Role of friction in the thermal development of ultrasonically consolidated foils and continuous fiber reinforced metal matrix composite tape
Date
2011
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Publisher
University of Delaware
Abstract
Ultrasonic consolidation (UC) is a low temperature bonding process which utilizes interfacial friction to promote bonding. Current research in the field of UC possesses a gap between theoretical predictions and actual processing temperatures; closing this gap allows for increased process control. This thesis seeks to develop and execute a model capable of predicting the thermal development during the UC of foils and continuous fiber reinforced metal matrix composite (MMC) tapes. To achieve this a thermal model has been developed that utilizes a frictional work flux term containing an experimentally determined, process dependent, friction coefficient, μ. Friction coefficients were found to vary between 0.1 and 0.8 depending on material pairing and process settings. When compared to infrared (IR) temperature measurements, a constant friction coefficient lead to model predictions of temperature accurate to 15% on average, whereas a process dependent friction coefficient had an average error of 7%. A process dependent friction coefficient provides more consistent results, and lower maximum errors (21% versus 52% for a constant μ), when a wide array of process settings may be employed. There are several applications for the model developed in this thesis such as targeting a specific temperature to allow thermally sensitive materials to be processed, or to retain a heat treated state, additionally, the simulated temperature profile could be used as an input to diffusion or mechanical models.