Date on Master's Thesis/Doctoral Dissertation

5-2014

Document Type

Master's Thesis

Degree Name

M. Eng.

Department

Mechanical Engineering

Committee Chair

Bradshaw, Roger D.

Subject

Harbors--Management

Abstract

The Harbormaster Command and Control Center (HCCC) project provides mobile platforms intended to control harbor operations. The main component of the HCCC is a double-expandable shelter mounted on a 5 ton military flatbed truck. Kentucky Trailer Corporation manufactured a baseline shelter using standard materials (aluminum, steel, plywood, etc.) and also considered alternate designs using composite materials (carbon fiber laminates, glass fiber laminates, composite sandwich configurations, etc.). Two faculty members and several graduate students in the Department of Mechanical Engineering at the University of Louisville participated in this effort, primarily in terms of material selection, structural analysis, and design approaches. This thesis presents one portion of that work. This consists of a finite element model (FEM) of the HCCC using standard materials. This model was constructed to match the design proposed and later built and delivered by Kentucky Trailer. The thesis also presents two structural analysis simulations performed using the HCCC FEM. The HCCC FEM was built using ANSY Mechanical APDL. This software utilizes text-based “input files” to build, analyze and post-process the HCCC FEM entirely without user assistance. The author generated these input files to create the HCCC FEM structure using 3D beam elements, layered shell elements, and point mass elements. This approach represented a simplification to eliminate the need for more computationally intensive 3D solid elements; it also provides a simpler approach for changing the model as design changes occur. For example, the thickness of an aluminum plate in the HCCC FEM model is represented as a number that can be easily changed; for a 3D solid element model, revisions would involve changing solid model entities such as volumes and areas followed by remeshing. This is feasible in a small model but impractical in a large complex model such as the HCCC FEM. The HCCC FEM is constructed in a modular manner, with different models representing the roof, sides, rear and front, floor and both expandable sections. These various submodels are joined together using constraint equations to cause identical displacements and rotations along common boundaries between models. This also permitted scenarios such as analysis with the expandables retracted or expanded. Contact elements are used to simulate support of the HCCC FEM along is bottom by a rigid boundary simulating the truck bed carrying the HCCC. The HCCC FEM is a nonlinear model due to both the contact elements and the ability to solve in cases of arbitrarily large displacement needed for dynamic analysis. Two analyses using the HCCC FEM are presented. The first is a static analysis under various constant inertial (acceleration) loads to demonstrate that the structure is worthy for air transport using a C-17 aircraft. The second is a dynamic analysis simulating the structural response during a rail impact; this occurs when the HCCC is mounted on a rail car which then collides with another rail car. Both analyses were beneficial in demonstrating that the HCCC design performs sufficiently well in service.

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