Mechanical behavior of elastomers under cyclic loading and aggressive environments
Principal Supervisor and Project Leader
Dr. Andri Andriyana
Co-Supervisors
Prof. Dr. A.S.M.A. Haseeb, Dr. Mohd Ra e Johan
Department of Mechanical Engineering, University of Malaya
50603 Kuala Lumpur, Malaysia
A three years Ph.D. position is available at the Department of Mechanical Engineering, University of Malaya, Kuala Lumpur, Malaysia. The research fund is immediately available for the rst year and extendable for the next years based on performance. We are looking for a candidate who is capable of and interested in performing high quality research on the Mechanics of Elastomers.
Research Description
During the last decade, major advances have been achieved in the development of biofuels as alternative source of energy. The corresponding progress is mainly motivated by a variety of environment, political and economic concerns over the use of conventional energy sources such as gasoline and diesel fuel. The introduction of biofuels, derived from plant materials, is placing additional demands on the material compatibility. Indeed, changes in fuel composition often create many problems in rubber seals, pipes, gaskets and o-rings in the fuel system. Hence, durability in service of industrial rubber components becomes a critical issue.
Many factors are known to in uence the durability of rubber components including mechanical loading history, environment, rubber formulation and constitutive response. Since many aspects of fatigue failure remain incompletely understood, the study on the above factors is crucial at least for the following two reasons: to develop durable rubber components and to better predict their fatigue failure. In the majority of studies involving fatigue of rubber, only the fatigue behavior in room (non-aggressive) environment is investigated. However, considerably fewer studies which explicitly deal with the fatigue failure analysis of rubber in aggressive en-
vironments are available. Indeed, most of works focus on the change of rubbers properties whenever exposed to aggressive environments without directly relating them to fatigue behavior.
The present research can be regarded as a rst step toward an integrated durability analysis of industrial rubber components exposed to aggressive environments, e.g. oil environment in biofuel systems, during their service.
In this view, the understanding of the mechanical response of rubbers under cyclic loading has an important role. In the rst part of the work, the emphasis will be laid on the establishment of experimental database. Di erent types of rubber are considered, including Natural Rubber (NR), Nitrile Rubber (NBR), Fluorocarbon Rubber (Viton) and Chloroprene Rubber (CR). The e ect of biofuel environments on the mechanical responses such as viscoelasticity, stress softening (Mullin's e ect), hysteresis and volumetric strain (compressibility) will be investigated. The second part of the work consists in developing a continuum mechanical model to capture the
aforementioned responses. Here, the formulation is restricted to mechanical problem. Only isothermal processes are considered and thermal variables such as temperature and entropy are neglected.
The evolution equation corresponding to a particular irreversible process, e.g. volumetric damage, will be phenomenologically derived by considering the experimental
database and the principle of the thermodynamics of irreversible processes. Finally, the proposed model will be implemented into a nite element code in order to simulate the response of industrial rubber components.
This research will be conducted in a strong collaboration with Ecole Centrale de Nantes and Ecole Nationale Sup erieure d'Arts et M etiers de Bordeaux in France and with Institut Teknologi Bandung in Indonesia.
Applicants and Salary
Applicants should have earned a Master's degree in Mechanical/Materials Engineering or in closely related eld. The minimum English pro ciency of 5 for IELTS or 550 for TOEFL is required for applicants whoserst language is not English. Preference will be given to candidates having basic knowledge in Continuum Mechanics and Mechanics of Polymers. The monthly salary is RM 1,700 and can increase gradually each year up to RM 2,000 based on performance. Applicants should send by email a complete curriculum vitae, copies of graduate/undergraduate certi cates and transcripts, proof of English pro ciency and two references to following address andri.andriyana@um.edu.my. Screening of applications begins immediately and will continue until the position is lled.
Contact and Information
Dr. Andri Andriyana
Department of Mechanical Engineering
University of Malaya
50603 Kuala Lumpur, Malaysia
Phone: +60 3 7967 5254 Fax: +60 3 7967 5317
Email: andri.andriyana@um.edu.my
Website: http://mechanical.eng.um.edu.my/andriyana
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