Grazing Bifurcations and Chaos of a Hydraulic Engine Mount

The constitutive relationships of the rubber materials that act as the main spring of a hydraulic engine mount are nonlinear. In addition to material induced nonlinearity, further nonlinearities may be introduced by mount geometry, turbulent fluid behavior, temperature, boundary conditions, decoupler action, and hysteretic behavior. In this research all influence the behavior of the system only certain aspects are realistically considered using the lumped parameter approach employed. The nonlinearities that are readily modeled by the lumped parameter approach constitute the geometry and constitutive relationship induced nonlinearity, including hysteretic behavior, noting that these properties all make an appearance in the loaddeflection relationship for the hydraulic mount and may be readily determined via experiment or finite element analysis. In this paper we will show that under certain conditions, the nonlinearities involved in the hydraulic mounts can show a chaotic response.