弹簧钢喷丸成形残余应力及回弹弧高有限元模拟

针对实际生产中弹簧钢的喷丸成形过程进行了有限元建模。以随机弹丸的形式模拟弹丸的动态显示冲击,同时引入材料阻尼以减少振荡对弹丸连续冲击的影响,并以静力通用分析模拟了工件回弹过程。分析结果表明,最大的等效塑性变形区位于表层,随着速度的增大等效塑性应变不断增大,并且最大残余应力所在的深度也是随入射速度的增大而增大。随着弹丸数量的增大,试片回弹弧高增大,但是回弹高度存在一个饱和点,其饱和回弹的弧高度约为1.17 mm。     

基于Deform的Cr20Ni80合金锻造过程的裂纹成因分析

为了分析Cr20Ni80电热合金锻造开裂的因素,利用Deform软件对其锻造过程进行数值模拟,并根据应力应变分析其产生裂纹的影响因素.结果表明,随着时间的推移,Cr20Ni80合金的温度逐渐降低,锻造应力逐渐增大;Cr20Ni80合金在1200℃等温条件下锻造时,其应力最大值远低于其抗拉强度650MPa,可以得到高质量锻件.为了避免微裂纹的产生,Cr20Ni80合金的锻造温度应为910~1200℃.     

加工残余应力诱导的薄壁件变形预测

针对侧铣过程的变形分析,考虑到三维仿真模拟的时间成本比较高,将侧铣过程简化为二维有限元模型进行计算分析,基于简化的铣削模型研究了切削工艺参数对于残余应力的影响以及切削残余应力诱导的薄壁件加工变形。忽略残余应力在加工表面的不均匀分布,并且将薄壁件简化为梁结构,利用残余应力的有限元仿真结果,通过微元法和等效应变能计算得到薄壁件的最大变形量。     

等轴态TC4钛合金热加工性能及本构关系显微组织研究

本文探索了通过对TC4钛合金等轴组织形貌与力学性能的关系,并通过进行热模拟压缩试验,研究了变形速率、变形温度、变形量等参数对TC4钛合金盘条组织和性能的影响规律。通过热加工图的绘制,为对TC4钛合金在中低温区(500℃～~800℃),以不同应变速率进行了热变形实验研究。通过对真应力-真应变分曲线的分析,探索了相应的软化机制,确定了低温区的热变形激活能,建立了流变应力本构关系,探索了峰值应力与温度和变形速率之间的函数关系,为TC4钛合金棒丝材的加工控制了提供理论基础,对金相组织的观察表面,显微组织特征和热加工图规律基本相符。     

基于Simufact轴承内圈辗压成形有限元模拟仿真

针对轴承内圈综合力学性能及疲劳特性要求较高等问题,以深沟球轴承内圈为研究对象,对其辗压成形原理进行分析;运用专业有限元软件Simufact建立其连辗压成形有限元模拟仿真模型,对其在不成形率下的等效应力、等效应变变化规律及不同辗压成形工艺参数下的等效应力、等效应变变化规律进行仿真分析。有限元模拟仿真结果表明:随着辗压成形率增加,等效应力及应变呈现逐渐增加的趋势,且在不同的成形率下,等效应力、应变大小及分布位置不同;随着辗压温度及进给速度的增加,等效应力及应变呈现逐渐减小的趋势;随着摩擦因数的增加,等效应力及等效应变都呈现先减小后增加的趋势;该研究为轴承内圈辗压成形模具设计和工艺参数优化提供了理论依据。     

TC18合金动态力学行为研究

为分析和表征TC18合金的动态力学行为与性能,采用电子万能试验机对TC18合金进行了常温准静态压缩实验,得到合金在准静态下的实验数据,根据实验数据,选用分离式Hopkinson压杆对TC18合金在温度分别为298、523、773和1 023K,应变率分别为500、1 000和1 500s~(-1)下进行动态力学性能实验,得到了合金在高温动态压缩条件下的应力-应变曲线,分析了温度和应变率对TC18合金动态力学行为的影响。结果表明,在同一温度下,随着应变速率的增加,TC18合金的塑性应变明显增大,表现出一定的应变率增塑效应;在同一应变率下,随着温度的增加,材料的流变应力有显著的下降,表现出明显的热软化效应;在高应变率下的塑性变形过程中,应变率强化和热软化作用同时进行,当温度超过773K时,热软化作用大于应变率强化作用。     

