Nonlinear Normal Modes in a Two-Stage Isolator Using a Modified Finite-Element Galerkin Method

Figure 1

Schematic diagrams of three types of nonlinear two-stage isolators. The payload is set on the upper stage in each type: (a) type I isolator of which two stages are both connected to the foundation [3]; (b) type II isolator of which upper stage has no direct connection with the foundation [4]; (c) type III isolator of which lower stage only connects with the upper one.

(a)

(b)

(c)