航空2024铝合金VIC-3D静载分析和疲劳试验

通过VIC-3D技术测量静态拉伸全场二维应变及应力,基于航空载荷谱进行动态载荷疲劳试验,利用扫描电子显微镜对试件断口进行观察,研究航空2024铝合金的力学性能。结果表明,利用Y方向应变随时间变化云图,可以探究裂纹出现及发展规律,疲劳试样在第34周循环,总第169 973次循环后发生疲劳断裂。疲劳断口可观察到疲劳源区、疲劳裂纹扩展区及瞬时断裂区,并呈扇形向外扩展。疲劳裂纹萌生于试件表面,裂纹扩展区二次长裂纹方向和裂纹扩展方向垂直,并存在疲劳辉纹,瞬时断裂区呈现出塑性断裂韧窝状形貌,局部存在冲击面形貌。     

激光沉积TA15钛合金裂纹扩展行为研究

采用标准CT试样测定了激光沉积TA15钛合金疲劳裂纹扩展速率,结合微观组织、裂纹扩展路径以及断口形貌分析疲劳裂纹扩展机理;并基于ABAQUS与FRANC 3D联合仿真的方法,模拟裂纹尖端应力强度因子并进行寿命预测。结果表明激光沉积制造态的裂纹扩展速率低于锻造态,裂纹主要穿过片状α相(),少量沿扩展,稳定扩展区清晰可见疲劳条纹,并伴随大量的二次裂纹,瞬断区为典型的韧性断裂。另一方面ABAQUS与FRANC 3D联合仿真计算的应力强度因子与理论值吻合较好,预测寿命相对误差低于5%,且证实了预测结果保守,验证了模拟分析的可靠性,确保了工程应用中的安全性。     

钻具失效断裂浅谈

从断口侧面观察,整个断口较为平齐,无明显塑性变形痕迹,断口断裂并非因载荷大而引起的塑性断裂;从正面观察,可见钻杆接头断口可以明显分成两个区域:裂纹扩展区和剪切唇区。裂纹扩展区断口表面平坦,局部区域可见挤压痕迹,尤其在裂纹扩展区的外圆弧中部可见一处发亮,挤压痕迹明显,瞬断区断口表面以剪切唇为主,属典型塑性断裂区。     

应力比对热等静压Ti-6Al-4V钛合金疲劳裂纹扩展速率的影响

采用标准C(T)试样测定热等静压Ti-6Al-4V钛合金在应力比R=0.1、0.4和0.7的条件下疲劳裂纹扩展速率,获得相应条件下的疲劳裂纹扩展数据,绘制了对应的裂纹扩展速率与应力场强度因子(da/dN-ΔK)关系曲线,并结合疲劳裂纹扩展路径和断口形貌分析探究应力比R对热等静压Ti-6Al-4V钛合金裂纹扩展速率的影响。结果表明,随着应力比R的增大,裂纹扩展门槛值ΔKtn减小。相同ΔK下,裂纹扩展速率da/dN随应力比R一同增大,致使da/dN-ΔK关系曲线向左上移动;裂纹能够穿过等轴晶α相和纤薄的α片层结构呈直线型扩展,遇到较厚的α片层结构时,裂纹偏转并沿原始α片层方向继续扩展,最终发生断裂;断口由预裂区、稳态扩展区和快速断裂区构成,分别对应于疲劳裂纹扩展的三个阶段。     

预腐蚀7050-T7651铝合金裂纹扩展行为

开展不同预腐蚀时间下含单边裂纹7050-T7651铝合金单轴拉伸实验;利用数字图像相关观测试件在加载过程中的表面变形场信息,描述裂纹扩展的时空演化特征;通过扫描电镜观测试件断口显微形貌,分析其断裂特征。结合加载曲线,变形场演化和断口分析讨论腐蚀损伤对铝合金材料裂纹扩展的影响。实验结果表明：腐蚀损伤达到一定程度会导致铝合金试件承载能力的下降;腐蚀损伤较轻时(腐蚀4小时),腐蚀损伤能够引发裂纹偏折,改变裂纹扩展路径;腐蚀损伤进一步加剧(腐蚀6小时),腐蚀损伤会引起次裂纹萌生,裂纹联合、扩展导致了试件的最终失效。断口分析表明裂纹扩展的关键区域均存在腐蚀和材料脆化特征,证实腐蚀损伤对材料断裂路径和失效模式的重要影响。     