5083铝合金高温流变本构关系研究

采用动态热模拟技术进行高温压缩变形试验, 分析了5083铝合金的流变行为, 建立了该材料的高温流变应力模型。结果表明: 应变速率和变形温度显著影响5083铝合金流变应力, 流变应力随变形温度升高而降低, 随应变速率提高而增大, 在高应变速率下出现明显的动态软化。     

铝合金7075-T6铣削加工有限元仿真分析

针对薄壁叶片等复杂曲面的制造,铣削过程中刀具的受力稳定性显得尤为重要。分析了立式铣刀加工过程中的影响因素,建立铣削力模型和铣刀动态模型,考虑刀具变形、工件及刀具材料性能,建立了有限元模型。利用Advant Edge FEM有限元分析软件对铝合金7075-T6材料进行铣削仿真模拟,获得切削力、工件变形、应力应变、铣削温度、刀具变形、切屑等规律。表明切削力有限元模型可行性,有效地预测薄壁件的铣削加工变形。为进一步研究线接触铣削加工的振动分析提供一定的理论基础。     

半球形件拉深失稳起皱的数值模拟研究

半球形件拉深是一个大应变过程,运用有限元法模拟了半球形件拉深变形的起皱过程,分析了等效应力的分布,塑性应变的分布规律。采用正交实验方法从板料厚度、冲压速度、摩擦系数和凹模圆角半径中找出防止起皱的拉深条件组合。     

疏排水沉降地层高性能混杂纤维混凝土井壁受力特征北大核心

为解决深厚表土层中混凝土井壁支护难题,采用ANSYS有限元软件对比分析混杂纤维高强度混凝土井壁和普通高强度混凝土井壁在表土层厚度200~600 m范围变化时的变形和受力情况。计算结果表明:2种井壁在同等受力情况下,混杂纤维混凝土井壁应变大于普通混凝土,掺杂纤维可以改善井壁脆性;井壁受到的最大环向应力随着表土层厚度增大而增大,且沿着井壁径向由外到内逐渐增大,环向应变始终是压应变且内表面大于外表面;随着埋深增加,井壁变形从以轴向变形为主变成以径向变形为主;最后给出应力应变与表土层厚度之间关系的回归公式,可指导工程实际。     

Current situation and future trend of China rare earth luminescent material industry

<正>Rare earth luminescent material is one of the most important application sectors of rare earths.China enjoys the exceptional advantage to develop rare earth luminescent material for its abundant rare earth resources.After several decades'endeavor,China's rare earth luminescent material industry,headed by rare earth phosphor for lamp and LED and high efficient rare earth energy-saving light source,has been gradually developed into a scale industry.China has become a major production base of rare earth phosphor for lamps and rare earth     

China rare earth market review

正June 1~10,2014Rare earth market remained weak.Quoted price of rare earth products was similar to that in May.There was no sign of recovery in downstream market.The market of NdFeB magnetic materials and phosphor was depressed.Catalyst,polishing powder and ceramic industries remained inactive.Demand from downstream industry was soft.Consumers purchased on their needs.Suppliers had strong intention to sell.Prices of rare earth products     

Annual Report analysis of Chinese rare earth-related listed companies in 2013

<正>Chinese rare earth-related listed companies have published their 2013 annual reports.It can be understood from their reports that production and operation activities of Chinese rare earth-related companies were still heavily affected by macro economy and industrial policies.They basically followed the steps of national economy.In 2013,world economy recovered slowly but the economy     

