棉纺精梳机钳板驱动机构动力学及有限元分析

为研究精梳机速度对钳板驱动机构各机件受力的影响及不同速度时钳板驱动机构各机件的选材方案,利用ADAMS软件得出了不同速度时一个工作周期内钳板驱动机构各机件的最大受力;利用Ansys有限元分析软件对钳板驱动机构各机件应力分布进行有限元仿真。结果表明：钳板驱动机构各机件连接副在一个工作周期内滑套与曲轴铰接处受力最大,滑套与滑杆处次之;钳板驱动机构各机件连接副的最大受力随着精梳机速度的增加而迅速增大,当精梳机的速度由500钳次/分钟增大到700钳次/分钟时,滑套与曲轴铰接处的最大受力增加了92.73%。从钳板驱动机构运行的安全性及选材的经济性两方面考虑,得出了精梳机速度分别为500、600及700钳次/分钟时各机件最合适的选材方案。     

激振室变位机组筋板对故障原因及改进措施

压路机激振室采用机器人自动化焊接,对筋板组对精度要求较高,筋板组对精度差,焊枪在寻位、焊接过程中容易出现撞工件现象.通过改变变位机与工件装夹方式,提高筋板组对精度,实现了程序的普遍适用性,提高了焊接质量和工作效率.     

大型机床工作台的动态性能研究及结构优化

设计了用于大型落地镗铣床的新型工作台,利用ANSYS对工作台整体进行结构优化,根据可去除材料的分布云图,得到了工作台内部筋板的布置以及筋板上出砂孔的位置.对基本筋格单元进行变量的动态优化,研究了筋格结构参数对筋格固有频率的影响及筋格相关参数对工作台整体的影响,再次优化后得到理想的工作台筋格结构.优化后的工作台能减轻质量、提高刚性及动态性能.     

一种简易自动化模切机设计

重点介绍一种简易自动化模切机的结构设计。通过设计升降板、限位夹板、伸缩气缸、导向套以及限位环等机构,实现不同材料模料的模切,同时可以更换模切板,切割不同的厚度模料,大大增加了其实用性。     

大型数控铣床床身结构的动态特性分析

以数控铣床床身为研究对象,运用结构动态设计原理和有限元法,依据零件的振型特点,研究了不同筋板型式和筋板厚度对床身动态性能的影响,通过比较选用适宜的筋板型式以提高其动刚度.     

横向框架式液压机新机架结构设计

介绍了一般框架式压机机架的结构形式.提出了在横向框架式压机上梁和侧支柱处增加筋板的方法,提高压机机架强度和刚度,并对有无筋板的压机进行了分析比较,计算结果显示,其增加筋板后的机架强度和刚度有显著提高,满足压机的生产使用要求.     

液压挖掘机连杆开裂原因及改进方法

正1.开裂现象某型号30t级多台挖掘机均出现铲斗连杆(以下简称连杆)开裂故障。该连杆用于连接铲斗缸和铲斗,是挖掘机作业时的重要受力部件。挖掘时,铲斗缸产生的推力通过连杆传递到铲斗上,连杆承受较大的压力。卸土时,铲斗自身质量及斗内粘接的土壤对连杆产生较大的拉力。由此可见,连杆承受较大的交变载荷。连杆受力如图1a所示。该型挖掘机连杆下端销套与铲斗连接,上端销套与铲斗缸活塞杆连接。中间连接部分为16mm厚的筋板,两侧用22mm厚钢板弯曲成弯板,筋板和弯板材料均为Q345B型钢,与上、下端销套焊接在一起。连杆结构及开裂部位如图     

薄壁扇形筋板挤压成形开裂抑制及翻转展宽策略

通过对大高厚比扇形筋板挤压成形机理进行数值模拟和物理实验,明确了扇形筋板局部变形不协调和角部应力集中是筋板角部产生开裂的主要原因。提出采用应力转移法在筋板成形初期提前预制局部切口,有效改变筋板内部拉应力分布形态,使筋板与侧壁的连接处拉应力由原有的120 MPa降低到50 MPa甚至更低。实验与模拟分析证明,预制切口可释放筋板自身变形约束,使筋板变形以切口为中心分界,左侧部分筋板向左侧面内弯曲,右侧部分筋板向右侧面内弯曲。得出在小拉应力作用下依靠筋板的面内弯曲可大幅度增加筋板长度的结论。     

