叉车座椅的振动特性研究

对叉车常用座椅的振动传递特性进行了测试,并分析了动态参数之间的关系,结合相关标准,阐述了与叉车振动相匹配的座椅性能参数的设计。     

座椅垂直振动传递特性的试验研究

本文阐述了开展对驾乘人员座椅传递特性试验研究的重要意义;介绍了座椅传递特性的试验方法。并应用此法对座椅的测试方法、座垫的结构材料、座椅的高度、靠背倾斜的角度以及输入座椅振动量级的大小等因素对座椅传递特性的影响进行了深入的试验研究,有助于人们充分认识和了解座椅传递特性的内在规律。这对座椅的动态设计、座椅的测试与评价,都有着重要的指导意义。     

基于Matlab／Simulink的振动压路村振动影响的研究

结合单钢轮振动压路机的振动模型和振动衰减公式，利用Matlab／Simulink软件仿真，得出了振动对驾驶员、压路机周围的人和建筑物的振动响应量。     

振动冲击锤动力学模型研究

振动冲击锤可简化为两自由度动力学模型进行研究，其非线性区间冲击力可用一次谐波描述，各项动力学参数可由运动微分方程组获得确定的解，为进一步研究振动冲击锤的动力学特性提供了基本的理论与方法。     

智能振动压路机建模与试验

针对一种新型智能压路机分析了调整激振力方向和振幅的原理，根据该机的结构特点分别建立了垂直方向和水平方向振动的动力学模型。通过试验数据分析，得到的动力学特性一般规律与理论分析结果一致，验证了模型的可行性。     

基于MATLAB／Simulink的冲击压路机牵引主机座椅悬架系统的研究

作为冲击压路机牵引主机主要减振环节之一的驾驶员座椅悬架系统,其振动特性不仅与整车的平顺性有密切的关系,而且还对驾驶员的身体产生直接的影响。针对冲击压路机牵引主机座椅悬架系统与车的刚性连接问题,分析振动对人体的危害以及对此问题进行研究的必要性,讨论引起座椅振动的主要原因,建立三自由度的座椅系统数学模型,并在MATLAB／Simulink中进行座椅动态特性仿真分析。分析表明：冲击压路机牵引主机座椅的舒适性尚需进一步改善,以减小振动对人体的伤害。     

翻斗车振动测试

陕西省金属结构厂研制生产的JS-1型建设牌翻斗车,在国内外用户中得到普遍的好评。尤其是新产品JS-lj型,增加了驾驶棚,自翻及机械回斗机构,驾驶员座椅上增添了减振器及弹簧、减少车辆振动,改善了劳动条件。为了了解该类车辆振动情况,西北农学院与厂方一起于80年12月至81年7月,对JS-1型,JS-lj型及进口的意大利P.G.S型,西班牙AUSI型四种翻斗车进行了振动测试。由于国家没有颁布正式的试验大纲,本试验的项目及要求,系根据试验条件研究制定的。一、测试方案及实施车辆在工作中由于地面的高低不平,发动机和传动系统的激励而引起的振动,是通过驾驶员的座椅而传递到驾驶员身上的。根据有关资料,决定人体对振动的反应有四个重要     

振动压路机五级减振系统分析

振动压路机是集振动的利用和控制于一体的典型机械。振动的控制即减振,更确切地说是隔振。目前绝大多数的振动压路机为三级隔振系统,即：第一级隔振──压轮框架与振动轮之间即振动轮减振器;第二级隔振──操纵台与压轮框架之间即操纵台减振器;第三级隔振──驾驶员与操纵台之间即座椅。 一般情况下,三级隔振系统完全能够满足人体及机器大部分零部件（一般处于一级隔振状态）对振动的承受要求,因为第一级隔振的效率可达９０％－９５％。然而,随着振动压路机吨位越来越大以及人们对驾驶舒适性要求的提高,三级隔振系统面临着严峻的挑…     

电梯轿厢水平振动模型

建立2自由度电梯轿厢水平振动模型，对电梯导轨的激励进行分析，用MATLAB／SIMULINK编制软件对振动模型进行仿真分析，为电梯水平振动分析提供了一种有效的模拟方法。     

振动压实系统动力学模型及其解析

振动压路机和土壤在振动压实过程中构成一个完整的振动系统，机械和土壤之间存在着复杂的动态相互作用，土壤特性影响机械的动态响应，机械参数则决定土壤的压实效果。因此，建立完整的并尽可能接近实际的动力学模型是研究振动压路机压实效果和动态特性的前提和基础。本文以双驱双振铰接式振动压路矶为例，建立振动压实系统的动力学模型。     

汽车驾驶室内烟头火灾的研究

通过模拟汽车驾驶室烟头火灾的情况,试验研究了不同的汽车沙发座椅面料阴燃的难易程度及特点,从而对汽车火灾的现场勘查及原因定性提供了证据支持。     

An effective approach to prediction of the collapse mode in automotive seat structure

