GOALI: Investigation by Ultrasonic Methods of the Very long Life Fatigue Behavior of Structural Aluminum and Magnesium Alloys

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This project investigates the long life fatigue behavior of cast aluminum and magnesium structural alloys that find application in automotive and other technologies where lightweight materials are required. An objective of the study is to develop accurate models of crack initiation and short crack growth that can be used for predicting fatigue life. Very long lifetimes will be achieved in a practical timeframe using ultrasonic fatigue in which cyclic loading is applied at frequencies of approximately 20 kHz. The proposed method is far more cost effective than the conventional techniques that are extremely time consuming. The proposed program will examine the fundamental mechanisms responsible for the presence or absence of endurance limits in this important set of alloys. A significant effort will be focused on the potential use of ultrasonic fatigue techniques as a viable alternative or replacement for more conventional testing methods, especially where critical fatigue lives are in the very long life regime. This proposed GOALI program would continue a successful collaboration between the University of Michigan and the Ford Research Laboratories (FRL) of Ford Motor Company. The co-PI will co-advise a PhD student on this project. The educational impact of this work lies in close contact of the graduate students with the industrial counterpart through summer internships as well as the research direction by the co-investigator from Ford.This project provides an opportunity to graduate research students and university personnel to work with industrial counterparts at the Ford Motor Company in developing cast aluminum and magnesium alloys with very long fatigue life. The results of the study will benefit not only automotive industry but also technologies that require lightweight fatigue resistant metallic alloys. The research will establish new techniques of characterizing very long fatigue lifetimes that find many practical applications by taking advantage of the expertise and facilities at the academia and industry.