Date of Award

4-2001

Degree Name

Doctor of Philosophy

Department

Mechanical and Aeronautical Engineering

First Advisor

Dr. Judah Ari-Gur

Second Advisor

Dr. Koorosh Naghsnineh

Third Advisor

Dr. Dennis J. VandenBrink

Fourth Advisor

Dr. Anthony M. Waas

Abstract

A new technique for enhancing aircraft safety in the event of an on-board explosion was studied. The method under study employs deployable vent panels located on the fuselage which are activated by an array of pressure sensors in the aircraft interior. In the event that an explosion is detected, appropriate vent panels are rapidly released from the aircraft. This approach seeks to provide timely relief of explosive pressures within an aircraft to prevent catastrophic structural failure.

In this study, the approximate time scale of an explosive detonation and the subsequent sensing and electronic processing was determined. Then, the actuation response times of several vent panel systems were determined through analytical modeling and scale-model experimental testing with good correlation achieved.

A scale-model experimental analysis was also conducted to determine the decompression venting time of an aircraft fuselage under a variety of conditions. Two different sized pressure vessels were used in the experimental work and the results correlated quite favorably with an analytical model for decompression times.

Finally, a dynamic finite element analysis was conducted to determine the response of a portion of a typical commercial aircraft fuselage subjected to explosive pressure loading. It was determined from this analysis that the pre-stressing of the fuselage from cabin pressurization increases the damage vulnerability of a commercial aircraft fuselage to internal explosions. It was also learned from the structural analysis that the peak fuselage strains due to blast loading occur quickly (within approximately 2 milliseconds) while it was conservatively estimated that approximately 5 to 7 milliseconds would be required to sense the explosion, to actuate selected vent panels, and to initiate the release of cabin pressure from the aircraft. Additionally, since it was determined that predicted fuselage strains for both pressurized and unpressurized load cases remained well below the material strain limit, ultimate failure of the aircraft under blast loading may occur later than originally thought due to secondary explosive pressure reflections and the significant overall increase in cabin pressure after detonation. This delayed onset of failure indicates that an active venting system may indeed be capable of functioning rapidly enough to reduce significant fuselage explosive damage.

Access Setting

Dissertation-Open Access

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