Date of Award

12-2019

Document Type

Thesis - Open Access

Degree Name

Master of Science in Aerospace Engineering

Department

Aerospace Engineering

Committee Chair

Dr. Sirish Namilae

First Committee Member

Dr. Sandra Boetcher

Second Committee Member

Dr. Daewon Kim

Abstract

Resin shrinkage due to chemical changes and thermal gradients plays an important role in the residual stress evolution during composite manufacturing. In this thesis, we develop a new in-situ experimental approach for measuring resin shrinkage during curing with the help of digital image correlation (DIC) instrumented on a specially designed autoclave with borosilicate viewports. The images of the resin sample are captured at regular intervals with the help of DIC to measure the displacement and strains during the curing process. We utilize this method for a comparative analysis of resin shrinkage in two common aerospace epoxies, Epoxy 105 and EPON 862. An average compressive strain of 0.00896 was observed for Epoxy 105 and 0.01042 for EPON 862. Differential Scanning Calorimeter (DSC) is used to measure the degree of cure for the two epoxies, and to correlate resin shrinkage to the cure state. We also observed the effect of fibers on the shrinkage of the resin using carbon fiber, glass fiber and crepe bandage as fillers. We observed that as the stiffness of the fillers increased the strain in the matrix decreased.

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