The elastic characteristics of engine mountings must be considered in early stages of vehicle design. The paper proposes a model with six degrees of freedom (three translational, three rotational) for evaluating these systems.
A mathematical treatment develops a second-order differential equation of motion with homogeneous and non-homogeneous formulations (the latter representing static loadings, including the engine's own weight). Solutions for dynamic loadings encompass variables such as engine torque. Subsequently, the formulations are applied to a mechanical model and incorporate roadway characteristics and vehicle parameters. In particular, spring stiffness and damping of rubber mountings are examined with respect to vibrational characteristics.
The described model may be applied to an arbitrary system with the six described degrees of freedom; specifically, design of an engine mounting or evaluation of an existing mounting may be performed. Nevertheless, optimization of spring stiffness characteristics is limited by choice of materials and extra-analytical considerations; final selection of characteristics remains the task of the engineer