基于有限元的落地镗铣床滑枕结构设计

为完成四川省德阳市某机械制造有限公司委托开发数控落地镗铣床的项目,从根本上提高TX6916落地镗铣床的动态性能和市场竞争力。针对滑枕内部筋板结构形式,利用有限元法分析了米字型筋板、十字型筋板和X型筋板三种不同筋板结构形式下滑枕的静、动态性能。在选定筋板形式条件下根据外壁板厚度、筋板厚度和内筋板厚度对固有频率的灵敏度分析,选择优化设计变量改进滑枕结构,对改进的结构进行有限元分析并与原有结构相比较,改进结构在静、动态性能都有显著提高。     

机床T型床身结构的筋板布置型式研究

针对某型号磨床的典型T型床身结构,研究内部筋板的布置型式.基于有限元分析方法,以V轨水平方向的平均变形、床身整体的应变能、床身质量及1阶固有频率为评价指标,对若干种不同筋板布置的床身结构性能进行分析比较.研究结果表明:筋板布置型式对床身的静动态特性具有较大的影响,纵、横组合筋板型式的传统床身抗弯抗扭性能较好,能够满足一般的机床加工精度,且制造简单,所以广泛采用;斜置型式的筋板抗弯和抗扭性能都比较好,适用于长度大、抗弯刚度较低的床身;纵、斜组合筋板型式因抗弯刚度和抗扭刚度都较高,适用于重载荷且床身又宽又长的大型机床.     

金刚石串珠锯荒料车的轻量化设计

运用SolidWorks和ANSYS Workbench对金刚石串珠锯荒料车设备进行结构设计和轻量化设计。通过改变荒料车的槽钢结构,观察荒料车的静态特性情况,得出了荒料车的优化结构。在AWE优化环境中,应用DOE实验设计方法,以荒料车槽钢尺寸为设计变量,同时控制质量、受力、变形等多个目标因子,对荒料车进行轻量化处理,最终获得了综合指标趋向最好的荒料车结构。     

Optimal design of stiffened laminated plates using a homotopy method

The use of a homotopy method is demonstrated for optimal design of a stiffened laminated plate for maximum buckling load. Instead of obtaining a single optimum, the homotopy technique generates in a single computer execution an entire family of optimum designs with a given parameter. In the present application the parameter is set to the total structural weight, and the optimal designs are obtained as a function of the weight of the laminated plates. It is seen that the number of simultaneous buckling modes of optimum plates is increased as the total weight is increased. So for low weights the optimal design starts with unimodal design and for higher weight the optimal design becomes bimodal, trimodal, and finally it becomes tetramodal.     

均匀化理论在多孔板结构优化中的应用研究

多尺度均匀化理论自从上世纪 70年代产生以来 ,就被认为是确定复合材料当量性能的一种不可替代的方法。本文将多尺度均匀化方法应用于基于有限元分析的多孔板结构优化设计中 ,简述了求解当量板有效弹性常数的均匀化理论 ,在此基础上 ,建立了基于有限元分析的多孔板结构优化流程 ,编写了FORTRAN程序 ,并将其与AN SYS软件相连接 ,完成了一个多孔板结构的优化设计 ,所得结果表明 ,它能够满足工程应用的需要 ,并为多孔板结构设计提供了一种新思路     

大型汽轮发电机定子端部绕组的动态优化设计

将大型汽轮发电机定子端部绕组及支承简化为连续锥壳——板组合结构。在ANSYS平台上设计了几何建模和模态分析的参数化程序,建立了定端结构的参数化动态仿真模型,以支承板的数量及位置、锥壳的半锥角为设计变量,进行了定端结构动特性的灵敏度分析和动态优化设计。通过大量计算分析得出了最佳结构型式为支承板均布且数量为17、锥壳的半锥角为24.6°。这种定端结构型式具有良好的动态特性,且安装制造方便,为300 MW和600 MW大型汽轮发电机定子端部绕组的固定提供了重要的设计手段和依据。     

