基于ANSYS的塔机不同拉杆吊臂的力学性能研究

日趋发展的建筑行业要求塔机的起重幅度越来越大,促使塔机在双拉杆吊臂的基础上衍生出两种加撑杆式双拉杆吊臂。通过ANSYS构建线框模型,对比分析在相同典型工况、相同起重性能下3种拉杆形式吊臂的应力应变情况。结果表明,加撑杆的吊臂受力更均匀,更安全;另外从选配拉杆方面看,加撑杆固接式吊臂的可选拉杆截面最小。     

塔机吊臂拉杆的可靠性设计

对塔机吊臂的两个拉杆进行了可靠性设计。与安全系数设计法相比较,在两个吊点不变的情况下,为发挥材料的力学性能,两个拉杆在等应力条件下,重新确定塔帽的高度,然后对二拉杆进行可靠性设计,二拉杆可以节省40%的材料。     

永茂STT系列平头塔式起重机

永茂建机STT系列平头塔式起重机的技术性能非常适合我国大型建筑施工高空吊装的需要,其机构合理、使用安全,与带塔头和拉杆的传统塔机相比,吊臂和平衡臂力学模型简单明确,臂架和平衡臂本身即可保证自身的工作强度,特别适合多台塔机同时使用.     

塔式起重机的安全使用

二、塔机类型及主要参 塔机的分类和型号编制方法如下： 由于塔机的型号和规格较多、较杂,目前流行的水平吊臂型塔机虽已是主流,但旧式塔机也还存在,现行的标准对塔机所规定的分类方式也不是唯一的,使现行塔机在使用中存在许多混淆与模糊的观念。对此问题的理解及解释如下。     

100t铁路起重机箱形伸缩吊臂结构的模糊优化设计

对100 t铁路救援起重机箱形伸缩吊臂进行模糊优化设计。考虑强度、刚度、稳定性和几何参数约束的模糊性,以吊臂自重最轻为目标,吊臂截面参数为设计变量,建立了非对称模糊优化模型,采用最优水平截集法求解。应用混合离散变量优化的MDOD优化子程序和遗传算法,分别编写相应的优化程序进行计算,在传统优化的基础上使吊臂自重降低了9%左右。     

永茂STT系列平头塔式起重机

永茂建机STT系列平头塔式起重机的技术性能非常适合我国大型建筑施工高空吊装的需要,其机构合理、使用安全,与带塔头和拉杆的传统塔机相比,吊臂和平衡臂力学模型简单明确,臂架和平衡臂本身即可保证自身的工作强度,特别适合多台塔机同时使用。起升机构(LFV)变频调速机构调速范围宽、精度高、响应快、性能平稳。变     

塔顶变形对双吊点吊臂体系内力计算的影响分析

以双吊点桁架水平式吊臂结构为例,分析了塔顶变形对吊臂体系内力计算的影响.首先对臂架使用的刚拉杆或钢丝拉索进行了分析处理,给出吊臂在荷载作用下内力计算的模型,然后分析了在塔顶客观变形的影响下,双吊点桁架水平式臂架内力的变化情况,同时得到吊臂体系内力的变化与塔顶变形量、吊臂长度、吊点位置、吊臂拉杆夹角、塔顶的刚度及工况等因素有关,最后提出了双吊点吊臂内力计算时塔顶变形影响的计算方法.     

塔式起重机的使用与维护

1.塔机选型和对操作人员的要求 选择塔机的要求:塔机在覆盖范围内(即臂长、吊臂最小和幅度为最大时)的起质量、提升速度、塔机的独立高度、最大提升高度等技术参数,均需根据施工现场的实际情况和安全需要而确定.若所选的能力过大,将造成资源的浪费;反之,又会带来使用和安全上的问题.     

