2007 Vol. 27, No. 1
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2007, 27(1): 1-6.
doi: 10.11883/1001-1455(2007)01-0001-06
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Abstract:
On the basis of the developed numerical treatment to numerically simulate flows with moving and deforming objects, the movement of a cover induced by the bursting from a pressurized vessel and its effects on the environmental flow field are investigated. The influences of bursting size and cover weight on the blast loads are examined in detail. The results show that the influence of the cover movement on the blast loads is significant.
On the basis of the developed numerical treatment to numerically simulate flows with moving and deforming objects, the movement of a cover induced by the bursting from a pressurized vessel and its effects on the environmental flow field are investigated. The influences of bursting size and cover weight on the blast loads are examined in detail. The results show that the influence of the cover movement on the blast loads is significant.
Analysis of evolutionary power spectra density functionof ground motion induced by blasting seismic
2007, 27(1): 7-11.
doi: 10.11883/1001-1455(2007)01-0007-05
Abstract:
According to Priestly evolutionary random process theory, the evolutionary power spectra density function of nonstationary random process is presented by theory method. By means of nonstationary random evolutionary theory, the evolutionary power spectra density function of blasting seismic is suggested on the basis of uniformity modulating random process. Compared with experimental results, the suggested theoretical models are coincided with experimental phenomena and data.
According to Priestly evolutionary random process theory, the evolutionary power spectra density function of nonstationary random process is presented by theory method. By means of nonstationary random evolutionary theory, the evolutionary power spectra density function of blasting seismic is suggested on the basis of uniformity modulating random process. Compared with experimental results, the suggested theoretical models are coincided with experimental phenomena and data.
2007, 27(1): 12-17.
doi: 10.11883/1001-1455(2007)01-0012-06
Abstract:
This paper focuses on the study of launch dynamics for self-propelled artillery. In order to exactly compute the motion of projectile in gun tube and the initial disturbance, the theory of two-phase flow interior ballistic is applied to the study on launch dynamics. The equations group of launch dynamics for self-propelled artillery is formed, including the body dynamics equation of gun system, the dynamics equations of projectile moving in gun tube and the equations of the two-phase flow interior ballistic. For a self-propelled artillery the computational program is achieved, by which the simulation of launch process is realized. The interior ballistic, motion of projectile in gun tube, dynamic response of the artillery and initial disturbance of projectile are exactly simulated. Some computational results are in good agreement with test results. The simulation results under the classical and two-phase flow interior ballistic models respectively show that the computational accuracy will be improved when the two-phase flow model is used to study launch dynamics. This work provides a necessary base for researching firing dispersion of self-propelled artillery.
This paper focuses on the study of launch dynamics for self-propelled artillery. In order to exactly compute the motion of projectile in gun tube and the initial disturbance, the theory of two-phase flow interior ballistic is applied to the study on launch dynamics. The equations group of launch dynamics for self-propelled artillery is formed, including the body dynamics equation of gun system, the dynamics equations of projectile moving in gun tube and the equations of the two-phase flow interior ballistic. For a self-propelled artillery the computational program is achieved, by which the simulation of launch process is realized. The interior ballistic, motion of projectile in gun tube, dynamic response of the artillery and initial disturbance of projectile are exactly simulated. Some computational results are in good agreement with test results. The simulation results under the classical and two-phase flow interior ballistic models respectively show that the computational accuracy will be improved when the two-phase flow model is used to study launch dynamics. This work provides a necessary base for researching firing dispersion of self-propelled artillery.
2007, 27(1): 18-25.
doi: 10.11883/1001-1455(2007)01-0018-08
Abstract:
The main characteristics of seismic source function in underground explosion are studied by seismological method and numerical method. Especially, the influence of water content on seismic source function is studied, and it reveals that the coupling energy of underground explosion increases with the increase of the water content. The steady-state value of RDP in water-saturated granite is higher than that in dry granite, and correspondingly, the value increases with the increase of water content. However, the corner frequency of RVPs amplitude spectrum of water-saturated granite is lower than that in dry granite, and its value decreases with the increase of water content. The asymptotic behavior of RVP at high frequencies, or roll-off, is thought to be steeper than f-2. The overshoot of RDP at the far-field is not obvious.
