1、毕 业 设 计（论 文）外 文 参 考 资 料 及 译 文译文题目： MECHANISMS AND MACHINE THEORY 机构和机器原理 学生姓名： 学 号： 专 业： 所在学院： 指导教师： 职 称： 20xx年 2月 27日 外文资料MECHANISMS AND MACHINE THEORY1.Introduction to Mechanism：The function of a mechanism is to transmit or transform motion from one rigid body to another as part of the action of a
2、 machine. There are three types of common mechanical devices that can be used as basic elements of a mechanism.1、Gear system, in which toothed members in contact transmit motion between rotating shafts. 2、Cam system, where a uniform motion of an input member is converted into a nonuniform motion of
3、the output member. 3、Plane and spatial linkages are also useful in creating mechanical motions for a point or rigid body. A kinematic chain is a system of links, that is, rigid bodies , which are either jointed together or are in contact with one another in a manner that permits them to move relativ
4、e to one another. If one of the links is fixed and the movement of any other link to a new position will cause each of the other links to move to definite predictable position, the system is a constrained kinematic chain. If one of the links is held fixed and the movement of any other link to a new
5、position will not cause each of the other links to move to a definite predictable position then the system is an unconstrained kinematic chain,A mechanism or linkage is a constrained kinematic chain, and is a mechanical device that has the purpose of transferring motion and/or force from a source to
6、 an output. A linkage consists of links (or bars), generally considered rigid, which are connected by joints, such as pin Cor revolute) or prismatic joints, to form open or closed chains (or loops). Such kinematic chains, with at least one link fixed, become mechanisms if at least two other links re
7、main mobility, or structures if no mobility remains. In other words, a mechanism permits relative motion between its rigid links; a structure does not. Since linkages make simple mechanisms and can be designed to perform complex tasks, such as nonlinear motion and force transmission they will receiv
8、e much attention in mechanism study.Mechanisms are used in a great variety of machines and devices. The simplest closed-loop linkage is the four-bar linkage, which has three moving links (plus one fixed link) and four pin joints. The link that is connected to the power source or prime mover and has
9、one moving pivot and one ground pivot is called the input link. The output link connects another moving pivot to another ground pivot. The coupler or floating link connected the two moving pivots, thereby coupling the input to the output link.The four-bar linkage has some special configurations crea
10、ted by making one or more links infinite in length. The slider-crank (or crank and slider) mechanism is a four-bar chain with a slider replacing an infinitely long output link. The internal combustion engine is built based on this mechanism. Other forms of four-link mechanisms exist in which a slide
11、r is guided on a moving link rather than on a fixed link. These are called inversions of the slider-crank, produced when another link (the crank, coupler, or slider) is fixed link.Although the four-bar linkage and slider-crank mechanism are very useful and found in thousands of applications, we can
12、see that these linkages have limited performance level. Linkages with more members are often used in more demanding circumstances. However it is often difficult to visualize the movement of a multiloop linkage, especially when other components appear in the same diagram. The first step in the motion
13、 analyses of more complicated mechanisms is to sketch the equivalent kinematic or skeleton diagram. The skeleton diagram serves a purpose similar to that of the electrical schematic or circuit diagram .Organization movement analysis second step: Draws a graphic chart, is must determine the organizat
14、ion the number of degrees of freedom. Based on degree of freedom, but Italy refers needs certain independent inputs the movement number, by determined organization all components are opposite in the ground position. The people have thousands of different types conceivably the link motion gear. You m
15、ay imagine a bag containing massive link motion gear the component: Two pole groups, three pole groups, four pole groups and so on, as well as components, rotation, motion, cam follower, gear, tooth chain, chain wheel, leather belt, belt pulley and so on. (Sphere movement, screw vice-as well as the permission three dimensional relative motion other connections not yet includes, here, discusses in parallel planes merely plane motion). Moreover you conceivable put these components various types link motion gear possibility which forms in
