Loading...

Table of Content

    10 April 2009, Volume 31 Issue 2
    Education Study
    Discussion of Serval Issues for Pure Beam Deflection Curve by Metheds of Graph Multiplication and Double Integral
    2009, 31(2):  82-83.  DOI: 10.6052/1000-0992-2007-030
    Asbtract ( 1416 )   PDF (258KB) ( 613 )  
    Related Articles | Metrics
    The accuracy key to the deflection curve of a uniform section straight beam subjected to the moment is a circle,however,the answers are both parabolas by metheds of graph multiplication and double integral .The reasons are analysed,and the error is given with a parabola replacing a circle.
    Application study
    MIXED MODE DYNAMIC STRESS INTENSITY FACTORS OF CRACKED STRAIGHT THROUGH FLATTENED BRAZILIAN DISC SPECIMENS
    2009, 31(2):  40-45.  DOI: 10.6052/1000-0992-2007-382
    Asbtract ( 1649 )   PDF (1060KB) ( 639 )  
    Related Articles | Metrics
    In order to establish a standard for the test of mixed mode dynamic fracture of rock with the cracked straight through flattened Brazilian disc (CSTFBD) specimen, we use finite element method first to check the related results in literature on the cracked straight through Brazilian disc specimen (CSTBD). The I-II mixed mode dynamic stress intensity factors (SIFs) of the two kinds of discs with different dimensionless crack lengths (i.e. the half length of the crack normalized by the radius of the specimen) are obtained to show that the differences of the dynamic SIF's time history between these two kinds of specimens are within 10{\%}, and the numerical method used in this paper is valid. Then for CSTFBD specimens, the I-II mixed ratio, the angle of crack initiation, and the loading angle for pure mode II fracture test are obtained. The results are useful for mixed mode dynamic fracture test of CSTFBD, including specimens preparation, the location and directional alignment of the strain gages, as well as the estimation for the crack initiation time and the crack initiation direction.
    Education Study
    Application study
    INFLUENCE OF THE VOID DISTRIBUTION ON MACRO-RESPONSES OF FUNCTIONALLY GRADED PLATES
    2009, 31(2):  55-59.  DOI: 10.6052/1000-0992-2007-503
    Asbtract ( 1247 )   PDF (900KB) ( 579 )  
    Related Articles | Metrics
    Complex microstructures of functionally graded materials and their geometry make related strucutres more complex than plates, cylindrical shells and spherical shells. Therefore, the analytic solution of functionally graded structure is difficult to obtain, and the approximate solution and other calculation methods are used frequently. A new microelement method for the analysis of functionally graded structures is suggested to establish a quantitative relation between the macro-characteristics and microstructures of functionally graded materials, and different combinations of materials for different macro-characteristics can be found. By this microelement method, the influence of voids on the macro-responses can be analyzed. The three-dimensional distributions of mechanical quantities of the functionally graded plates with different distributions, forms and positions of the voids are given, a trans-scale analysis between micro-constitution and macro-response of the functionally graded materials and structures can be carried out.
    A NEW THEORETICAL MODEL FOR ARMOR-PIERCING MECHANICS
    2009, 31(2):  22-26.  DOI: 10.6052/1000-0992-2007-511
    Asbtract ( 1334 )   PDF (809KB) ( 813 )  
    Related Articles | Metrics
    Penetration mechanics is important both as a science and in practice of military engineering. For a quasi-steady penetration of long rod projectile into semi-infinite thick target, a simplified model is developed, where the bullet incorporated mushroom head consists of unbroken zone, crush zone and hole dilating zone, and the target consists of hole dilating zone, crush zone and unbroken zone, with the strain rate effect being considered. A set of ODE is obtained through conservation laws of every part. Through theoretical analysis and calculation, the influences of the crush strain rate, crash strength of the projectile and the strain rate effect of the crash strength of the target on penetration depth are analyzed. The excellent agreement of the calculation results and the experiment shows the effectiveness of the simplified model.
    Education Study
    The analysis of section relative displacement in antisymmetric statically indeterminate frame without external restrctions
    2009, 31(2):  78-79.  DOI: 10.6052/1000-0992-2007-531
    Asbtract ( 1137 )   PDF (350KB) ( 568 )  
    Related Articles | Metrics
    On the basis of the principle of virtual work, the building of unit-load state, when solving section relative displacement in antisymmetric statically indeterminate frame without external restrctions, is analyzed principally. The essential of the unit-load method can be understood well by students from the analysis of this paper.
