条状缺陷倾角对砂岩力学特性影响的模拟研究

为探究不同倾角条状缺陷对砂岩强度及其破坏演化过程的影响,利用PFC^2D离散元模拟软件,设置倾角φ为0°、15°、30°、45°、60°、75°、90°的7种方案,对含有条状缺陷砂岩的裂纹扩展过程、损伤演化特征和强度特征进行了研究。结果表明：条状缺陷对试样起裂位置及裂纹扩展路径均有影响,并在一定程度上决定试样最终破坏形式;条状缺陷倾角φ=30°时试样初始损伤应变最小,φ=45°时试样初始损伤应变最大,φ=90°时试样损伤应变范围最大,φ=60°时试样脆性破坏程度最高;条状缺陷对砂岩的峰值强度、峰值应变及弹性模量均有明显劣化作用,不同倾角条件下砂岩劣化程度不同,破坏时缺陷结构上端部峰值应力相对较高。     

离散裂隙网络的几何参数对裂隙岩体力学参数的影响研究

构建不同结构特征的离散裂隙网络,然后建立相应的等效岩体模型,通过单轴压缩数值试验得到等效岩体模型的力学参数,分析离散裂隙网络的几何参数对裂隙岩体力学参数的影响。结果表明：随着裂隙密度P₃₂的增加,单轴抗压强度、弹性模量及峰值应变近似线性递减,泊松比近似线性递增；随着裂隙倾角均值的增加,单轴抗压强度、弹性模量及峰值应变先减小后增大,泊松比先增大后减小,在60°时达到极值；对于裂隙倾角的分布特征,当裂隙倾角均值为60°时,单轴抗压强度、弹性模量及峰值应变随Fisher分布常数的增加而减小,泊松比随Fisher分布常数的增加而增加,而对于其它裂隙倾角均值的情况,Fisher分布常数对裂隙岩体力学参数的影响较小；对于裂隙直径的分布特征,幂律分布指数对裂隙岩体力学参数的影响较小；敏感性分析结果表明,单轴抗压强度对于离散裂隙网络几何参数的敏感性最大,弹性模量的敏感性最小。     

预固结煤泥的气压差脱水

高浓度煤浆采用液压冲压机固结,直至达到力学平衡状态。挤压力在350×10~5Pa时,物料可达到的最终孔隙比随挤压力加大而呈近似对数关系连续减小。固结速度却随挤压力增加而加快,经固结的物料再以低于50×10~5Pa的气压差脱水。这种方法比纯气压差脱水法的最终水分更低。用挤压和气压差组合工艺脱水时,最终水分受压力的影响不大,仅取决于所用气压差的大小。本文描述了煤泥在该阶段中的压缩模型。随着挤压力增加,各颗粒间的间隙先减小,随后孔径最大亦最不稳定的孔隙被破坏。机械脱水物料的气耗量随挤压力上升而下降,又随气压差加大而上升。     

围包角对改向滚筒应力应变的影响

以1m改向滚筒为例,根据滚筒的尺寸结构类型、材料参数属性和载荷状况,利用ABAQUS软件进行有限元分析,进行了围包角对改向滚筒应力应变影响的研究。研究表明:当围包角α=180°时,既保证了滚筒轴所受最大应力应变远小于其许用应力值,又有效减小了筒体所受的最大应力应变,为改向滚筒的设计提供了理论依据。     

对称X型裂隙类岩体的力学特性及破坏机制研究

为了研究对称X型裂隙对岩石力学特性及破坏机制的影响,对预制对称X型裂隙类岩体试件进行单轴压缩试验和数值模拟分析,结果表明：1)预制裂隙角度影响裂隙尖端的受力状态,是试件裂纹起裂特征和破坏模式的主要因素;2)对比完整试件,裂隙试件的应力应变曲线峰前出现应力降现象,峰后表现为延性下降,且峰值强度、弹性模量和弹性应变能明显下降,表明试件的力学特性和能量特征对预制裂隙的敏感性高;3)当0°＜α＜90°时,随着预制裂隙角度α的增大,K_e和T应力值减小,裂纹尖端抵抗开裂的能力增强,裂隙试件峰值应力增大,且裂尖抵抗I和II型断裂能力的强弱是造成裂隙试件破坏模式差异的主要原因。     

制片压力对有机电解液双电层电容器性能的影响

通过扫描电镜对不同制片压力下极片的表观形貌进行观察,以及通过交流阻抗和恒流充放电,研究了不同制片压力对极片的比电容、等效串联电阻、功率特性和循环性能的影响.结果表明,在0～45MPa压力范围内随着制片压力的增大,极片的等效串联电阻先减小后增大,比电容先增大后减小,功率特性也是先变好后变差.当制片压力为35 MPa时,极片各种性能达到最佳:极片得到最小的等效串联电阻0.92 Ω;在不同的电流密度下比电容均为最大,当电流密度为0.15 A/g时,比电容达到118.3 F/g;电流密度从0.15 A/g增加到9.6 A/g,其比电容仅衰减了4.5,,功率特性较佳.     