The main characteristics of seismic source function in underground explosion are studied by seismological method and numerical method. Especially, the influence of water content on seismic source function is studied, and it reveals that the coupling energy of underground explosion increases with the increase of the water content. The steady-state value of RDP in water-saturated granite is higher than that in dry granite, and correspondingly, the value increases with the increase of water content. However, the corner frequency of RVPs amplitude spectrum of water-saturated granite is lower than that in dry granite, and its value decreases with the increase of water content. The asymptotic behavior of RVP at high frequencies, or roll-off, is thought to be steeper than f-2. The overshoot of RDP at the far-field is not obvious.
2007, 27(1): 26-33.
doi: 10.11883/1001-1455(2007)01-0026-08
Abstract:
In order to explore an optimization design method to design explosion protection stiffened plates, finite element modeling was carried out to simulate the response of clamped rectangle single stiffened plates subjected to blast load. Failure modes of the stiffened plates were analyzed. The influence of relative rigidity and intensity of the blast load was studied. The 3 types deformation modes of failure mode Ⅰ and 2 types of sub-failure mode of failure mode Ⅱ were put forward. The approximate formula to predict the largest deflection of stiffener and the stiffened plates and the criteria of the 2 failure modes were proposed. At last, the optimization design of single stiffened plates subjected to blast load was performed. The results show that it is feasible to optimize the structure of explosion protection stiffened plates, when the critical conditions of transformation from large plastic deformation (failure mode Ⅰ) to breakage damage (failure mode Ⅱ) are acquired by numerical simulation or experiment. The relationship between the mass of stiffened plates and the dimension and space of the stiffeners can be derived from these critical conditions, under the condition that the explosion protection capability of the stiffened plate is best. Thereby the optimization design of explosion protection stiffened plates can be achieved.
In order to explore an optimization design method to design explosion protection stiffened plates, finite element modeling was carried out to simulate the response of clamped rectangle single stiffened plates subjected to blast load. Failure modes of the stiffened plates were analyzed. The influence of relative rigidity and intensity of the blast load was studied. The 3 types deformation modes of failure mode Ⅰ and 2 types of sub-failure mode of failure mode Ⅱ were put forward. The approximate formula to predict the largest deflection of stiffener and the stiffened plates and the criteria of the 2 failure modes were proposed. At last, the optimization design of single stiffened plates subjected to blast load was performed. The results show that it is feasible to optimize the structure of explosion protection stiffened plates, when the critical conditions of transformation from large plastic deformation (failure mode Ⅰ) to breakage damage (failure mode Ⅱ) are acquired by numerical simulation or experiment. The relationship between the mass of stiffened plates and the dimension and space of the stiffeners can be derived from these critical conditions, under the condition that the explosion protection capability of the stiffened plate is best. Thereby the optimization design of explosion protection stiffened plates can be achieved.
2007, 27(1): 34-39.
doi: 10.11883/1001-1455(2007)01-0034-06
Abstract:
The vibration is induced by blasting during tunnel excavation that can have some adverse effect on the adjacent concrete lining. A theoretical method to determine safety velocity of concrete lining under blasting vibration loading is proposed, by calculating the stress on concrete-rock interface caused by blasting seismic (P wave), and analyzing the tensile strength of the interface. Calculated results show that the safety vibration velocity decrease with the increase of elasticity modulus of bedrock, and that the effect of the frequency of blasting seismic is weak. The safety vibration velocity for young foundation concrete adopted in our country is of some safety.
The vibration is induced by blasting during tunnel excavation that can have some adverse effect on the adjacent concrete lining. A theoretical method to determine safety velocity of concrete lining under blasting vibration loading is proposed, by calculating the stress on concrete-rock interface caused by blasting seismic (P wave), and analyzing the tensile strength of the interface. Calculated results show that the safety vibration velocity decrease with the increase of elasticity modulus of bedrock, and that the effect of the frequency of blasting seismic is weak. The safety vibration velocity for young foundation concrete adopted in our country is of some safety.