    Application study
    NUMERICAL SIMULATION OF INFLUENCE OF THE INNER STRUCTURE OF ULTRASONIC NOZZLES ON THE CHARACTERISTICS OF THE AIR MILLER
    2009, 31(2):  17-21.  DOI: 10.6052/1000-0879-2007-592
    Asbtract ( 1124 )   PDF (1144KB) ( 846 )  
    Related Articles | Metrics
    The structure and parameters of the nozzle of a jet mill device are optimized, numerical simulations of the inner structure are carried out with hydrokinetics software, the stress analysis of the structure is conducted with finite element software, and the effects of inlet diameter, section area of throat region, passage shape and diffusion angle on supersonic nozzle are analyzed. Optimized operation parameters include pressure of 3.5\,MPa and inlet diameter of 6\,mm after comparing different simulations. In the range of $8^\circ \sim 12^\circ$, the diffusion angle has little effect on the performance of the designed supersonic nozzle.
    Review
    ADVANCES IN HYPERVELOCITY IMPACT DYNAMICS AND SPACECRAFT PROTECTION RESEARCH
    Yi-yong LI Huai-rong SHEN Zhi LI
    2009, 31(2):  11-16.  DOI: 10.6052/1000-0879-2008-017
    Asbtract ( 1307 )   PDF (1272KB) ( 749 )  
    Related Articles | Metrics
    Hypervelocity impact dynamics and spacecraft protection as an important part of hypervelocity impact technology, is reviewed in this paper. Its research background is outlined. Its research progress covers the following five aspects: making hole in the thick board, penetration in the critical thick board, forming debris cloud from the thin board, experimental simulation technique and numerical simulation technique. The damage effect of hypervelocity impact spacecraft is analyzed. The spacecraft protection requirements are given, and the project design and performance of the spacecraft protection structure are discussed.
    Application study
    WIND LOADS ON MULTI NATURAL DRAFT COOLING TOWERS IN A POWER PLANT
    Li Yinan
    2009, 31(2):  65-68.  DOI: 10.6052/1000-0879-2008-018
    Asbtract ( 1308 )   PDF (851KB) ( 672 )  
    Related Articles | Metrics
    Natural draft cooling tower is a high-rise thin shell structure. The displacement in the top of the cooling tower can be tens of centimeters under wind loads, several times of the wall thickness. Cooling tower is very sensitive to wind loads, especially in multi-towers conditions, where the wind velocity, wind pressure distribution and airflow among towers are quite complex. On the basis of the experiment results on irregular multi-towers, this paper put forward some proposals about determining wind loads of natural draft cooling tower in multi- towers conditions.
    ESTIMATING THRESHOLDS OF DAMAGES BASED ON NATURAL FREQUENCY METHOD
    2009, 31(2):  50-54.  DOI: 10.6052/1000-0879-2008-023
    Asbtract ( 1243 )   PDF (938KB) ( 784 )  
    Related Articles | Metrics
    The damage thresholds obtained by natural frequency method can be used as a criterion to justify the usefulness of practical engineering structure. The natural frequency method consists of analyzing the influential factors of the damage, and a cantilever beam model is taken as an example. Both numerical and theoretical results indicate that, if the frequency measurement error is known, this method can be used to estimate the thresholds, during the early period of damage. The thresholds obtained by this method agree with the numerical results very well.
    DESIGN OF PARTIAL SIMILARITY MODELS AND THEIR EVALUATION METHOD IN WATER FLOODING PHYSICAL SIMULATION
    Bai Yu-Hu
    2009, 31(2):  27-30.  DOI: 10.6052/1000-0879-2008-034
    Asbtract ( 1175 )   PDF (785KB) ( 510 )  
    Related Articles | Metrics
    To quantitatively evaluate the partial similarity models of water flooding, a new numerical approach of sensitivity analysis is proposed for the sensitivity of the relaxed dimensionless parameter. The sensitivity factor quantifying the dominance degree of the relaxed dimensionless parameter is defined. By solving the dimensionless governing equations including all dimensionless parameters, the sensitivity factor of each relaxed dimensionless parameter is calculated for each partial similarity model, thus the dominance degree of the relaxed one is quantitatively determined. Based on the sensitivity analysis, the influence coefficient of the partial similarity model is defined as a criterion to evaluate each partial similarity model. The partial similarity model with the smallest influence coefficient can be singled out. Results show that the precision of the partial similarity model is not only determined by the number of dimensionless parameters but also by the relative relaxation quantity.
