Date of Award

8-2013

Level of Access

Campus-Only Thesis

Degree Name

Master of Science (MS)

Department

Civil Engineering

Advisor

Roberto A. Lopez-Anido

Second Committee Member

William Davids

Third Committee Member

Vincent Caccese

Comments

The objective of this research is to characterize the experimental response and to provide documentation for the use of composite materials in modular marine construction; by using and developing mechanics-based modeling tools in the prediction of performance of secondarily bonded joints, quantifying the effect of surface treatments used, and comparing the validity of coupon and component level test methods for determining tensile strength. Properties of the substrate and resins are obtained through coupon scale experimental analysis. These properties are then used in mechanics-based modeling and finite element analysis to predict the performance of transverse joint designs for modular construction. The transverse joint designs and baseline non-joint samples along with stiffener joints and their associate baseline non-joint samples were fabricated independently at component level single panel scale and tested in tension. These same members were then fabricated as a unit at mock-up fabrication scale to reflect final construction conditions and tested to determine effects of manufacturing conditions on their properties. All composites fabrication was performed by a Navy contractor using standard practice.

Investigation results concerning fabrication methods for treatment of surfaces used in secondarily-bonded joint indicates the use of isopropyl alcohol over acetone as a surface cleaning agent, the use of white polyester peel ply over super release blue nylon peel ply due to better properties. Investigation results concerning experimentation methods for discriminating between surface treatment methods indicate the use of single sided lap shear as the choice for determining apparent strength comparisons, and the use of Mode I and Mode II experimentation for determining interlaminar fracture toughness characteristics. Research results concerning fire resistant resins indicate little advantage to changing to an explicitly fire resistant resin utilized in this study over the studied baseline. Research concerning novel sandwich composite panel joint tension experimentation methods indicates the methods studied are reliable for determination of characteristic tensile properties of the joints studied. Investigations concerning scale and manufacturing effects show decreased ultimate strength with increased size and manufacturing complexity. This decrease is modeled as a series of adjustment factors to be applied to reference strengths to achieve a nominal strength. Research concerning modeling assumptions indicates the acceptable use of these assumptions to predict ultimate strengths of the joints studied under loads studied. Finite element modeling research indicates the acceptable use for predicting both ultimate strength and failure modes of the joints studied. The testing and analysis have resulted in the availability of applicable fabrication methods and tools for the prediction of transverse joint performance in modular construction.

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