2007, 27(1): 40-44.
doi: 10.11883/1001-1455(2007)01-0040-05
Abstract:
The dynamic tension experiments of OFHC Cu rings at different voltages were carried out by electromagnetically driven expansion technique. The plastic instability, i.e. multiple necking fracture before the fragmentation was fundamentally analyzed, and the fragments distribution was obtained from the energy balance theory. The 3-D numerical simulation shows that the temperature rise of necking region is higher than that of no-necking region. The multiple necking fracture distribution on the circumference yields to random Poisson distribution.
The dynamic tension experiments of OFHC Cu rings at different voltages were carried out by electromagnetically driven expansion technique. The plastic instability, i.e. multiple necking fracture before the fragmentation was fundamentally analyzed, and the fragments distribution was obtained from the energy balance theory. The 3-D numerical simulation shows that the temperature rise of necking region is higher than that of no-necking region. The multiple necking fracture distribution on the circumference yields to random Poisson distribution.
2007, 27(1): 45-49.
doi: 10.11883/1001-1455(2007)01-0045-05
Abstract:
Measuring technology and data processing method of two-path optical current sensor were proposed. High pulse current could be measured by two-path configuration and arc-tangential function processing method with the constant output power of laser. The electric guns short current was contrastively measured by two-path optical current sensor and Rogowski coil at 18 kV voltage, 31.8 F capacity. The experimental result of optical current sensor agreed well with that of Rogowski coil. It proves that two-path optical current sensor can be used to measure high pulse current effectively.
Measuring technology and data processing method of two-path optical current sensor were proposed. High pulse current could be measured by two-path configuration and arc-tangential function processing method with the constant output power of laser. The electric guns short current was contrastively measured by two-path optical current sensor and Rogowski coil at 18 kV voltage, 31.8 F capacity. The experimental result of optical current sensor agreed well with that of Rogowski coil. It proves that two-path optical current sensor can be used to measure high pulse current effectively.
2007, 27(1): 50-56.
doi: 10.11883/1001-1455(2007)01-0050-07
Abstract:
In order to perfectly analyze the dynamics problem by numerical manifold method (NMM), adopts the Newmark method of dynamic finite element method to improve the algorithm in original NMM on the basis of analyzing the solution idea of dynamics problem in NMM. The improved method has three evident advantages over the original one: (1) The solution of this method is convergent without any condition, when selecting suitable parameters; (2) The time step that can be adopted in this method is much longer than that in the original one; (3) The damp effect in the dynamics problem is fully considered. In the end, a calculation example is adopted to illustrate that the improved numerical manifold method can perfectly simulate the whole process of rock failure under impact load, which overcomes the deficiency of FEM in simulating the block movement of rock after failure.
In order to perfectly analyze the dynamics problem by numerical manifold method (NMM), adopts the Newmark method of dynamic finite element method to improve the algorithm in original NMM on the basis of analyzing the solution idea of dynamics problem in NMM. The improved method has three evident advantages over the original one: (1) The solution of this method is convergent without any condition, when selecting suitable parameters; (2) The time step that can be adopted in this method is much longer than that in the original one; (3) The damp effect in the dynamics problem is fully considered. In the end, a calculation example is adopted to illustrate that the improved numerical manifold method can perfectly simulate the whole process of rock failure under impact load, which overcomes the deficiency of FEM in simulating the block movement of rock after failure.
