest occurs due to the attenuation of stress waves and dissipation of the blasting energy.In addition,crack arrest toughness is smaller than the crack initiation toughness,applied pressure waveforms(such as the peak pressure,duration,waveforms,wavelengths and loading rates)have a great influence on DSIFs.It is conducive to our deep understanding or the study of blasting stress waves dominated fracture,suggesting a broad reference for the further development of rock blasting in engineering practice. 展开更多
关键词 Crack propagation blasting stress wave dynamic stress intensity factor pressure waveform numerical simulation
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Stress wave analysis of high-voltage pulse discharge rock fragmentation based on plasma channel impedance model 被引量:1
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作者 黄仕杰 刘毅 +5 位作者 赵勇 徐尤来 林福昌 李化 张钦 李柳霞 《Plasma Science and Technology》 SCIE EI CAS CSCD 2023年第6期52-64,共13页
High-voltage pulse discharge(HVPD)rock fragmentation controls a plasma channel forming inside the rock by adjusting the electrical parameters,electrode type,etc.In this work,an HVPD rock fragmentation test platform wa... High-voltage pulse discharge(HVPD)rock fragmentation controls a plasma channel forming inside the rock by adjusting the electrical parameters,electrode type,etc.In this work,an HVPD rock fragmentation test platform was built and the test waveforms were measured.Considering the effects of temperature,channel expansion and electromagnetic radiation,the impedance model of the plasma channel in the rock was established.The parameters and initial values of the model were determined by an iterative computational process.The model calculation results can reasonably characterize the development of the plasma channel in the rock and estimate the shock wave characteristics.Based on the plasma channel impedance model,the temporal and spatial distribution characteristics of the radial stress and tangential stress in the rock were calculated,and the rock fragmentation effect of the HVPD was analyzed. 展开更多
关键词 stress wave shock wave plasma channel impedance model rock fragmentation high-voltage pulse discharge
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The attenuation of stress waves in fluid saturated porous rock
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作者 席道瑛 程经毅 +1 位作者 易良坤 张斌 《Acta Seismologica Sinica(English Edition)》 CSCD 1997年第5期13-18,共6页
The dynamic mechanical frequency spectrum and temperature spectrum measurements of dry and saturated sandstone with three different porosity are conducted by use of the viscoelastic spectrum instrument in the 0.01~10... The dynamic mechanical frequency spectrum and temperature spectrum measurements of dry and saturated sandstone with three different porosity are conducted by use of the viscoelastic spectrum instrument in the 0.01~100 Hz frequency region. The frequency responses of the attenuation and modulus at different temperature peaks are obtained. With increase of the porosity and the loss of the complex modulus, the attenuation in the saturated sandstones is increased, and the frequency dispersion is enhanced. The relation between the frequency spectrum and the temperature spectrum are also discussed. 展开更多
关键词 dynamic response stress wave ATTENUATION saturated sandstone
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Improving tree health assessment accuracy at low temperatures:considering the effect of trunk ice content on electrical resistance and stress wave tomography
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作者 Jiaxing Guo Peng Wang +1 位作者 Yuting Wang Huadong Xu 《Journal of Forestry Research》 SCIE CAS CSCD 2023年第5期1503-1510,共8页
Accurate decay detection and health assessment of trees at low temperatures is an important issue for forest management and ecology in cold areas.Low temperature ice formation on tree health assessment is unknown.Beca... Accurate decay detection and health assessment of trees at low temperatures is an important issue for forest management and ecology in cold areas.Low temperature ice formation on tree health assessment is unknown.Because electric resistance tomography and stress wave tomography are two widely used methods for the detection of tree decay,this study investigated the effect of ice content on trunk electrical resistance and stress wave velocity to improve tree health assessment accuracy.Moisture content,trunk electrical resistance and stress wave velocity using time domain reflectometry were carried out on Larix gmelinii and Populus simonii.Ice content is based on moisture content data.The ice content of both species showed a trend of increasing and then decreasing.This was opposite with ambient temperatures.With the decrease of temperatures,daily average ice content increased,but the range narrowed gradually and both electrical resistance and stress wave velocity increased.Both increased rapidly near 0℃,mainly caused by ice formation(phase change and freezing of free water)in live trees.In addition,both are positively correlated with ice content.The results suggest that ice content should be considered for improving the accuracy of tree decay detection and health evaluation using electric resistance tomography and stress wave velocity methods under low temperatures. 展开更多
关键词 Cross-section electrical resistance Cross-section stress wave velocity Ambient temperatures Ice content Wood decay detection Tree heath
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The nonlocal solution of two parallel cracks in functionally graded materials subjected to harmonic anti-plane shear waves 被引量:5
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作者 Jun Liang Shiping Wu Shanyi Du Center for Composite Materials and Structure,Harbin Institute of Technology,Harbin 150001,China 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2007年第4期427-435,共9页
