基于CFD的深水气井防砂筛管冲蚀仿真模拟

深水气井出砂,气流携砂快,筛管冲蚀更严重,极易造成防砂失效,加剧后期修井成本。为准确掌控深水气井防砂筛管冲蚀磨损情况,采用耗时短、成本低的仿真模拟实验开展研究,相较于室内实验研究更具实用和教学价值。构建了防砂筛管的整体物理模型和局部筛孔物理模型,并采用分阶段修正以匹配筛网冲蚀的孔径变化,建立离散颗粒广角度筛管冲蚀模型,引入气固耦合流动模型,采用亚松弛迭代计算两相流场分布和冲蚀磨损情况,形成筛管冲蚀仿真模拟方法,应用于XX井进行冲蚀磨损分析。提出的筛管冲蚀磨损模拟方法为深水气井防砂筛管优选和冲蚀磨损量计算提供了一种研究方法和理论依据,对保障海洋油气资源的安全高效开发具有重要意义。     

基于网络的数控加工仿真技术

目前的数控加工仿真程序都是仿真本地数据代码,限制了仿真技术对异地数控加工代码的仿真,而模拟仿真加工不能真实地反映出实际加工中存在的问题。针对此,提出建立基于网络的数控加工仿真系统,建立了切削过程中的刀具磨损力学仿真模型,并通过实例进行了验证。     

基于CFD-DEM的含沙水介质下球阀磨损性能分析

球阀在含沙水介质中工作时容易因磨损过大而失效。为了解球阀在含沙水介质中的磨损情况,采用CFD-DEM方法建立了球阀在含沙水介质下的数值仿真模型,探讨了球阀开启范围、沙粒半径和水流速度对球阀磨损的影响规律,分析了球阀的磨损位置分布。结果表明：球阀的总磨损量随着开启范围的增大而减小;沙粒粒径和水流速度越大,总磨损量越大;磨损位置主要集中在球阀流通处附近,并在靠近流道出口区域产生局部磨损。     

摩擦副磨损与亚表面应力虚拟仿真平台开发

机械摩擦副的摩擦磨损是"机械设计"课程的重要教学内容。影响摩擦磨损的因素错综复杂,具有时空的跨尺度性,难以开展真实实验教学。以不同材料配对的线接触摩擦副和柱销-盘摩擦副为例,分别开展适用于网络平台使用的摩擦副复合磨损量和亚表面应力的模型及其数值计算方法研究,以及线接触复合磨损系数实验研究。建立模拟磨损量和亚表面应力网络实验平台,实现不同材料线接触摩擦副磨损量随时间变化以及柱销-盘摩擦副亚表面应力随载荷与摩擦系数变化仿真。实践验证了仿真算法快速,实验操作简单、实用,有助于学生理解零件摩擦磨损引起的各种失效。     

基于粘着磨损机理的内燃机汽缸粘着磨损分析

粘着磨损的存在极大地危害着工程机械的正常使用,内燃机汽缸的粘着磨损更是严重地影响着内燃机的使用效率和使用寿命。因此,工程中对汽缸粘着磨损的分析显得尤为必要,针对其危害提出行之有效的减小粘着磨损的方案,便成为机械工程设计人员的一项主要任务。     

含氮节镍型QN2109Mo奥氏体不锈钢组织和性能

选择含氮节镍型QN2109Mo奥氏体不锈钢作为研究对象,采用XRD、TEM、SEM、EDS、摩擦磨损试验机和电化学工作站等检测手段,研究QN2109Mo不锈钢的组织结构、摩擦磨损性能以及耐腐蚀性能,并与316L不锈钢进行对比。实验结果表明:N原子主要以间隙固溶形式存在于QN2109Mo不锈钢中,对QN2109Mo不锈钢组织起到了细化作用,提高了QN2109Mo 不锈钢的硬度。在干摩擦状态下,QN2109Mo不锈钢的耐磨损性能优于316L不锈钢,其磨损机理为氧化磨损和磨粒磨损共同作用。在w(NaCl)为3.5%的溶液中,QN2109Mo不锈钢表现出比316L不锈钢更低的自腐蚀电流密度和更高的点蚀电位,具有更优异的耐NaCl 溶液腐蚀性能。     