    Education Study
    Research in Teaching of Finite Element Method for Aerospace Structures
    Zhiping Qiu
    2009, 31(2):  87-88.  DOI: 10.6052/1000-0879-2008-057
    Asbtract ( 1226 )   PDF (881KB) ( 809 )  
    Related Articles | Metrics
    The Finite Element Method (FEM) is one of the basic classes for undergraduate teaching in mechanics. For the undergraduate who major is aeronautics or astronautics, especially, the FEM is a necessary tool in scientific research and engineering practice in the future. By analyzing the course’s features, roles, goals and some problems existing in the teaching at present, this article gives some suggestions on teaching reform in course system, course content, teaching methods and assessment methods etc. The purpose is cultivating students’ interest and ability to innovate. All that will make one learn and master the FEM more comprehensively and profoundly.
    Application study
    SINGLE COMPONENT MULTIPHASE DISPLACEMENT WITH LATTICE BOLTZMANN MODELS
    2009, 31(2):  31-34.  DOI: 10.6052/1000-0879-2008-071
    Asbtract ( 1032 )   PDF (1515KB) ( 640 )  
    Related Articles | Metrics
    By introducing fluid-fluid and fluid-solid surfaces interactions, the process of the non-wetting vapor phase displacing complete-wetting liquid phase in two-dimensional pore-networks is simulated based on the Shan-Chen single component multiphase model of lattice Boltzmann method. The fluid interfaces form naturally and the displacement is of capillary fingering. With the capillary number increasing, the viscous force becomes more and more dominating and the sizes of the pores invaded by vapor decrease, leading to rich behaviors of the displacement. With the imposition of the gravity, the gravity plays a stabilizing role on the vapor invasion front.
    PROGRESSIVE FAILURE ANALYSIS AND RESIDUAL LIFE PREDICTION FOR FUEL
    2009, 31(2):  46-49.  DOI: 10.6052/1000-0879-2008-080
    Asbtract ( 1279 )   PDF (752KB) ( 732 )  
    Related Articles | Metrics
    The progressive failure analysis and residual life prediction of composite fuel tank are an important part of safety evaluations of RLV. In this paper, based on classical laminates theory, analytic and token models of composite fuel tank are built. By the finite element software ABAQUS, the progressive failure analysis is carried out and the residual life of a fuel tank is predicted. Compared with literature data, good agreements are obtained, which validates the methods proposed in the paper.
    STUDY ON THE ACOUSTIC EMISSION MODEL OF WOOD DAMAGE
    2009, 31(2):  74-77.  DOI: 10.6052/1000-0879-2008-187
    Asbtract ( 1178 )   PDF (698KB) ( 616 )  
    Related Articles | Metrics
    There is a quantitative relationship between damage and acoustic emission in wood. Based on damage theory and the acoustic emission signal in wood with defects and cracks in different damage phases, this paper establishes wood mechanics models of damage evolution under alternating load and static load, as two kinds of common situations. Analytical results agree with lumber's actual situation. With special characteristics of the acoustic emission, wood mechanics model of damage evolution with is established, which can be used to forecast the damage in advance, and it is shown that inhomogeneity is one of the main causes of damage.
    THE ANALYSIS AND APPLICATION OF DOUBLE LAYER CONTACT FINITE ELEMENT ABOUT ROD AND TUBING STRING IN WELL BORE
    Yue Qian-bei
    2009, 31(2):  35-39.  DOI: 10.6052/1000-0879-2008-276
    Asbtract ( 1499 )   PDF (833KB) ( 720 )  
    Related Articles | Metrics
    Constructing the double layer multi-directional contact gap element to describe the random contact problem about slim tubing string with inside and outside string, combining with dimensional beam element and adopting variable and equivalent stiffness to solve equations, the contact condition, the contact position, the size of friction and the generalized inner force, stress and deformation in arbitrary well depth of the rod and tubing string were obtained. The arithmetic example about three wells demonstrated that the corrigendum of hang weight in well head was low by 10 percent. Therefor, it supplied reliable computational methods and theoretical references for designing and failure analysis of the rod and tubing string.