2007, 27(1): 57-62.
doi: 10.11883/1001-1455(2007)01-0057-06
Abstract:
Complex function method and multi-polar coordinate and Fourier series expansion technology are used to study the scattering of fixed circular inclusion in right-angled plane to steady incident planar SH-wave. The incident wave and the reflection wave in the right-angled plane which has no circular inclusion are constructed; and the scattering solution excited by the boundary of the circular inclusion existing in the space, which satisfy the free stress conditions of the two right-angled boundaries are formulated, therefore, the total displacement field can be constructed using overlapping principle. An infinite algebraic equation of unknown coefficients appearing in the scattering wave solution field can be gained using multi-polar coordinate transformation and Fourier series expansion technology and the conditions of displacement at the boundary of the circular inclusion. It can be solved by using limit items in the infinite series which can give a high computation precision. An example is given to illustrate the variations of the displacement ratio and the phase of the displacement on the horizontal boundary of the right-angled plane with the variations of dimensionless wave number and the incident angle and the location of the circular inclusion. The results of the example show the effectiveness and efficiency of the method introduced here.
Complex function method and multi-polar coordinate and Fourier series expansion technology are used to study the scattering of fixed circular inclusion in right-angled plane to steady incident planar SH-wave. The incident wave and the reflection wave in the right-angled plane which has no circular inclusion are constructed; and the scattering solution excited by the boundary of the circular inclusion existing in the space, which satisfy the free stress conditions of the two right-angled boundaries are formulated, therefore, the total displacement field can be constructed using overlapping principle. An infinite algebraic equation of unknown coefficients appearing in the scattering wave solution field can be gained using multi-polar coordinate transformation and Fourier series expansion technology and the conditions of displacement at the boundary of the circular inclusion. It can be solved by using limit items in the infinite series which can give a high computation precision. An example is given to illustrate the variations of the displacement ratio and the phase of the displacement on the horizontal boundary of the right-angled plane with the variations of dimensionless wave number and the incident angle and the location of the circular inclusion. The results of the example show the effectiveness and efficiency of the method introduced here.
2007, 27(1): 63-67.
doi: 10.11883/1001-1455(2007)01-0063-05
Abstract:
The propagating regularity and influencing factor of shock wave in a T-shaped tunnel were studied experimentally. On the basis of nondimensional analysis, a simplified engineering model was established. By collecting data gained from 4 experiments, a formula was propose. This formula can be used to calculate arrival time and propagation velocity of shock wave in a T-shaped tunnel due to explosion from high explosive charges
The propagating regularity and influencing factor of shock wave in a T-shaped tunnel were studied experimentally. On the basis of nondimensional analysis, a simplified engineering model was established. By collecting data gained from 4 experiments, a formula was propose. This formula can be used to calculate arrival time and propagation velocity of shock wave in a T-shaped tunnel due to explosion from high explosive charges
2007, 27(1): 68-74.
doi: 10.11883/1001-1455(2007)01-0068-07
Abstract:
Based on the principle of blasting seismic waves energy disperse in clay stone, the predominant direction of waves energy flowing and the relation between vibrations peek values and the distance from blasting sources, are researched, so that the rule of vibrations peak values strike is drawn, furthermore, the relation between slopes vibration intensity, and the angle between the slop plain and the envelope in which explosive charges exist, is obtained. By the regulation, blasting cutting in slop of Pan-Xi highway are redesigned, adjusting the dip angle of the envelope in which the explosives lie, to restraint the seismic vibration of the slope and to remain stableness of the slop.
Based on the principle of blasting seismic waves energy disperse in clay stone, the predominant direction of waves energy flowing and the relation between vibrations peek values and the distance from blasting sources, are researched, so that the rule of vibrations peak values strike is drawn, furthermore, the relation between slopes vibration intensity, and the angle between the slop plain and the envelope in which explosive charges exist, is obtained. By the regulation, blasting cutting in slop of Pan-Xi highway are redesigned, adjusting the dip angle of the envelope in which the explosives lie, to restraint the seismic vibration of the slope and to remain stableness of the slop.
