含能材料热力学计算在闪光烟火药剂配方设计中的应用

本文采用最小自由能法，通过C语言编辑的计算程序对各种含能材料的燃烧爆炸反应的能量特性参数进行热力学计算，计算结果与试验值进行比较，取得很好的一致性，并将该程序计算用于烟火药配方设计，取得良好的效果。     

一掺多回流程掺水参数优化

大庆油田某区块采用一掺多回的掺水集输流程,但在系统运行过程中,能耗大,运行费用高等问题日益凸显。为降低掺水系统能耗,针对一掺多回掺水集油流程,以掺水量、掺水温度为设计变量,系统运行费用最低为目标函数,压力、温度为约束条件,建立能耗关联模型。利用混合惩罚函数法和改进的共轭方向法对模型求解,得到掺水系统的最佳掺水温度与最佳掺水量。与优化前相比,一掺多回流程掺水系统年掺水量降低27 841 t,掺水温度降低5.5℃,每年可节约能耗费用6.95×105元。     

Discrete element visco-elastic modelling of a realistic graded asphalt mixture

The Discrete Element Model has been used here to simulate constant strain rate uniaxial compression tests for a realistic asphalt mixture comprising graded aggregates. A numerical sample preparation procedure has been developed to represent the physical specimen. A parallel bond model has been used in the elastic modelling to give moment resistance at the contacts. Uniaxial constant strain rate loading and unloading tests have been simulated. The effects of the normal to shear contact stiffness ratio on the bulk properties, the parallel bond radius, the number of particles and their positions, and the loading speed have been investigated. A modified Burger's model has been used to introduce time-dependent contact stiffness with the ability to transmit moment and torsion. Two-ball clumps have been used to investigate the effect of particle shape. The effect of Burger's model parameters, the ratio of normal to shear Burger's model parameters, the bond radius multiplier, the friction coefficient and the bond strength distribution in the viscoelastic simulations have been investigated. Constant strain rate uniaxial compression tests have been undertaken in the laboratory where the axial stress–strain response has been measured for comparison with the numerical modelling results. The modified Burger's model has proved to be useful and ready for simulating uniaxial constant strain rate and creep tests in the laboratory.     

大型露天矿半连续工艺台阶爆破参数优化试验

针对大型露天矿半连续工艺生产的需求,通过爆破优化试验,运用非连续变形分析、激光机器视觉台阶坡面成像系统、台阶爆破智能设计系统和精确钻孔信息化施工等技术手段,对台阶爆破中孔网参数、装药结构以及延时时间等爆破参数进行优化,有效控制爆堆的前冲和后翻,实现了控制爆堆前冲距离不大于50m、后翻距离不大于15m的优化研究目标。     

Process Development and Product Quality of Micro-Metal Powder Injection Molding

Injection molding has been found to be an efficient and cost-effective manufacturing technique for the production of a wide variety of parts and components at both macro- and microscale. This is attributed to the application of robust design and process development. However, every manufacturing technique is challenged by quality issues and part defects, but tackled by continuous improvement framework(s). This systematic monitoring and control approach of dimensional accuracy, mechanical properties, and surface quality of the finished part strongly depend on process conditions at different production stage. Therefore, the aim of this study is to review process development of micro-metal injection molding; focusing on critical factors influencing part quality and optimization of process parameters. The critical factors that influenced the finished part quality are part design, mold design, material selection, machine, and process conditions. Optimizing mold temperature, melt temperature, injection speed, injection pressure, cooling time, packing, and holding parameters improve the quality of the molded part. This trend of process development of injection molding gave rise to a broad scope of applications with brighter future potentials for the next decades, particularly for medical and electronics applications.     

