固定式塔机基础稳定性校核

1。混凝土基础抗倾翻稳定性校核 据国标GB／T13752—92《塔式起重机设计规范》第4．63条规定,在已知塔机载荷和基础尺寸的情况下,应对塔机固定式基础抗倾翻稳定性校核验算（见图1）。     

混凝土泵车主动防倾翻控制技术

基于混凝土泵车工作原理与负载特性,建立了整机力学模型.通过理论分析,得到了泵车的倾翻条件与安全工作区域,并设计了安全系数计算模型.通过支腿压力、开度等实时反馈信息,基于安全系数计算模型,搭建了泵车主动分级防倾翻控制系统,实现任意工况下泵车作业的稳定性判断,并根据安全系数大小对泵车的执行机构进行主动分级控制,有效防止泵车倾翻.样机验证结果表明:主动防倾翻控制系统可以实时掌控泵车的安全状态,在不同的安全等级下准确地对臂架等执行机构进行主动干预,确保施工安全.     

倾翻力矩对轧机稳定性的影响

倾翻力矩的存在对轧机的稳定性会造成影响,主要表现形式是造成轧机倾翻。轧机在设计时需要考虑倾翻力矩的影响,在安装时需要考虑地脚螺栓的预紧力。通过理论计算了四辊轧机的倾翻力矩对扎及稳定性的影响及安装时需要的预防措施。     

隧道锚杆台车工作稳定性分析计算及仿真

为保证隧道锚杆台车在各种危险工况下工作时不出现失稳现象,以现有MT-11A型锚杆台车为依据,分别从最容易发生失稳现象的双臂水平伸出状态、双臂同时左摆至极限状态以及双臂同时右摆至极限状态下钻孔等几种工况出发,对锚杆台车工作时的倾翻趋势以及稳定性进行分析计算.得出在各种危险工况下的倾翻趋势以及稳定力矩与倾翻力矩的计算方法,获得相应工况下的失稳比和安全系数;同时利用SolidWorks Motion分析功能对各种工况下的稳定性进行动力学分析,获得了临界倾翻时所承受的最大外载荷.     

PRO/E在翻罐卷扬机设计中的应用

叙述了在翻罐卷扬机的设计中用PRO/E进行铁水罐的三维实体造型工作,并模拟了铁水罐的倾翻过程,进而精确地计算出了在这一进程中铁水罐地倾翻特性,为翻罐卷扬机地设计提供了准确地数据。     

新型悬挂起重机防倾翻装置的设计

介绍了新型防倾翻装置设计,即采用反滚轮在轨道下平面上运行的形式,不但能够实现防倾翻,而且解决了起重机在大车负轮压时正常运行的问题,论述了该装置的原理、结构及稳定性的验算方法,指出了设计新型防倾翻装置的注意点,具有实用价值,供同行业参考。     

一种新型轮椅机器人爬越楼梯过程倾翻稳定性分析

提出了一种采用新型变形履带机构的轮椅机器人,这种新型机构能够在主动张紧力控制的基础上配合"凸"形地形使履带构型产生"凹"形变。针对爬越楼梯这种典型的越障运动,给出了机器人构型变化规律以及乘坐者姿态描述方法,并利用Force-Angle方法通过系统质心计算以及危险倾翻边线判定得到了能够反映机器人爬越楼梯过程倾翻稳定性状况的倾翻稳定角。仿真分析了机器人在自身不同运动状态及乘坐者不同姿态等影响下爬越楼梯过程的倾翻稳定性变化情况。     

整体式倾翻叉承载能力计算

倾翻叉机构承载能力取决于油缸缸径和机构铰点的设计,而机构铰点的位置是由倾翻叉的倾翻角度等整体性能参数决定的。整车稳定性承载能力则需综合叉车起重系统前悬距等性能参数和倾翻叉机构水平重心等结构参数计算所得。     

一种可翻转星球探测车原型——先锋号

将星球探测车抗倾翻失效的方法总结为3类:改进移动系统结构方式、主动复位方式和被动适应地形方式。在分析各种解决方法存在问题的基础上,提出了一种可翻转探测车原型——先锋号,它四面都可着地行驶,以被动适应地形方式实现了抗倾翻失效的功能。     

一种可翻转星球探测车原型——先锋号

将星球探测车抗倾翻失效的方法总结为3类：改进移动系统结构方式、主动复位方式和被动适应地形方式。在分析各种解决方法存在问题的基础上，提出了一种可翻转探测车原型——先锋号，它四面都可着地行驶，以被动适应地形方式实现了抗倾翻失效的功能。     

Vibration of rectangular Mindlin plates resting on non-homogenous elastic foundations

This paper is concerned with the vibration behaviour of rectangular Mindlin plates resting on non-homogenous elastic foundations. A rectangular plate is assumed to rest on a non-homogenous elastic foundation that consists of multi-segment Winkler-type elastic foundations. Two parallel edges of the plate are assumed to be simply supported and the two remaining edges may have any combinations of free, simply supported or clamped conditions. The plate is first divided into subdomains along the interfaces of the multi-segment foundations. The Levy solution approach associated with the state space technique is employed to derive the analytical solutions for each subdomain. The domain decomposition method is used to cater for the continuity and equilibrium conditions at the interfaces of the subdomains. First-known exact solutions for vibration of rectangular Mindlin plates on a non-homogenous elastic foundation are obtained. The vibration of square Mindlin plates partially resting on an elastic foundation is studied in detail. The influence of the foundation stiffness parameter, the foundation length ratio and the plate thickness ratio on the frequency parameters of square Mindlin plates is discussed. The exact vibration solutions presented in this paper may be used as benchmarks for researchers to check their numerical methods for such a plate vibration problem. The results are also important for engineers to design plates supported by multi-segment elastic foundations.     

