Experimental approach in studying temperature effects on composite material structures realized with viscoelastic damping treatments

Abstract

This paper presents a study aimed at evaluating how viscoelastic materials embedded in composite plates affect structural damping during the flight of a civil aircraft. The vibro-acoustic responses of composite fuselage structures realized with embedded viscoelastic damping treatments have been experimentally characterized at different temperature conditions. The real influence of viscoelastic materials on composite structures has been investigated, focusing the investigations on aspects still unknown, related mostly to temperature effects. In order to simulate the temperature level of commercial transport aircraft in cruise flight conditions, tests were performed using a climatic room where temperature and humidity were controlled. Vibrational tests were performed on two composite fuselage skin coupons: one treated with embedded viscoelastic damping treatments and the other one untreated. The tests were performed at temperatures of $-{35}^{\circ }\text{C}$ for the untreated composite fuselage structure, and ${15}^{\circ }\text{C},-{20}^{\circ }\text{C},-{25}^{\circ }\text{C}$ and $-{35}^{\circ }\text{C}$ for the treated composite fuselage structure. The damping values were carried out by the impulse response decay method and the loss factor was obtained as an average of many repeated acquisitions. In order to maximize the damping effect, the best temperature interval for the treated composite fuselage skin coupon was evaluated, and the behavior for both composite fuselage structures (treated and untreated) was characterized. Thanks to the high number of tests, a statistical analysis was performed in order to validate the approach used.