Evaluation of effective bulk modulus of oil in automotive hydraulic dampers - effects of cylinder shell elastic deformation

This paper presents a theoretical model of cylinder shell bulk modulus (K/sub c/) to achieve more accurate modeling of effective bulk modulus of oil (K/sub e/) in automotive hydraulic dampers. The theoretical model of K/sub c/ has been derived based on the elastic theory for thick-walled cylinder incorporating not only radial but longitudinal deformation. The new model on K/sub c/ was examined through numerical computations. A cylindrical container and a twin-tube type automotive damper were chosen as the objects of numerical computation. K/sub c/ itself and K/sub e/ in connection with K/sub c/ of the objects were computed with the new model and traditional models of K/sub c/. By showing the computational results, the effects of K/sub c/ on K/sub e/ in automotive hydraulic dampers were explained clearly.