Table of Content

31 March 1994, Volume 15 Issue 1

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Paper

Mathematical Model and Computer Simulation Program fpr a Military Vehicle as a 3-D Random Dynamic System

Ju Naijun,Liu Tonglong,ChenrZkeng

1994, 15(1):  2-9.  doi:10.3969/j.issn.1000-1093.1994.01.001

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Based on the mathematical modelling for a military vehicle as a 3-D dynamic system, this paper studies the statistic simulation of the system’s random exci-tation—resulting from double side tracked road-surface roughness, solves for the time series response from the system state equations, and gives out the results in probability statistics as well as those in functional evaluations.

A Study on the General Mollon qf a Projectite Touchiiig an Increasing Twist Rifled Bore

Rui Xiaoting,Xu Buzheng

1994, 15(1):  10-14.  doi:10.3969/j.issn.1000-1093.1994.01.002

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The general differential equations of a symmetrical projectile motion touch?ing the bore wall of a flexible, increasing twist rifled gun with the bourrelet are devel?oped in this paper. The patterns of motion for the symmetrical projectile touching the wall of an ideal increasing twist rifled bore with the bourrelet are studied.

A Two-Dimensional Fluid Dynamics Model of Interior Ballistics and Its CalGulation

Song Ming,Wang Hao

1994, 15(1):  15-20.  doi:10.3969/j.issn.1000-1093.1994.01.003

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This paper puts forward a two-dimensional fluid dynamics model of interi?or ballistics under the two-dimensional fitted coordinate system In guns, gives a charac?teristics analysis for the basic set of equations, and establishes a numerical method with the non-identical definition nets. A concrete example of calculation is finally given.

Measurement of Temperature Distribution around a Cavity Penetrated fey Shaped Charge Jet

Gao Juxian,Bai Rongshang

1994, 15(1):  21-26.  doi:10.3969/j.issn.1000-1093.1994.01.004

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The feasibility of measuring the instantaneous temperature around a cavity on a metallic or non-metallic target penetrated by shaped charge jet is theoretically and experimentally studied. The thickness of the foil thermocouple used is 30nm. Results of measurement around a cavity on a target made of epoxy-glass fiber reinforcement composite and on a medium carbon steel target agree with the observed phenomena. It is proved that the method of temperature measurement is effective and reliable. Mea?surement of temperature distribution provides important data of reference in the study of mechanism of penetration.

Cratering Experiments with Hypervelocity Impact upon Thick Metallic Targets

Sun Gengchen,Tan Qingming,Zao Chengxiou,Ge Xiezhen

1994, 15(1):  27-31.  doi:10.3969/j.issn.1000-1093.1994.01.005

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An Investigation of the Deflagration-to-Detonation Transition of the AP/HMX/HTPB Composite Propellant

Liu Dehui,Peng Peigen,Wang Zhenfang et at.

1994, 15(1):  32-36.  doi:10.3969/j.issn.1000-1093.1994.01.006

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In this paper, investigations into the deflagration-to-detonation transition (DDT ) processes of the AP/HMX/HTPB composite propellants are given in some de?tail. The effects of the size and shape of propellant grains, oxygen balance of charges and its permeabilities on the DDT are analyzed. Characteristics of both the shock-to- detonation transition and the deflagration-to-detonation transition are discussed , and possibilities of occurance of DDT in charges of AP/HMX/HTPB composite propellants used in rocket motors are analysed.

Sensitivity Analysis by the Nonlinear Modal Synthesis Methpd

Lin Lizong,Wang Xiaofeng,Xu xiaoli

1994, 15(1):  37-41.  doi:10.3969/j.issn.1000-1093.1994.01.007

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The paper presents the integral equation-set for the sensitivity analysis of nonlinear systems of piece-by-piece linearity using nonlinear modal synthesis equation- set taking the deformations of the nonlinear elements as the generalized coordinates. A program software has been built up on IBM — PC computers. It can be used to calculate the sensitivity of responses of nonlinear systems to the parameters of the nonlinear in?terfaces. Applications on the redesign and optimization of structures are then taken as illustrative examples.

Effects of Kinematic Nonlinearity on Linearly Elastic Bodies under Extremely- Heavy Impact

Gong Yunning

1994, 15(1):  42-46.  doi:10.3969/j.issn.1000-1093.1994.01.008

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Kinematic nonlinearities concerned with nonlinear motion of material parti?cles are investigated in this paper. It is found that the effects of the kinematic nonlin?earity are significant when a body is subjected to extremely heavy impact，even if the material is assumed to be linearly elastic. The nonlinear response is nonnegligible. Shock formation and propagation of kinematically nonlinear waves in linearly elastic bodies are studied as well.

Response Analysis for Structures with Random Parameters

Chen Suhuan,Han Wanzhi,Wang Jialin

1994, 15(1):  47-52.  doi:10.3969/j.issn.1000-1093.1994.01.009

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The randomness in the response of structures is due to two primary fac?tors. One is the randomness in the load, which has been discussed extensively in the past. The other is the randomness associated with structural parameters. To insure rel?iability of a design , design engineers need to know the effect of the randomness in the structure on the response. In this paper, a practical and effective method to calculate the response statistics, mean values and standard deviations of random structures, is presented. As the application of this method , a numerical example is presented.

Methods for Excitation and Sampling in Modal Tests

Pan Xufeng,Wang Dan

1994, 15(1):  53-59.  doi:10.3969/j.issn.1000-1093.1994.01.010

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An intelligent front end has been developed to better utilize the modal analysis technique. This paper discusses the method used for the excitation and sam?pling in conjunction with the front end. The method is aimed at reducing the leakage error, enhansing the signal/noise ratio and bringing up the efficiency of tests.

