Based on the expression of overall loss factor, it can be inferred that another way to increase the same is by increasing the maximum stress at the outer layers. Indeed, it has been shown that by using a series of cylindrical inserts one can enhance damping. If the inserts are made of high damping material the effect is further enhanced.

Figure 11.3: Enhanced damping using inserts

The method of enhancing damping capacity of a structure by high-damping inserts can be extended to design composite materials with high-damping spherical inclusions, which has a good balance of stiffness and damping. Composites of viscoelastic materials with suitable choices for relaxation times of the constituents can also be designed, which can maintain high damping over a wide frequency range.

Congratulations! You have finished Lecture 11.