Date of Award

2018

Degree Type

Capstone Project

First Advisor

Bahram Nassersharif

Second Advisor

Nicholas Lemos

Abstract

The main objective of the "Let it Grip" 2017-2018 NUWC Universal Undersea Gripper project was to design an effective and efficient individual gripper capable of securing a pay- load of various sizes, shapes, and orientations. This an important and relevant project being that the current way of securing payloads throughout the duration of a mission involves pre-installed molds that can only hold a payload of a specific size and shape. Though there were many ways to improve upon the current payload-carrying apparatus, the team decided to focus on finding the optimal shape and material of a potential universal gripper.

After conducting rigorous patent and literature searches, a more thorough understanding of how to accomplish this specific, yet challenging goal was established. In addition to increased comprehension, this research aided in further understanding of competition in terms of current devices already used in practice. Upon discovering current products, an in-depth analysis of each was conducted in order to find ways to improve and capitalize on mistakes of these current products. Through a means of preliminary concept generation, 120 possible designs were produced varying from gripper material, gripper layout, as well as the individual gripper itself. These designs varied in practicality, however, led to a plethora of truly useful and feasible ideas. With these possible concepts in mind, comprehensive QFD and engineering analyses were conducted. This process was used to aid in logical analysis in terms of specific needs required by NUWC to efficiently accomplish the goal of designing the universal gripper.

Using these analyses, the 120 possible concepts were narrowed down to a select two. The first of which was an extending, pyramid-shaped, hybrid design with a metallic base for increased strength, with an elastomer tip for increased shock absorption and coefficient of friction against the payload. The second design incorporated a hydraulically powered, conical telescopic device with a convex metallic head coated with an elastomer layer to increase shock absorption and coefficient of friction against the payload. Stress, shock, displacement, and factor of safety analyses were conducted on these two concepts using SolidWorks simulations to determine how each possible gripper design would perform under the acute stresses that will inevitably be subjected to it. After careful consideration, the conclusion was made that the hydraulically powered, conical telescopic convex-tipped gripper would be able to accomplish the goal of securing a payload of varying size, shape, and orientation in the most effective and efficient way possible.

Throughout the year, the team conducted further research and FEA analysis including internal pressure and deformation due to load testing in order to optimize the gripper design. This resulted in redesign additions such as guiding track lines to prevent unwanted gripper rotation and chamfered edges to prevent payload damage. As a result of this work, the team was able to produce a realistically modeled 3D high quality prototype and be a considerable improvement on the current apparatus in place.

Comments

Sponsor: NUWC

Sponsor Representatives: Peter Hardro, James Gutkowski, Kristin Giles

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