The Effect of Damping Medium on the Plastic Dynamic Response of a Short Shell under High Load

Liu Fulin

1994, 15(1):  60-65.  doi:10.3969/j.issn.1000-1093.1994.01.011

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In this paper, the effect of damping medium on the plastic dynamic response of a short shell under high load is analysed by the moment subdomain method. Analytical solutions of every moving stage are developed.

comprehensive Reviews

The Developing Supercpnductor Electronic Technology

Zeng GuangIi,Li Guozhen

1994, 15(1):  66-71.  doi:10.3969/j.issn.1000-1093.1994.01.012

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This paper briefly introduces four important fields in the application of su?perconductivity： (I) Measurement of weak magnatism (1O-15T) and weak electricity (1O-15V ) , and especially in the various applications of superconducting interference de?vices (Squid). (2) Infrared-millimeter wave detectors. Superconducting detectors based on Josephson effect have set up a bridge across the infrared and microwave. Further it will fill in the gaps in the fields of submillimeter waves. (3) Measurement standards. The superiority of superconducting technique in areas of metrology science is already well acknowledged. (4) Superconductivity computer. Superconductivity computer will eventually come out and further enhance our present level in information transfer, In addition? the developmental prospect of HTSC electronic devices is reviewed compen?diously in this paper. HTSC thin film will vitalize superconductivity in electronic technology.

Short Duration，High Power MHD Power Generation

Zhang He Fang,Guangyao,Lai Yuzhu

1994, 15(1):  72-76.  doi:10.3969/j.issn.1000-1093.1994.01.013

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This paper introduces a short duration, high power magnetohydrodynamic power generation with a plasma, driven by explosive or combustion. It is a pulse power generation system which can provide hundreds of MW of pulse power. It also is a suit?able energy source that can be used in a new concept gun. It has broad prospects of ap?plications. This paper also introduces the basic principle of MHD power generation, state-of-the-art developments abroad and what we have attempted so far. Some prob?lems met in the research are reviewed.

Research Notes

Calculation of the Strained Strength for a Cartridge Case

Sun Zhenhe

1994, 15(1):  77-79.  doi:10.3969/j.issn.1000-1093.1994.01.014

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In general, the strength after strain-hardening can be calculated with fair accuracy with the formula reflecting the power law σ==Aεπ . But the strength of the cartridge case after ironing drawing cannot be accurately calculated by this formula, be?cause the result of calculation is lower than that reached in practice- In this paper a new formula is given, in which the effect of the die angle to the strain-hardening is included into consideration. Agreement between the calculated value and that from practical tests proves to be satisfactory.

A Study on the Acceptance Inspection Sampling Plans for Fuze Lot under Field Cpnditions

Cao Kunzeng

1994, 15(1):  80-83.  doi:10.3969/j.issn.1000-1093.1994.01.015

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This paper discusses the so-called (3,1) switching rules of acceptance sam?pling generally in use in the U . S. Army for the inspection of fuze lots, and derives the formulas of calculation for the combination operating characteristic functions by the mother function method. The paper explaines why MIL-STD-105D is not generally used for the U,S. Army ground tests of fuze lots. It also establishes a design principle for the acceptance, sampling plan group for ground tests of fuze lots.

The Optimization Performance of Irreversible Carnot Heat Engines under the Condition of Mixed Heat Resistance

Chen Wenzhen,Sun Fengrui,Zhou Meng,et al.

1994, 15(1):  84-87.  doi:10.3969/j.issn.1000-1093.1994.01.016

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This paper studies the irreversible Carnot cycles under the condition of linear and nonlinear heat transfer. The irreversible heat transfer obeys the conditions: heat absorbed Q1 ∝ T-m and heat rejected Q2 ∝ Tm , where m = — 1.1 . The irre?versibility caused by nonequilibria within the cycle is expressed by internal efficiency ηi in terms of the method used in engineering practice. The optimization relation between the power P and efficiency η is derived. Some applications of the relation are discussed. The results obtained can provide more abundant theoretical basis for the design of heat engines in practice.

Spatio-Temporal Channels pf the Human Visual Motion System

Wu Xinnian,Yao Guozheng,Wang Yunjiu

1994, 15(1):  88-92.  doi:10.3969/j.issn.1000-1093.1994.01.017

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The measurements of the human spatio-temporal channels reported in this paper were made at three velocities (0°%, 10°%, 30°/s) and three contrast levels (thr?eshold contrasts, 0. 035 , 0. 155 ) of moving gratings. The effects of velocities and con?trasts of moving gratings on the bandwidth and optimal resoluble frequencies of the channels were investigated. Empirical formulas predicting the spatial channels of the human visual motion system at different velocities and contrasts of the objects being ob?served are presented.

A Study on Protective Effects of Armored Vests BPV-Ⅰ.Ⅱ

ZhangJunkui,Li Xiaoyan,Leng Huaguang et al.

1994, 15(1):  93-96.  doi:10.3969/j.issn.1000-1093.1994.01.018

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Bullet-proof effects of composite materials and the protective capability of armored vests BPV- I、Ⅱ were investigated. Materials constituting the BPV- I、Ⅱ armored vests include ： aluminium alloy plates processed through quenching and ageing , high intensity polyamide fabric and trauma packs having special structures. The results showed that armored vest BPV- I can effectively prevent the penetration of 7. 62mm pistol bullets (Model 54，Made in China) fired at a distance of 3. 41m or more and that armored vest BPV- Ⅱ can be used to protect from shell fragments traversing at 422. 1m/s ?426. 8m/s in V50. Animal experiments proved that armored vests BPV- I、Ⅱ can avoid or remarkably attenuate non-penetrating trauma (NPT ) which has appeared puzzling for so many years because of the special design of the trauma pack.