弹

After the airdrop experiments of the system of the projectile and speed-down parachute, the balance velocity obtained from the optics apparatus on the ground、the balance spinning speed obtained from the gyroscope on the projectile and the image obtained from the infrared detector on the projectile are all used to simulate the six-dimension exterior trajectory of the projectile and identify the roll damping moment derivatives, and the identification can safely come to a conclusion that the absolute value of roll damping moment derivatives from the engineering calculation are on the low side.

对卷弧尾翼弹与减速伞系统进行空投试验，由地面光测系统给出平衡落速、弹上陀螺给出平衡转速、弹上红外探测器拍摄地面图像判断弹的姿态。通过六自由度弹道模拟，对弹滚转阻尼导数进行参数辨识，得到工程估算所得滚转阻尼导数绝对值偏小的结论。 5。对空投试验中出现弹姿态摆动现象，从受力分析及红外图像分析两个方面进行探讨，给出合理解释，并根据分析对弹外形进行修改，在后来的试验中收到很好的效果。

In this paper,a new concept of the depth charge with projectiles is put forward from the cargo projectiles used in the ground guns,in order to improve the interception probability of the depth charge.

火箭深弹是水面舰艇拦截鱼雷的常用武器，为提高火箭深弹拦截鱼雷的概率，提出了子母深弹的概念，将地面火炮中常用的子母弹技术应用于深弹反鱼雷攻击中，通过分析子母弹的散布特性，来比较子母深弹和火箭深弹毁伤鱼雷的效能，并通过Monte-Carlo法仿真了这一过程，分析了影响子母深弹的毁伤概率的因素。

Therefore it is necessary to research the mechanism of greensand used for high compacted molding methods thoroughly.This subject is one section of the National Natural Science Foundation subject ""Ivestigation on Predicting Method and Mechanism of Springback for High Compacted Sand Molds"", followed of the other completed one named ""Research on Microdeformation of Molding Sand"". A serious of experiments has been done on the reequipped three axial machine under certain technological conditions, and the mechanics, material science, rheologic science. It is systematically studied that the influences on the springback of sand mold were caused by the main influence factors: pressure, compacted rate and the content of soil. Through the analyzed experiments' data, the experienced stress-strain relationship concerning the main influence factors were obtained;under different technical parameter, the springback and spingback's potential energy are compared, the differences and indifferences between them are found out, and the springback's mechanism is discussed;according to the tests' data of YangGuoping coming from Tinghua University, experienced formula of molding sand's springback displacement is induced, the displacement and springback are compared, the margin of error's reasons are analyzed, and they are tested and verified mutually.

本课题为国家自然科学基金项目"高紧实度砂型预测方法及回弹机理的探讨"的一部分，是已结题的国家自然科学基金项目"铸造型砂微变形的研究"的后继，运用力学、材料学及流变学理论，利用改装的三轴仪，在一定的工艺条件下，作了大量系列实验，系统的研究了压实比压、紧实率和膨润土含量对砂型回弹的影响；对实验数据进行了分析和处理，得出了型砂关于压实比压、紧实率和膨润土含量的本构关系的经验公式；把各工艺参数下的型砂产生的回弹量与回弹势能进行比较，找出两者存在的异同点，并对回弹机理进行了探讨；通过清华大学杨国平的实验数据，推导出型砂回弹位移场的经验公式，并与实验测出的回弹量进行比较，分析误差造成的原因，并互相进行了验证。

In order to reasonably depict four basic problems with friction, one Coulomb friction new form in first Kirchhoff stress is proposed to deal with finite deformation problems, other Coulomb friction form in incremental mode to elastoplastic flow theory; Hilbert function spaces concerning elastoplastical problems with friction are established, so it makes all operations and calculations in the treatise standardized within the scope of reasonably topologic structure; In view of functional extremum, the equivalence between generalized variational inequalities principles in elastoplasticity with friction and corresponding basic problems are testified by inducing Lagrangian multipliers, so it provides a rationally theoretical basis for numerical methods in elastoplasticity with friction; From the viewpoint of variational inequality, the theory of generalized variational inequalities in elasticity and elastoplasticity with frictional constraint is studied, and the uniqueness and existence of the solution of FEM is proofed under the proposed conditions of stress compatibility, and them FEM approximation and a discrete solution are discussed; Based on the principles of generalized variational inequalities in elastoplasticity with friction, direct generalized variational inequalities methods is pretended, which is a natural generalization and development of direct variational methods; Using generalized variational inequalities methods, some examples in metal forming including plane deformation, upset and extrusion are analyzed and the results prove that all the theories and methods in the paper are right, feasible, accurate and advanced.

