入射角对跳弹现象影响的数值模拟

利用ANSYS/LS-DYNA3D有限元分析软件,选择适当的弹丸和土壤材料参数建立了弹丸侵彻靶板的有限元实体模型,在同一初始入射速度条件下,对弹丸不同入射角斜侵彻半无限厚土壤靶进行了数值模拟.结果表明当入射角不大于75°时不能出现跳弹现象,当入射角由小变大时,弹丸从侵入靶板演变为出现跳弹现象,随着入射角的增大,越容易产...     

Plasticine modelled high velocity oblique impact and ricochet of long rods

A review of the literature on high velocity oblique impact and the ricochet of projectiles of various shapes is given, with emphasis on long rod projectiles. Aspects of cratering and penetration in oblique impact are highlighted and the mechanics of ricochet off solid, fluid and granular media are also discussed.     

High velocity oblique impact and ricochet mainly of long rod projectiles: An overview

A review of the literature on high velocity oblique impact and the ricochet of projectiles of various shapes is given, with emphasis on long rod projectiles. Aspects of cratering and penetration in oblique impact are highlighted and the mechanics of ricochet off solid, fluid and granular media are also discussed.     

斜入水高速冲击的理论建模及缓冲分析

以入水冲击的理论动力学和入水弹道学理论为基础,根据鱼雷头部尖拱的结构外型,采用精确形体法建立斜入水高速冲击运动学和动力学耦合模型,充分考虑入水冲击引起的液面隆起现象以及流体阻力的影响。编制入水冲击耦合冲击的时间步进仿真程序,比较液面隆起现象对高速入水冲击载荷的影响,以及给出了入水初始状态条件和入水冲击载荷之间的关系和入水过程中的转动力矩的变化规律。最后比较尖拱体和截头尖拱体以50°角斜入水高速冲击的过载值,分析采用尖拱体进行缓冲卸载和截头尖拱体起到防止弹跳的理论原因。这为缓冲头帽的结构优化,忽扑、击水弹跳现象或后继的弹道提供预报以及为入水冲击缓冲技术提供了理论依据。     

An empirical relation for the volume of the crater formed during high velocity oblique impact tests

An empirical equation relating the volume of the crater formed during high velocity oblique impact tests to the velocity and angle of impact and to the target material hardness has been proposed. It is further demonstrated that this equation can predict the volume of the crater formed quite accurately over a wide range of impact velocities (50–350 m s^-1), impact angles (up to 60°) and target hardnesses (1–4 GPa).     

浮标入水冲击仿真分析

浮标在空投入水瞬间承受的巨大冲击载荷,有可能损坏浮标外壳及内部元件。掌握浮标以不同姿态、不同速度入水时所受的冲击载荷对提高浮标可靠性具有重要意义。文中利用ANSYS/ LS-DYNA建立了浮标入水的有限元模型,计算了浮标以不同姿态、不同速度入水时所受的冲击载荷及入水速度变化等,并分析了浮标外壳的强度。通过仿真结果分析,总结出浮标入水冲击的规律,可作为浮标结构设计的依据。     

Numerical simulation and experiments of magnetic flux leakage inspection in pipeline steel

The magnetic flux leakage (MFL) method is currently the most commonly used pipeline inspection technique. In this paper, numerical simulation and experimental investigation on defect inspection in pipeline steel using MFL were carried out. In theoretical analysis, typical three-dimensional (3D) defects were accurately modeled and detailed MFL signals in the test surface were calculated by 3D finite element method (FEM). To confirm the 3D FEM results, different artificial defects were made and the MFL experiments were performed. The experimental study demonstrated that the results were agreement with the 3D FEM result. The results show that the 3D FEM is an effective analysis method for pipeline steel MFL inspection. This paper was recommended for publication in revised form by Associate Editor Jooho Choi Xun-Bo Li received his M.S. and Ph.D degree from University of Electronic Science and Technology of China in 1991 and 2001, respectively. Dr. Li is currently a Professor at the School of Mechatronics Engineering, University of Electronic Science and Technology of China in Chengdu, P.R. China. Dr. Li’s research interests are in the area of Mechatronics, measurement and NDT.     

