高转速下薄壁球壳应力应变分析

在球转子外面嵌套一个厚度为1～2mm的球壳,使延期解除保险时间为球壳转正时间与球转子转正时间之和,可以延长球转子最小解除保险时间。球壳上开有一圆弧形槽,在高转速下,开槽处与其保险件离心销相互作用,可能使球壳开槽处产生变形,从而影响球壳的解除保险运动。针对这一情况,利用有限元仿真软件ansys／ls—dyna对球壳的解除保险运动过程进行仿真,分析球壳开槽处应力应变。结果表明,球壳开槽处根部有微小变形,但并不影响球壳的解除保险运动过程。     

强化体厚壁球壳的弹塑性分析

前言受内压作用的厚壁球壳是很多工程中(特别是化工及军事工业等)经常应用的结构件,因此,很多学者曾研究过厚壁球壳受准静态或冲击内压作用时的弹塑性准静态或动力     

薄壁球壳受刚性平面压缩的连续变形测量

建立了非接触光学测量实验系统,对薄壁球壳受刚性平面压缩的连续变形及失稳行为进行了实验研究。实验以理想弹塑性材料制成的薄且壁厚均匀的乒乓球为压缩对象,采用透明石英玻璃板作为刚性平面,用相机透过玻璃板采集清晰的散斑图像。然后利用具有非接触、全场、高精度等优点的三维数字图像相关(3D-DIC)技术对与刚性平面接触的乒乓球表面的连续变形进行直接测量,同时利用二维数字图像相关技术结合压力传感器得到对应的力-位移关系。实验研究表明,基于3D-DIC方法测量三维表面变形场,实现了对受刚性平面压缩的乒乓球表面从局部压平阶段到轴对称屈曲阶段,进而演化到非轴对称屈曲阶段等力学行为的可视化。实验结果表明,对乒乓球半径的测量精度可达0.5%,利用Abaqus有限元方法得到的结果与实验结果非常吻合,验证了所提方法的有效性。     

不同壳厚聚苯乙烯/氧化铈复合磨料的合成及其抛光特性

以表面带负电荷的聚苯乙烯(Polystyrene,PS)微球为内核,采用液相工艺合成不同壳厚的聚苯乙烯/氧化铈(PS/Ce02)核壳包覆结构复合磨料,并用透射电子显微镜、场发射扫描电子显微镜、激光拉曼(Raman)光谱仪、热重示差扫描量热仪和动态光散射仪等手段对样品进行表征.用原子力显微镜观察和测量抛光表面的微观形貌、轮廓及粗糙度,考察复合磨料壳厚对硅晶片热氧化层抛光性能的影响.结果表明,所制备的PS/Ce02复合磨料呈规则球形,粒径在200～250 nm,壳厚在10～30nm.化学机械抛光结果显示,PS/CeO2复合磨料对硅晶片热氧化层表现出良好的抛光特性,且复合磨料壳厚对抛光表面粗糙度和材料去除率具有较大影响.经壳厚为20 nm的复合磨料抛光后晶片表面在5μm×5 μm范围内粗糙度平均值和方均根值分别为0.196 nm和0.254 nm,材料去除率为568.2 nm/min.     

汽车驱动桥壳的有限元法分析及提高强度措施

汽车的驱动桥是车辆运行中提供动力和承载力的主要构件。其桥壳的设计和生产质量的优劣将影响车辆的安全性和实用性。对桥壳的设计和模拟实验的关键环节作了阐述,介绍了桥壳有限元分析方法和提高桥壳强度措施。     

核电站一回路冷却剂主泵铸造不锈钢泵壳不规则壁厚的测量

主要介绍了核电站一回路冷却剂主泵铸造不锈钢泵壳不规则壁厚的测量方法,分为粗加工前的余量确认测量和精加工完成后的精确测量两个阶段。详细介绍了样板测量、激光跟踪仪测量的具体工艺。     

商用车驱动桥壳强度和模态的有限元分析

根据汽车振动及有限元理论,建立驱动桥壳动态分析的力学模型。利用UG建立某型商用车驱动桥壳三维几何实体模型,并将该模型与AN-SYS Workbench进行协同仿真,对桥壳进行强度分析,以及在自由状态和预应力状态2种条件下的模态分析,并对结构进行改进优化。其计算结果可为商用车驱动桥壳的结构设计,优化和轻量化以及疲劳寿命预测提供理论依据,具有重要意义。     

