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The Plastic Valve Cover System (PVCS) should provides a leak proof seal to the cylinder head under engine temperature, isolate the vibrations transmitted from the engine through the cover to the environment, control the crankcase pressure and house the device to separate oil from the blow-by gas. In order to increase the stiffness of PVCS, short glass fibers and minerals are added during the injection molding of the plastic valve cover. The presence of the fibers results in a component with highly anisotropic thermo-mechanical properties that was not accounted in the previously approach [1]. This paper describes the updated CAE approach with the incorporation of the short fiber anisotropy into the design of cylinder head valve covers.

In order to increase the stiffness of cylinder head plastic valve cover system (PVCS), short glass fibers and minerals are added during the injection molding of the plastic valve cover. The fibers orient themselves according to the local characteristics of the flow and the geometry of the part. The presence of the fibers results in a component with highly anisotropic thermo-mechanical properties. Traditional finite element analysis methods do not account for this, very important, phenomenon. The present manuscript describes work conducted at Dana Corp. aimed at incorporating short fiber anisotropy into the design of cylinder head valve covers.

This paper presents the development of a Plastic Valve Cover System (PVCS) using Finite Element Analysis (FEA). This approach results in a shorter development period and reduced costs. The numerical methodology is divided into two steps. First, a two-dimensional analysis is of the rubber components (gasket, grommet) determines the load-deflection response and the system equilibrium for the complete range of component tolerances. These curves are utilized in a second step. Applied to a three-dimensional model of the cover, the analysis determines the valve cover optimal design. The paper describes other relevant issues related to PVCS's such as: a) influence of strain damage on elastomeric response. b) element type, size and order selection for optimum modeling. Comparisons with experimental results are presented and the appropriate conclusions are drawn.