基于离散元法的凿形深松铲磨损行为的仿真分析

磨损是凿形深松铲失效的最主要方式。采用离散元法对凿形深松铲的深松过程进行了仿真,从土壤颗粒运动、凿形深松铲受力、磨损识别和磨损机理等方面分析了凿形深松铲的磨损行为。结果表明,深松过程中凿形深松铲前方的不同层土壤颗粒没有发生混合,土壤与凿形深松铲前表面的相互作用主要为滑动摩擦;凿形深松铲前表面附近的土壤颗粒运动方向与凿形深松铲半径方向存在一定的夹角,凿形深松铲前表面附近的土壤颗粒与凿形深松铲存在一定的相对滚动;铲尖在水平方向和垂直方向的受力大小相接近,铲柄受力主要来源于土壤颗粒对铲柄前进的阻碍作用;深松铲在切向上的累积接触能大于法向上的累积接触能,法向累积接触能的最大值为0.895 8 J,切向累积接触能的最大值为2.047 6 J,即切向磨粒磨损作用大于法向冲击磨损作用,铲柄切削刃磨损深度平均值随着高度的增加不断减小,铲尖上表面磨损深度平均值随着高度的增加不断增大,铲尖前表面是凿形深松铲磨损最严重的区域;随着深松速度的不断增加,铲柄切削刃磨损深度平均值的增长率也不断增大,铲尖上表面磨损深度平均值的增长率也不断增大。     

继电器机械结构模型的建立和仿真分析

主要解决卫星用继电器摩擦磨损,因此,通过运动学和动力学仿真来模拟经过简化后继电器机械系统各部件的运动状态,并得出各摩擦副之间的应力应变情况。     

低声说话更清楚

正刮完胡子再长出来会变硬。严格地说,不是胡子变硬了。胡子(包括其他毛发)在生长过程中会逐渐磨损,而刚刮完胡子后长出的新胡茬,一方面比较短,没怎么磨损,加之刚经过切割,断面上有尖锐的棱角,所以感觉上会更硬、。     

基于DEFORM-3D的难加工材料切削性能比较

运用DEFORM-3D有限元仿真软件分别对300M超高强度钢、钛合金TC4、镍基合金In718、铜合金Cu C2进行切削仿真。切削仿真研究表明：切削300M超高强度刚的切削力最大;切削镍基合金In718时刀具与工件间的切削温度最高、刀具应力与刀具磨损最大。     

Experimental and FEM Study of Coated and Uncoated Tools Used for Dry Milling of Compacted Graphite Cast Iron

Compacted graphite cast iron (CGI) has been the material for high-power diesel engines recently, but its increased strength causes poor machinability. In this study, coated and uncoated carbide tools were used in dry milling experiment and FEM simulation to study the machinability of CGI and wear behaviour of tools. The experimental and FEM simulation results show that coated tool has great advantage in dry milling of CGI. SEM and EDS analysis of tool wear indicate the wear morphology and wear mechanism. Adhesive wear is the main mechanism to cause un-coated tool wear, while abrasive wear and delamination wear are the main mechanism to cause coated tool wear. Stress and temperature distribution in FEM simulation help to understand the wear mechanism including the reason for coating peeled off.     

Quasi-static-model-based wear analysis of helical gears

A quasi-static wear model for helical gears is proposed based on finite element method and Archard’s formula to investigate the wear characteristics of tooth surface in real operation conditions. The numerical simulation reveals that the wear depth distributes unevenly along the tooth lead and varies along the tooth profile. The surface wear depth claims its minimal value at the pitch circle and reaches its maximal value near the tooth root of the pinion. The effects of misalignment on wear depth are further investigated to provide useful information for gear designers. The numerical simulation reveals that the vertical misalignment is more influential than the parallel misalignment on the gear wear depth. Therefore, to eliminate the negative effects of misalignment, the misalignment should be strictly controlled.     

浅谈童装的仿生设计

仿生设计,顾名思义是指有关模仿生物的设计。自从20世纪60年代仿生学作为一门学科正式诞生以来,经过几十年的探索与实践,巳发展成为横跨多门学科的边缘性学科。服装仿生设计作为仿生学的一个重要分支,也得到了广泛的研究与应用。从童装的仿生设计角度入手,研究童装仿生设计方法,探讨童装仿生设计当中的规律。并且从儿童的角度研究了几种主要的童装仿生方法,既可以使儿童穿上自己喜欢的仿生童装,也能够培养儿童的智力发展和兴趣发展。     