    Education Study
    A new method of solving problems of elasticity with the help of calculator
    2009, 31(2):  84-86.  DOI: 10.6052/1000-0879-2008-286
    Asbtract ( 1564 )   PDF (428KB) ( 822 )  
    Related Articles | Metrics
    A direct method of using polynomial terms as stress function and combining with Matlab program design is introduced for solving problems of elasticity. First the present method has very strong rule for choice stress function, on the other hand, it simplifies the process of determining unknown coefficients. The method improves disadvantages of traditional inverse method or semi-inverse method that is necessary that choice stress function through repeated tasting and modifies for obtaining satisfactory results. Meanwhile we denote that some problems doesn't possess polynomial solution. The present approach is successful conjunction example of between modern computer technology and traditional elasticity analytical method. It pump new activity into elasticity analytical method.
    Application study
    NUMERICAL ANALYSIS FOR TYMPANOSTOMY TUBE IN HUMAN EAR
    Li Sheng
    2009, 31(2):  60-64.  DOI: 10.6052/1000-0879-2008-293
    Asbtract ( 1244 )   PDF (924KB) ( 645 )  
    Related Articles | Metrics
    Tympanostomy tube is an effective treatment for secretory otitis media. There have been very few analyses of the biomechanical behavior of the ventilation tube. In this paper, a three-dimensional finite element model of the human ear is established, including the external ear canal, tympanic membrane, tympanostomy tube, ossicular bones, middle ear suspensory ligaments/ muscles, and inner ear fluid, which can describe the complicated structures and boundary conditions. The finite element model is used to analyze the displacement change of tympanic membrane and stapes footplate. At the same time, it is found that the presence of tympanostomy tube significantly affects the displacement vibration of the tube. The effect of tympanostomy tube on sound transmission is explained based on numerical method. The results may be useful to the therapy of secretory otitis media and the design of ventilation tube.
    Education Study
    A NEW MECHANICAL EXPERIMENT-MEASUREMENT OF STRESSES IN HOMOGENEOUS CURVED BEAMS AND COMPOSITE CURVED BEAMS
    2009, 31(2):  89-91.  DOI: 10.6052/1000-0879-2008-295
    Asbtract ( 1360 )   PDF (677KB) ( 807 )  
    Related Articles | Metrics
    A new experiment equipment of measuring stress for homogeneous curved beams and composite curved beams is developed. This achievement of scientific research will be applied to educational experiment. Problems in engineering structures are introduced in the new experiment. Hence, it provides with an opportunity for students to improve their practical ability. The differences of curved beams, composite curved beams and straight beams can be found in the experiment. The present equipment can be used to measure the normal and shear stresses in simply supported curved beam made of steel and composite curved beam of steel and copper with trapezoid cross sections. The concentrated force is applied at the arch top of the curved beams. Good agreement between the experiment measurements and theoretical solutions is found.
    Application study
    NUMERICAL STUDY ON THE MINING-INDUCED WATER OUTBURST IN DEEP TUNNEL WITH FAULTS
    2009, 31(2):  69-73.  DOI: 10.6052/1000-0879-2008-466
    Asbtract ( 1148 )   PDF (1844KB) ( 629 )  
    Related Articles | Metrics
    For mining-induced water outburst in deep tunnel of Hongtoushan Copper Mine, a hydraulic model for rock mass in Copper mine is proposed, based on the hydro-geological conditions in Hongtoushan Copper Mine. The Coupling System of Flow {\&} Solid in Rock Failure Process Analysis is applied to simulate and study the whole process of the initiation of fractures, extension and formation of water inrush pathway. With the analysis of damage distribution, stress and seepage field evolution, the process of the evolution from surrounding rock to inrush pathway is clearly revealed, and the water rush pathways are determined. The work can provide a scientific guide for the support and watertight design of tunnel.
    Review
    SIMULATION AND DESIGN OF MICRO-ELECTRONIC PACKAGING
    2009, 31(2):  1-10.  DOI: 10.6052/1000-0879-2008-575
    Asbtract ( 1630 )   PDF (4991KB) ( 801 )  
    Related Articles | Metrics
    In recent years, the product of semiconductor related technologies tend toward to the direction of high density, high performance, multi-physics and miniaturization characteristics. Furthermore, high reliability, low fabrication cost and time-to-market features are the key elements making microelectronic devices to meet the worldwide highly competitive competition. Facing the aforementioned severe challenges, a new design methodology based on the computer simulation technology should be developed to adapt to the new era of ever so various fabrication processes, system integration and next generation electronic packaging devices. Miniaturization induced technology barriers such as process/material uncertainty, structural complexity, high fabrication cost and long development cycles, etc. make conventional design procedure (experiment based design technology, e.g., try-and-error method) inapplicable. Therefore, nowadays, simulation based design-on-simulation design concept has been widely adopted as the mainstream technology by worldwide semiconductor related companies and institutions.
