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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.

The combustion gas management is extremely important to fit an engine to the ever-stricter environmental legislation requirements [1]. During the combustion, some gas flow through the piston gaps and goes to the crankcase. It is known by the term Blow-by. In order to reduce the emission, this gas is re-injected in the intake manifold as clean as possible to be re-burned - Figure 1. This paper shows the methodology applied to validate a standalone air/oil separation system (AOS) developed by DANA for a 7.2 liter diesel engine.

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.