Date of Award

9-9-2009

Document Type

Thesis

Degree Name

Master of Science in Aeronautical Engineering

Department

Department of Aeronautics and Astronautics

First Advisor

Robert A. Canfield, PhD

Second Advisor

Richard G. Cobb, PhD

Abstract

Buffet-induced vibrations can have a disastrous impact on aircraft structures. Early attempts at combating buffet vibrations included passive methods such as structural enhancements and leading edge fences. Active methods have shown greater promise, including active airflow control, control surface modulation, and active structural control using piezoelectric actuators. Surface mounted piezoelectric actuators impart directional strain reducing the negative effects associated with harmful vibration. The Block-15 F-16 ventral fin represents an aircraft structure prone to failure when subjected to the buffet field from the wake of a LANTIRN pod. This research takes advantage of the susceptibility to buffet vibration of the Block 15 ventral fin in an effort to design an active control system to alleviate vibrations using piezoelectric actuators and sensors and to demonstrate its capability during flight test. It was sponsored by the United States Air Force (USAF) Test Pilot School (TPS). The development of an active control system began with the specification of piezoelectric actuators and sensors to be used in a collocated design to alleviate the vibrations of the first two modes of the ventral fin. A switching amplifier was designed and built to drive the actuators during all phases of testing. For the piezoelectric actuators to be effective, they needed to be located within the regions of highest strain energy and aligned with the principal strain vectors in those regions, the direction of principle strain was experimentally determined to ensure the proper orientation of the piezoelectric hardware on the ventral fin's surface. Two control techniques were used in this research: positive position feedback and Linear Quadratic Gaussian compensator.

AFIT Designator

AFIT-GAE-ENY-09-S01

DTIC Accession Number

ADA506375

Comments

co-advised thesis.

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