Modeling and Analysis of Vibration Characteristics of Rectangular Plate with Circular Through Hole Under Complex Boundary Conditions

This paper presents a method to study the free vibration of a plate with circular holes.The circular hole is regarded as a virtual small plate in which the mass density and Young's modulus are zero.Therefore,the free vibration problem of the circular hole plate can be transformed into the free vibration problem of the equivalent rectangular plate with non-uniform thickness.The model is derived from the spectral geometry method(SGM),and the displacement of the plate with circular holes is expanded by the modified Fourier series.Virtual springs are added to the boundary of the plate to simulate the boundary conditions of simply supported and fixed supports.The accuracy of this method is verified by comparison with the finite element calculation results.The relationship between modal numerical solutions of plates with circular holes and boundary conditions and geometry of the plate is studied.

FEM Analysis and Simulation for Prediction of Press-Forming and Spring Back of Spiral Plates

In order to provide technical supports for designing a new type of spiral plate forming machine, FEM analysis and simulation were carried out based on pressing tests. Deformation, stress distribution, residual stress and spring back of the spiral plate were calculated. Relationships between the spiral pitch to inclination angle of the punch and die, material properties and thickness of the plate were analyzed. A data converter was developed and effectively used in the analysis. The results of FEM analysis and simulation have been applied to design the spiral plate forming machines.

Residual Stresses and Forming Quality of Metal Bipolar Plates for PEMFC During the Stamping Process

Stamping is a critical step in the manufacture of metallic bipolar plates.Typically,residual stress and a spring back effect appear on the bipolar plate after the stamping process,which impacts on the performance and lifetime of the proton exchange membrane fuel cell(PEMFC).The residual stress and spring back behavior which occur as a result of stamping a bipolar plate are investigated in this study.The effects of the punch radius,the die radius,the channel depth,and the clearance between the punch and the die on the residual stress and forming quality of the bipolar plate are examined.The stamping process can be divided into three stages.The high stress area and the middle section residual stress area were selected to study the formation process and to obtain the composition of the residual stress regions.Spring back was mainly related to the position of the fixed end of the sheet and the degree of plastic deformation,and the sheet thickness have increased by 2μm after spring back.Based on the results of finite element analysis,as described by the distribution of residual stress,the formation,the thickness of the middle cross section and the equivalent plastic strain,it was found that all the tool parameters affected the distribution of the residual stress.This research can provide a design reference for the manufacture of metallic bipolar plates based on the stamping process.

Spring-Value in Kirchhoff-Love Plate: Displacement, Buckling, Pure-Shear, Vibration

The stiffness model of the finite element is applied to the Kirchhoff-love closed-form plate buckling;buckling is always in focus in plate assemblages. The useful Eigen-value solutions are unable to separate a square plate from a much weaker long one in the most commonly-used all-simply supported plate (SSSS), among others. Spring-values of the Kirchhoff-Love plate are sought;once found, displacement-factors can be determined. Comparative displacements allow an easier and better evaluation of buckling-factors, pure-shear, vibration and so are termed “buckling-displacement-factors”. In testing, many plates in mixed boundary conditions are evaluated for displacement assisted buckling-solutions, first. The displacement-factors made from fundamental Eigen-vectors, in a single-pass, are found to be within about one-percent of known elastic values. It is found that the Kirchhoff-Love plate spring and the finite-element spring, demonstrated, here, in the assemblage of beam-elements, are equivalent from the results. In either case, stiffness is first assembled, ready for any loading—transverse, buckling, shear, vibration. The simply-supported plate draws the only exact vibration solution, and so, in an additional new effort, all other results are calibrated from it;direct vibration solutions are made for comparison but such results are, hardly, better. In the process, interactive Kirchhoff-Love plate-field-sheets are presented, for design. It is now additionally demanded that the solution Eigen-vector be developable into a recognizable deflection-factor. A weaker plate cannot possess greater buckling strength, this is a check;to find stiffness the deflection-factor must be exact or nearly so. Several examples justify the characteristic buckling displacement-factor as a new tool.

