SDT-visc         Contents     Functions              PDF Index

2. Viscoelastic FEM models

The design of viscoelastic treatments is typically composed of a series of steps which are outlined in this section

• definition of dynamic objectives
• potential area localization by combination of technological constraints on placement and sensitivity analysis on treatment potential

This chapter analyzes properties of models used to represent damped structures. In the case of linear viscoelasticity these models have the general form

(2.1)

where physical loads [b]{u(s)} are decomposed into vectors b, characterizing spatial localization, and u(s), characterizing time/frequency responses and vector {y} represents outputs (physical quantities to be predicted, assumed to depend linearly in DOFs q.

Section ?? details the case of models with viscous and structural damping. Although one saw in the last chapter that these models did not allow a correct representation of material behavior over a wide frequency band, they are more easily accessible and can be used to illustrate the difference in needs when modeling vibration damping in a structure and dissipation in a material.

Section ?? details strategies that can be used to create models with realistic representation of viscoelastic materials.

Section ?? deals with issues of spectral decompositions and model reduction which are central to the analysis of the vibratory behavior of damped structures.

The objective of this chapter is to introduce equations used to solve viscoelastic problems. The next chapter will focus on numerical techniques used for the resolution.