All ETDs from UAB

Advisory Committee Chair

Charles A Monroe

Advisory Committee Members

Robin D Foley

Haibin Ning

Ian E Hosch

Laurentiu Nastac

Document Type

Dissertation

Date of Award

2017

Degree Name by School

Doctor of Philosophy (PhD) School of Engineering

Abstract

Cast iron is the most common as-cast materials used in present time. Various grades of cast iron have been developed by modifying process parameters to meet the property re-quirements. Destructive and nondestructive tests are routinely performed to maintain the integrity of the produced cast iron. Numerical and multiple linear regression models have also been developed to obtain mechanical properties from process variables such as chem-ical composition, cooling rate, liquid metal treatment. The applicability of property predic-tion models were studied by comparing predicted mechanical properties reported in pub-lished literature. Summary of the comparison is reported to guide cast iron producers to choose most appropriate model for their respective process variables. Nondestructive tests such as ultrasonic velocity measurement has been shown to differentiate between graphite shapes. Recently, use of acoustic resonant inspection, a nondestructive test, is also being explored in identifying cast iron nodularity variation and defective part identification. Resonant test of experimentally produced cast iron alloys of microstructural variation – graphite shape, size and matrix modification were inspected. Rectangular shaped samples were machined for comparison and to validate the usability of resonant inspection in identifying microstructural variation. Resonant frequency were found to identify graphite shapes and matrix variations. However, resonant frequency shift does not provide conclusive evidence in identifying the graphite size variation due to section size. The microstructure variation due to the location of casting sample compar-ative to the mold surface was shown to be identifiable by resonant frequency shift. A comparative study of available experimental methods – ping and ring, frequen-cy sweep, finite element simulation (FEA) methods and analytical solutions are done to verify the usability of each techniques in measuring and estimating resonant frequency of cast iron samples. The variation between different experimental methods to measure the first resonant frequency or the fundamental natural frequency is less than 1%. The analyt-ical solutions could be used to predict natural frequency of simple shape geometry. The FEA models is found to be useful in predicting resonant frequency of complex shapes. The accuracy of the prediction methods is shown to improve by using more accurate property data. A full factorial analysis of a brake rotor disc with elastic modulus, density and Poisson’s ratio was done and it was show the elastic modulus has the highest impact on resonant frequency as expected.

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