塔式起重机力矩限制器全力矩取矩中心的确定

在双吊点吊臂塔式起重机 (以下称塔机 )产品检验中 ,力矩限制器难以调整 ,目前常用的起重性能特性方程并不适用于该机型 ,因此应对其所选取矩的根部铰点进行修正。通常 ,确定塔机起重性能曲线的数学表达式即起重性能特性曲线方程为Ｍｅ=(Ｑ ｑ) (Ｒ -ｃ) ( 1)式中　Ｑ———幅度为Ｒ时所对应的额定起重量　ｑ———吊具系统重量　Ｍｅ———恒力矩 (常数 )　Ｒ———幅度　ｃ———吊臂根部铰点到回转中心的距离对于实际生产和设计过程 ,式 ( 1)给出的起重性能曲线对单吊点吊臂塔机而言是准确的。而对于双吊点吊臂塔机 ,由该式确定的起重性…     

吊管机吊臂结构有限元优化及研究

以ANSYS Workbench软件为工具,对吊管机吊臂进行三维实体建模、网格划分、载荷和约束处理,并对吊臂3种基本工况进行有限元分析。在保证吊臂安全性的前提下,选取吊臂截面的宽度、高度和厚度作为参数,以吊臂质量最小为目标进行有限元优化,优化后明显减轻了吊臂材料的消耗,为吊管机吊臂的设计和改进提供了理论依据。     

基于ANSYS的汽车发动机连杆有限元分析

采用ANSYS软件建立汽车连杆三维模型，并通过ANSYS软件对连杆进行应力分析，得到变形过程中的应力场、应变场分布，为进行发动机连杆的优化设计建立基础。     

Exact solutions for longitudinal vibration of rods coupled by translational springs

The objective of this paper is to present exact analytical solutions for longitudinal vibration of non-uniform rods with concentrated masses coupled by translational springs. Using appropriate transformation, the governing differential equation for longitudinal vibration of a rod with varying cross section is reduced to Bessel's equation or an ordinary differential equation with constant coefficients by selecting suitable expressions, such as power functions and exponential functions, for the area variation. The exact solutions for free longitudinal vibration of rods with varying cross-section are derived. The initial parameter method and the transfer matrix method are proposed to establish the frequency equation for the longitudinal vibration of two rods coupled by translational springs. The advantage of the proposed methods is that the frequency equation for two rods coupled by translational springs can be established in terms of a determinant of 2-order for any number of translational springs and concentrated masses. The proposed methods can be used to solve the problem of free longitudinal vibration of uniform and non-uniform rods with concentrated masses coupled by various translational springs, and thus to investigate the axial stiffness and mass distribution among the rods to alter the system's dynamic characteristics. A numerical example shows that the fundamental longitudinal natural frequency of two reaction towers coupled by a pipe calculated by the proposed methods is in good agreement with the full scale measured data, suggesting the proposed methods are applicable to engineering practices.     

振动棒磨机非线性振动试验研究

研究了用于超微颗粒制备的振动棒磨机振动系统的非线性,证明了散体激励与阻尼的时变性,讨论了碰撞质量的时变参数模型,为系统建模、分析和控制奠定了基础。     

Complete dynamic modeling and approximate state space equations of the flexible link manipulator

This work treats the problem of dynamic modeling and state space approximation for robotic manipulators with flexibility. Case studies are planar manipulators with a single flexible link together with clamped-free ends and tip mass conditions. In this paper, complete dynamic modeling of the flexible beam without premature linearization in the formulation of the dynamics equations is developed, whereby this model is capable of reproducing nonlinear dynamic effects, such as the beam stiffening due to the centrifugal and the Coriolis forces induced by rotation of the joints, giving it the capability to predict reliable dynamic behavior. On the other hand, in order to show the joint flexibility effects on the model dynamic behaviors, manipulator with structural and joint flexibility is considered. Thus, a reliable model for flexible beam is then presented. The model is founded on two basic assumptions: inextensibility of the neutral fiber and moderate rotations of the cross sections in order to account for the foreshortening of the beam due to bending. To achieve flexible manipulator control, the standard form of state space equations for a flexible manipulator system (flexible link and actuator) is very important. In this study, finite difference method for discretization of the dynamic equations is used and the state space equations of the flexible link with tip mass considering complete dynamic of the system are obtained. Simulation results indicated substantial improvements on dynamic behavior and it is shown that the joint flexibility has a considerable effect on the dynamic behavior of rotating flexible arm that should not be simply neglected. The effects of tip mass is proved to be increasing the elastic deformations?? amplitudes and increasing stability.     

