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In the present study, the NVH performance of an engine valve cover assembly is analyzed by the use of “spatial transmissibility (TR)”. It is a measure of the spatial response of the cover relative to the spatial response of the underlying structure to which it is connected. A prototyped engine valve cover assembly is examined. The cover transmissibility is computed through the finite element method and also measured by experimental testing. Various isolation systems have been examined and different cover materials have been investigated, including magnesium and thermosetting plastic. The transmissibility provides a strategy for evaluating the NVH characteristic of engine cover assembly in a much more timely, cost-effective manner, while the product is still in the early conceptual stage.

Accelerated testing techniques for cylinder head gaskets have become absolutely necessary because of developments at engine manufacturers including: shorter engine development times, high costs of vehicle and dynamometer testing, new material generations for engine components, and new engine generations and longer engine life This paper will describe two accelerated test methods for Multi-Layer Steel (MLS) cylinder head gaskets and will discuss the most important parameters which influence MLS cylinder head gasket functional performance. We will describe how these parameters have been duplicated in the laboratory using the accelerated tests: the Bending Simulator and the Hydraulic Pulsator. The test method results have been confirmed based on detailed metallurgical analysis of MLS gaskets; comparing field (dynamometer and vehicle) tested gaskets to those gaskets evaluated on accelerated tests.

In spite of being a popular topic in technical publications, scuffing between piston ring face and cylinder liner is an extremely unpredictable and hard-to-reproduce phenomenon that significantly decreases engine performance. This paper will discuss results of metallurgical and metrological (post-mortem) examinations of the scuffing between hard and soft cylinder liners and different piston ring coatings after field, engine and bench testing. Detailed metallurgical analysis describes the lubricity mechanism between various piston ring coatings and iron cylinder liner at different temperatures with and without oil. The paper will explain the origin of the scuffing through lack of or inadequate lubrication at top dead center, particularly for hardened iron heavy-duty diesel cylinder liners.

Microalloyed (MA) steels have been developed as one of the most significant metallurgical advances over the last thirty years, with their property improvement and cost effectiveness characteristics. Even though the underlying principles for microstructural property control of these steels have been well established, applications of these steels are still limited in scale mainly due to a lack of their understanding. This review paper focuses on mechanical property control of these steels. Since the properties depend mainly on the composition and microstructure which in turn are controlled by steel making and processing, metallurgical variables are reviewed in this first part of the review. These include their strengthening mechanisms, effects of composition and processing on their behavior, and the various MA steel microstructures.

This paper will discuss metallurgical failure analysis of microwelded iron piston rings and aluminum pistons in internal combustion engines. “Microwelding” is defined as adherence of sporadic particles of aluminum from the piston to the bottom side of the piston ring. The paper will describe the high output water-cooled two-stroke engine accelerated test which reproduces the microwelding phenomenon in 30 minutes. SEM and EDS analyses have been used in the identification of the mechanism of this surface damage. Evidence of extreme temperatures during pre-ignition and normal operating conditions was obtained by studying hardness distributions through the piston cross section. As a potential solution, decreasing temperature through use of a thermal barrier coating was investigated. Also, test results of piston ring coatings, including molybdenum and tungsten disulfide, electroplated chromium, PVD titanium and chromium nitride, and fluoroplastic materials were compared.

A major concern in head gasket reliability of an industrial diesel engine is flange cracking. This paper will discuss head gasket flange cracking and the head gasket joint environment as they relate to an industrial diesel engine head gasket joint. The paper will discuss metallographic and finite element analysis of head gasket field failures. The metallographic analysis will discuss the evaluation of production, assembled, laboratory tested, and field tested gaskets. The above will give head gasket designers and engine manufacturers insight into the industrial head gasket joint environment. The metallographic work will explain the method of creating micro sections as well as micro section measurements to aid in the understanding of the head gasket loading.

New analysis methods have been developed which allow heavy duty diesel engine cylinder head to block joints to be studied in a more effective manner. Failure analysis can yield more meaningful, quantitative results through the use of X-rays and microhardness measurements. Experimental methods of determining direction and magnitude of thermal motion, interactions between cylinder pressure and thermal cycling, and the relationship between leak pressure and thermal condition have been developed. Deep thermal cycle dynamometer testing has also been used successfully to duplicate failure modes seen in the field.