整体弹性关节刚度系数的计算

导出了整体弹性关节旋转和拉伸刚度系数的计算公式,为微型或纳米运动机构设计及其动力学研究提供了基本工具。     

Dynamic stability of a cantilevered Timoshenko beam on partial elastic foundations subjected to a follower force

This paper presents the dynamic stability of a cantilevered Timoshenko beam with a concentrated mass, partially attached to elastic foundations, and subjected to a follower force. Governing equations are derived from the extended Hamilton’s principle, and FEM is applied to solve the discretized equation. The influence of some parameters such as the elastic foundation parameter, the positions of partial elastic foundations, shear deformations, the rotary inertia of the beam, and the mass and the rotary inertia of the concentrated mass on the critical flutter load is investigated. Finally, the optimal attachment ratio of partial elastic foundation that maximizes the critical flutter load is presented.     

Vibration analysis of viscoelastic single-walled carbon nanotubes resting on a viscoelastic foundation

Vibration responses were investigated for a viscoelastic Single-walled carbon nanotube (visco-SWCNT) resting on a viscoelastic foundation. Based on the nonlocal Euler-Bernoulli beam model, velocity-dependent external damping and Kelvin viscoelastic foundation model, the governing equations were derived. The Transfer function method (TFM) was then used to compute the natural frequencies for general boundary conditions and foundations. In particular, the exact analytical expressions of both complex natural frequencies and critical viscoelastic parameters were obtained for the Kelvin-Voigt visco-SWCNTs with full foundations and certain boundary conditions, and several physically intuitive special cases were discussed. Substantial nonlocal effects, the influence of geometric and physical parameters of the SWCNT and the viscoelastic foundation were observed for the natural frequencies of the supported SWCNTs. The study demonstrates the efficiency and robustness of the developed model for the vibration of the visco-SWCNT-viscoelastic foundation coupling system.     

Non-linear dynamic analysis of shallow spherical shells on elastic foundations

The present study investigates the effect of Winkler-Pasternak elastic foundation parameters on the nonlinear dynamic response of shallow spherical shells. The values of foundation parameters ( and ) have been determined for the minimaximum central response of the shallow shells for both the clamped as well as simply supported immovable edge conditions. Donnell type partial differential equations governing the moderately large amplitude behaviour of shallow spherical shells resting on Winkler-Pasternak elastic foundations under step pressure loading, have been analysed. The space and time-wise integrations of governing equations have been carried out using Chebyshev series and Houbolt techniques, respectively. It is also shown that the present analysis can be extended to study the dynamic buckling of shallow shells resting on elastic foundations.     

Postbuckling of shear deformable laminated plates under biaxial compression and lateral pressure and resting on elastic foundations

Postbuckling analysis is presented for a simply supported, shear deformable laminated plate subjected to biaxial compression combined with uniform lateral pressure and resting on an elastic foundation. The lateral pressure is first converted into an initial deflection and the initial geometrical imperfection of the plate is also taken into account. The formulations are based on the Reddy's higher-order shear deformation plate theory, and including the plate-foundation interaction. The analysis uses a perturbation technique to determine the buckling loads and the postbuckling equilibrium paths. Numerical examples are presented that relate to the performances of perfect and imperfect, antisymmetrically angle-ply and symmetrically cross-ply laminated plates under combined loading and resting on Pasternak-type or softening nonlinear elastic foundations from which results for Winkler elastic foundations are obtained as a limiting case. The effects played by foundation stiffness, transverse shear deformation, plate aspect ratio, total number of plies, fiber orientation, the biaxial load ratio and initial lateral pressure are studied.     

索道建设中的冻土问题及其解决方法

介绍索道支架基础和设备基础在高寒地带遇到冻土时的施工情况,分析冻土开挖、基底处理以及混凝土浇注应该采取的方法和需注意的问题。     

Nonlinear bending of Reissner–Mindlin plates with free edges under transverse and in-plane loads and resting on elastic foundations

A nonlinear bending analysis is presented for a rectangular Reissner–Mindlin plate with free edges subjected to combined transverse partially distributed load and compressive edge loading and resting on a two-parameter (Pasternak-type) elastic foundation. The formulations are based on the Reissner–Mindlin plate theory considering the first-order shear deformation effect, and including the plate-foundation interaction. The analysis uses a mixed Galerkin-perturbation technique to determine the load–deflection curves and load–bending moment curves. Numerical examples are presented that relate to the performances of moderately thick rectangular plates with free edges subjected to combined loading and resting on Pasternak-type elastic foundations from which results for Winkler elastic foundations are obtained as a limiting case. The influence played by a number of effects, among them foundation stiffness, transverse shear deformation, loaded area, the plate aspect ratio and initial compressive load are studied. Typical results are presented in dimensionless graphical form.     

油气田用往复压缩机无固定基础安装的结构设计及应用

阐述了油气田用固定基础及无固定基础压缩机在橇体结构及安装方面的差异,根据压缩机橇体的结构特征进行了地基土层的承载力计算,并进一步对引起压缩机振动的动载荷进行了分析核算,提出了压缩机橇体结构及安装基础结构的设计建议。     

光轴任意取向的单轴晶体薄膜间的“菲涅耳公式”

给出了在光轴取向任意的一般情况下 ,光在两各向异性的单轴晶体薄膜间的反射、折射时所遵循的“菲涅耳公式”(界面间的折、反射系数 )的表达式 ,为晶体光学器件的设计和应用提供了重要的理论基础。