Semester of Graduation

Fall 2019

Degree

Master of Science in Mechanical Engineering (MSME)

Department

Mechanical Engineering

Document Type

Thesis

Abstract

Adhesive repair of carbon fiber composite structures is commonly done on damaged structures to extend the service life. This method requires careful preparation of the damaged surface with intricate steps to ensure good bonding between the repair patch and the parent structure by means of an adhesive film. As with many forms of composite manufacturing, it is required to perform vacuum bagging, debulking, and a heated cure depending on the resin. All these steps make the repair process costly and time consuming.

In this present work, an alternative method of repair is investigated which explores the experimental feasibility of using ultrasonic vibrations as a substitute to the vacuum bagging and debulking steps. This would ultimately reduce the manufacturing time, labor, and cost. Ultrasonic welding parameters were explored (time, travel, force, and amplitude) with two welding modes to optimize the consolidation process. Welded specimens were then post-cured in the oven following the recommended cure cycle from the manufacturer. Temperature measurements were obtained during the welding process and cure kinetics and viscosity behavior were predicted using semi-empirical models developed for Cycom 5320. Interlaminar shear strength was compared for welded and vacuum bagged samples. Repair of composite structures was simulated by applying flat repair patches over an open-hole and testing in uniaxial tension. The strength recovery was compared for welded and vacuum bagged repair samples.

Date

11-6-2019

Committee Chair

Palardy, Genevieve

Available for download on Wednesday, October 28, 2020

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