In this paper, the dynamic interaction of two parallel cracks in functionally graded materials (FGMs) is investigated by means of the non-local theory. To make the analysis tractable, the shear modulus and the mater... In this paper, the dynamic interaction of two parallel cracks in functionally graded materials (FGMs) is investigated by means of the non-local theory. To make the analysis tractable, the shear modulus and the material density are assumed to vary exponentially with the coordinate vertical to the crack. To reduce mathematical difficulties, a one-dimensional non-local kernel is used instead of a twodimensional one for the dynamic problem to obtain stress fields near the crack tips. By use of the Fourier transform, the problem can be solved with the help of two pairs of dual integral equations, in which the unknown variables are the jumps of displacements across the crack surfaces. To solve the dual integral equations, the jumps of displacements across the crack surfaces are expanded in a series of Jacobi polynomials. Unlike the classical elasticity solutions, it is found that no stress singularity is present at the crack tips. The non-local elastic solutions yield a finite hoop stress at the crack tips. The present result provides theoretical references helpful for evaluating relevant strength and preventing material failure of FGMs with initial cracks. The magnitude of the finite stress field depends on relevant parameters, such as the crack length, the distance between two parallel cracks, the parameter describing the FGMs, the frequency of the incident waves and the lattice parameter of materials. 展开更多
关键词 CRACK The non-local theory stress waves Functionally graded materials
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A STUDY ON THE EFFECT OF RADIAL INERTIA ON THE ELASTO-PLASTIC COMBINED STRESS WAVE PROPAGATION IN THIN-WALLED TUBES 被引量:2
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作者 Li Yongchi Huang Chengyi Yuan Fuping Jin Yongmei 《Acta Mechanica Solida Sinica》 SCIE EI 2001年第1期58-66,共9页
An in-depth analysis of propagation characteristics ofelasto-plastic combined stress waves in circular thin-walled tubeshas been made. In obtaining the simple-wave solution, however, mostresearches have ignored the in... An in-depth analysis of propagation characteristics ofelasto-plastic combined stress waves in circular thin-walled tubeshas been made. In obtaining the simple-wave solution, however, mostresearches have ignored the influence of the circumferential stressrelated to the radial inertial ef- fect in the tubes. In this paperthe incremental elasto-plastic constitutive relations which areconve- nient for dynamic numerical analysis are adopted, and thefinite-difference method is used to study the evolution adpropagation of elasto-plastic combined stress waves in a thin-walledtube with the radial inertial effect of the tube considered. Thecalculation results are compared with those obtained when the radialinertial effect is not considered. The calculation results show thatthe radial inertial effect of a tube has a fairly great influence onthe propagation of elasto-plastic combined stress waves. 展开更多
关键词 circular thin-walled tube elasto-plastic combined stress waves radialinertial effect
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Effect of sensor quantity on measurement accuracy of log inner defects by using stress wave 被引量:10
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作者 WANG Li-hai XU Hua-dong ZHOU Ci-lin LI Li YANG Xue-chun 《Journal of Forestry Research》 SCIE CAS CSCD 2007年第3期221-225,共5页
Wood nondestructive testing (NDT) is one of the high efficient methods in utilizing wood. This paper explained the principle of log defect testing by using stress wave, and analyzed the effects of sensor quantity on... Wood nondestructive testing (NDT) is one of the high efficient methods in utilizing wood. This paper explained the principle of log defect testing by using stress wave, and analyzed the effects of sensor quantity on defect testing results by using stress wave in terms of image fitting degree and error rate. The results showed that for logs with diameter ranging from 20 to 40 cm, at least 12 sensors were needed to meet the requirement which ensure a high testing accuracy of roughly 90% of fitness with 0.1 of error rate. And 10 sensors were recommended to judge the possible locations of defects and 6 sensors were sufficient to decide whether there were defects or not. 展开更多
关键词 Sensor quantity Log defect testing stress wave Image fitting degree
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Dynamic response and failure of rock in initial gradientstress field under stress wave loading 被引量:10
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作者 WENG Lei WU Qiu-hong +1 位作者 ZHAO Yan-lin WANG Shi-ming 《Journal of Central South University》 SCIE EI CAS CSCD 2020年第3期963-972,共10页
Once an opening is created in deep underground,the stresses surrounding the opening will be redistributed,inducing a gradient stress field.To understand how the ground rock in such a gradient stress field responses to... Once an opening is created in deep underground,the stresses surrounding the opening will be redistributed,inducing a gradient stress field.To understand how the ground rock in such a gradient stress field responses to dynamic stress loading,the gradient stress distribution at a circular opening was first analyzed and the propagation of 1D stress wave in rock mass under gradient stress field was theoretically derived.By using an implicit to explicit solution method in LS-DYNA code,the dynamic mechanical behaviors of rock in gradient stress field were numerically investigated.The results indicate that the damage is mainly produced at or near the free face,partly due to the straight action of compressive stress wave and the tensile stress wave generated at the free face.The range of the induced damage zone is narrowed under the conditions of higher gradient stress rate and lower dynamic stress amplitude.However,under lower gradient stress field and higher dynamic stress,the damage becomes severer and wider with discontinuous failure regions. 展开更多
关键词 deep opening gradient stress rate(GSR) stress wave damage zone LS-DYNA
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