微波照射后花岗岩裂纹扩展规律试验研究

硬岩裂隙的形成和扩展规律是研究岩石损伤机理的重要内容。为了探究微波照射下,岩石裂隙的扩展规律,为微波辅助破岩技术提供理论依据,利用扫描电镜(SEM)设备对花岗岩试件在微波照射及单轴抗压强度测试后进行扫描观测,分析岩石断口的形貌、裂纹的类型及断裂模型。结果表明：高功率微波照射后,试件表面出现颜色变化,并伴随有张拉裂纹出现,在压缩试验后,试件上部结构呈粉末状破碎|SEM设备观测下花岗岩断口形貌特征主要为平坦面状和条纹状断裂|花岗岩的裂纹类型主要为张拉裂纹和压剪裂纹|花岗岩的断裂模型主要为沿晶断裂、穿晶断裂以及两者叠加。     

基于FRANC3D的三维疲劳裂纹扩展的数值模拟

介绍了三维断裂分析软件FRANC3D(Fracture Analysis Code in 3 Dimensions)以及相关原理,详细说明了FRANC3D对于复合型裂纹断裂的判定依据、断裂后新裂纹前缘面的形成过程以及软件进行疲劳裂纹扩展计算的一个完整过程。最后,由应用实例验证了FRANC3D预测疲劳裂纹扩展路径及构件寿命的准确性。     

微波照射后花岗岩裂纹扩展规律试验研究

硬岩裂隙的形成和扩展规律是研究岩石损伤机理的重要内容。为了探究微波照射下,岩石裂隙的扩展规律,为微波辅助破岩技术提供理论依据,利用扫描电镜(SEM)设备对花岗岩试件在微波照射及单轴抗压强度测试后进行扫描观测,分析岩石断口的形貌、裂纹的类型及断裂模型。结果表明：高功率微波照射后,试件表面出现颜色变化,并伴随有张拉裂纹出现,在压缩试验后,试件上部结构呈粉末状破碎|SEM设备观测下花岗岩断口形貌特征主要为平坦面状和条纹状断裂|花岗岩的裂纹类型主要为张拉裂纹和压剪裂纹|花岗岩的断裂模型主要为沿晶断裂、穿晶断裂以及两者叠加。     

低温对铝合金在SSRT过程中裂纹萌生与扩展规律的研究

本文采用一种电化学阻抗谱的解析方法原位研究低温对7A04铝合金在慢应变速率拉伸过程（SSRT）中裂纹萌生与扩展规律的影响,采用扫描电子显微镜对断口形貌进行观察,并通过KramersKronig转换验证电化学阻抗谱实验数据的可靠性。结果表明：裂纹的萌生和扩展过程大致可分为氧化膜溶解、裂纹萌生、动态平衡、裂纹明显扩展四个阶段;温度的降低会改变断裂方式,表现为从混合断裂向脆性穿晶断裂发展;由常温向低温的变化可以有效抑制铝合金在SSRT过程中的裂纹萌生和扩展,具体表现为温度越低对裂纹萌生和扩展的抑制效果越不明显,其中-5℃时抑制效果最强。     

低温对铝合金在SSRT过程中裂纹萌生与扩展规律的影响

采用一种电化学阻抗谱(EIS)的解析方法,原位研究低温对7A04铝合金在慢应变速率拉伸过程(SSRT)中裂纹萌生与扩展规律的影响。利用扫描电子显微镜(SEM)观察断口形貌,并通过Kramers-Kronig转换验证EIS实验数据的可靠性。结果表明,裂纹的萌生和扩展过程大致可分为氧化膜溶解、裂纹萌生、动态平衡、裂纹明显扩展四个阶段;温度的降低会改变断裂方式,表现为从混合断裂向脆性穿晶断裂发展;由常温向低温的变化可以有效抑制铝合金在SSRT过程中的裂纹萌生和扩展,具体表现为温度越低对裂纹萌生和扩展的抑制效果越不明显,其中-5℃时抑制效果最强。     

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。