Date

6-2016

Degree Name

BS in Mechanical Engineering

Department

Mechanical Engineering Department

Advisor(s)

Joseph Mello

Abstract

The main objective of this project is to improve upon the current stitching pattern used in UAV catch net applications with the intention of lengthening their useable life cycle. To achieve this, a testing setup and procedure has been developed to produce material strength and stiffness data for nylon­ webbing strap, and for sewn intersections of the same strap material. The current stitching pattern was tested, and quantitatively characterized based on strength and stiffness. New stitching designs were generated and tested using the same procedure, and the results compared. This allowed for the selection of the most optimized stitching pattern that achieves the longest life without failure of the stitching or the base material (webbing). Our testing procedure is comprised of two main tensile tests; one that tests the stitching intersection in shear failure, and the other in peel failure. Force and displacement data is output through the data acquisition system for each of the tests, which yields stress­ strain data that can be analyzed to characterize the relative strength and stiffness of each setup. The test procedure outlines in detail the loading of the test specimen into the machine, the setup for the machine, and the setup for the data acquisition system. Our stitching pattern redesign begins with a failure model based on theoretical assumptions about how each independent stitched joint is loaded. This theoretical analysis is complimented by our experimental data, to determine what characteristics contribute to the strength of the stitching pattern. The main design goal is to improve the design in peel failure, which is the primary failure mode for nets currently in use. Pattern redesign is an ongoing and iterative process; and thus, additional testing iterations could result in an even more improved design.

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