Date of Award

Summer 1996

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Mechanical & Aerospace Engineering

Program/Concentration

Engineering Mechanics

Committee Director

R. Prabhakaran

Committee Director

Tom Gates

Committee Member

Y. Mikata

Call Number for Print

Special Collections; LD4331.E57 F46

Abstract

Development of a High Speed Civil Transport is considered by the commercial aviation industry to be one of the next big challenges for our national aircraft industry. Critical to the success of this aircraft is the development of advanced polymeric composites for both the primary and secondary structures and the predictive methodology necessary for assessment of long term durability. While polymeric composites offer an excellent strength to weight ratio a key disadvantage is the time dependent properties exhibited by the polymer matrix which can age and ultimately effect the resultant stiffness of a laminate.

Experimental studies were performed to determine the effects of elevated temperature on the physical aging of IM7/K3B, a carbon fiber reinforced thermoplastic composite, and K3B resin. Testing consisted of short term sequenced isothermal creep and recovery tests, with the creep segments performed at constant load. The matrix dominated transverse and in-plane shear behavior of the composite was measured at temperatures ranging from 200o C to 230oC. The resin creep compliance tests were performed at temperatures between 200o and 225o. Through the use of time-aging-time shift procedures, momentary master curve fit parameters, aging shift factors and shift rates were determined at each temperature. The composite viscoelastic parameters were used as input to a predictive methodology, which was based upon effective time theory and linear viscoelastic theory combined with classical lamination theory. While the resin theoretical predictions were based only on the momentary viscoelastic parameters and effective time theory. Long term composite and resin creep compliance test data was compared to the predictions to verify the method.

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DOI

10.25777/k1g6-8p28

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