基于ANSYS Workbench的商用车驱动桥壳结构强度分析

以某商用车驱动桥壳为例,运用三维CAD软件UG建立三维几何模型,导入到ANSYS Workbench后再用其对桥壳进行各工况下的最大应力、变形值进行有限元分析,分析结果表明桥壳的结构设计合理,为驱动桥壳的设计和试验提供参考依据。     

土压平衡盾构机盾壳的应力分析及改进

根据土压平衡盾构机的工作地质环境,分析计算盾壳结构在实际工作中所承受荷载类型及大小,结合盾壳的设计原则,确定盾壳结构应力分析需设置的边界条件;对方案结构进行合理简化处理,采用Ansys有限单元法对盾壳进行应力分析,计算分析过程采用8节点壳单元用以提高分析精度和计算效率,根据相应工况下计算结果给出盾壳结构补强及缓解消除应力集中的解决措施,为土压平衡盾构机盾壳设计及分析提供技术参考。     

基于ANSYS的球壳开孔接管区应力分析

球壳开孔接管区的应力高且分布状况复杂。利用ANSYS软件,通过获取应力分布云图及线性化处理提取的各类应力,探讨了过渡圆角半径对球壳开孔接管区应力的影响。结果表明,球壳与接管连接处存在明显的应力集中。采用圆角过渡可以降低应力集中系数。只有圆角半径较大时,应力集中系数才会显著降低,并且主要是降低了其中的弯曲应力和峰值应力。当圆角半径增加到一定程度,应力集中系数降低极其缓慢。结果为工程实际中球壳开孔接管区圆角半径的选取提供借鉴。     

机载光电平台球罩的视轴指向误差

摘要:机载光电平台光学镜头前的通光窗口,多选用内外球心重合的等厚球形玻璃球罩。球罩在加工过程中产生内外表面球心不重合,会给视轴指向精度带来附加误差。本文根据光路图推导出了产生这种误差的数学表达式,分析了内外球心偏离对视轴指向精度的影响。实验结果表明,实测数据与数学推导结果吻合得很好。当某型号球罩的内外表面球心沿视场中心线的偏离达到0.26mm时,45视场处的视轴指向误差实测值达到0.075,超出了0.029（0.5mrad）的允许值。为了将球罩加工误差带来的视轴指向偏差减小到0.017（0.3mrad）,内外球心偏离必须控制在0.10mm以内。     

异形真空室壳体的结构强度分析

异形真空薄壳结构在航天、航空产品中的应用越来越广泛,基于减重和可靠性考虑,需要对这一类承受负压的压力容器进行结构强度分析和优化设计。首先应用基于经验的规则设计方法对该结构进行了强度校核。进一步,利用有限元分析软件HyperMesh、Ansys对该异形壳体建立了整体有限元模型。通过分析设计,证明该结构应力分布合理,并采用参数设计方法得到最优壁厚。从结果来看,基于经验的方法和基于有限元分析的方法得到的强度结果接近,但后一种方法不仅能够给出应力、应变的分布云图,而且在优化设计方面的选择也更加灵活。提到的设计方法对该类负压容器的设计具有一定的借鉴作用。     

Nonlinear bending response of laminated composite spherical shell panel with system randomness subjected to hygro-thermo-mechanical loading

In the present paper, the effect of random system properties on transverse nonlinear central deflection of laminated composite spherical shell panel subjected to hygro-thermo-mechanical loading is investigated. System properties such as material properties, thermal expansion coefficients, hygro-contraction coefficients, load intensity and lamina plate thickness are taken as independent random variables. The higher order shear deformation theory and von-Karman nonlinear kinematics are used for basic mathematical formulation. The elastic and hygrothermal properties of the composite material, which are considered to be dependent on temperature and moisture concentration, have been obtained based on micromechanical modeling. A direct iterative based C⁰ nonlinear finite element method combined with mean centered first-order perturbation technique (FOPT) proposed by present authors for the plate is extended for the spherical shell panel subjected to hygro-thermo-mechanical loading. The influences of random system properties with plate geometry, stacking sequences, support conditions, fiber volume fraction and temperature, and moisture distributions on the response of laminated spherical shell panel are examined in detail. The performance of the proposed approach is validated through comparison with those available in the literature and independent Monte Carlo simulation (MCS).     

