Influence of temperature on structural joints with designed-in damping

An innovative means to enhance the inherent damping in structures is provided by the designed-in incorporation of viscoelastic materials in joints. The joints, as envisioned, are double-lap shear joints that dissipate energy when worked in an axial direction. The damping and stiffness characteristics of such joints have been evaluated experimentally at various temperatures and frequencies that are expected to be representative for large space structures. A new, nonresonant experimental technique has been utilized for this investigation. It provides the complex stiffness of the test specimen at extremely low strain levels, and accounts for elastic deformations in the test setup by means of carefully measured calibration factors. The temperature and frequency variations of the overall joint properties follow, in general, the same trends as the corresponding properties of the particular viscoelastic material used in the joint. The test data show that properly selected viscoelastic materials and design configurations can reduce the dependence of the joint properties on temperature and frequency variations. Significant damping benefits are possible without unacceptable stiffness penalties.