Abstract—The kick boss and shaft assembly of a typical commercial motorcycle is a commonly encountered failure. The typical observation, kick boss becomes loose on spline and rotates freely on the shaft, as all teeth of splines are worned off. The kick slips over the kick shaft not generating the sufficient torque to start the, engine. Most common reason is the kick boss splines worn out decrease the depth of splines and/or the splines of the shaft worn out. The oblivious reason for this failure is the high shear stresses at contact zone. The work include, studying the geometrical feature of kick boss and shaft. Creating the CAD model of the kickboss and kick splines shaft assembly with various position of kick boss bolt so as to represented the actual possible engagement scenario between kick shaft and kick boss. Each of these CAD model is converted to FE model and is analyzed using commercial analyzing software. The empirical relations for the shear stress on spline were theoretically calculated using machine design handbook. The empirical relation shows as the contact coefficient as one of the important coefficient for finding the shear stresses. For a good spline with ideal contact it is four and may varied up to six as the spline are becomes misaligned/separated. The shear stresses varying values of contact coefficient were calculated and found to have increase as the coefficient increases. The finite element model were created for the various contact condition which were the analyze using FE for the above referred contact variation. The results are convergent with the prediction that the prime reason for failure is decreasing of contact with the loosening in use. The report describes the details of theoretical as well as FE analysis carried out to reach above conclusion.

Index Terms—Failure analysis, Kickboss, Kick splined shaft, Finite element method

Cite: Pradip G Lad, Yogesh L Yenarkar, and Deepak V Bhope, "Failure Analysis of Motorbike Kick Splined Shaft and Kickboss by Finite Element Method," International Journal of Mechanical Engineering and Robotics Research, Vol. 2, No. 4, pp. 307-315, October 2013.