Optimum Weight Design of Functionally Graded Material Gears

Traditional gear weight optimization methods consider gear tooth number, module, face width or other dimension parameters of gear as design variables. However, due to the complicated form and geometric features peculiar to the gear, there will be large amounts of design parameters in gear design, and the influences of gear parameters changing on gear trains, transmission system and the whole equipment have to be taken into account, which increases the complexity of optimization problem. This paper puts forward to apply functionally graded materials（FGMs） to gears and then conduct the optimization. According to the force situation of gears, the material distribution form of FGM gears is determined. Then based on the performance parameters analysis of FGMs and the practical working demands for gears, a multi-objective optimization model is formed. Finally by using the goal driven optimization（GDO） method, the optimal material distribution is achieved, which makes gear weight and the maximum deformation be minimum and the maximum bending stress do not exceed the allowable stress. As an example, the applying of FGM to automotive transmission gear is conducted to illustrate the optimization design process and the result shows that under the condition of keeping the normal working performance of gear, the method achieves in greatly reducing the gear weight. This research proposes a FGM gears design method that is able to largely reduce the weight of gears by optimizing the microscopic material parameters instead of changing the macroscopic dimension parameters of gears, which reduces the complexity of gear weight optimization problem.

Design of Co-sedimentation Experiments Used to Fabricate Functionally Graded Materials with a Continuous Change of Composition

In the process of particle settling in a dilute,a density graded distribution of the liquid below the suspension needs to be designed according to the gravity of the suspension prior to sedimentation.In the present paper a compositionally graded W-Mo composite was formed via the settling of the W and Mo particles,with a density gradient distributed in the initial clear liquid along the settling direction.

Optimization design and residual thermal stress analysis of PDC functionally graded materials

The distribution of thermal stresses in functionally graded polycrystalline diamond compact (PDC) and in single coating of PDC are analyzed respectively by thermo-mechanical finite element analysis (FEA). It is shown that they each have a remarkable stress concentration at the edge of the interfaces. The diamond coatings usually suffer premature failure because of spallation, distortion or defects such as cracks near the interface due to these excessive residual stresses. Results showed that the axial tensile stress in FGM coating is reduced from 840 MPa to 229 MPa compared with single coating, and that the shear stress is reduced from 671 MPa to 471 MPa. Therefore, the single coating is more prone to spallation and cracking than the FGM coating. The effects of the volume compositional distribution factor (n) and the number of the graded layers (L) on the thermal stresses in FGM coating are also discussed respectively. Modelling results showed that the optimum value of the compositional distribution factor is 1.2, and that the best number of the graded layers is 6.

THERMO ELASTO—PLASTIC OPTIMUM DESIGN OF CERAMIC—METAL FUNCTIONALLY GRADED MATERIALS-Ⅰ.MICROMECHANICAL AND GEOMETRICAL EFFECTS

The thermo elasto-plastic optimum design of ceramic-metal functionally graded materials (FGMs)was investigated in this paper. The inelastic properties were first evaluated using micromechanical approaches, then an elasto-plastic finite element model was used to calculate the thermal stress in the material . The effects of micromechanical approaches, plasticity and graded interlayer thickness on the thermal stress relaxation characteristics and stress distributions were studied. The results show that: (1) the macro elas-to-plastic response given by the mean-field micromechanics and self-consistent micromechanics is nearly the same but the response given by the rule of mixture is different; (2)the thermo elasto-plastic behavior must be considered to realistically evaluate stress reduction, and the elasto-plastic optimum design can get helpful information to determine the graded interlayer thicknesses;and(3) to optimize the microstructure of the graded material achieves reductions in critical stress components and rational stress distributions.

Machinability Study of Titanium (Grade-5) Alloy Using Design of Experiment Technique

This paper presents the findings of an experimental investigation into the effects of cutting speed, feed rate, depth of cut and approach angle in turning of titanium (Grade 5) alloy. A two-level factorial experiment has been used to accomplish the objective of the experimental study. The main cutting force, i.e. tangential force (Fc) and surface roughness (Ra) were the response variables investigated. The experimental results indicate that the proposed mathematical models suggested could adequately describe the performance indicators within the limits of the factors that are being investigated. The feed, cutting speed and depth of cut is the most significant factor that influences the surface roughness and the tangential force. However, there are other factors that provide secondary contributions to the performance indicators.

