Natural frequencies of vibration of a class of solids composed of layers of isotropic materials

In a recent paper, the Ritz method with simple algebraic polynomials as trial functions was used to obtain an eigenvalue equation for the free vibration of a class of homogeneous solids with cavities. The method presented is here extended to the study of a class of non-homogeneous solids, in which each solid is composed of a number of isotropic layers with different material properties. The Cartesian coordinate system is used to describe the geometry of the solid which is modelled by means of a segment bounded by the yz, zx and xy orthogonal coordinate planes and by two curved surfaces which are defined by fairly general polynomial expressions in the coordinates x, y and z. The surface representing the interface between two material layers in the solid is also described by a polynomial expression in the coordinates x, y and z. In order to demonstrate the accuracy of the approach, natural frequencies are given for both a two- and three-layered spherical shell and for a homogeneous hollow cylinder, as computed using the present approach, and are compared with those obtained using an exact solution. Results are then given for a number of two- and three-layered cylinders and, to demonstrate the versatility of the approach, natural frequencies are given for a five-layered cantilevered beam with a central circular hole as well as for a number of composite solids of more general shape.     

叶切面最大厚度数值计算与应用

以叶切面最大厚度的数值计算方法为基础,探讨叶切面最大厚度计算的计算机实现,介绍叶切面厚度数值计算法的应用实例.     

双丝杠驱动机构同步分析

介绍了双丝杠驱动机构工作原理,论述了双丝杠运动产生不同步的原因以及如何判定与解决同步问题。     

膨胀套导向机构的设计

通过分析膨胀套在实际使用产生滑移受阻现象、卡死现象原因的实质,并在分析产生问题原因的基础上提出了改进措施即：增加导向机构。     

一种涡旋压缩机径向随变机构的设计

详细介绍了运用随变原理设计的一种新型径向密封机构的结构特点,工作原理及主要参数的确定方法,该机构可补偿由于涡旋体加工精度不高而造成的功率损失,适用于涡旋压缩机的批量生产。     

Specific features of operation of electrostatic microgenerators of energy

Specific features of operation of one- and two-capacitor microelectromechanical converters (MEMC) of energy of mechanical microscopic vibrations into electric energy with a modulated electrode-gap magnitude and with allowance for the mutual influence of electrical and elastic forces are analyzed, and the characteristics of these two devices are compared. The main factors restricting the increase in MEMC power are demonstrated to be the effects of “collapsing” and the condition of conservation of positive rigidity of the system. Expressions for estimating the limiting MEMC parameters are derived. The possibility of electrical energy generation in the presence of “real“ sources of wide-spectrum microscopic vibrations is considered.     

两种仪表功能合理性评述

本文以某些积算和双笔记录仪产品为例说明由于仪表功能设计的不合理或选型不当，影响了仪表的正常使用，制造厂和用户应关注这类问题。     

Method of implementation of the positive gradient of mechanical properties of triboengineering materials

Modern methods of implementation of the rule of positive gradient of mechanical properties are considered; this rule was formulated by I.V. Kragelskii and its application serves to minimize the friction and wear of solids. The given methods include the application of coatings with the method of finishing antifricton abrasion-free treatment; application of new metal-cladding lubricating materials; and creation of a nanostructural state of the surface iron nitride layer by nitriding steel with a positive gradient of hardness normal to the surface.     

串联混合动力牵引车蓄电池SOC的监测

文中提出了基于安时法计算混合动力电动牵引车蓄电池已用电量，在求出当前蓄电池荷电状态的基础上，利用根据能量守恒模型计算出的蓄电池SOC进行荷电状态校正，采用80C196KC加上相应的感应器来实现。实验表明，该方法测出的蓄电池荷电状态比较准确，有较高的精度。     

我校工业设计教育改革初探

针对目前市场对工业设计人才的需求,本文论述了我校在工业设计教育方面的改革措施,着重介绍了我校工业设计教育在软件和硬件方面所进行的一系列的改革。     

某型号飞机起落架支柱减振筒内壁腐蚀原因分析

飞机起落架减振支柱在飞机起落和滑跑时,吸收撞击能量,对飞机安全起降的意义重大.减振筒是减振支柱中的重要部件,本文从工艺流程、理化分析、外场使用和腐蚀机理分析等方面,对减振支柱减振筒内壁的腐蚀原因及危害进行了综合分析,并提出了相应措施.     