    Education Study
    Discussion of Serval Issues for Pure Beam Deflection Curve by Metheds of Graph Multiplication and Double Integral
    2009, 31(2):  82-83.  DOI: 10.6052/1000-0879-lxysj2007-030
    Asbtract ( 1378 )  
    Related Articles | Metrics
    The accuracy key to the deflection curve of a uniform section straight beam subjected to the moment is a circle,however,the answers are both parabolas by metheds of graph multiplication and double integral .The reasons are analysed,and the error is given with a parabola replacing a circle.
    The analysis of section relative displacement in antisymmetric statically indeterminate frame without external restrctions
    2009, 31(2):  78-79.  DOI: 10.6052/1000-0879-lxysj2007-531
    Asbtract ( 1035 )  
    Related Articles | Metrics
    On the basis of the principle of virtual work, the building of unit-load state, when solving section relative displacement in antisymmetric statically indeterminate frame without external restrctions, is analyzed principally. The essential of the unit-load method can be understood well by students from the analysis of this paper.
    Research in Teaching of Finite Element Method for Aerospace Structures
    Qiu Zhiping & strXing & Xiaojun Wang Qi Wuchao
    2009, 31(2):  87-88.  DOI: 10.6052/1000-0879-lxysj2008-057
    Asbtract ( 1098 )  
    Related Articles | Metrics
    The Finite Element Method (FEM) is one of the basic classes for undergraduate teaching in mechanics. For the undergraduate who major is aeronautics or astronautics, especially, the FEM is a necessary tool in scientific research and engineering practice in the future. By analyzing the course’s features, roles, goals and some problems existing in the teaching at present, this article gives some suggestions on teaching reform in course system, course content, teaching methods and assessment methods etc. The purpose is cultivating students’ interest and ability to innovate. All that will make one learn and master the FEM more comprehensively and profoundly.
    A new method of solving problems of elasticity with the help of calculator
    Yu-Chuan JIANG
    2009, 31(2):  84-86.  DOI: 10.6052/1000-0879-lxysj2008-286
    Asbtract ( 1487 )  
    Related Articles | Metrics
    A direct method of using polynomial terms as stress function and combining with Matlab program design is introduced for solving problems of elasticity. First the present method has very strong rule for choice stress function, on the other hand, it simplifies the process of determining unknown coefficients. The method improves disadvantages of traditional inverse method or semi-inverse method that is necessary that choice stress function through repeated tasting and modifies for obtaining satisfactory results. Meanwhile we denote that some problems doesn't possess polynomial solution. The present approach is successful conjunction example of between modern computer technology and traditional elasticity analytical method. It pump new activity into elasticity analytical method.
    A NEW MECHANICAL EXPERIMENT-MEASUREMENT OF STRESSES IN HOMOGENEOUS CURVED BEAMS AND COMPOSITE CURVED BEAMS
    Yu Aimin
    2009, 31(2):  89-91.  DOI: 10.6052/1000-0879-lxysj2008-295
    Asbtract ( 1311 )  
    Related Articles | Metrics
    A new experiment equipment of measuring stress for homogeneous curved beams and composite curved beams is developed. This achievement of scientific research will be applied to educational experiment. Problems in engineering structures are introduced in the new experiment. Hence, it provides with an opportunity for students to improve their practical ability. The differences of curved beams, composite curved beams and straight beams can be found in the experiment. The present equipment can be used to measure the normal and shear stresses in simply supported curved beam made of steel and composite curved beam of steel and copper with trapezoid cross sections. The concentrated force is applied at the arch top of the curved beams. Good agreement between the experiment measurements and theoretical solutions is found.
    Application study
    Simulated numerically of influence of the inner structure of ultrasonic nozzles on the characteristics of the Air Miller
    2009, 31(2):  17-21.  DOI: 10.6052/1000-0879-lxxb2007-623
    Asbtract ( 1097 )  
    Related Articles | Metrics
    The paper optimizes the structure and parameters of nozzle at jet mill device with software and theories of engineering thermodynamics examining the performance of the designed nozzle by simulating its flow fields with liquid simulated software as well as discussing the effection of passage shape and diffuse angle on supersonic nozzle. The optimized nozzle was then designed to be one with opening pressure of 3.5MPa and opening diameter of 6mm after comparing different simulations. When changing between 8°and 12°, the diffuse angle poses little effect on the performance of the designed supersonic nozzle. And when it is of curve shape, the passage shape betters the performance of the supersonic nozzle.
