SYNTHESIS OF PLANER EIGHT BAR MECHANISM FOR FUNCTION AND PATH GENERATION

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GRD Journals- Global Research and Development Journal for Engineering | Volume 1 | Issue 12 | November 2016 ISSN: 2455-5703

Synthesis of Planer Eight Bar Mechanism for Function and Path Generation Ramanagouda C. Biradar Assistant Professor Department of Mechanical Engineering WIT, Solapur Deepak M. Kalai Assistant Professor Department of Mechanical Engineering DKTE, Ichalakaranji

Kashinath I. Swami Assistant Professor Department of Mechanical Engineering WIT, Solapur

Rahul B. Patil Assistant Professor Department of Mechanical Engineering WIT, Solapur

Mallesh Jakanur Assistant Professor Department of Mechanical Engineering WIT, Solapur

Abstract Linkages have an advantage of easily modifying their output by suitable adjustments compared to cams and geared mechanisms. But at the same time it is usually difficult to change the dimensions of mechanisms every time to do different tasks. Also we cannot synthesize exactly the necessary mechanism because of limitation of maximum precision points. This problem is addressed by using adjustable Crank-Rocker linkages that are capable of generating multiple paths with a simple adjustment of the length of the rocker guider. Little work has been done in the area of synthesis of adjustable four-bar and six bar linkages for function and continuous path generation, especially of adjustable crank-rocker linkages. The present work is an attempt to synthesize adjustable eight bar mechanism to overcome this difficulty. The link lengths are computed using Cheybychev’s spacing and Fruedenstein’s equations. A procedure is developed to compute the values of design variable which satisfies the input – output relationship. Analytical and programmable method is developed in Matlab to generate desired function and path. Keywords- Planar eight bar mechanism, Adjustable link, Fruedensteins method, Chebychiv spacing

I. INTRODUCTION The important and complementary area called kinematics synthesis, where mechanism is created to meet certain motion specification is touched upon only by a consideration of the simple aspect of planar linkage synthesis. Linkages include garage door mechanisms, car wiper mechanisms, gear shift mechanisms. They are a very important part of mechanical engineering which is given very little attention. Maximum application of mechanisms is found in mechanical systems. Although there are many phases in the design process which can be approached in a well ordered, scientific manner, the overall process is by its very nature as much an art as a science. It calls for imagination, intuition, creativity, judgment, and experience. Types of Synthesis Problems. Function Generation It is defined as the correlation of an input motion with an output motion in a mechanism. A function generator is conceptually a black box that delivers some predictable output in response to a known input. Example~ of function generation includes the automobile accelerator, the control stick in an aircraft, and the piston in an engine mechanism. Path Generation defined as the control of a point in the plane such that it follows some prescribed path. This is typically achieved with at least four bars, wherein a point in the coupler traces the desired path. No attempt is made in path generation to control the orientation of the link that contains the point of interest. However, it is common for the timing of the arrival of the point at particular locations along the path to be defined. This case is called path generation with prescribed timing and is analogous to function generation in that a particular output function is specified. Motion Generation (Rigid-body Guidance) defines locations through which the tracer point passes and the corresponding orientation of the coupler link at those rocations. Examples of motion generation include the power lift, gate on a truck, the lift mechanism on a dumpster truck, and the windshield wipers on an automobile.[1] Most engineering design practice involves a combination of synthesis and analysis. However, one cannot analyze anything until it is synthesized into existence.[3] The optimal synthesis model is set based on the positional structural error of the

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