Interfacial Thermal Resistance and the Solidification Behavior of the Al/SiCp Composites

The objective of this investigation is to study the effects of applied pressure on the solidification time and interfacial thermal resistance of A356/10% SiC_p during squeeze casting. Samples were prepared for various but constant squeeze pressures up to 130 MPa while maintaining the melt and mold temperatures at 800°C and 400°C, respectively. It was observed that the solidification time was 60 s when no squeeze pressure was applied but it decreased to 42 s when the squeeze pressure was maintained at 130 MPa. The results also showed that the cooling rate increased with squeeze pressure. The solidification time calculated from one-dimensional heat flow theory was found to be close to that obtained from the experimental cooling curves. The interfacial thermal resistance between the mold and the casting was calculated and it decreases when the squeeze pressure increases.     

Effects of Technical Parameters of Semi-Solid Stirring and Rheo-Rolling on Microstructure of A356–5wt.%B4C Composite Strip

Aluminum boron carbide composite strip was prepared by semi-solid stirring and rheo-rolling, and the effects of process parameters on microstructure of A356–5wt.%B₄C composite strip were studied. The results showed that the distribution of B₄C particles in the matrix became homogeneous, and the average diameter of α-Al and its roundness decreased with the increase of the stirring speed and the stirring time as well as the decrease of the stirring temperature. The average diameter of the primary α-Al grain increased with the increase of the roll speed. When the stirring speed was 500 rpm, the stirring time was 20 min, the stirring temperature was 853 K (580 °C), and the roll speed was 0.2 m/s, the microstructure of A356–5wt.%B₄C composite strip was mainly composed of spherical or rosette α-Al grains, and the distribution of B₄C particles was homogeneous. The hardness of A356–5wt.%B₄C composite strip was 98 HV, and the ultimate tensile strength and elongation were 186 MPa and 1.8%, respectively. The hardness was improved by 25% comparing with casting alloy A356. The ultimate tensile strength and elongation were improved, respectively, by 28.3% and 5.9%.     

Influence of Processing Variables on Dynamic Mechanical Response of Laser-Sintered Glass-Filled Polyamide

For establishing selective laser sintering in manufacturing technology, a wide knowledge about the influence of processing variables on the quality of sintered part is mandatory. In this regard, this article addresses the influence of key process parameters (i.e., bed temperature, laser power, beam speed, hatch distance, hatch length) on the dynamic mechanical properties of laser-sintered glass-filled polyamide specimens to enhance their service life. A face-centered central composite design of response surface methodology was employed to gather data, and mathematical models were developed to investigate the effects and interactions of selected input processing variables on the different performance characteristics. Experiments revealed that dynamic mechanical properties reduced with decrease in bed temperature. This was due to nonuniform fusion of powder particles and increased porosity. Specimens fabricated at high energy density (ED) were strong, solid, and isotropic but become weak, porous, and anisotropic, as the ED decreased. Poor material integrity and weak interparticle bonding were the main reasons of low dynamic mechanical strength. In addition, microstructural analysis was also performed to examine the surface morphology of sintered specimens. Further, optimum working conditions for producing parts with maximum dynamic mechanical response were determined.     

LY12硬铝合金高速切削加工残余应力的研究

对LY12硬铝合金在高速切削加工过程中出现的高度非线性问题,采用有限元软件心US对切削过程进行仿真,得到了高速切削加工过程中的残余应力分布。讨论了高速切削加工过程中影响残余应力分布的几个关键因素：切削速度、背吃刀量、刀尖圆角半径,从而为以后获得基于残余应力的刀具参数优化方案提供了依据。     

多功能小型扫雪除冰车的研制

针对目前国内外的除雪或除冰车结构复杂、售价高、使用维修成本大、推广和普及困难的发展现状,成功研制了一台多功能的扫雪除冰车。该车同时具有前螺旋扫雪,中间破冰滚筒除冰,后扫冰机构收集破碎冰块的多重功能。详细介绍了该车的典型结构与工作原理,运用PROE软件对其进行了建模、虚拟装配和运动仿真;制造出了实物样机并给出了主要性能参数。实践证明该扫雪除冰车外形尺寸小、功能全、操作简单和性价比高,最后分析了其应用前景。