基于颗粒破碎特性的盐岩集料基层级配组成设计研究

为实现内陆干盐湖区盐岩集料基层级配组成的科学设计,以罗布泊盐岩为研究对象,分析了不同粒径及含卤水率条件下单粒组盐岩集料颗粒破碎演化特征,构建了复杂粒组下盐岩集料级配转移模型,提出了盐岩集料基层级配组成设计方法,验证了盐岩集料基层级配组成设计方法的合理性,并对比了不同级配组成及失水率下盐岩集料的工程性质。结果表明:击实作用下各粒组盐岩集料均发生颗粒破碎,随着击实能量增加,盐岩集料级配趋于稳定,卤水的赋存会降低单粒组盐岩颗粒破碎率。Weibull分布可有效表征盐岩集料破碎颗粒级配分布特征。推荐的盐岩集料基层级配组成设计方法可有效推演盐岩集料基层的级配演化特征并实现考虑卤水影响的级配修正。盐岩集料颗粒间卤水盐分结晶有利于盐岩集料基层强度形成,失水率为75%的盐岩集料无侧限抗压强度可达到4.1 MPa,盐岩集料可用于干盐湖区公路基层填筑工程。

应力驱动的2.5D梯度各向异性维诺多孔零件轻量化建模方法

为了提高多孔零件的设计自由度、内部力学性能梯度与实际应力分布的匹配度,提出一种应力驱动的2.5D梯度各向异性维诺多孔零件轻量化设计方法。将零件有限元分析结果分解为应力标量场和应力方向场,通过加权随机采样算法将应力标量场映射为零件设计域内的维诺站点分布,实现零件内部力学性能的梯度分布;将应力方向场映射为二维黎曼流形,提出一种基于胞元择优方向生长策略的各向异性维诺图生成算法,生成胞元沿黎曼流形分布的各向异性维诺图。在此基础上,通过偏置算法、调和距离场和拉伸算法生成光滑的梯度各向异性维诺多孔零件。最后,采用有限元分析、三点弯曲实验等方法将所设计的多孔零件和其他多孔零件进行比较分析。实验结果表明,所提出的梯度各向异性维诺多孔零件建模方法能有效提升零件内部力学性能梯度与实际应力分布的匹配度,降低材料消耗,实现轻量化设计。

基于大动态范围放大的无增益调节超声放大电路设计

针对大型复合构件状态动态变化过程和多谱成像检测的需求,提出了一种无增益调节的宽带大动态范围超声放大电路的设计方法,设计了一种带宽为10 kHz~1.25 MHz,增益大于120 dB的无增益调节的超声信号放大电路。该电路采用多级放大器对信号进行分级放大,分割门限控制和信号状态识别与记录,最后通过数据合成实现了超声发射信号、回波信号全信号大动态、宽频带范围超声的放大。仿真实验表明,该电路可满足大型复合构件状态变化中信号的放大和多谱成像检测需求,其电路设计方法也可应用于其他如冲击波测试、声学测量等领域。

基于交通设计理念的道路平交口交通阻塞问题的道路精细化设计

基于交通设计理念,从交通阻塞问题与特征入手,进而对交通阻塞问题成因进行研究,然后通过交叉口车道匹配设计、合理设置掉头车道、通过交通标线加强交通疏导和慢行交通一体化设计来改善交通基础设施和通行条件,以此增强道路平面交叉口的交通供给能力,从而提高交叉口通行能力,改善交叉口阻塞问题。

级配碎石基层沥青路面材料优化研究

为缓解级配碎石基层沥青路面上面层所发生病害,优化级配碎石基层沥青路面材料应用效果。本文分别对AC-13、AC-20和AC-25进行级配设计;通过马歇尔试验检测各级配类型混合料最佳油石比;通过测定混合料抗车辙性能和动态模量性能综合评定不同类型沥青混合料应用效果。结果表明,掺加0.35%PE抗车辙剂对提升沥青混合料抗车辙性能效果显著,高模量沥青混凝土适合用于需要优异低温性和水稳定性的沥青路面。