Market opportunities and challenges for rare earth polishing powder

正1.Status of rare earth polishing powder Rare earth polishing powder with high content of cerium oxide began to replace iron oxide for glass polishing and became one of the key materials in glass polishing process since 1940.Compared with traditional iron oxide,rare earth polishing powder has many advantages,such as fast polishing rate,high polishing quality and long service life.It can achieve good surface quality and improve operation conditions.For example,in lens polishing,the polishing work that cerium     

Baotou Research Institute of Rare Earths developed a new RE alloy preparation technology

正Pyrometallurgy Laboratory of Baotou Research Institute of Rare Earths had independently developed a new preparation technology of rare earth alloy for NdFeB.The alloy can remarkably enhance the coercivity of NdFeB magnet but also evidently reduce the production cost of the magnet.The new master alloy was prepared in the kA pilot-scale electrolytic cell by the independent technology.The rare earth master alloy can be used as the raw material for NdFeB.Compared     

矿用防爆轴流对旋主要通风机叶片ANSYS模态分析及应用

高效节能矿用防爆对旋主要通风机的叶片是主要通风机运行的关键部件,叶片在运行时不断受到气流的作用力,从而使叶片产生振动,当叶片振动的频率与叶片的固有频率接近时,容易产生共振从而导致叶片的断裂。一旦叶片断裂时,对主要通风机的安全运行产生致命的影响,从而导致矿山、化工等企业发生重大事故,将会产生不可估量的损失。基于有限元分析软件ANSYS,对高效节能矿用防爆轴流对旋主要通风机叶片进行模态分析及产生对应的六阶模态频率,对主要通风机叶片的运行频率、固有频率及产生的共振问题进行了原理分析,并且解决了叶片频率共振的问题,从而为主要通风机叶片结构设计提供理论依据,并对主要通风机叶片的安全运行提供保障。     

2013 NdFeB export analysis

<正>China totally exported nearly 24,000 tonsof NdFeB products during 201 3,including 18,825 tons of permanent magnet,valued USD 1.34 billion at an average price of 71.4 USD/kg;3,277 tons of NdFeB magnetic powder,valued USD 1 01 million at an average price of 30.9 USD/kg;1,334 tons of strip casting ribbon,with total export value of USD 74million at an average price of 55.3 USD/kg;and 586     

Market and recycling of NiMH battery

<正>Market status and future trend of NiMH battery1.Global market of small NiMH battery Global market size of small NiMH batteries declined year on year since 2011.The trend will continue to 2018,at the rate of 5%to 10%annually.Demand for small NiMH batteries will be stable gradually.Many electrical apparatuses are powered by the built-in lithium battery today,which is the main reason for the shrunk market of small NiMH batteries.But,for some products,small NiMH     

China rare earth market review

正September 1-10,2014 Affected by the National Day holiday,rare earth transaction was stagnant and the market showed a weak steady state.As there was no good news for downstream market,some products with flat demand would likely rally slightly for some time to     

唐口煤矿深部复杂开采工作面瓦斯分源涌出规律研究

研究工作面瓦斯涌出规律对工作面瓦斯治理有重要意义。为了得到唐口煤矿深部3号煤层复杂开采条件下工作面回采时期瓦斯涌出时空演化规律,选取6304工作面作为对象,采用实测方法研究6304工作面瓦斯涌出规律。结果表明:6304工作面瓦斯涌出量为6.534 m³/min,其中煤壁占34.27%,落煤占29.62%,采空区占36.11%;沿工作面倾向由低到高,瓦斯浓度整体为上升趋势,其中1—76号架工作面瓦斯浓度小于0.20%,76—102号架瓦斯浓度上升明显,最大为0.387%;上隅角的后部采空区是工作面的瓦斯主要涌出源,上隅角1号测点瓦斯浓度0.78%,上隅角周边3号、5号、7号、8号、9号测点瓦斯浓度平均为0.643%;周期来压时,上隅角瓦斯相对平时较高。研究为针对性的瓦斯分源监控与灾害防治提供基础。