300 t转炉悬挂系统应力测试与分析

对于大型转炉,目前国内已可以自主设计和制造。托圈与炉壳之间的连接方式是设计时的关键,某钢铁厂300 t转炉经过综合评估后采用的是8点弹簧板式连接。设计过程中,虽然采用有限元法模拟分析了弹簧板的应力应变状态,计算预测了该连接结构在理论状态下的使用寿命及其安全性,但是实际生产过程中弹簧板应力状态会受到静不定、角部应力集中等因素扰动,需通过获取现场实测数据来对计算过程加以验证与修正。本文建立了该300 t转炉下悬挂系统应力测试模型,对空炉和满载两种工况进行了弹簧板应力测试,得到不同工况弹簧板各点的受载情况,分析了弹簧板应力分布状态,其结果可为转炉悬挂系统的设计提供参考和实践意义。

抗震钢支座中新型钢板簧的优化

钢弹体抗震钢支座是一种新型抗震支座,其通过在传统球型钢支座外侧增设的新型钢板簧为支座提供必要的地震恢复力以及地震耗能,在小震下保证了支座在震后的基本复位;强震作用下吸收地震能量,并可实现支座在震后的部分复位,满足基本的通车要求。首先,对该新型钢板簧进行了力学性能试验,建立了有限元模型,并利用试验结果验证了支座有限元模型的有效性。其次,对单个钢板簧和钢支座整体结构进行了动力特性分析,研究了新型钢板簧对抗震耗能的贡献;同时,对新型钢板簧结构进行了参数分析,找出各参数的影响规律。最后,对新型钢板簧的刚度和尺寸参数进行了多参数拟合,得到拟合函数,完成了新型钢板簧尺寸的结构优化,达到了节省材料、缩小结构空间的目的。

低速冲击下碳纤维面板泡沫夹芯复合材料的损伤分析

主要研究了夹层复合材料受外来载荷作用下的凹痕、横向位移、接触力随时间的变化规律.采用高阶剪切变形理论给出夹层板的广义内力表达式,再由薄板小挠度理论、Hertz接触理论、夹层板平衡方程、Navier法推导出夹层板在外来载荷作用下的动态响应过程.其中,夹层板的接触力和横向位移由两自由度弹簧-质量模型给出.将推导的结果与文献中的理论结果对比,本文计算的误差均不超过6%.并在此基础上比较了不同冲击条件下夹层板的抗冲击性能.

成都市域快轨减振措施效果分析

为评价市域快轨的减振效果,以成都市域快轨18号线某圆形盾构隧道为例,选取了线路条件基本相同的相近断面,对双层非线性减振扣件、减振垫浮置板、钢弹簧浮置板3种减振措施及对应普通道床断面进行现场测试,研究市域快轨减振措施的减振效果。通过对实测数据进行时域、频域和1/3倍频程分析,得到不同减振措施和普通断面的隧道壁最大Z振级(VL_(Zmax)),并对比得到不同减振措施的减振效果;通过对测点的隧道壁振动加速度级及地面振动进行1/3倍频程分析,得到振动的传播衰减情况。结果表明:3种减振措施都有减振效果,双层非线性减振扣件减振效果为7.3 dB,减振垫浮置板的减振效果为16.2 dB,钢弹簧浮置板的减振效果最好,达到了19.7 dB。

城轨交通下不同扣件参数对钢弹簧浮置板振动响应影响研究

钢弹簧浮置板轨道具有较好的结构稳定性,能够承受地铁列车的运行冲击和乘客的集中载荷,确保地铁站台的安全性和稳定性。文章以常见的地铁B型车及钢弹簧浮置板轨道为例,基于有限元仿真模型与多体动力学仿真模型,根据扣件不同参数工况下,对浮置板的振动响应进行了仿真分析。结果表明:扣件刚度对轨道系统的振动影响非常大,扣件刚度过小会影响轮轨系统的稳定性和安全性。通过增加扣件的阻尼,可以减少振动的幅值和能量,从而降低浮置板轨道的加速度响应,提高系统的稳定性和舒适性。

中碳27SiMn弹簧用板材开发

文章介绍了弹簧钢板27SiMn新产品生产工艺流程及相关的工艺参数。通过合理的轧后冷却参数设定,得到了产品需要的组织,该组织保证了产品的力学性能。用户使用情况表明,充分利用包钢现有的装备,采用合理的工艺参数,在原料及铁水都满足要求的情况下,生产出的27SiMn弹簧钢板性能良好,其抗拉强度不小于800 MPa,延伸率不小于19%。此外,加热炉的气氛对含硅中碳钢的表面脱碳层有重要影响,还原性气氛和加热炉内微正压操作使27SiMn弹簧钢板表面脱碳层只有国标GB/T 1222—2016要求的24%。