    MIXED MODE DYNAMIC STRESS INTENSITY FACTORS OF CRACKED STRAIGHT THROUGH FLATTENED BRAZILIAN DISC SPECIMENS
    2009, 31(2):  40-45.  DOI: 10.6052/1000-0879-lxysj2007-382
    Asbtract ( 1544 )  
    Related Articles | Metrics
    In order to establish a standard for the test of mixed mode dynamic fracture of rock with the cracked straight through flattened Brazilian disc (CSTFBD) specimen, we use finite element method first to check the related results in literature on the cracked straight through Brazilian disc specimen (CSTBD). The I-II mixed mode dynamic stress intensity factors (SIFs) of the two kinds of discs with different dimensionless crack lengths (i.e. the half length of the crack normalized by the radius of the specimen) are obtained to show that the differences of the dynamic SIF's time history between these two kinds of specimens are within 10{\%}, and the numerical method used in this paper is valid. Then for CSTFBD specimens, the I-II mixed ratio, the angle of crack initiation, and the loading angle for pure mode II fracture test are obtained. The results are useful for mixed mode dynamic fracture test of CSTFBD, including specimens preparation, the location and directional alignment of the strain gages, as well as the estimation for the crack initiation time and the crack initiation direction.
    INFLUENCE OF THE VOID DISTRIBUTION ON MACRO-RESPONSES OF FUNCTIONALLY GRADED PLATES
    2009, 31(2):  55-59.  DOI: 10.6052/1000-0879-lxysj2007-503
    Asbtract ( 1190 )  
    Related Articles | Metrics
    Complex microstructures of functionally graded materials and their geometry make related strucutres more complex than plates, cylindrical shells and spherical shells. Therefore, the analytic solution of functionally graded structure is difficult to obtain, and the approximate solution and other calculation methods are used frequently. A new microelement method for the analysis of functionally graded structures is suggested to establish a quantitative relation between the macro-characteristics and microstructures of functionally graded materials, and different combinations of materials for different macro-characteristics can be found. By this microelement method, the influence of voids on the macro-responses can be analyzed. The three-dimensional distributions of mechanical quantities of the functionally graded plates with different distributions, forms and positions of the voids are given, a trans-scale analysis between micro-constitution and macro-response of the functionally graded materials and structures can be carried out.
    A NEW THEORETICAL MODEL FOR ARMOR-PIERCING MECHANICS
    Li-Peng WU
    2009, 31(2):  22-26.  DOI: 10.6052/1000-0879-lxysj2007-511
    Asbtract ( 1291 )  
    Related Articles | Metrics
    Penetration mechanics is important both as a science and in practice of military engineering. For a quasi-steady penetration of long rod projectile into semi-infinite thick target, a simplified model is developed, where the bullet incorporated mushroom head consists of unbroken zone, crush zone and hole dilating zone, and the target consists of hole dilating zone, crush zone and unbroken zone, with the strain rate effect being considered. A set of ODE is obtained through conservation laws of every part. Through theoretical analysis and calculation, the influences of the crush strain rate, crash strength of the projectile and the strain rate effect of the crash strength of the target on penetration depth are analyzed. The excellent agreement of the calculation results and the experiment shows the effectiveness of the simplified model.
    WIND LOADS ON MULTI NATURAL DRAFT COOLING TOWERS IN A POWER PLANT
    Yinan Li
    2009, 31(2):  65-68.  DOI: 10.6052/1000-0879-lxysj2008-018
    Asbtract ( 1223 )  
    Related Articles | Metrics
    Natural draft cooling tower is a high-rise thin shell structure. The displacement in the top of the cooling tower can be tens of centimeters under wind loads, several times of the wall thickness. Cooling tower is very sensitive to wind loads, especially in multi-towers conditions, where the wind velocity, wind pressure distribution and airflow among towers are quite complex. On the basis of the experiment results on irregular multi-towers, this paper put forward some proposals about determining wind loads of natural draft cooling tower in multi- towers conditions.
