Date of Award

2021

Degree Type

Capstone Project

First Advisor

Dr. Bahram Nassersharif

Abstract

Water entry is a vast, unknown subject pertinent to the naval industry and the team set out to create a design to study it. Raytheon, a large defense contractor, is interested in understanding the forces felt on an object entering the water at different initial parameters across different nose cones. The team was tasked to investigate the peak impact of a cylindrical specimen, using g's as the metric for analysis. The problem definition intentionally left out specific target values and dimensions. The team decided to develop and test a design to determine how entry angle effects impact g's for the different nosecones.

The process started with the team producing 90 concepts until three were determined practical and effective through competitive analysis. The results were an Electromagnet, Fly Wheel, and Air Compressor. As the process of designing, ordering material, and assembly progressed the design was reduced to a sliding track with a support frame and an all-inclusive 3D printed specimen. Key features of the design are adjustable angle, variable sliding distance, different forward ends and waterproof sensor housing. The supporting frame has been kept simple to focus on repeatability and stay on budget. The final materials consisted of 2x4s, pipe clamps, PVC pipe, PLA plastic, heavy duty hinge, 3 axis accelerometer, and associated hardware.

The team completed trials at 30°, 45°, 60°, and 90° with three forward ends (cone, dome, and flat face) at a drop height of 18 inches. The data was collected at a 1000 samples per second and imported from a Vernier software to MATLAB to analyze. It was concluded at low angles, 30°, the dome performed best. This was the anticipated based on submarine construction and UUV's already in production. At all other angles, even free fall the cone head maintained the lowest g's at its peak impact with the water. Universally, the flat face performed the worst due to its abrupt introduction to water. The general problem definition encouraged the group to focus on variability so the user of the product can tailor the design to their specific real-life project. The 3D printed object can be altered in Solid works to introduce additional cavities, weight, and components to mimic naval devices. This is important for objects that house sensitive instrumentation critical to the mission purpose.

The final design address Raytheon's goal and did it in a manner that can be applicable to a broader audience. Reduction of impact g's can be done through nose cone and/or entrance angle decisions when engineering in the field. Based on nose cone restraints optimal angles can be determined or vice versa. Additional work comes from developing a constant entrance velocity among trials and exploring other regions of the data collected from the experiments. The past year has led to the current outcome that will aid in making conclusions and design decisions for engineering aspects of water entry.

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