电池分容设备的热设计与验证

电池分容化成设备总的热功耗大,充放电电流是化成工艺的数倍,受温度影响显著,更要求环境温度控制在±3℃范围内,因此热设计的好坏是影响分容化成设备工作性能的关键因素。分容库位的体积约1.98 m^(3),通过经验公式计算得设备单库位的总热功耗达到3.66 kW,根据GB/T31845-2015标准初步选择间接水冷方式散热。在考虑分容化成设备机械结构设计布局的基础上,对设备的风道进行初步设计。然后,借助CFD热仿真分析软件对分容化成设备进行热仿真分析,获得电池组、分容化成柜内环境温度和电子设备的温升与温差结果。CFD热仿真分析结果与实验结果相比,实际测试结果满足设计要求。考虑设备结构方便控制盒的大截面线缆的安装与维修要求,通过风机的合理布局与风道的优化设计,最终设计出满足产品结构布局与热设计的最佳方案,为同类型产品的热设计提供参考依据。

提升高等级公路交叉口通行能力的设计与研究

近年来国家为提高国省道的通行能力逐步将道路等级提高,道路等级提高后影响车辆通行能力的主要因素是较多的交叉口设置。目前公路行业针对平面交叉口的设计缺少相应的规范和量化标准,但交叉口一直是交通事故的多发点,人车混行严重、车辆通行缓慢,大大降低了高等级公路的通行能力。结合国道208线长治境内一级公路改扩建工程案例,通过分析影响平面交叉通行能力的因素(冲突点位置及数量),采用整体式路基分割岛法、整体式路基偏转岛法、分离式路基接线法三种新的设计理念来提高道路交叉口的通行能力,从而解决传统平面交叉口通行能力差的问题。

乡镇污水处理厂升级改造工程设计及运行效果

湖北省某乡镇污水处理厂设计规模1500 m^(3)/d,改造前出水水质执行《城镇污水处理厂污染物排放标准》(GB 18918—2002)一级B标准,改造后执行一级A标准。污水处理厂升级改造采用一体化污水处理装置+人工湿地处理工艺。介绍了项目运行现状、改造技术路线、主要设计参数、工艺特点和运行效果,改造工程自投产以来,工艺运行稳定、出水各项指标均达到设计要求。

10 kV与20 kV系统在半导体项目上的设计要点分析

半导体作为国家目前发展的重点,新建了很多200 mm(8英寸)和300 mm(12英寸)的半导体项目,而半导体项目自身又具有高用电需求的特点,所以针对10 kV和20 kV不同电压等级对技术要点进行分析和研究是十分必要。分别对10 kV和20 kV的电力系统方案进行分析,并对短路电流计算进行理论试算,归纳所对应的设备选型所对应参数,并结合实际案例分析比较所对应的站房需求和结构柱网型式,最终得出两种电压等级下所对应的设计要点,为其他设计人员在后续设计中提供借鉴。

辽宁省国省干线低等级公路概况分析与改扩建设计研究

依据公路统计资料,对辽宁省国省干线低等级公路的里程分布情况及具体类别划分情况进行了调查分析。在资料整合的基础上,总结梳理当前改扩建面临的农田、环保和资金问题,并提出改扩建总体设计、横断面设计、平面及纵断面设计、路面改造设计方面的实践经验,以期为类似工程和相关研究人员提供参考。

地震高烈度地区部分斜拉桥超大吨位减隔震支座设计研究

为确保地震作用下高烈度地区部分斜拉桥超大吨位减隔震支座的抗震性能,以靖远金滩黄河大桥为背景,对该桥20000 t级减隔震支座进行结构设计与性能研究,并开展全桥减隔震体系性能分析。通过将支座设计为具有自润滑功能,精准控制摩擦副摩擦系数使支座在常规工况下(摩擦系数在0.03以内)与地震工况下(摩擦系数大于0.05)分别发挥作用;正常位移及转动摩擦副与减隔震摩擦副的耐磨板分别采用改性超高分子量聚乙烯和改性聚四氟乙烯,保证了支座摩擦副的耐磨性能;将限位装置安装在支座侧面实现了支座限位装置的可更换性。结合仿真分析、抗剪销抗剪试验和支座缩尺模型试验对支座各构件强度、抗剪销性能及支座性能进行了验证。利用有限元软件开展了全桥减隔震体系性能分析,采用反应谱法与时程分析法分析了E2地震作用下桥墩及桩基础强度、支座剪切位移、伸缩缝变位,结果表明主墩、过渡墩及其桩基础截面抗弯能力,主墩支座剪切位移,过渡墩墩顶伸缩缝宽度均满足要求。