Metal sandwich plates optimized for pressure impulses

Survival of a plate against an intense, short duration impulsive loading requires the circumvention of failure modes, including those associated with excessive overall deflection and shear-off at supports and webs. All-metal sandwich plates have distinct advantages over comparable weight monolithic plates, especially for intense water loadings. A recently developed mechanics of dynamically loaded sandwich plates by N. A. Fleck and V. S. Deshpande is extended and modified to address the problem of the minimum weight design of plates of given span that must sustain a uniformly distributed impulsive wave in air or water environments. Requirements for core crushing strength and energy absorption are discussed, as are conditions governing shear-off of the face sheet. Dimensionless parameters governing optimal designs are identified. Specific results are presented for plates with square honeycomb cores outlining trends for the best performance that can be achieved and the optimal distribution of mass between faces and core. Optimally designed sandwich plates can sustain water shocks that are two to three times as large monolithic plates of the same mass and material. The model is used to discuss a number of issues relevant to the design of effective metal sandwich plates, including differing requirements for air and water environments, face sheet shear-off resistance, the role of core strength, and the relation between small-scale tests and full-scale behavior.     

Investigation of laser-welded titanium and stainless steel specimens using digital radiography methods

Specimens of ??titanium-titanium?? and ??titanium-12X18H10T steel?? welded joints that were obtained using laser radiation were investigated. When ??titanium-12X18H10T steel?? welded joints were formed, a copper plate was used as the intermediate insert. The digital computer radiography method using phosphorous image plates was used to study specimens; images were read out from image plates using an HD-CR 35 laser reader produced by Durr NDT. Fuji SR and Kodak SO-170 image plates were used in the experiments. The relative contrast sensitivity of X-ray images of specimens that was obtained experimentally was 1?C1.5% at exposures that were two to three times lower than for conventional radiography on an X-ray film. Defects with openings of > 0.1 mm were detected.     

Grillages of least weight—Simply supported boundaries

In previous papers, kinematic optimality conditions were derived for grillages of maximum strength and maximum stiffness as well as fibre-reinforced plates of least fibre volume and then a general method was given for deriving optimal solutions for any clamped boundary. In this paper rules for deriving rigorous analytical optimal solutions for any simply supported boundary are presented.     

Optimal design of stepped circular plates with allowance for the effect of transverse shear deformation

Presented herein is a canonical exact deflection expression for stepped (or piecewise-constant thickness) circular plates under rotationally symmetric transverse loads. The circular plates may be either simply supported or clamped at the edges. As the plates may be very thick or certain portions of the optimal design may become rather thick, the significant effect of transverse shear deformation on the deflections cannot be ignored. This effect was taken into consideration in accordance to the Mindlin plate theory. Based on the analytical deflection expression, necessary conditions are derived for the optimal values of segmental lengths and thicknesses that minimize the maximum deflection of stepped circular plates of a given volume. These optimality conditions are solved using the Newton method for the optimal segmental lengths and thicknesses. Local minima are observed for this nonlinear problem at hand and they may pose some difficulties in getting the solutions. The shear deformation effect increases the plate deflections, but interestingly it affects the thickness variation marginally.     

基于多条激光线的钢板表面缺陷三维检测方法

将一激光器投射出的多条线型激光垂直向下照射钢板表面,用面阵CCD摄像机采集这些激光线的图像.根据标定的结果可将图像坐标转换为空间坐标,从而可以得到钢板表面的高度坐标.通过这种方式可以检测钢板表面的三维缺陷,并获取缺陷的深度信息.通过对实际钢板缺陷进行验证,采用该方法计算的深度值与实际值非常接近.     

Plastic analysis of perforated plates for orthotropic yield criteria

The concept of an equivalent orthotropic material is used in evaluating the collapse loads for perforated plates. Uniformly loaded circular plates are investigated. Limit pressure solutions are obtained for both the simply supported and rigidly built-in edge conditions. Statically admissible radial and circumferential bending moment fields are found and the associated velocity fields are shown to be kinematically admissible. Numerical results are given in dimensionless form covering arbitrary plate geometries over the entire range of material orthotropy.These solutions are quite useful in the plastic analysis and design of perforated plates used as pressure vessel heads, tube sheets, reactor core support plates and the like. Perforated plates have considerably higher effective yield strengths when subjected to equi-biaxial loading than when subjected to loading of arbitrary biaxiality and orientation with respect to the penetration pattern. Thus, the equivalent orthotropic plastic material concept is ideally suited to the analysis of such plates. The resulting limit load pressures are substantially lower than the values obtained using isotropic Tresca yield criterion based on the yield strength for equi-biaxial loading. The results are substantially higher than the values obtained using the maximum isotropic Tresca yield condition falling entirely within the orthotropic yield surface.