集束式钨丝穿甲弹穿甲性能研究

针对钨合金和贫铀动能穿甲弹弹芯沿轴线方向上强度不高的情况，采用黏结法制备出一种新型的钨丝集束复合弹芯，并对该弹芯材料制成的模拟弹进行了穿甲侵彻试验，利用数值模拟的方法对其侵彻过程进行了分析。研究结果表明，利用钨丝集束方法制作穿甲弹用弹芯材料在原理上是可行的，能够充分发挥钨丝的高强度和大长径比的性能与结构优势，试验结果与理论预测的侵彻机制一致。     

A study on penetration fracture characteristics of glass plates subjected to impact loadings

In this study, a comparison between theoretical solutions and experimental results are examined for fracture conditions in the case of float glass plates subject to static loadings. The ranges from fracture-generated initiations to critical penetration energies are confirmed according to the impactor mass under high velocity, and an analytical method is presented to determine the fracture strength and penetration strength. Also, fracture patterns are investigated according to impact velocities.     

平头弹撞击角度对2A12-T4铝合金板失效特性影响的数值模拟

利用有限元软件ABAQUS建立模拟模型,开展38CrSi钢弹体撞击2A12-T4铝合金板数值模拟研究,分析撞击过程中弹体撞击角度对弹道姿态及靶体失效特性的影响。基于数值仿真和实验结果,分析靶体的失效特性,确立不同撞击条件下靶体主要失效模式的转变规律,以及由此对靶体抗撞击性能的影响。研究结果表明：弹体的弹道极限速度随其撞击角度的增大先减小后增大,弹道极限速度在撞击角度约为15°时达到最小值;弹体撞击角度对靶体失效模式存在很大影响,随着弹体撞击角度的增大,靶体主要失效模式由剪切破坏逐渐过渡到撕裂破坏,靶体的撕裂程度不断加剧;弹体初始撞击角度和速度对其在撞击过程中的弹道姿态存在影响,在弹道极限速度附近表现尤为显著。     

Crashworthiness of aluminum extrusions subjected to oblique loading: experiments and numerical analyses

Oblique loading was studied through quasi-static experiments and numerical simulations. The behavior of square aluminum columns in alloy AA6060 subjected to quasi-static oblique loading was investigated experimentally for three different load angles. The square columns were clamped at one end and oblique load conditions were realized by applying a force with different angles to the centerline of the column. These tests were used to validate a numerical model. Numerical studies of oblique impact were carried out using the validated model, and the mean crush load was investigated through factorial analysis with parameters as load angle, thickness, length, and heat treatment of the alloy and impact velocity.     

The ricochet of spheres and cylinders from the surface of water

A theory of ricochet is proposed which permits the effect of projectile spin to be accounted for. This effect is not explained by previous theories. The critical angles for ricochet for a sphere and for a spinning cylinder are calculated, and the theory of the spinning cylinder is applied to the Barnes Wallis “bouncing bomb” developed during World War II.     

断裂准则对TC4钛合金板抗卵形头弹冲击的影响

为了解TC4钛合金的抗冲击力学性能,利用一级轻气炮进行了卵形头弹冲击TC4钛合金靶板的试验,撞击速度范围为125.9~240.0 m/s。通过撞击试验获得弹体的初始-剩余速度以及靶板的失效破坏模式,并利用公式拟合弹体初始-剩余速度得到弹道极限速度。利用ABAQUS/Explicit有限元软件建立弹体冲击靶体的三维模型,研究断裂准则对TC4钛合金板抗卵形头弹冲击性能的影响,分别采用不同断裂准则进行数值模拟,并将数值模拟预测结果与试验结果进行对比。研究结果表明,从弹道极限和失效破坏模式综合考虑,Hancock-Mackenzie (H-M) 准则预测的结果与试验结果更接近,说明考虑失效应变随应力三轴度的变化关系能提高数值仿真精度。     

Penetration of semi-infinite metal targets by deforming projectiles

Experimental results are presented on the velocity dependence of the penetration of semi-infinite metal targets by cylindrical projectiles. The strengths of penetrators and targets are varied in order to change the relative amounts of deformation of the target and penetrator. A one-dimensional finite difference model is developed which treats the penetrator and target as colliding cylinders with the target strength increased by a constraint factor to account for the surrounding material. The portion of the penetrator which enters the target may also be subject to constraint, and account is taken of shearing of target elements, shearing at the interface between the projectile and the target, radial inertia and erosion effects. The model gives good quantitative results and correct form of the velocity dependence of the depth of pentration and the projectile final length for the cases considered. The model provides a simple scheme for classifying projectile/target interactions.     