温度场下功能梯度圆锥壳-环板振动特性分析

针对功能梯度圆锥壳-环板组合结构振动问题,本文采用一阶剪切变形理论和Rayleigh-Ritz法分析了温度场下组合结构的振动特性。组合结构位移变量采用谱几何法来表征,考虑材料参数与温度相关并引入人工边界弹簧建立了组合结构振动特性分析模型。数值算例中,通过将文中求解结果与文献解和有限元法结果进行对比验证了模型的正确性,进而分析尺寸、材料、温度和连接位置等参数对结构振动特性的影响。研究结果表明:组合结构基频随厚度增加而增加,随着幂律指数、半顶角和温度场参数增加而降低,随环板内径和连接位置变化会呈现非单一变化趋势。

高速动车组轴箱内置式转向架复合材料板弹簧技术研究及应用

针对轴箱内置式转向架一系悬挂结构横向空间尺寸相对较小的特点,为了保证高速动车组良好的动力学性能,文章设计、开发了新型的一系悬挂系统,采用了转臂定位+上置复合材料板弹簧结构,速度等级可达400km/h。对其进行了仿真分析和台架试验,并将其安装在试验转向架上进行了滚振试验和整车的线路动力学性能试验测试。结果表明,复合材料板弹簧强度和性能指标均达到了设计要求,为高速动车组的轻量化、全包覆减阻设计等提供了新的技术思路。

航天用T9A-D弹簧表面离子液体镀Al工艺研究

针对弹性金属材料在表面电镀处理过程中易发生析氢现象,进而降低材料的安全稳定性,产生氢脆隐患,采用离子液体镀Al技术在T9A-D弹簧和同材质试片的表面进行改性处理,并对离子液体镀Al弹簧和试片进行形貌表征和相关性能研究。研究发现:宏观上,离子液体镀Al层连续、均匀、致密、色泽一致;微观上,Al镀层晶粒大小均匀,排列致密,无缺陷产生,截面上镀层与基体间结合良好,界面分明,无空隙,镀厚介于8.91~11.20μm,镀厚均匀。经盐雾实验测试,96 h无白色腐蚀产物出现,336 h无红色腐蚀产物出现,耐蚀性良好。经过氢含量测试,弹簧基体氢含量无增加趋势,弹簧镀Al后无氢脆倾向。弹簧镀铝前、后力值波动小于1.8 N;经划格法检测,镀Al层与弹基体间结合力良好,无脱落现象。

一种主螺栓孔清洗装置的研制

提出一种主螺栓孔清洗装置的研制方案和系统构成,对该清洗装置的基本功能及关键技术进行了理论研究。对清洗装置的行走状态,以及清洗组件和定位干燥组件升降模组进行了分析,分析结果表明,该装置可正常行走且不打滑、可完成升降模组的升降操作。提出一种新型自适应定位系统,该清洗装置通过接近开关感应清洗位置实现粗定位,再利用定位干燥筒的导向定位段实现精定位;支架组件始终提供一个径向拉力,车架组件受拉力有向中移动的趋势,但由于侧轮作用将始终与法兰外圆贴紧,从而实现清洗装置的完全定位。对精定位后的误差进行了分析,清洗组件轴线偏差不超过0.3453mm,满足要求。提出利用弹簧片对清洗刷进行限位和复位的方法,并对其设计参数进行仿真优化分析,结果表明,当弹簧片厚度取0.4mm时可有效清洗螺孔。

航天用高强度弹簧镀锌工艺替代方案研究

[目的]高强度弹簧是常用于为导弹空气舵、弹翼展开锁定提供驱动力的零件,通常采用高强度钢制造,以镀锌作为其表面防护手段,但该工艺过程存在氢脆导致弹簧脆性断裂的风险。[方法]分别对高强钢进行镀锌、镀锌镍合金、达克罗涂覆和离子镀铝,对比了不同镀(涂)层的厚度、结合力和耐蚀性,以寻找镀锌替代方案。[结果]达克罗涂覆、离子镀铝和镀锌镍合金都属于无氢脆或低氢脆表面处理工艺,但更推荐采用镀锌镍合金代替高强钢镀锌工艺。[结论]选择合适的表面处理工艺能够在一定程度上避免高强钢弹簧氢脆断裂问题。

