Constrained layer damping test results for aircraft landing gear

Abstract

In aircraft, weight reduction represents one of the principal design goals, and landing gear design is no exception. Accounting for 3-7% of an aircraft's weight, the landing gear is essentially dead weight after takeoff, and so reducing this weight becomes a priority of aircraft design. In addition to keeping the weight low, fixed gear designs can add significant drag if the design has not been optimized. The ideal landing gear should be low weight and low drag, but these criteria are typically at odds with a requirement for absorbing landing loads and preventing rebound. The use of constrained layer visco-elastic damping on landing gear structural members is a new application since historic use of constrained layer damping has been found on thin plate-like structures. Benefits of low weight and low drag are achievable using the conformai treatment, and this paper investigates specific constrained layer damping applications for cantilever-loaded spring steel landing gear. The design of the damped system considers the high stiffness and low surface area typical on a cantilever landing gear leg. Damping levels are examined for a 163 kg. aircraft with and without a Dyad 606 constrained layer damping treatment on the main and nose gear members. A 29% increase in damping was observed on the main landing gear, and a 25% increase in damping was observed on the nose gear when the treatment was applied. A full aircraft drop test is performed that showed inconclusive results in damping. ©2010 Society for Experimental Mechanics Inc.