Analytical and experimental analysis of deep drawing process for bimetal elements

The paper presents the concepts of solving of deep drawing process for bimetal elements of sheet materials. The inertia forces, plastic hardening behaviour of the deformed material and dynamic stress are utilized in the problems of plasticity. The experimental results and general conclusion are presented at the end of the paper.     

PHYSICAL SIMULATION OF INTERFACIAL CONDITIONS IN HOT FORMING OF STEELS

1.~nonNUInericalmodellingbythefiniteelement(FE)methodhasbecomeaneffectiveandeconomyicmeansforsimulatingmetalfoeingprocesses.However,accuratemodellingdemandsthecorrectdefinitionandinputsofthedataforthethermalandphysicalpIDPertiesoftheworkpieceandtoolmaterials,theboUndaryconditionsattheworkpiece--toolinterfaceandinotherareas,inadditiontoappropriatemeshgenerationandnumericalsolutions.Althoughmostofthematerialdataareavailable,thedataforinterfacialheattransferandfrictionconditions,Whichhavesubst…     

Friction and wear properties of pitch／resin densified carbon—carbon composites used for airbrakes

By use of X-ray diffractometry and scanning electron microscope(SEM),the friction and wear results obtained from MM-1000 dynamometer tests of CVI pitch/resin C/C composites were analyzed.By investigating the factors that affected the friction and wear properties,such as matrix carbon,applcation environment,graphitization degree and brake pressure,etc,friction and wear mechanism of carbon materials were probed.The results indicate that pitch densified CVI initially treated composite is more graphitizable with its graphitization degree up 59 62%,and which results in uniform small debris easier to generate,more smooth friction curves with the coefficient of 0.3-0.4 and relatively higher wear and mass loss,compared with CVI/resin C/C composites.It was further proved by SEM observation that tribological behavior of C/C composite was system dependent.Factors determining the friction and wear properties such as the size of debris and its influence on friction and wear,brake pressure,graphization degree and debris bilm formation interacted and affected each other.The friction and wear mechanism of C/C composites under different high temperature treatments needs further research.     

搅拌摩擦加工(FSP)AZ91D镁合金的组织分析

研究了AZ91D镁合金经搅拌摩擦加工后的组织。发现组织中搅拌摩擦区、热机械影响区和热影响区分区不明显。在搅拌摩擦区主要为再结晶形成的细小均匀的等轴晶结构,共晶组织α-Mg β相(Mg17Al12)完全均匀化,仅在晶界处有少量存在。     

刹车鼓工作面龟裂失效分析

用化学成分分析、金相组织检验、硬度测试以及对刹车鼓的宏观和微观分析等方法,对刹车鼓刹车失灵进行分析,并探讨了刹车鼓失效的原因、失效形式以及对刹车鼓铸件质量控制。     

等温淬火球铁在铁道车辆耐磨件上的应用研究

考虑到等温淬火球铁具有强度高、韧性好、出色的耐磨性等优点，根据铁道车辆斜楔和衬套配件的服役要求，对等温淬火球铁和传统的金属材料进行了大量摩擦磨损性能比较试验，结果表明，等温淬火球铁斜楔和衬套具有比传统材料高得多的耐磨性，特别是等温淬火球铁斜楔的使用寿命是以往ZG230-450斜楔的6～10倍。因此，等温淬火球铁斜楔和衬套件已在我国铁路车辆上得到了广泛应用。     

Tribological behavior of high specific strength PTFE-Al alloy composite

Solid lubricants lead to substantial weight savings relative to the use of liquid lubricant, especially in the weight-conscious aerospace industry. A new PTFE-Al alloy composite（A） containing 60% area proportion of PTFE composite was developed. Another type of common metal-plastics multilayer composite, also called DU, was selected for a comparative investigation. Friction and wear tests were carried out in an oscillating sliding tribotester in air at an oscillating frequency of 0.13 Hz and contact mean pressures from 10 to 80 MPa. The composites slid against a 38CrMoAlA steel shaft. The results show that the composite A exhibits low coefficient of dry sliding friction less than 0.1 and long wear life of 2 000 m. This is because the composite A can provide a sufficient solid lubrication during the whole tests. SEM examination of the transfer films for the composite A confirms that uniform, thin and coherent transfer films are prerequisites for low friction and good wear resistance.     

金属板料成形数值模拟的研究现状

本文对板料成形数值模拟的几个主要研究方向 :有限元算法、接触与摩擦、成形极限图、缺陷等的研究现状进行了介绍 ,并且讨论了板料成形数值模拟今后的研究方向     

液锻连挤硅线石粒子/铝复合材料的摩擦磨损行为

采用液锻连挤成形工艺获得了一种新型硅线石颗粒增强LY12铝基复合材料,其性能可与常规热挤压件媲美.摩擦磨损性能测试表明:硅线石颗粒增强铝基复合材料具有优良的摩擦磨损性能,且其耐磨性能随粒子体积分数增加而增加.材料经液锻连挤后,硅线石粒子在强大三向压应力作用下嵌镶于基体内,粒子很难拉脱,承受摩擦力的作用时,硅线石粒子起支承作用,粒子硬度高,故使复合材料整体耐磨性能提高.     

The prediction of transport parameters in filamentous fermentation broths based on results obtained in pseudoplastic polymer solutions

Transport phenomena studies on single phase “model” fluids are of limited value in biochemical engineering if they cannot be translated to the heterogeneous systems encountered in real fermentation processes. In this paper we discuss the utility of polymer solutions as models of filamentous fermentation broths for evaluation of: pipeline friction factors and impeller power numbers (turbine and helical ribbon). To a first approximation, polymer solutions can serve as suitable models for the prediction of laminar flow pressure drop in pipelines and turbulent power consumption in stirred tanks. However, results obtained on polymer solutions do not directly apply to filamentous fermentation broths for predictions of laminar flow impeller power consumption and the transition point for turbulent flow in stirred tanks. These discrepancies are believed to result from the existence of a time dependent yield stress in filamentous fermentation broths.