主要内容有：为了合理地描述金属塑性成形中摩擦约束弹性、弹塑性基本问题，提出和研究了有限变形下以Kirchhoff第一应力表示的Coulomb摩擦定律形式和弹塑性流动理论下以增量形式表示的Coulomb摩擦定律表示形式；系统建立了摩擦约束弹塑性问题的Hilbert函数空间，使本文规范在一个具有合理的代数拓扑结构内进行一切操作和运算；利用Lagrange乘子，从泛函极值的角度系统地阐述和论证了一系列摩擦约束弹性、弹塑性广义变分不等原理与相应的实际问题之间的等价性，它为处理摩擦约束的弹塑性力学数值方法提供了合理的理论基础；从变分不等式的角度出发，阐述了对应于摩擦约束弹性、弹塑性问题的广义变分不等式理论，首次提出了在应力相容性条件下，它的有限元解具有存在唯一性，进而讨论了其有限元近似及离散解法；基于摩擦约束弹塑性广义变分不等式原理，首次提出了直接广义变分不等式方法，这一方法是直接变分法的合理推广和发展；利用直接广义变分不等式方法对金属压力加工中的平面变形问题、镦粗、挤压等塑性成形问题进行了分析计算，验证了该理论和数值算法的正确性、实用性、精确性和优越性。

Considering the effect of the stress Lode angle or the third stress invariant, the author presents a new yield function and develops the Ohta-Sekiguchi's elasto-plastic model and Sekiguchi-Ohta's elasto-viscoplastic model to be a true three-dimensional model. This new model can take account of the effects of anisotropy induced by initial anisotropically consolidated state and the rotation of principal stress axes.

在太田-关口弹塑性模型及关口-太田弹粘塑性模型基础上，考虑应力劳台角的影响，提出软土真正三维应力空间的各向异性弹塑性及弹粘塑性本构方程（模型中各向异性主要指初始各向不等压应力状态所诱发的各向异性），这是对太田-关口弹塑性模型及关口-太田弹粘塑性模型的进一步发展。

Mathematical model was set up,on the basis of dynamics formulation,normal expanse of the target interface ,and supposed concrete medium was constringent material.

根据弹体动力学基本方程和假定混凝土为可压缩材料，基于弹靶接触表面处靶体材料的法向膨胀性，对跳弹现象进行理论分析，在合理假设的前提下，建立了跳弹现象的数学模型； 2）针对该模型编制计算机程序，在给定初始入射速度、入射角后可以判断出能否产生跳弹现象，输出产生跳弹现象时所对应的初始侵彻条件，并通过穷举法得出跳弹临界相图，对于斜侵入情况，能计算出弹体在不同侵彻阶段下的运行时间并能绘制出侵彻轨迹，结合现有的试验数据，进行对比分析，二者符合良好，证实了理论分析模型的合理性； 3）开展了跳弹现象的数值模拟研究。

Incurrent research, aiming at the rupture problem engendered in the shooting process of acertain 5.56mm automatic rifle, the strain and stress distributions on the cartridge caseunder the action of axial pull have been analyzed. Based on the theories of elastic-plasticmechanics and contact mechanics, a mathematic and physical model of the cartridge-caseand chamber system has been set up; and based on the platform of the general softwarepackage APDL of ANSYS for finite element analysis, a parameterized model of thecartridge-case and chamber system has also been established. The method for nonlinearFEA has been adopted to analyze the stress distribution on the entire cartridge-case andchamber system, and the method of contact element has been employed to investigate thecontact stress between the cartridge case and chamber, and then the influences of frictioncoefficient and locking space on the static and dynamic stress and strain response of thecartridge case and chamber to the action of power gas have also been discussed. On thebasis of a lot of numerical tests, a kind of element Plane13, which is concentrated incoupled computation of heat and construction, has been used finally to simulate thetransient response of the cartridge-case and chamber system to the power gas. Throughloading the temporary thermal characteristics of explosive gas in the procedure of emulate, the corresponding transient thermal stress distributed on the entire system under thecombined load of transient thermal stress and transient pressure has been obtained. Owingto these comprehensive considerations, the numerical results obtained in this paperrepresent the actual situations comparatively exactly.