高速列车车轮多边形对车内噪声的影响

研究目的：研究高速列车车轮多边形特征对轮轨噪声和车内噪声的影响规律,讨论目前国内高速列车车轮镟修指标的不足,为高速列车车轮镟修方法的优化改进提供科学依据。创新要点：系统分析高速列车车轮多边形阶次、幅值和相位等参数对车内噪声的影响规律;提出车轮镟修中仅考虑车轮径跳作为限值是不够的。研究方法：1．基于线路试验,初步分析高速列车车轮多边形状态对车内噪声的影响,进而对车轮多边形特征进行剖析;2．基于带通滤波和快速傅里叶变换,使用MATLAB程序生成不同阶次、幅值和相位的车轮多边形粗糙度数据;3．基于TWINS轮轨噪声原理,使用HWTNS预测含有不同车轮多边形特性的轮轨噪声;4．基于混合有限元-统计能量分析（FE—SEA）方法,建立高速列车客室端部车内噪声预测模型,预测车内噪声;5．通过分析车轮多边形参数、车轮径跳和车内噪声之间的相互关系,研究目前的高速列车车轮镟修指标是否合适。重要结论：1．高速列车车轮径跳值相同,但车轮多边形状态不同时,轮轨噪声与车内噪声有明显差异;2．当车轮多边形幅值相同时,高阶多边形可以引起更高的轮轨噪声和车内噪声;3．改变车轮多边形的相位,可以获得不同的车轮径跳值,但是对轮轨噪声和车内噪声几乎没有影响。     

Development and validation of a model for predicting wheel wear in high-speed trains

In this paper, we present a comprehensive model for the prediction of the evolution of high-speed train wheel profiles due to wear. The model consists of four modules: a multi-body model implemented with the commercial multi-body software SIMPACK to evaluate the dynamic response of the vehicle and track; a local contact model based on Hertzian theory and a novel method, named FaStrip (Sichani et al., 2016), to calculate the normal and tangential forces, respectively; a wear model proposed by the University of Sheffield (known as the USFD wear function) to estimate the amount of material removed and its distribution along the wheel profile; and a smoothing and updating strategy. A simulation of the wheel wear of the high-speed train CRH3 in service on the Wuhan-Guangzhou railway line was performed. A virtual railway line based on the statistics of the line was used to represent the entire real track. The model was validated using the wheel wear data of the CRH3 operating on the Wuhan- Guangzhou line, monitored by the authors’ research group. The results of the predictions and measurements were in good agreement.     

基于ADAMS对独立悬架主销偏移距优化设计

基于一种四轮独立转向独立驱动电动轿车的独立悬架,以优化主销偏移距减轻转向和轮胎磨损为目标,在ADAMS软件里建立参数化模型,对悬架导向机构进行优化设计和仿真实验,验证了设计方法的合理性．     

水压轴向柱塞马达配流盘的研究

This paper has introduced the developments of water hydraulic axial piston equipments.According to the effects of physicochemical properties of water on water hydraulic components,a novel valve plate for water hydraulic axial motor has been put forward,whose moment exerted by the fluid field between valve plate and bearing plate is balanced entirely.The material screening experiment of valve plate is done on the test rig.Through numerical simulation the effects of some geometry parameters on the performance of water hydraulic motor have been studied.The silencing grooves on the valve plate in water hydraulic motor can reduce the pressure shock and the occurrence of cavitation effectively.It is evident that the appropriate structure should change the wear status between matching paris and reduces the wear and specific pressure of the matching pairs.The specimen with the new type valve plate is used in a tool system.     

Wear behavior of diamond-coated drawing dies

The failure behavior of diamond-coated die was investigated experimentally and analytically through finite element method (FEM) simulation in the present work. Diamond coatings were fabricated by straight hot filament chemical vapor deposition (CVD) passing through the interior hole of the drawing die using a mixture of hydrogen and acetone as source gases. The performance tests were made under real drawing condition. Scanning electron microscopy (SEM) was used for the study of coating wear after die service. The coating wear appears on two regions of the reduction zone: one is near the entrance where the contact begins, and the other is at the end of the reduction zone. FEM simulation was made for calculating the von Mises stresses distribution on the coating and substrate during the drawing process. The present work was of great practical significance for the improvement of drawing performance of diamond-coated drawing dies.     

Failure analysis of crush hammers based on damage fracture energy

To prolong the life-span of crush hammers in the pyrite concentrate workplace of Ganbazi Coal Preparation Plant of Chongqing Nantong Mining Ltd., we used a progressive damage constitutive model based on the ductile and shear damage fracture energy to analyze the hammer wear failure caused by the impact and abrasion on the hammer surface by pyrite, and carried out simulation analysis with the explicit algurithm on hammer leftovers from the plant during the process of coarser pyrite comminution. The simulation results are consistent with hammer wear failure caused by pyrite impact. Then we proposed corrective measures to prolong hammer life-span. Results of the production test in the Ganbazi Coal Preparation Plant showed that non-clearance hammers can avoid wear erosion, and adding steel bonded tungsten carbides F3002 prolonged the hammer life- span. The effect of austenitic manganese steel work-hardening was not prominent. Therefore, the hammer failure was mainly caused by superficial abrasion instead of fatigue cracks appearing when grains acted on the hardening layer.