Designing with Damping Materials to Reduce Noise and Structural Fatigue

Increasing the amount of structural damping in aircraft components has several design advantages in the control of noise and vibration problems. Principal of these advantages are weight and design cost savings. However, proper design requires a knowledge of the structure environment and would include factors such as the operating temperature and vibration frequency. The engineer must also have a complete characterization of the damping materials viscoelastic properties. The damping material is most conveniently presented using the reduced temperature format which shows the loss factor and stiffness as a continuous function of both temperature and frequency. When the structural environment and damping properties are known, an accurate determination of composite panel behavior can be determined using standard beam equations. This paper describes some of the steps necessary in damping design for constrained layer dampers. Also presented are a few case histories where damping has been successfully used to minimize resonant noise and vibration problems.