球壳大开孔平齐接管补强设计方法评价

为了对球壳大开孔补强结构做出合理安全评价,利用我国现行标准中的补强方法,对D=500 mm,直径厚度比D/T=68、接管与壳体半径比r/R分别为0.5,0.6,0.7,0.8的球壳大开孔结构进行了补强计算,对补强后的球壳大开孔平齐接管结构,选择其高应力区的若干截面,按照"分析设计"方法进行了应力强度评定.结果表明,按极限分析法和压力面积法进行补强后的结构按分析设计可以通过;随着D/δ的增大,接管有效厚度与最小厚度之比g值随之增加;时多数大开孔情况,利用极限分析法补强后的结构更安全.     

Three-dimensional vibration analysis of thick, tapered rods and beams with circular cross-section

A three-dimensional (3-D) method of analysis is presented for determining the free vibration frequencies and mode shapes of thick, tapered rods and beams with circular cross-section. Unlike conventional rod and beam theories, which are mathematically one-dimensional (1-D), the present method is based upon the 3-D dynamic equations of elasticity. Displacement components u_r, u_θ, and u_z in the radial, circumferential, and axial directions, respectively, are taken to be sinusoidal in time, periodic in θ, and algebraic polynomials in the r and z directions. Potential (strain) and kinetic energies of the rods and beams are formulated, the Ritz method is used to solve the eigenvalue problem, thus yielding upper bound values of the frequencies by minimizing the frequencies. As the degree of the polynomials is increased, frequencies converge to the exact values. Convergence to four- digit exactitude is demonstrated for the first five frequencies of the rods and beams. Novel numerical results are tabulated for nine different tapered rods and beams with linear, quadratic, and cubic variations of radial thickness in the axial direction using the 3-D theory. Comparisons are also made with results for linearly tapered beams from 1-D classical Euler–Bernoulli beam theory.     

Three-dimensional vibration analysis of spherical shell panels subjected to different boundary conditions

This paper presents the elasticity solutions for free vibration analysis of doubly curved shell panels of rectangular planform. The vibratory characteristics of panels subjected to different boundary conditions have been obtained via a three-dimensional displacement-based energy formulation represented in the spherical coordinates. The p-Ritz method is employed for the solution of the problem. To validate the accuracy of the results and the ease of implementation of the present methodology, selected cases have been compared against the results existing in the literature.     

球壳大开孔内伸接管补强分析

球壳大开孔的补强设计中,相比于压力面积法和ASME法,有限法更直观和快速。建立一系列有限元模型,利用应力强度评定的方法,分析球壳大开孔内伸接管补强中接管内伸长度以及接管与球壳壁厚比t/T对补强效果的影响,结果表明:随着接管内伸长度的增长,局部薄膜应力逐渐减小,弯曲应力逐渐增大,一次应力加二次应力则先减小后又增大;随着接管厚度增加,局部薄膜应力、弯曲应力、一次应力加二次应力都逐渐减小,但减小的幅度下降;在模型下,接管内伸长度h2≤80mm、接管与球壳壁厚比1.5≤t/T≤2.7时,补强效果良好。     

Stress analysis of two-dimensional cellular materials with thick cell struts

Finite element analyses (FEA) were performed to thoroughly validate the collapse criteria of cellular materials presented in our previous companion paper. The maximum stress (von-Mises stress) on the cell strut surface and the plastic collapse stress were computed for two-dimensional (2D) cellular materials with thick cell struts. The results from the FEA were compared with those from theoretical criteria of authors. The FEA results were in good agreement with the theoretical results. The results indicate that when bending moment, axial and shear forces are considered, the maximum stress on the strut surface gives significantly different values in the tensile and compressive parts of the cell wall as well as in the two loading directions. Therefore, for the initial yielding of ductile cellular materials and the fracture of brittle cellular materials, in which the maximum stress on the strut surface is evaluated, it is necessary to consider not only the bending moment but also axial and shear forces. In addition, this study shows that for regular cellular materials with the identical strut geometry for all struts, the initial yielding and the plastic collapse under a biaxial state of stress occur not only in the inclined cell struts but also in the vertical struts. These FEA results support the theoretical conclusion of our previous companion paper that the anisotropic 2D cellular material has a truncated yield surface not only on the compressive quadrant but also on the tensile quadrant.     

球阀动水关闭应力分析

通过对球阀动水关闭有限元应力分析得出,球阀球体关闭约60°时,球阀承受的应力最大。因此球阀进行有限元分析时,不仅要考虑球体全关闭工况,还要考虑球体在60°状态时的应力水平。