本文针对某5.56mm自动步枪在工作中出现断壳的问题，分析了弹壳在轴向拉力作用下的应力应变；基于弹塑性力学及接触理论，建立了弹壳弹膛系统的数学、物理学模型，在通用有限元ANSYS软件的参数化建模工具APDL平台上，建立了弹壳弹膛系统的参数化模型；采用非线性有限元法计算了弹壳弹膛系统的整体应力，引入接触单元法分析弹壳和弹膛的接触压力，探讨了在不同的摩擦系数和不同的闭锁间隙对弹壳弹膛静、动态响应的影响；本文进行了大量的尝试，最后确定采用热、结构耦合单元Plane13，在计算中加载了火药气体的温度历程，成功的获得了弹壳弹膛系统在瞬态的热载荷和瞬态的压力载荷同时作用下弹壳弹膛系统的热应力数值解，考虑因素全面，比较真实的反映了弹壳弹膛系统在火药气体压力和热载荷下作用的情况。

The M249 is gas-operated and air-cooled. It has a quick-change barrel, allowing the gunner to rapidly replace an overheated or jammed barrel. A folding bipod is attached near the front of the gun, though a M192 LGM tripod is also available. It can be fed from both linked ammunition and STANAG magazines, like those used in the M16 and M4. This allows the SAW gunner to use rifleman's magazines as an emergency source of ammunition in the event that he runs out of linked rounds. However, this will often cause malfunctions because the magazine spring has difficulty feeding rounds quickly enough to match the SAW's high cyclic rate.

M249采用气动、风冷原理，枪管可快速更换令机枪手在枪管故障或过热时无须浪费时间修理，机枪下前方装有折叠式两脚架，也可使用M192轻机枪的三脚架。M249采用弹链及STANAG弹匣双重供弹，机枪手在断链缺乏弹药等紧急情况时可向装备M16或M4步枪的步兵借用弹匣来射击，但以弹匣供弹时会因弹匣弹簧弹力太大而射速过高及可能出现故障。

Initially, assuming that the contact between cam and tappet is"dry contart", a dynamics model of Hertzin contact stiffness and impact damping is established. Next, with dynamic load on cam—tappet pair from the model, an analysis is made both to unsteady EHD oil film in cam—tappet pair under condition of full and partial lubrtication and to wear characteristics of cam profile. then, according to the fact that the lubrication in cam—tappet contact surface is EHD lubrication, taking the interaction between stiffness and damping of unsteady EHD oil film and rigidity of solid object contact into account, a dynamics equation of valve train relating to the dynamic effect of EHD oil film is built up and solved. Consequently, a further study is made on the dynamic characteristics of valve train under interaction of EHD oil film dynamic behavior and the problem of EHD lubrication in cam—tappet pair. Finally, the dynamic effect of full and partial EHD oil film is studied accordingly.

首先，通过对凸轮—挺杆接触为&干接触&的假设，建立了考虑赫兹&接触刚度&和冲击&阻尼&的配气机构动力学模型，用由此求得的凸轮—挺杆表面动载荷对凸轮—挺杆进行了全膜状态和部分膜状态非稳态弹流润滑分析，并研究了凸轮轮廓的磨损规律；然后，是在凸轮挺杆表面存在弹流动压油膜这一事实的基础上，相当于在动力学方程中考虑非稳态弹流油膜的&刚度&、&阻尼&和固体接触&刚度&的耦合作用，建立并求解了考虑弹流润滑行为动力学效应的配气机构的动力学方程，从而深入地研究了弹流润滑行为与动力学行为耦合作用下的配气机构动力学特征以及凸轮挺杆弹流润滑问题；作为前面工作的对应部分，考虑弹流油膜动力学效应的研究工作也同样分为全膜状态和部分膜状态进行。

Optional hand armaments: NF·GMG-Type.37/100mm machine gun, clip-fed, 2 spare clips stored on hip armor; bazooka gun, clip-fed, 7 rounds per clip; 6-tube missile launcher; beam rifle, powered by rechargeable energy cap

可选手持武器：NF GMG-Type.37/100mm机关枪，弹荚供弹，2只备用弹荚，收容于大腿的裙甲上；巴祖卡火箭炮，弹荚供弹，每只弹荚7发；6管导弹发射器；光束步枪，由充电动力罩提供出力

I am accused of being overreligious," she said in her quiet, frank manner,"but that does not prevent me thinking the children very cruel who obstinately commit such suicide.""

客人们在卡罗利娜·埃凯家里，举止就文雅一些，因为卡罗利娜的母亲治家很严厉。

Designed by French fashion house Herm è s, this elegant uniform was manufactured in our home, Hong Kong, and was the first without a hat.

由著名品牌 Herm è s 设计，这件高贵的制服是香港本土制造，是我们第一套不配帽子的制服。