EFFECTS OF VISCOELASTICITY ON RUBBER VIBRATION ISOLATOR DESIGN

The influence of viscoelasticity of rubber materials on the performanc e of rubber isolators is presented. Dynamic properties of both neat ru bber and filled rubber with filler content phi<phi(c) are Linear visco elastic while those of filled rubbers with filler content phi greater than or equal to phi(c), are strongly strain dependent and nonlinear v iscoelastic. The Kramers & Kronig relationship and its approximation i s used to simulate the performance of a linear viscoelastic rubber iso lator. Two specific conditions for viscoelastic rubber systems, (a) sy stems with constant loss tangent and (b) systems in the region of omeg a(0.5) frequency dependence, are studied. The limitation on the transm issibility of a linear viscoelastic rubber isolator is also illustrate d through the Kramers & Kronig relationship. The performance of a vibr ation isolator made from filled rubbers with filler content phi greate r than or equal to phi(c), however, can be simulated by the L-N-B mode l. When the strain amplitude at natural frequency is greater than the apparent strain amplitude epsilon(app), the stability problems such as Jump effect are likely to happen. (C) 1998 American Institute of Phys ics.