某型汽车减振器异响成因分析及技术对策

对汽车减振器的异响成因进行了分析,并提出技术对策。     

大型港口机械钢结构细部处理问题的研究

大型港口机械钢结构细部结构处理问题研究,以卸船机为主要研究对象,基于板壳理论,采用有限元法,梁壳单元混合建模,对卸船机的细部钢结构进行分析,并得到细部结构处理问题的意见和建议。     

镍铬接触对接触电阻失效原因分析

描述了用于K型热电偶回路中的镍铬接触对在电连接器的振动过程中发现接触电阻变大的失效现象,从接触电阻的理论构成和失效接触对的实物状态进行原因分析,通过更换绝缘体材料、固定接触对及更换接触对等方式进行试验验证,确定主要原因。针对分析结果,通过降低表面粗糙度、提高接触压力、涂覆固体膜润滑剂和调整接触对固定机构等方式,解决了镍铬接触对在振动过程中的接触电阻失效问题。通过一系列的试验,总结了避免镍铬接触对失效的关键措施。     

微机械系统建模与仿真技术研究

简要分析了微电子机械系统建模仿真的原因,指出了微电子机械建模仿真需要克服的四个方面技术难题,即尺度效应、开发快速的表面力计算方法、多物理场耦合分析、宏模型的建立,为微电子机械系统的建模仿真指明了研究方向.详细分析了微电子机械系统建模仿真的技术关键,多物理场耦合计算的理论方法和器件及系统宏观模型的建立,介绍了用于MEMS系统级模拟仿真的宏模型建立的几种方法,最后结合硬件描述语言VHDL-AMS提出了建立微电子机械系统模型实现系统级模拟的方法.     

自动摊铺机主交互模块的硬件设计

介绍了自动摊铺机控制系统的原理和结构;在此基础上,详细介绍了主交互模块的硬件设计。整个主交互模块可以划分成五个部分：主控制器、LCD液晶显示功能、专用PVC键盘功能．通信功能和电源部分。为了提高系统的可靠性．采用了一些抗干扰措施。     

一起造船门式起重机减速器断轴事故分析

造船门式起重机起升机构减速器出现高速轴断轴的情况较为少见,分析事故原因有利于起重机的安全使用.文中以某造船厂一台造船门式起重机发生的减速器断轴事故为例,依据其设计图纸和实际受力情况,结合轴的力学、断口形貌和材质等方面进行分析,研究断轴发生的原因.该方法可以有效判断该类起重机事故原因,可为其它类型起重机事故分析提供借鉴.     

载重汽车变速器齿轮的可靠性优化设计

以载重汽车变速器的台架实验数据的可靠性分析为基础，对变速器齿轮进行可靠性优化设计，使得各档齿轮的可靠性及承载能力都有显著提高，从而满足了对变速器高可靠性的要求。     

某卫星转播车方舱减重设计

对某型卫星转播车方舱的装载要求进行分析,结果证明,必须对方舱舱体的质量进行严格的控制,在不影响整舱强度的条件下,采取各种方法,尽量将方舱质量减到最轻。本文从方舱的舱板、舱门及孔口和舱体拼装等几个方面,对可能采取的减轻质量的方法进行了分析,对方舱所用型材、拼装结构和涂胶量进行优化、减重分析和处理,结果可满足对整车的功能性要求和质量限制。     

Effect of Impregnation of Iodine Complex on Friction of Anodic Oxide of Aluminum

Polyvinyl pyrrolidone-Iodine complex (PVP-I) molecules were impregnated into the anodic oxide of an aluminum disk specimen. It was rubbed against a silicon nitride ball specimen using a ball-on-disk type friction test rig. Over the limited range of parameters studied (load: 0.2-1.0 N, sliding velocity: 0.6 mm/s, and sliding distance: 1-7 m), the coefficient of friction decreased to a value as low as 0.01 from values of 0.3 to 0.7 for the anodic oxide surface. Single-crystal iodine rubbed against silicon nitride showed a coefficient of friction of 0.1. The low coefficient of friction is attributed to the thin PVP-I film on the relatively hard anodic oxide. The mechanism of coefficient of friction reduction is the same as that of a thin soft film on a hard substrate.