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A comprehensive and robust analytical tool was developed to study three-dimensional (3D) ring-bore and ring-groove interactions for piston rings with either symmetric or asymmetric cross-section. The structural response of the ring is modeled with 3D finite element beam method, and the interfaces between the ring and the bore as well as between the ring and the groove are modeled with a simple asperity contact model. Given the ring free shape and the geometry of the cross-section, this analytical tool can be used to evaluate the ring-bore and ring-groove conformability as well as ring twist angle distribution under different constraints. Conversely, this tool can be used to calculate the free shape to provide the desired ring-bore contact pressure distribution for specific applications.

Thermoplastics have been used increasingly for automobile components for both interior and under-the-hood applications. The plastic parts are made through various molding process such as compression molding, injection molding and blow molding. For parts with large or complicated geometry, small portions of the part may have to be molded first, then joined together using a welding process. The welded regions usually exhibit inhomogeneous and inferior mechanical performance compared to the bulk regions due to the differences in thermal history. The microstructures and mechanical properties of welded thermoplastics have been examined using hot-plate welded polyethylene. The specimens are prepared at various thermal conditions to simulate the real welding process. The thermal properties in welds are monitored using DSC (Differential Scanning Calorimetry) and the crystallinities are calculated.

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.

The powertrain engine is a major source of vibration and noise in automotive vehicles. Among the powertrain components, the valve cover has been identified as one of the main noise contributors due to its large radiating surface and thin shell-like structure. There has been an increasing demand for rapid assessment of the valve cover noise level in the early product design stages. The present study analyzes the radiated sound pressure level (SPL) of a valve cover assembly using the finite element method (FEM). The analysis is first performed using a fully coupled structural-acoustic approach. In this case the solid structure is directly coupled to the enclosed and surrounding air in a single analysis, and the structural and acoustic fields are solved simultaneously. In the next approach, the analysis is performed in a sequential manner, using a submodeling technique. First, the structural vibration of the cover is analyzed in the absence of the surrounding air.

The present research constitutes an engineering approach to the performance level prediction of starting a vehicle without use of a throttle. The study is based on a dynamic clutch engagement model. A computer simulation of engagement dynamics is used in order to study the lock-up mechanism and to develop proper prediction procedures. In addition, the engagement model is used to develop guidelines and recommendations in order to optimize the engagement system including clutch components, clutch controls, and engine controls. The mathematical model presented in this paper incorporates important, new features in comparison to similar models from previous publications. Consisting of two inertias, it includes not only elastic properties of the clutch damper but also varying engine torque and clamping (pressure) force. Functions of engine torque and plate load simulate the actual control process, including human factors.

The present paper is a continuation of engineering efforts devoted mathematical modeling and computer simulation presented in [1]. The modeling and study is extended on starting a vehicle with use of a throttle. The basic mathematical model utilized in [1] has had to be modified because clutch engagement with throttle make investigators consider new human factors contributing strongly to starting conditions. In particular, not only the clutch release but also the accelerator pedal are controlled by a vehicle operator. This has made the authors modify the definition of an ideal engagement and incorporate both the throttle level and the throttle lead time to the mathematical model. Moreover, the model has been adjusted to consolidate dissimilar low range characteristics for diesel and gas engines.

The intent of this paper will be to address the level of performance and cost of the various complex instruction set computers (CISC-80X86) versus the reduced instruction set computers (RISC). The original concept of reduced instruction set computers will be explained. The above information will be contrasted with how the second generation system functions. Once the operations are established, a discussion of operating performance as related to several types of benchmarks will be cited. A typical FEA model will be used as the final benchmark to determine realistic performance versus speed (wall clock time). The final comparison will be of cost.

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.

A detailed methodology is presented in this paper for a complete assessment of various forces, torques, and kinematic effects due to universal joint angularities and shaft yoke phasing. A modular approach has been adopted wherein constitutive equations represent each of the key elements of a driveline namely the driveshaft, coupling shaft, universal joint, and the transmission/axle shafts. Concentrated loads are used wherever loads are being transferred between the elements of a driveline. Local matrices are developed for the equilibrium of the respective driveline members. The local matrices are then assembled into a global matrix and solved for the kinematic state of the complete driveline. A 6x15 matrix has been developed to represent a general shaft in the system and a 6x10 matrix has been developed for a universal joint cross. This gives us a complete picture of all the loads on all driveline members.

A few years ago hydraulic fluid power component manufacturers had the luxury of long lead times to develop new products. In today's competitive global market, pump and valve design engineers must be able to shorten development lead times and get new, less costly products to production in order to satisfy customer demands. This paper describes how one fluid power component manufacturer uses rapid prototyping technology to speed up the development cycle by making: fit and form models, design evaluation test samples, and tooling for prototype castings.

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.

