Three-dimensional combined finite-discrete element approach for simulation of single layer powder Compaction process

The application of a combined finite-discrete element modeling approach to simulate the three-dimensional microscopic compaction behavior of single-layer metal powder system was described. The process was treated as a static problem, with kinematical component being neglected. Due to ill condition, Cholesky‘s method failed to solve the system equations, while conjugate gradient method was tried and yielded good results. Deformation of the particles was examined and compared with the results of physical modeling experiments. In both cases, the inner particles were deformed from sphere to polygonal column, with the edges turning from arc to straight line. The edge number of a particle was equal to the number of particles surrounding it. And the experiments show that the ductile metal particles can be densified only by their plastic deformation without the occurrence of rearrangement phenomenon.     

Coupled mechanical and thermal simulation of warm compaction

1 Introduction Powder metallurgy is an advanced manufactural technology widely used for volume-producing mechanical parts with high performance and high precision[1?3]. Warm compaction is a low cost and effective technique to produce green compact with de…     

CL60（H）钢连铸圆管坯的试制研究

通过采用BOF→LF→RH→B→CCM的技术路线生产的连铸圆管坯,产品质量稳定可靠,完全符合客户的要求.     

大口径火炮身管主动冷却温度场分析

利用有限元软件分析了某大口径火炮身管的温度场分布,并对自然散热条件下的单筒身管和主动冷却条件下的复合身管温度场进行了比较,其结果为(1)身管温度场分布存在初始和正规工况阶段,后者的单筒身管热状态可以通过测定任意两发身管外表面温度来评估;(2)持续射击过程中,单筒身管始终处于非稳态导热过程,主动冷却身管则包括非稳态和准稳态两个过程,实现了身管热状态由不可控向可控转变;(3)对流传热系数h和身管壁厚δ的组合对降低内膛温度具有很大影响.临界对流传热系数hc的存在表明,对自然散热条件下单筒身管来说(h＜hc),在重量、刚度允许条件下,增加壁厚可以达到降低内膛温度的目的;就主动冷却身管而言(h＞hc),选择大h、小δ时需兼顾强度和制造工艺性.     

钝圆刀刃切削的有限元模拟

利用商业有限元分析软件Marc对考虑切削刃钝圆半径的切削加工过程进行了有限元模拟。分析了切削刃钝圆半径在切削加工过程中对切削力和切削温度的影响     

专卖店功能细化其定位

净水电器市场在广东的发展相对于其他城市处于一个比较靠前的态势．可以说与北京市场的发展相媲美。2004年我们开始做沁园净水电器品牌总经销，目前在广东我们负责的区域相对比较广．涉及广州、中山．佛山．珠海以及周边的地县市。在我们可控的这些终端当中销售一直名列前茅．沁园无热胆饮水机加亲水膜净水器前几年在广东的成功推广销售．     

Numerical modeling and simulation of metal powder compaction of balancer

1 Introduction “Cold” compaction, which is operated at room temperature, is currently the most generally used compacting method in powder metallurgy industry. Under this circumstance, metal powder is often considered a kind of time-independent, elasto-…     

弹簧压缩变形的数值分析

用有限元方法分析了一种圆柱疏圈螺旋弹簧的压缩变形过程,获得了弹簧的力学参量分布、载荷-行程曲线等结果,包括了弹簧发生塑性变形的情况。     

射击过程中热影响及身管热控制措施综述

射击过程中高温火药燃气及弹带摩擦的热作用造成的热影响，如内膛烧蚀磨损、身管热应力、身管热弯曲、发射药自燃甚至膛炸，引起初速、射程、精度等丧失，严重限制了火炮性能的发挥，成为火炮威力提高的障碍。文中在简述各种热影响基础上，对目前采取的各种身管热控制措施按作用机理，从传热学的角度划分为隔热和冷却两大类，并对具体技术实现作了较详细阐述，同时就大口径自行榴弹炮身管主动冷却问题进行了讨论。     

Numerical simulation of warm compacted synchronous pulley

A new mechanical model for warm powder compaction was presented. Warm compaction process of iron-based powder was investigated to deal with the existence of elastic, plastic and thermal strains. A coupled mechanical and thermal model was developed based on ellipsoidal yield criterion and continuum theory. The constitutive equations were integrated into the constitutive integral arithmetic and solved employing incremental iterative solution strategy. The flow stress model of iron powder was nonlinearly fitted according to uniaxial warm compaction. The constitutive model was implemented into user-subroutines of MSC.Marc. With the equations, algorithms and programs developed, the compaction procedures of a complex synchronous pulley were simulated. Two different compaction schemes with different punch displacements were tested and the relative density distribution was obtained. Comparison with experimental data shows that the homogeneity of green compact is greatly affected by the compaction mode. The simulation results agree with the experiments very well.