Dynamic response and optimization of an inclined steel rock shed by the graded energy dissipating method

Blocking rockfalls directly by reinforced concrete(RC) flat sheds with thick sand cushions is an outdated method. Such conventional sheds typically accumulate rock heavily, and become progressively damaged and are difficult to repair, and are very costly. To address these problems, we propose a new structure called a Graded Dissipating Inclined Steel Rock(GDISR) shed that utilizes the graded energy dissipation method. Here, we study the dynamic response of the GDISR shed with model test and numerical simulation, and give its optimization design combining with a practical engineering case. Our results show that the optimized modular E-block and corrugated steel tube can deform to sufficiently absorb the energy of different impact intensities. This efficiently and economically provides GDISR sheds with two security lines. Compared with conventional RC sheds, GDISR sheds with optimal incline have a more efficient anti-impact function, are faster and easier to repair, and are much simpler and cheaper to build.

电子级超纯水制备的现存问题及解决思路

电子行业的蓬勃发展催生电子级超纯水市场的广阔空间,其纯度直接影响到电子元器件的产品质量及生产成品率,因此电子级超纯水制备是电子行业发展的重要一环。然而,我国在电子级超纯水制备领域面临三大关键难题:一是国内电子级超纯水市场自主调节能力不足;二是设备部件过度依赖进口;三是制水工艺仍有待优化,设备运营成本高。为此,提出三条对应解决思路:一是优化制水工艺流程,提高自主生产能力;二是加快核心设备研发,推动市场应用进程;三是提高智能化水平,精准控制电子级超纯水的品质。

离散元设计嵌挤密实级配对再生砖混骨料水稳料性能的影响

基于三维离散元法,对再生砖混骨料级配进行优化设计,并通过击实与强度试验对比研究了设计得到的嵌挤密实级配与规范中规定的骨架密实和悬浮密实级配对水泥稳定再生砖混骨料性能的影响。结果表明:不同水泥掺量下,采用嵌挤密实级配再生砖混骨料制备的水稳料,其最大干密度、最佳含水率和7 d无侧限抗压强度介于采用骨架密实和骨架悬浮级配制备的水稳料之间,28 d无侧限抗压强度和7,28 d劈裂强度大于骨架密实和悬浮密实级配再生水稳料。当水泥掺量为3%时,嵌挤密实级配水稳料7 d无侧限抗压强度在4 MPa以上,满足规范二级及以下公路基层强度的要求。

油茶青果分级机结构设计

【目的】分级处理能提高油茶青果机械化破壳率,然而目前尚无成熟的油茶青果分级机,人工分拣劳动强度大、效率低,急需设计出一套结构简单、效率高的油茶青果分级机,以实现油茶脱壳全程机械化。【方法】课题组通过分析已有水果类物料分级装置的特点,设计了一种结构简单、维修成本低、作业效率高的油茶青果分级机。该机具由多级圆筒筛、螺旋绞龙、传动系统、多级出料斗、机架等组成。为确保分级机工作可靠性,对螺旋绞龙、圆筒筛等关键部件进行结构设计和参数计算。【结果】绞龙直径取512 mm,螺距取300 mm,每级筛孔数取618,每级筛孔直径分别取25 mm、34 mm、43 mm、52 mm,每级筛孔间隙分别取14mm、18 mm、22 mm、26 mm时,可满足油茶青果机械化破壳需要。【结论】该油茶青果分级机结构简单,维修成本低,作业效率高。本研究为油茶青果分级机样机制造提供了理论和数据基础,推进了油茶加工全程机械化,进一步促进了油茶产业高质量发展。