    ESTIMATING THRESHOLDS OF DAMAGES BASED ON NATURAL FREQUENCY METHOD
    2009, 31(2):  50-54.  DOI: 10.6052/1000-0879-lxysj2008-023
    Asbtract ( 1208 )  
    Related Articles | Metrics
    The damage thresholds obtained by natural frequency method can be used as a criterion to justify the usefulness of practical engineering structure. The natural frequency method consists of analyzing the influential factors of the damage, and a cantilever beam model is taken as an example. Both numerical and theoretical results indicate that, if the frequency measurement error is known, this method can be used to estimate the thresholds, during the early period of damage. The thresholds obtained by this method agree with the numerical results very well.
    DESIGN OF PARTIAL SIMILARITY MODELS AND THEIR EVALUATION METHOD IN WATER FLOODING PHYSICAL SIMULATION
    Yuhu Bai
    2009, 31(2):  27-30.  DOI: 10.6052/1000-0879-lxysj2008-034
    Asbtract ( 1112 )  
    Related Articles | Metrics
    To quantitatively evaluate the partial similarity models of water flooding, a new numerical approach of sensitivity analysis is proposed for the sensitivity of the relaxed dimensionless parameter. The sensitivity factor quantifying the dominance degree of the relaxed dimensionless parameter is defined. By solving the dimensionless governing equations including all dimensionless parameters, the sensitivity factor of each relaxed dimensionless parameter is calculated for each partial similarity model, thus the dominance degree of the relaxed one is quantitatively determined. Based on the sensitivity analysis, the influence coefficient of the partial similarity model is defined as a criterion to evaluate each partial similarity model. The partial similarity model with the smallest influence coefficient can be singled out. Results show that the precision of the partial similarity model is not only determined by the number of dimensionless parameters but also by the relative relaxation quantity.
    SINGLE COMPONENT MULTIPHASE DISPLACEMENT WITH LATTICE BOLTZMANN MODELS
    2009, 31(2):  31-34.  DOI: 10.6052/1000-0879-lxysj2008-071
    Asbtract ( 978 )  
    Related Articles | Metrics
    By introducing fluid-fluid and fluid-solid surfaces interactions, the process of the non-wetting vapor phase displacing complete-wetting liquid phase in two-dimensional pore-networks is simulated based on the Shan-Chen single component multiphase model of lattice Boltzmann method. The fluid interfaces form naturally and the displacement is of capillary fingering. With the capillary number increasing, the viscous force becomes more and more dominating and the sizes of the pores invaded by vapor decrease, leading to rich behaviors of the displacement. With the imposition of the gravity, the gravity plays a stabilizing role on the vapor invasion front.
    PROGRESSIVE FAILURE ANALYSIS AND RESIDUAL LIFE PREDICTION FOR FUEL
    Wang Zhengqing
    2009, 31(2):  46-49.  DOI: 10.6052/1000-0879-lxysj2008-080
    Asbtract ( 1224 )  
    Related Articles | Metrics
    The progressive failure analysis and residual life prediction of composite fuel tank are an important part of safety evaluations of RLV. In this paper, based on classical laminates theory, analytic and token models of composite fuel tank are built. By the finite element software ABAQUS, the progressive failure analysis is carried out and the residual life of a fuel tank is predicted. Compared with literature data, good agreements are obtained, which validates the methods proposed in the paper.
    STUDY ON THE ACOUSTIC EMISSION MODEL OF WOOD DAMAGE
    2009, 31(2):  74-77.  DOI: 10.6052/1000-0879-lxysj2008-187
    Asbtract ( 1106 )  
    Related Articles | Metrics
    There is a quantitative relationship between damage and acoustic emission in wood. Based on damage theory and the acoustic emission signal in wood with defects and cracks in different damage phases, this paper establishes wood mechanics models of damage evolution under alternating load and static load, as two kinds of common situations. Analytical results agree with lumber's actual situation. With special characteristics of the acoustic emission, wood mechanics model of damage evolution with is established, which can be used to forecast the damage in advance, and it is shown that inhomogeneity is one of the main causes of damage.
