Failure analysis of non-circular composite bicycle chainring

Name: Zhorachaid Thanavarothon

LCSH: Burapha University.Faculty of Engineering

Abstract: Non-circular composite chainring shows interest in sport competition but two major drawbacks limits their use. Firstly, the optimized non-circular shape is not defined and therefore the effectiveness of the non-circular chainring is not proven from mechanical point of view. Secondly, composite non-circular chainring shows teeth failure during the life cycle. In this project, non-circular composite chainring is studied with the objectives of optimize the shape and the stiffness of the composite structure. Firstly, the non-circular shape is optimized to obtain the highest wheel torque. An analytical model is developed and the non-constant chainring radius is defined. Then, the optimized non-circular shape is used as composite chainring. An 11 plies of carbon/epoxy composite non-circular chainring is manufactured and quasistatic tests are performed. Results show only the failure of the chain. Due to the high cost of the experiments, numerical simulation is developed to analyze the chainring mechanical behavior and especially the teeth damage. The simulation is verified thanks to the experiments and it is used to optimize the chainring. Finally, the number of plies can be reduced to 9 plies in order to reduce the cost of the part. Moreover, lay-up is proposed to reduce the production time. Low velocity impact on composite structure can create large internal damage that can reduce strongly the failure strength. Therefore, low velocity drop test is carried-out to determine energy required to damage the teeth of an 11 plies carbon/epoxy non-circular chainring. Experimental results show that the required energy is larger than the chain impact energy. However, impact due to tool drop can still damage the part and teeth protection needs to be considered.

Burapha University. Library

Address: CHONBURI

Email: buulibrary@buu.ac.th

Name: Laurent Patrick Mezeix-Varagnat

Role: Principal advisor

Created: 2018

Modified: 2020-07-13

Issued: 2020-07-13

วิทยานิพนธ์/Thesis

application/pdf

eng

DegreeName: Doctor of Philosophy

Level: Doctoral Degree

Descipline: Mechanical Engineering

Grantor: Burapha University

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