基于Simufact环锥形零件剪切旋压仿真分析

针对环锥形零件成形加工难度较大、成形件易出现应力集中等不良现象,以某型环锥形零件为研究对象,分析其剪切旋压成形原理,运用专业旋压有限元分析软件Simufact建立其剪切旋压成形仿真分析模型,对其在不同剪切旋压成形时间下的等效应力、等效应变及成形件在距中心不同距离下的最大等效应力、最大等效应变变化规律进行仿真。仿真结果表明:随着剪切旋压不断进行,等效应力、等效应变都呈现逐渐增加的趋势,且在不同剪切旋压阶段,最大等效应力及最大等效应变分布区域不同;随着距中心距离逐渐增加,最大等效应力、最大等效应变都呈现先增加后减小的趋势。该研究为环锥形零件剪切旋压成形及其工艺参数、模具结构优化提供理论依据。     

孔底抵抗线对VCR爆破的影响研究

大直径深孔爆破是常用的矿山破岩方法,孔底抵抗线过长导致炮孔冲孔破岩效果差,孔底抵抗线过小,使得爆炸能过多的浪费。为了合理利用爆炸能量,改善破岩效果,采用LS-DYNA软件对大直径深孔爆破中孔底抵抗线进行优化研究,通过分析等效漏斗半径、等效漏斗体积可知,随着孔底抵抗线的增大,等效漏斗半径和等效漏斗体积先增大后减小,当孔底抵抗线为5cm时,爆破效果最好;通过分析监测点有效塑性应变可知,应变值与初始应变率随着炸药距离的增大而减小。结合数值模拟成果并进行现场试验发现,当抵抗线长度为1.0 m时,爆破块度较为均匀,未出现冲孔现象,现场试验与模拟结果基本一致。     

非均匀椭圆载荷下套管抗外挤能力分析

目前大多数油井套管的损坏很大程度上是由非均匀载荷引起的,外载荷的非均匀性等因素大大降低了套管的承载能力,为此,揭示这些因素对套管抗挤能力的影响具有重要的实际意义。根据非均匀椭圆载荷作用下套管的受力特点,利用材料力学理论建立了理想套管的环向应力计算模型,分析了套管的应力分布规律,结果表明:套管承载的危险点为圆周方向与最大水平地应力成90°夹角的内壁上,与有限元数值模拟结果有着很好的一致性。并以危险点应力状态为依据,得到了套管在不同的非均匀载荷下的等效外挤压力计算的新公式。计算结果表明,椭圆载荷中的非均匀部分对套管等效外挤压力影响极大;外载荷非均匀度越大,径厚比越大,套管承受外挤载荷能力越差,越容易发生挤毁失效。     

考虑剪胀与中间主应力的被锚巷道围岩稳定性分析

为研究被锚巷道围岩稳定性,将锚杆的支护作用考虑成作用于锚固体两侧的一组夹紧力与强化了锚固体强度参数,综合考虑围岩剪胀特性与中间主应力效应,建立被锚圆巷弹塑性力学模型,推导出围岩的应力场与位移场解析解,求得围岩塑性区半径表达式。算例研究表明:随着中间主应力系数增大,塑性区半径、洞壁位移与锚杆轴力均减小,最大主应力峰值增大;随着剪胀角增大,塑性区半径稍有减小,最大主应力峰值稍有增大,洞壁位移与锚杆轴力急剧增大;影响因素最不利组合(b=0,ψ=30°)与影响因素最有利组合(b=1,ψ=0°)相比,塑性区半径增大了23.49%,最大主应力峰值变化很小,洞壁位移增大了76.20%,锚杆轴力增大了1.94倍。该结果在围岩稳定分析方面具有一定工程实用价值,也可为锚杆支护设计和优化提供一定理论基础。     

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。