Improved information fusion approach based on D-S evidence theory

Conventional D-S evidence theory has an unavoidable disadvantage in that it will give counter-intuitive result when fusing high conflict information. This paper proposes an improved method to solve this problem. By reassigning weight factors before fusing, the method can give reasonable results especially when the initial weight factors of conflict evidences are almost equal. It gives an adjustable factor to adjust the reassigning force. An example is given to illustrate these advantages. This paper was recommended for publication in revised form by Associate Editor Eung-Soo Shin Rui Sun, PhD candidate. He received M.E. in mechatronics engineering from University of Electronic Science and Technology of China. He is currently a Ph.D. candidate in School of Mechatronics Engineering, University of Electronic Science and Technology of China. His research interests include system reliability analysis and mechanical fault diagnosis. Hong-Zhong Huang is a full professor and the Dean of the School of Mechanical, Electronic, and Industrial Engineering at the University of Electronic Science and Technology of China, Chengdu, Sichuan, China. He has held visiting appointments at several universities in Canada, USA, and elsewhere in Asia. He received a Ph. D. degree in Reliability Engineering from Shanghai Jiaotong University, China. His current research interests include system reliability analysis, warranty, maintenance planning and optimization, and computational intelligence in product design. Dr. Qiang Miao obtained B.E. and M.S. degrees from Beijing University of Aeronautics and Astronautics and Ph.D. degree from University of Toronto. He is currently an associate professor of the School of Mechanical, Electronic, and Industrial Engineering, University of Electronic Science and Technology of China, Chengdu, Sichuan, China. His current research interests include machinery condition monitoring, reliability engineering, and maintenance decision-making.     

Development of dynamic response analysis algorithm for beam structures using transfer of mass coefficient

The authors developed the transfer mass coefficient method (TMCM) in order to compute effectively the dynamic response of a beam structure. In this paper, the algorithm for the dynamic response analysis of a three-dimensional beam structure is formulated. Through the computation results of numerical models, which are plane and space beam structures, obtained by the transfer mass coefficient method and the direct integration method, we verify that the transfer mass coefficient method can remarkably decrease the computation time of the direct integration method without the loss of accuracy in spite of using small computer storage. This paper was recommended for publication in revised form by Associate Editor Hong Hee Yoo Myung-Soo Choi received his B.S. and M.S. degrees from National Fisheries University of Pusan, Korea, in 1992 and 1994, respectively. He then received his Ph.D. degree from Pukyong National University in 1999. Dr. Choi is currently an Assistant Professor at the Department of Maritime Police Science at Chonnam National University in Yeosu, Korea. His research interests include mechanical vibration, structural dynamics, and optimum design. Jung-Joo Suh received his B.S., M.S. and Ph.D. degrees from National Fisheries Uni-versity of Pusan, Korea, in 1972, 1985 and 1995, respec-tively. Dr. Suh is currently a Professor at the Faculty of Marine Technology at Chonnam National University in Yeosu, Korea. His research interests include internal combustion engines and numerical analysis. Dong-Jun Yeo received his B.S., M.S. and Ph.D. degrees from National Fisheries University of Pusan, Korea, in 1981, 1985 and 1996, respectively. Dr. Yeo is currently a Professor at the Faculty of Marine Technology at Chonnam National University in Yeosu, Korea. He serves as an Academic Director of the Korean Society for Power System Engineering. His research interests include structural dynamics, vibration, and analytic techniques. Jung-Kyu Yang received his B.S. degree from Pusan Fisherise College, Korea, in 1973. He then received his M.S. and Ph.D. degrees from Chungnam National University in 1985 and 1996, respectively. Dr. Yang is currently a Professor at the Faculty of Marine Technology at Chonnam University in Yeosu, Korea. His research interests include combustion engineering, air flow characteristics, and numerical analysis. Jung-Hwan Byun received his B.S. and M.S. degrees from National Fisheries University of Pusan, Korea, in 1992 and 1995, respectively. He then received his Ph.D. degree from Pukyong National University in 1997. Dr. Byun is currently an Associate Professor at the Faculty of Marine Technology at Chonnam National University in Yeosu, Korea. His research interests include numerical analysis and synchronous control.     

The effect of spherical projectile speed in ricochet off water and sand

Experimental results are reported for the ricochet of steel and duralumin spheres ( and 1 in. dia.), from shallow depths of water and dry sand. The critical angle for ricochet off water is shown to increase with speed to approach the theoretical limit of . For ricochet off sand the critical angle decreases with speed but a cut-off angle exists, , for which no ricochet occurs at any speed.     