基于Abaqus数值模拟厚板冲压件回弹影响因素研究

以厚板V形件为研究对象,采用Abaqus对其成形过程进行了数值模拟及参数分析,并利用正交试验对各参数对厚板回弹的影响程度进行了分析。结果表明:改变V形件R角、凹模开口宽度W、成形角度及模具与板材之间的摩擦系数,V形成形件的回弹会发生明显的变化,通过适当的参数组合,可显著减小V形件成形后的回弹数值,提升成形精度。

CPG Human Motion Phase Recognition Algorithm for a Hip Exoskeleton with VSA Actuator

Due to the dynamic stiffness characteristics of human joints, it is easy to cause impact and disturbance on normal movements during exoskeleton assistance. This not only brings strict requirements for exoskeleton control design, but also makes it difficult to improve assistive level. The Variable Stiffness Actuator (VSA), as a physical variable stiffness mechanism, has the characteristics of dynamic stiffness adjustment and high stiffness control bandwidth, which is in line with the stiffness matching experiment. However, there are still few works exploring the assistive human stiffness matching experiment based on VSA. Therefore, this paper designs a hip exoskeleton based on VSA actuator and studies CPG human motion phase recognition algorithm. Firstly, this paper puts forward the requirements of variable stiffness experimental design and the output torque and variable stiffness dynamic response standards based on human lower limb motion parameters. Plate springs are used as elastic elements to establish the mechanical principle of variable stiffness, and a small variable stiffness actuator is designed based on the plate spring. Then the corresponding theoretical dynamic model is established and analyzed. Starting from the CPG phase recognition algorithm, this paper uses perturbation theory to expand the first-order CPG unit, obtains the phase convergence equation and verifies the phase convergence when using hip joint angle as the input signal with the same frequency, and then expands the second-order CPG unit under the premise of circular limit cycle and analyzes the frequency convergence criterion. Afterwards, this paper extracts the plate spring modal from Abaqus and generates the neutral file of the flexible body model to import into Adams, and conducts torque-stiffness one-way loading and reciprocating loading experiments on the variable stiffness mechanism. After that, Simulink is used to verify the validity of the criterion. Finally, based on the above criterions, the signal mean value is removed using feedback structure to complete the phase recognition algorithm for the human hip joint angle signal, and the convergence is verified using actual human walking data on flat ground.

一种宇航轴向电涡流阻尼器的研究设计与试验

相比于传统阻尼器,电涡流阻尼器具有结构简单、寿命长、非接触、无摩擦、无磨损等优点[1],在振动控制领域方面未来具有很好的应用前景。在电涡流阻尼器设计时,最关键的阻尼器特性需要在永磁体厚度、导体材料及导体长度等体积和重量约束条件下不断优化迭代获得的最优结果才有意义。本文针对某宇航领域使用的阻尼器任务需求,采用Ansoft软件二维瞬态磁场分析和结构约束条件,提出一种空间结构紧凑的双弹簧片结构电涡流阻尼器方案,并重点分析对永磁体厚度、导体材料、导体长度以及铜磁间隙等相关参数与阻尼系数之间的变化规律,获得阻尼系数最优的阻尼器,同时进行了弹簧片形状和刚度设计。最后,根据相关理论分析和设计后采用半功率带宽法获得阻尼器的阻尼比、一阶固有频率和阻尼系数,并通过了刚度试验和寿命试验,最终符合任务要求。

石墨密封组件波形弹簧回弹仿真性能分析

该文采用ABAQUS搭载动力显式计算仿真法,对GH738波形弹簧的成形以及卸载回弹进行研究后发现,在设计总高为8 mm,波数N=3的波形弹簧如采用基于原高度所设计的液压模,回弹量为2.165 mm。峰谷过渡段区域在卸载后所表现出的回弹量相比波峰更大,而波峰波谷在回弹后依然保持部分弯曲,这是由于过渡段塑性变形区面积更小所致。此外,波簧的回弹量与板材厚度息息相关,随着厚度的增加,成形过程中表现出更大的回弹量,这是由于截面厚度增加导致弹性区变大,从而引起卸载过程中的回弹增加。

T10A材料磁电机弹簧片断裂原因分析

通过对T10A材料弹簧片外观形貌、化学成分分析、力学性能、显微组织、扫描电镜断口形貌观察,并结合一定的热处理工艺试验进行分析,确定了弹簧片断裂原因。结果表明,T10A材料回火脆性是导致弹簧片外场发生批次性断裂的根本原因。