In today's global fluid power industry, successful hydraulic component manufacturers must utilize technical resources to maintain a competitive edge. When designing new products, past practice required an understanding of engineering theory and reliable and accurate lab and field testing of new products, but today's designers have a new tool at their disposal. Personal computer based software can be used to model and simulate individual hydraulic components or entire systems before prototypes are available for design and performance evaluation. This paper discusses the design of a hydraulic safety valve and how PC simulation was used to design and analyze valve performance during the design process.

Heat generated in hydraulic systems can be responsible for reduced life of equipment. Current Industry trends look to load-sensing variable-displacement pumps and closed-center valves to combat the problem. A comparison is made between the load-sensing variable-displacement pump with closed-center control valves and the fixed-displacement pump (both wet and dry valve types) with open-center control valves, to determine the heat generation tradeoffs. The use of tanks, lines and cylinders as a heat radiator is considered. Heat generated by high-pressure leakage of driven members is addressed. The primary focus of this paper is on packer and body hydraulics of refuse trucks.

The wear patterns of the rings and grooves of a diesel engine were analyzed by using a ring dynamics/gas flow model and a ring-pack oil film thickness model. The analysis focused primarily on the contact pressure distribution on the ring sides and grooves as well as on the contact location on the ring running surfaces. Analysis was performed for both new and worn ring/groove profiles. Calculated results are consistent with the measured wear patterns. The effects of groove tilt and static twist on the development of wear patterns on the ring sides, grooves, and ring running surfaces were studied. Ring flutter was observed from the calculation and its effect on oil transport was discussed. Up-scraping of the top ring was studied by considering ring dynamic twist and piston tilt. This work shows that the models used have potential for providing practical guidance to optimizing the ring pack and ring grooves to control wear and reduce oil consumption.

The engine valve cover is known to be major contributor to powertrain noise due to its large surface area and relatively small thickness. Thus, the acoustic analysis of the valve cover has become one of the key steps in the design process. The present paper describes an acoustic infinite element approach to model the sound radiation of the valve cover. The valve cover bolted to the engine block behaves like a vibrating membrane in an acoustic medium of infinite extent. Typically, the effect of the infinite medium is modeled using either the boundary element method (BEM), or by specifying an equivalent boundary impedance on the terminating surface of an acoustic finite element mesh (NRBC). In this paper, a third method is introduced, wherein the boundary impedances are replaced by acoustic infinite elements. The methodology is presented using two different models. In the first model, a cover with a geometrically simple shape is analyzed.

The transmissibility technique has been traditionally used for evaluating the NVH performance of isolated, rigid structures such as the elastomer mount isolated automobile engine. The transmissibility quantity provides information on how a structure reduces vibration as subjected to dynamic loading and thereby attenuates noise. In the present study, the transmissibility is applied to a non-rigid, plastic structure - the engine cylinder-head cover module. The cover module includes primarily a thin, plate-like cover and the elastomer isolation system. At low frequencies, the cover will behave as a rigid mass and thus display a major peak at its resonant frequency. At high frequencies, the cover will vibrate as a flexible panel and thus display multiple peaks with magnitudes differing from point to point across the cover surface. As a result, the transmissibility calculated would have a spatial resolution, called the spatial transmissibility.

ON THE basis of laboratory and field tests of passenger-car and light-truck rear axles, the authors conclude: 1. The capacity of present axles can be increased, without increasing axle size, when greater load-carrying antiwear and antiscore lubricants are available. 2. Gear noise will always be a major problem because axle gears are operating at varying speeds and loads whenever a car is in motion. Many gear noise problems can be overcome by proper tooth development and by testing in the actual car model under which the axle will be used. 3. The only reliable basis for torque-capacity rating is the tractive effort (wheel-slip torque). 4. The limited-slip type of differential will eventually become standard equipment on all passenger cars, if only to improve car handling and stability during high-speed driving under varying traction conditions.

This paper describes a method of vehicle performance prediction which adapts readily to digital programming. A prime mover which may be a gas turbine or a reciprocating internal combustion engine, a hydraulic torque converter, and/or a mechanical transmission, comprising the vehicle drive train, are transformed into numerical equivalents. The performance prediction itself is in three major parts, namely, the engine-converter compatibility, the converter range performance, and the lockout or direct drive performance. The computer transforms the engine data into equation form by curve fitting; predicts the optimum shift point as the intersection of the net tractive effort in converter drive with net tractive effort in direct drive; calculates; stores; interpolates; and prints a complete set of data.

THE INCREASED use of midship-mounted transmissions in large equipment has emphasized the need for a torsionally resilient connection from the engine to reduce vibration transfer. To increase the torsional flexibility needed in these systems, the spring rate of the system must be reduced by such constructions as a flexible coupling, a spring-loaded damper, or a rubber torsional spring. This paper discusses these systems, emphasizing rubber springs. Some advantages of such a drive are: it provides an amplitude limitation with impact loads and a cushion to reduce noise and prevent clattering and contacts noises on parts with backlash, it smooths out transition periods to reduce loads on bearings and gears, its clamping characteristics can be adjusted by various rubbers, and its rubber cushion provides a degree axial flexibility.*