【作者】 陈小安；

【导师】 宋顺成；

【作者基本信息】 西南交通大学 ， 工程力学， 2012， 博士

【摘要】 本论文主要研究钨合金材料从制备到应用的数值模拟和理论实验研究,对如何通过有效的方法提高钨合金粉末的等离子制备性能进行了分析,数值计算了通过等离子炬方法制备超微钨粉过程中的速度场和温度场；钨粉在等离子烧结过程中的温度场和致密过程,及温度场与材料细微观性能和力学性能之间的关系。将制备出的钨合金成品和不同靶板进行不同温度下的动态的拉伸、压缩和剪切实验,并通过一定的数值方法拟合得到不同材料的参数,将实验得到的数值模型添加到LS-DYNA数值计算软件计算了钨合金长杆弹高速侵彻不同靶板侵彻过程中弹体和靶板的力学性能,为高比重钨合金长杆弹的研制和性能研究提供一定的理论数值支持。全文主要研究内容如下：(1)研究了利用等离子炬制备超微钨粉的过程。根据传热学Navier-Stocks方程以及电磁理论,在高频感应等离子炬中建立了电热以及流体耦合控制方程,通过添加有限外场简化对向量势边界条件的描述,首次利用多场耦合软件通过有限元方法对制粉过程中的电热效应以及流体热交互耦合进行了数值模拟,得到了高频等离子炬气动过程中的速度场以及温度场,并依据一定输入功率下高频感应等离子炬的特征探讨了在实际制粉过程中的一些参数。(2)研究了利用等离子烧结技术制备钨块体材料过程中的温度场及其对成品的性能影响。根据传热学以及电磁理论,在放电等离子体烧结的典型烧结条件下建立了电热耦合控制方程,利用有限元方法对钨粉试样在烧结中的电热效应进行了数值模拟,得到烧结过程中电流密度,能量密度以及温度场分布,并使用一种适用于导电粉体的等离子烧结机制解释了烧结过程中的一些现象。(3)采用自制冷却及加温设备和Hopkinson缸、杆分离式直接拉伸装置、Hopkinson动态压缩装置和冲塞装置测试了钨合金、钢及铝材料在不同温度下的动态拉伸、压缩及剪切性能。采用不同材料模型对几种材料的动态拉伸、压缩及剪切性能进行分析,拟合出不同材料数值模型的参数,并对材料断口的微观形貌进行了分析,为研究钨合金弹体侵彻性能提供理论和数值基础。(4)将得到的数值模型输入到LS-DYNA程序中,采用显式动力学有限元计算方法研究了高速钨合金长杆弹对钢／铝复合板的侵彻过程,并对1000-3000m/s范围内钨合金长杆弹对物理非对称半无限混凝土的超高速侵彻及损伤进行了分析,采用在超高速撞击下混凝土Johnson-Holmquist模型分析了弹体和靶板的损伤破坏和能量消耗情况。模型能够有效的模拟岩石及混凝土在高速冲击下的成坑、层裂及裂纹扩展,长杆弹在侵彻中存在弹道偏移和本身变形,给出估算弹体破坏形式临界速度的方法。更多还原

【Abstract】 Theoretical analysis, experiment investigation and numerical simulation on preparation and application of tungsten alloys were implemented. The way to enhance the preparation properties of tungsten powders was analyzed. The velocity and temperature distribution of induction plasma torch in preparation of superfine tungsten powders, temperature field and densification during spark plasma sintering processing were obtained, and the relationship among temperature field, microscopic properties and mechanical properties were determined by numerical simulation method. Experiments and numerical simulation were carried out to obtain dynamic tensile, compression and shearing properties of tungsten alloys and different targets at vary temperatures and strain rates. And the mechanical properties of long rod tungsten alloys and targets during high speed penetration process were simulated by adding numerical model to LS-DYNA numerical software. The results have certain reference value for preparation and property research of tungsten heavy alloys. The detailed contents are as following:(1) Numerical simulation of temperature distribution of induction plasma torch in superfine tungsten powders preparation was carried out. To obtain the velocity and temperature field in radio frequency induction plasma torch, the control equations coupling electric field, temperature field and flow field were set up based on the theory of heat transfer, electromagnetic and incompressible Navier-Stocks equations. An extended field model was proposed for inductively coupled plasma to optimize the simple infinite field boundary condition. The velocity and temperature distribution of inductively coupled plasma in flow process were simulated based on the finite element method, and the vortex was obtained in the flow field. The parameters during powder preparation processing were researched on the different power inputs of induction coupled plasma torch.(2) The temperature field during spark plasma sintering processing and its effect on bulk tungsten materials were investigated. The control equations of electrothermal coupling electric field and temperature field were set up based on the theory of heat transfer and electromagnetic under typical spark plasma sintering (SPS) conditions. The electrothermal phenomena of tungsten powder during sintering process were simulated using the software COMSOL MULTIPHYSICS based on the finite element method. The current density, power density and temperature distribution were obtained. And a new sintering mechanism model was carried out to explain the phenomena during the spark plasma sintering processing.(3) The dynamic tensile, compression and plugging test were performed to explore the dynamic tensile, compression and shearing properties of tungsten alloys, steels and alumina at different temperatures and strain rates by the self-developed Hopkinson tensile system and improved Hopkinson pressure bar system. These properties were analyzed by vary material models, the parameters of different materials were determined by using the curve fitted method. By means of investigated the fractography of materials, the failure mechanisms of these materials were obtained. The results provide theoretical and numerical basis for researching the penetration property of long rod tungsten heavy alloy.(4) The penetration of steel/alumina composite plate by long rod projectile of tungsten heavy alloy at high speed velocity was investigated by adding the numerical model to LS-DYNA explicit dynamic software. To obtain the results of physical asymmetric semi-infinite concrete penetrated by long rod projectile of tungsten alloy at1000-3000m/s, the Johnson-Holmquist concrete model was used to analyze the damage and energy expenditure of projectile and target. The model could simulate the crater formation, spall of concrete target and the fracture occurring inside it during the process of impact effectively. The deformation and ballistic excursion of long rod projectile were obtained in the process of penetration, and a theory method for estimating critical velocity due to different failure types of projectile was given.更多还原