    THE ANALYSIS AND APPLICATION OF DOUBLE LAYER CONTACT FINITE ELEMENT ABOUT ROD AND TUBING STRING IN WELL BORE
    Qian-bei Yue
    2009, 31(2):  35-39.  DOI: 10.6052/1000-0879-lxysj2008-276
    Asbtract ( 1473 )  
    Related Articles | Metrics
    Constructing the double layer multi-directional contact gap element to describe the random contact problem about slim tubing string with inside and outside string, combining with dimensional beam element and adopting variable and equivalent stiffness to solve equations, the contact condition, the contact position, the size of friction and the generalized inner force, stress and deformation in arbitrary well depth of the rod and tubing string were obtained. The arithmetic example about three wells demonstrated that the corrigendum of hang weight in well head was low by 10 percent. Therefor, it supplied reliable computational methods and theoretical references for designing and failure analysis of the rod and tubing string.
    NUMERICAL ANALYSIS FOR TYMPANOSTOMY TUBE IN HUMAN EAR
    Sheng Li Yingxi Liu Sun Xiuzhen
    2009, 31(2):  60-64.  DOI: 10.6052/1000-0879-lxysj2008-293
    Asbtract ( 1177 )  
    Related Articles | Metrics
    Tympanostomy tube is an effective treatment for secretory otitis media. There have been very few analyses of the biomechanical behavior of the ventilation tube. In this paper, a three-dimensional finite element model of the human ear is established, including the external ear canal, tympanic membrane, tympanostomy tube, ossicular bones, middle ear suspensory ligaments/ muscles, and inner ear fluid, which can describe the complicated structures and boundary conditions. The finite element model is used to analyze the displacement change of tympanic membrane and stapes footplate. At the same time, it is found that the presence of tympanostomy tube significantly affects the displacement vibration of the tube. The effect of tympanostomy tube on sound transmission is explained based on numerical method. The results may be useful to the therapy of secretory otitis media and the design of ventilation tube.
    NUMERICAL STUDY ON THE MINING-INDUCED WATER OUTBURST IN DEEP TUNNEL WITH FAULTS
    2009, 31(2):  69-73.  DOI: 10.6052/1000-0879-lxysj2008-466
    Asbtract ( 1128 )  
    Related Articles | Metrics
    For mining-induced water outburst in deep tunnel of Hongtoushan Copper Mine, a hydraulic model for rock mass in Copper mine is proposed, based on the hydro-geological conditions in Hongtoushan Copper Mine. The Coupling System of Flow {\&} Solid in Rock Failure Process Analysis is applied to simulate and study the whole process of the initiation of fractures, extension and formation of water inrush pathway. With the analysis of damage distribution, stress and seepage field evolution, the process of the evolution from surrounding rock to inrush pathway is clearly revealed, and the water rush pathways are determined. The work can provide a scientific guide for the support and watertight design of tunnel.
    Review
    ADVANCES IN HYPERVELOCITY IMPACT DYNAMICS AND SPACECRAFT PROTECTION RESEARCH
    LI Yi-yong
    2009, 31(2):  11-16.  DOI: 10.6052/1000-0879-lxysj2008-017
    Asbtract ( 1238 )  
    Related Articles | Metrics
    Hypervelocity impact dynamics and spacecraft protection as an important part of hypervelocity impact technology, is reviewed in this paper. Its research background is outlined. Its research progress covers the following five aspects: making hole in the thick board, penetration in the critical thick board, forming debris cloud from the thin board, experimental simulation technique and numerical simulation technique. The damage effect of hypervelocity impact spacecraft is analyzed. The spacecraft protection requirements are given, and the project design and performance of the spacecraft protection structure are discussed.
    SIMULATION AND DESIGN OF MICRO-ELECTRONIC PACKAGING
    2009, 31(2):  1-10.  DOI: 10.6052/1000-0879-lxysj2008-575
    Asbtract ( 1496 )  
    Related Articles | Metrics
    In recent years, the product of semiconductor related technologies tend toward to the direction of high density, high performance, multi-physics and miniaturization characteristics. Furthermore, high reliability, low fabrication cost and time-to-market features are the key elements making microelectronic devices to meet the worldwide highly competitive competition. Facing the aforementioned severe challenges, a new design methodology based on the computer simulation technology should be developed to adapt to the new era of ever so various fabrication processes, system integration and next generation electronic packaging devices. Miniaturization induced technology barriers such as process/material uncertainty, structural complexity, high fabrication cost and long development cycles, etc. make conventional design procedure (experiment based design technology, e.g., try-and-error method) inapplicable. Therefore, nowadays, simulation based design-on-simulation design concept has been widely adopted as the mainstream technology by worldwide semiconductor related companies and institutions.