Durability Assessments of Motorcycle Handlebars 2005-01-0801

To investigate fatigue failure of motorcycle handlebars, fatigue analysis and durability experiments are conducted in this study. The finite element software, MSC.Nastran, was used to obtain the stress distribution of a handlebar subject to loadings in various directions. The results of FEM analysis were compared with those of static test to obtain optimum applied loading direction in the durability test. The strain history of the handlebar was measured when a motorcycle traveled on the Belgium (Pave) Road. The applied loading history in the durability test was obtained with remote parameter control technique. Three methods including “traditional S-N approach”, “BS 5400 approach” and “BS 5400 with Gurney thickness modification approach” were used to analyze the fatigue life of the handlebars. Rainflow cycle counting method and Miner’s damage accumulation rule were applied. FEM results show that when the loading angle of the actuator is 26° from the horizontal, a crack is produced where the handle was welded to the main pipe. This coincides with the test result in full vehicle simulation. The traditional S-N approach and BS 5400 standard approach cannot give a satisfactory result for fatigue life prediction. On the other hand, the BS 5400 standard with the Gurney thickness modified approach gives a satisfactory result. The difference between the predicted results and the experimental results was within an acceptable range of 2.5 times. It means the BS 5400 standard with the Gurney thickness modified approach could be used to assess the durability of motorcycle handlebars.