FORECAST VALIDITY OF ALUMINUM AND STEEL MECHANICAL PROPERTY TRENDS BASED UPON MICROHARDNESS BEHAVIOR
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Authors
Talarico, Phillip M.
Subjects
mechanical properties
radiation
climate
steel
aluminum
design
yield strength
weaken
exposure
radiation
climate
steel
aluminum
design
yield strength
weaken
exposure
Advisors
Kwon, Young W.
Date of Issue
2019-12
Date
Publisher
Monterey, CA; Naval Postgraduate School
Language
Abstract
Most metals used in naval applications are exposed to significant ultraviolet radiation and moisture; the most commonly constructed metals, steel and aluminum, are expected to lose their designed mechanical property integrity over time as a result. Multiple tensile specimens of steel and aluminum were created to undergo accelerated weather testing. Several periods of programmed Q-Lab Ultraviolet (QUV) testing were developed to produce comparable results to time exposure in the presence of high levels of radiation and moisture. Exposure was shown to decrease hardness properties in conjunction with the specimen’s calculated ultimate tensile strength for both materials. There was also preliminary evidence of depth of influence from cross-sectional test methods. Each of the three properties, hardness, tensile strength, and elastic modulus, were compared to studied microindentation software, which quantifies the relationship of indentation results to the actual tested mechanical changes. Modeling linear relationships for metal lifetime forecasts from hardness has been solidified by this study. Outcomes can be expanded upon with more elaborate finite element analysis if desired in future experimentation.
Type
Thesis
Description
Series/Report No
Department
Mechanical and Aerospace Engineering (MAE)
Organization
Identifiers
NPS Report Number
Sponsors
Funder
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Citation
Distribution Statement
Approved for public release; distribution is unlimited.
Rights
This publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. Copyright protection is not available for this work in the United States.