Date of Graduation

Spring 2018

Document Type

Honors Research Project

Degree Name

Bachelor of Science

Major

Mechanical Engineering - Cooperative Education

Research Sponsor

Dr. D. Dane Quinn

First Reader

Dr. Christopher C. Daniels

Second Reader

Dr. Scott Sawyer

Abstract

Sandia National Laboratories has requested a fully mechanical device to close a circuit after launch has occurred and the device enters a vacuum. Intended for applications in rockets and missiles, the device must fit in a 36 degree wedge with a 6.8 inch radius that is 6 inches in height and be ready to bolt onto a rocket. The pressure switch must be prevented from actuating until a launch acceleration ranging from 20 to 27g is detected. The pressure switch must close the circuit after a pressure of 10-1 Torr is reached and before a pressure of 10-6 Torr is reached. The switch must remain closed after the switch is actuated. The pressure switch is required to close a circuit carrying 30 VDC with a 15 ohm load for up to 15 seconds. The switch itself is allowed to have a maximum resistance of 0.2 ohms. The switch must be resettable for Sandia to conduct multiple test runs. Our contact at Sandia expressed interest in 3D printed components. This design detects the launch acceleration by separating a calibrated mass from a magnet. Before the acceleration sensor is tripped, it prevents the pressure switch from actuating. The pressure switch contains a substance which is a liquid at the temperatures and pressures experienced before the vacuum environment is reached and vaporizes in the vacuum environment. The phase change causes an expansion of the fluid container, which is used to move the actuator magnet near a reed switch and close the circuit. Thus, this project applies thermodynamics, system dynamics, numerical methods, material selection, and mechanical component design. A prototype of the design will be built and sent alongside a report to Sandia National Laboratories. Sandia will test the device on a sounding rocket. This project will provide Sandia with one of ten prototype devices to test. The switch provided will be used to detect when the rocket has left the atmosphere and has activated safety measures.

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