Transfer matrix for rotor coupler with parallel misalignment

A transfer matrix for shafts coupler with parallel misalignment (offset) was derived. The responses of a rotor system composed of flexible shafts, unbalanced disks, elastic supports and shafts coupler with misalignment were then investigated. Through the derivation, the boundary shears induced by a rotating shaft were first discovered to be coupled in two perpendicular directions. These coupling shears might reduce the first critical speed up to 50% in the free-free case. The studies showed that the shafts coupler altered the rotor’s critical speeds and the misalignment played as an external load resulting through the whole driven shaft. The combined effects of disk unbalance and shaft misalignment showed that the misalignment predominated the response in most of the rotation speeds, but the unbalance could become significant at high speed. The whirling orbits before and after the misalignment were illustrated as well, and numerical results showed that the two ends of the misalignment whirled asynchronously as the rotation fell into some regions. This paper was recommended for publication in revised form by Associate Editor Seong-Wook Hong Shyh-Chin Huang received a M.S. degree in Mechanical Engineering from University of Iowa in 1984, and a Ph.D. degree in Mechanical Engineering from Purdue University in 1987. Dr. Huang is currently a distinguished professor and researcher at National Taiwan University of Science and Technology. His research interests are in the area of vibration controls, smart materials and electric shunt damping design. Dr. Huang is currently an editor of Research Letters in Materials Science. Chao-Yang Tsai received a M.S. degree in Mechanical Engineering from National Taiwan University of Science and Technology in 1997.Now he is studying at the same department for the Doctor Program. He is currently an instructor at the Army Academy R.O.C, teaching basic technological science including Engineering Mechanics, Mechanics Materials and so on.     

Effect of imperfections on the mechanical behavior of wire-woven bulk kagome truss PCMs under shear loading

Wire-woven bulk kagome (WBK) materials are a new class of cellular metallic structures possessing desired mechanical performance and can be fabricated easily by assembling metallic wires. In previous studies, the WBK materials were shown to have high strength and weak sensitivity on imperfections under compressive loads. In this paper, we present numerical simulation results on the mechanical performance of WBK and its sensitivity on imperfections under shear loads. Two types of statistical imperfections on geometry and material property were introduced in the simulation models as likewise the previous studies. The simulation results were compared with the experimental measurement on the WBK made of stainless wire (SUS304). The WBK were shown to have a good isotropic mechanical strength under various orientations of shear loadings. This paper was recommended for publication in revised form by Associate Editor Maenghyo Cho Sangil Hyun received his B.S. and M.S. degrees in physics from Seoul National University, Korea, in 1986 and 1989. He received his Ph.D. degree in solid state theory from Michigan State Uni-versity in 1998. Dr. Hyun is currently a senior researcher at the simulation center in Korea Inst. of Ceramic Eng. & Tech. (KICET). He is mainly working on computational studies on multifunctional cha-racteristics of fine ceramics, metals, and composites. He also develops a multiscale modeling on nanotribology and nanofluidics. Ji-Eun Choi received her B.S. and M.S degrees in Mechanical Engineering from Chosun University, Korea, in 1999 and 2001. Ms. Choi is currently an associate research engineer at the automobile research center in Chonnam National University. She is mainly working on the theoretical and numerical analyses on truss PCMs (Periodic Cellular Metals). Ki-Ju Kang received his B.S. degree in Mechanical Engineering from Chonnam National University, Korea, in 1981. He then received his M.S. and Ph.D. degrees from Korea Advanced Institute of Science and Technology in 1983 and 1988, respectively. Dr. Kang is currently a Professor at the School of Mechanical Systems Engineering at Chonnam National University in Gwangju, Korea. Prof. Kang’s lab is designated as a national research Lab. His research interests include the optimal designs and manufacturing technologies of various types of porous cellular metals and mechanical behaviors of a thermally grown oxide at high temperature.     

航空机载弹药着速对侵彻靶板影响的仿真分析

航空机载侵彻型弹药由于姿态调整及过载冲击的影响，对着靶速度有一定的要求，利用冲击波理论对极限撞击速度进行理论计算。应用ANSYS／LS—DYNA分析技术对航空抛撒侵彻型弹药侵彻混凝土靶板进行分析，获取各着速下侵彻过程的速度、加速度曲线，结合极限撞击速度的理论计算值与模拟值比较分析，得到着速对靶板侵彻效果的影响，为引信抗冲击过载加速度传感器的设计及加速发动机功率的选择提供理论支持。