组合柔性机械臂动力学模型参数识别

将柔性机械臂做成组合结构,利用结合面摩擦效应抑制柔性机械臂的振动。用单根叠层组合柔性臂与实体柔性臂的自由振动对比试验验证组合柔性臂具有优良的抑振性能。用弹簧摩擦副双折线模型和三次非线性弹性力模型建立组合柔性臂的动力学模型。根据组合柔性臂有限元仿真激振试验数据,确定组合柔性臂的形函数和动态恢复力滞迟回线。用动能等效原理、滞迟回线分解法和最小二乘法确定组合柔性臂的动力学模型参数。在Simulink平台上,编制弹簧摩擦副恢复力计算模块,解决含有记忆环节的柔性臂非线性微分方程的数值求解问题。经试验验证,用该模型参数识别方法确定的动力学模型能较准确地反映组合柔性机械臂的动力学性质,为组合柔性机械臂动力学建模、减振性设计提供有效方法。     

低真空环境下四极杆质量分析器灵敏度仿真研究

为了实现低真空环境下质谱仪的质量分析,提出了利用Langevin碰撞理论模拟低真空环境下离子运动轨迹的方法,该方法可以更准确地反映离子的运动状态。针对四极杆质量分析器,在COMSOL Multiphysics中搭建了适用于低真空环境的离子运动仿真平台。利用该平台仿真得到了低真空条件下,背景气体压强、离子质荷比、背景气体质量、离子初始能量、四极杆半径以及温度对四极杆质谱仪灵敏度的影响。仿真结果表明,随着压强升高,质谱仪灵敏度降低,通过改变离子操作模式,可以削弱由压强变化引起的灵敏度降低,这为低真空质谱仪的设计提供参考。     

大型电机主轴内孔加工的镗杆设计及ANSYS静态分析

主轴内孔加工技术的研究是大型电机研制的重要环节.文中首先根据项目要求提出了四种镗杆的设计方案并加以分析.然后根据四种方案进行了相应的有限元静态分析,分析结果表明方案四由于形成框架结构,且在镗杆尾部插有硬质合金棒,其刚性提高,静变形最小.     

十极场成分对四极质谱性能的影响

从理论上研究了十极场A5,以及少量六极场A3、八极场A4等高阶场的产生方法以及它们对线形四极质谱性能的影响。结果表明,可以通过改变组成四极质量分析器的电极对称性,如使用特殊形状的电极将少量的十极场等高阶物加入到四极场中。也可以通过使用4根直径不等的圆柱形电极将十极场加入到四极场中,但此时也会有少量的十二极场A6、十六极场A8、二十极场A10等产生。这些高阶场成分的存在将会影响四极质谱的性能,如使得线形四极质量分析器的第一稳定区图的顶部形状发生改变,进而影响四极质谱的质量分辨能力等。但少量的六极场和八极场有助于四极质谱质量分辨能力的改善。     

Point mass identification in rods

The possibility of applying the acoustic free-vibration method to diagnose rods with localized masses is considered. Calculation data of vibration frequencies of loaded and unloaded rods that were obtained using the proposed model and other author’s models are compared.     

Improvement of four anode rods ion source

In this work, an improved form of a saddle field ion source has been designed and constructed. It consists of four anode rods made from copper and two copper cathode discs. The two cathode discs are placed symmetrically on both sides of the four anode rods. The electrical discharge and output ion beam characteristics were measured at different pressures using argon gas. The optimum distance between each two anode rods was determined. Also the optimum distance between the four anode rods and any cathode disc was obtained. It was found that the optimum distance between each two anode rods equal to 6 mm, while the optimum distance between the four anode rods and any cathode disc equal to 16 mm, where a stable discharge current and maximum output ion beam current can be obtained. The effect of negative extraction voltage applied to both the extractor electrode and Faraday cup on the output ion beam current was studied. The sputter yield of copper and aluminum targets using argon ions of different energies was determined.