Safety is an important issue in automobile design, in which the seat structure plays a crucial part. Engineering of the seat structure has a wide range of benefits for the manufacturer in the areas of cost savings and better design techniques. The seat in an automobile must not only be comfortable for the passenger, but must also be designed to protect the occupant from a wide range of impact situations. The seat structure in our advancing automotive world must also have a simple, lightweight design to keep down material and manufacturing costs. Despite the importance of seat structure design, many manufacturers do not have the time or money to perform an in-depth analysis of multiple different designs. The nonlinear behaviour of the seat structure forces engineers to use virtual prototyping and numerical analysis in its design. Use of a complex model and the long computation time of a numerical model drive up the cost and limit the turn around time in the production and design of an automobile seat structure.This paper proposes a cost-effective analysis of a seat system to ensure the safety of the occupants in the case of a frontal impact. In order to predict the major collapse mode of a seat structure in this scenario, the strength effectiveness of each component in the seat system is examined using a self-developed experimental procedure. To be sure of shear deformation of the inner track section of the seat structure, a detailed FE simulation is carried out, leading to an effective 2-D finite element method with plastic hinge to represent the major collapse mode. The simulation results are then compared with corresponding tests in order to verify their validity.     

非经典阻尼结构两种近似求解方法比较与分析

对于建筑结构的抗震研究通常要采用多自由度模型来进行分析和求解。对于多自由度结构体系往往运动方程是藕联的,给运动方程的求解带来不便。在大多数情况下结构的阻尼是非经典阻尼,本文采用强迫解耦法和瑞利阻尼来对运动方程进行解耦,从而将多自由度方程化为多个单自由度运动方程。最后通过算例对这两种算法进行比较、分析,找到计算相对比较简便且精度满足要求的方法。     

悬臂梁随机振动的最优控制

本文采用模态分析方法,导出了受控弹性悬臂梁的状态方程,研究了单振型单点控制模型,并求得其状态变量的方差与结构参数间的解析关系式。最后,对多振型多点控制模型进行了数值分析,并探讨了选择控制点个数和位置的方法。     

橡胶支座隔震结构计算模型与分析方法

详述了橡胶隔震支座的力学性能,包括竖向刚度、水平刚度及等效阻尼比各种理论公式或实际工程简化计算公式,并对隔震支座恢复力模型进行了分析,重点叙述了橡胶支座隔震结构计算模型,最后提出了对橡胶隔震支座研究发展的看法。     

水泥板打裂或打碎压稳后加铺沥青层结构分析

建立了水泥板打裂或打碎压稳后加铺沥青层结构l的三维有限元模型,通过对水泥板打裂或打碎压稳后加铺沥青层结构分析结果的比较,提出根据不同的道路状况以及周围环境采取相应的处理措施,得出"打碎压稳"处理后均匀性较好的结论.     

旧概念与新环境(八):洛克的“自由”

洛克的政治理论是英语文明主流,强调个人自由,认为私产是自由的保障,而保护私产是政府的主要职能。城市规划以公益名义约束私产,但在自由社会中,公益只可来自政治博弈,因此纷争不断。本文以区划法的公安权力去演绎在洛克式个人自由之下私利与公益的死结。结论是,中国应坚持土地产权国有。     

Driver and passenger exposure to aerosol particles in buses and trams in Helsinki, Finland

This study investigates commuter and driver exposure to aerosol particles in buses and trams in Helsinki, Finland. Particle number and PM_2.5 concentrations were determined in the cabin and the driver's compartment. In addition, the < 2.5 µm black carbon concentration was measured in the driver's compartment and PM_2.5 was collected for elemental analysis in the cabin. The measurements were repeated on two generations of buses and trams including two measurement days in each vehicle type. Fine particle number and mass concentrations in the driver's compartments were only slightly increased compared to Helsinki background air. Daily average ratios of number and mass to the background varied in range 0.8-4.3 and 1.0-2.9, respectively, both being the highest in the older bus type. However, the drivers were exposed to elevated levels of black carbon, which some studies have addressed to be strongly correlated with adverse health effects. The daily average ratio of black carbon to the background varied between 2.4 and 11.4. Additionally, the black carbon concentration had spatial variation. The drivers were exposed to higher peak concentrations of black carbon in downtown area. Particle concentrations were smaller in the driver's compartment than in the cabin. The newer technology in the newer model of the tram and bus seemed to decrease driver exposure to aerosol particles.     

带有地板辐射的座椅送风空调系统的节能分析

建立了带有地板辐射的座椅送风空调系统的模型，并进行了能耗模拟计算。计算结果表明，与无地板辐射的座椅送风空调系统以及普通的上送风空调系统相比较，该系统具有送风量小，更经济、更节能的特点。     

Isogeometric cohesive zone model for thin shell delamination analysis based on Kirchhoff-Love shell model

We present a cohesive zone model for delamination in thin shells and composite structures. The isogeometric (IGA) thin shell model is based on Kirchhoff-Love theory. Non-Uniform Rational B-Splines (NURBS) are used to discretize the exact mid-surface of the shell geometry exploiting their C¹-continuity property which avoids rotational degrees of freedom. The fracture process zone is modeled by interface elements with a cohesive law. Two numerical examples are presented to test and validate the proposed formulation in predicting the delamination behavior of composite structures.