IJIRST –International Journal for Innovative Research in Science & Technology| Volume 3 | Issue 02 | July 2016 ISSN (online): 2349-6010 All rights reserved by www.ijirst.org 136 Vibrational Analysis of Bicycle Chassis Rahul J. Pawar Dr. Kishor P. Kolhe Department of Mechanical Engineering Department of Mechanical Engineering JSPM’s Imperial College of Engineering & Research, Wagholi, Pune-14, India JSPM’s Imperial College of Engineering & Research, Wagholi, Pune-14, India Abstract It is important to recognize that the design of any machine is an interdisciplinary process, involving aerodynamics, thermodynamics, fluid dynamics, stress analysis, vibration analysis, the selection of materials, and the requirements for manufacturing. The operation of any mechanical system will always produce some vibration. Our goal is to minimize the effect of these vibrations, because while it is undesirable, vibration is unavoidable. The result of excess vibration can vary from nuisance disturbance to a catastrophic failure. Bicycle chassis is a major component in a system. This work involves vibration analysis to determine the key characteristics of a bicycle chassis. The dynamic characteristics of bicycle chassis such as the natural frequency and mode shape were determined by using finite element (FE) method. Al material will replace the conventional MS material. Experimental modal analysis was carried out to validate the FE models. Predicted natural frequency and mode shape were validated against the experimental results. Finally, the modification of the updated FE bicycle chassis model was proposed to reduce the vibration, improve the strength and optimize the weight of the bicycle chassis. Tools used are catiaV5 for 3D modelling, Hypermesh for meshing, and Ansys for post processing. Keywords: Bicycle Frame, Weight Optimization, Design of Frame, Alternate Material _______________________________________________________________________________________________________ I. INTRODUCTION Most modern bicycle frames have the simple form. This shape emerged in about 1895 following several decades of vigorous development and evolution and has remained basically unchanged since that time. The need for low weight coupled with high strength and stiffness has lead to continuing trail and development of high performance material for racing bicycles. Thus in trial and error method is costly and slow, and intuition does not always yield reliable result. A promising solution is to turn a proven tool of structural engineering; the Finite Element Analysis method. The method used for modelling will be described and theoretical predictions of frame stresses will be compared with F.E.A result for some simple loading cases. This design has been the industry standard for bicycle frame design for over one hundred years. The frame consists of a top tube, down tube, head tube, seat tube, seat stays, and chain stays. The head tube of the frame holds the sheerer tube of the fork, which in turn holds the front wheel. The top tube and down tube connect the head tube to the seat tube and bottom bracket. The seat tube holds the seat post, which holds the saddle. The bottom bracket holds the cranks, which hold the pedals. The seat stays and chain stays hold the rear dropouts, which connect the rear wheel to the frame. [1] Riding a bicycle, and mainly at professional level, goes hand in hand with the improvement of state of the art technology. For instance, during a time trial the position of the cyclist is of big importance. For this reason, it is important how air resistance can be reduced. Tests have already been done in wind tunnels to search for the best position on the bicycle, eventually also small adaptations at the frame is possible.[1] This is only one aspect, also research for better gears, brakes, tires, wheels, etc. makes progress. All these aspects cause the cyclist to achieve better results. The main component on a bicycle is still the frame itself. Even if all the other aspects of the bicycle are of top quality, no top performance will be achieved without a frame of the highest quality.[7] The cyclist wants his bicycle to be light, stiff, durable, strong, nice looking, weather resistant and it must also be comfortable. The developer of bicycle faces a great challenge, because designing a frame which meets all these requirements is barely impossible. For example, stiffness and comfort are each other's opposite, though a compromise between both must be found. Depending on the used material for the frame, one or other aspect can be fulfilled better. The behaviour of the frame is of big importance for the perception on comfort of the rider.[2] Because, the better vibrations coming from the road are absorbed by the frame, the better the rider will perform. Vibrations which are not absorbed by the bicycle (frame) must be absorbed by the rider and this causes fatigue of the muscles and thus diminished performance. Research to the aspect of the dynamic behaviour eventually leads to a better frame, so one gets one step closer to the ideal bicycle frame.[7]