2007, 27(1): 75-81.
doi: 10.11883/1001-1455(2007)01-0075-07
Abstract:
Based on the characteristic of blasting construction, the dynamic effect caused by blasting construction for the typical double side excavation method is studied by numerical simulation. The general laws of dynamic effect are proposed at the boundary of the existing tunnel. The secondary supporting time is important to the existing tunnel in the region influenced by blasting construction, and the key locations which blasting construction influences the stability of existing tunnel are given. The analysis shows that the dynamic effects caused by blasting on the stability of surrounding rock of existing tunnel are mainly the tensile damage at the surface of surrounding rock caused by blasting stress wave. The most serious damage locates at the face-blast-wall, arch feet, arch roof of the existing tunnel. The results provide some reference for the blasting construction of the tunnels with small spacing.
Based on the characteristic of blasting construction, the dynamic effect caused by blasting construction for the typical double side excavation method is studied by numerical simulation. The general laws of dynamic effect are proposed at the boundary of the existing tunnel. The secondary supporting time is important to the existing tunnel in the region influenced by blasting construction, and the key locations which blasting construction influences the stability of existing tunnel are given. The analysis shows that the dynamic effects caused by blasting on the stability of surrounding rock of existing tunnel are mainly the tensile damage at the surface of surrounding rock caused by blasting stress wave. The most serious damage locates at the face-blast-wall, arch feet, arch roof of the existing tunnel. The results provide some reference for the blasting construction of the tunnels with small spacing.
2007, 27(1): 82-86.
doi: 10.11883/1001-1455(2007)01-0082-05
Abstract:
The defense effect of underwater blast injury was experimentally researched to explore the defensive material and its structural style. Results show that the selected compound material is a good defense against underwater impact wave and provide a experimental reference for the protective study of underwater blast injury.
The defense effect of underwater blast injury was experimentally researched to explore the defensive material and its structural style. Results show that the selected compound material is a good defense against underwater impact wave and provide a experimental reference for the protective study of underwater blast injury.
2007, 27(1): 87-90.
doi: 10.11883/1001-1455(2007)01-0087-04
Abstract:
The mismatch of cross-sectional area especially for hard materials will result in distinct two-dimensional effect in SHPB experiment. With finite element method and dimensional analysis, the influence is defined as concave two-dimensional effect which leads to monstrous error in small strain measurement, not as conventional planar two-dimensional effect which can be ignored in this case. The conclusion has some significance for guiding SHPB experiment with relatively small cross-sectional area specimen.
The mismatch of cross-sectional area especially for hard materials will result in distinct two-dimensional effect in SHPB experiment. With finite element method and dimensional analysis, the influence is defined as concave two-dimensional effect which leads to monstrous error in small strain measurement, not as conventional planar two-dimensional effect which can be ignored in this case. The conclusion has some significance for guiding SHPB experiment with relatively small cross-sectional area specimen.
2007, 27(1): 91-96.
doi: 10.11883/1001-1455(2007)01-0091-06
Abstract:
Adiabatic shear bands and white layers in primary and secondary deformation zones within the serrated chips formed during high speed cutting of 30CrNi3MoV steel were investigated by optical microscope, microhardness tester, XRD, SEM and TEM. Results show that two types of adiabatic shear bands, i.e. deformed shear bands and transformed shear bands, were formed during lower and higher cutting speed respectively. The microhardness in the transformed shear bands is higher than that in deformed bands and matrix of chips. XRD investigation shows that martensitic phase transformation takes place in the white layers. TEM observation reveals the equiaxed grains with diameter of 50～100 nm in center of transformed shear bands, this means that dynamic recrystallization occur during formation of shear bands.
Adiabatic shear bands and white layers in primary and secondary deformation zones within the serrated chips formed during high speed cutting of 30CrNi3MoV steel were investigated by optical microscope, microhardness tester, XRD, SEM and TEM. Results show that two types of adiabatic shear bands, i.e. deformed shear bands and transformed shear bands, were formed during lower and higher cutting speed respectively. The microhardness in the transformed shear bands is higher than that in deformed bands and matrix of chips. XRD investigation shows that martensitic phase transformation takes place in the white layers. TEM observation reveals the equiaxed grains with diameter of 50～100 nm in center of transformed shear bands, this means that dynamic recrystallization occur during formation of shear bands.
