Search Results

The increasing use of diesel and gasoline particulate filters requires advanced on-board diagnostics (OBD) to prevent and detect filter failures and malfunctions. Early detection of upstream (engine-out) malfunctions is paramount to preventing irreversible damage to downstream aftertreatment system components. Such early detection can mitigate the failure of the particulate filter resulting in the escape of emissions exceeding permissible limits and extend the component life. However, despite best efforts at early detection and filter failure prevention, the OBD system must also be able to detect filter failures when they occur. In this study, radio frequency (RF) sensors were used to directly monitor the particulate filter state of health for both gasoline particulate filter (GPF) and diesel particulate filter (DPF) applications.

This paper reviews the relevant literature on the effects of sulfated ash, phosphorus, and sulfur on DPF, LNT, and SCR catalysts. Exhaust backpressure increase due to DPF ash accumulation, as well as the rate at which ash is consumed from the sump, were the most studied lubricant-derived DPF effects. Based on several studies, a doubling of backpressure can be estimated to occur within 270,000 to 490,000 km when using a 1.0% sulfated ash oil. Postmortem DPF analysis and exhaust gas measurements revealed that approximately 35% to 65% less ash was lost from the sump than was expected based on bulk oil consumption estimates. Despite significant effects from lubricant sulfur and phosphorus, loss of LNT NOX reduction efficiency is dominated by fuel sulfur effects. Phosphorus has been determined to have a mild poisoning effect on SCR catalysts. The extent of the effect that lubricant phosphorus and sulfur have on DOCs remains unclear, however, it appears to be minor.

The life of an automotive engine is often limited by the ability of its components to resist wear. Zinc dialkyldithiophosphate (ZDDP) is an engine oil additive that reduces wear in an engine by forming solid antiwear films at points of moving contact. The effects of this additive are fairly well understood, but there is little theory behind the kinetics of antiwear film formation and removal. This lack of dynamic modeling makes it difficult to predict the effects of wear at the design stage for an engine component or a lubricant formulation. The purpose of this discussion is to develop a framework for modeling the formation and evolution of ZDDP antiwear films based on the relevant chemical pathways and physical mechanisms at work.

Design analysts, who work with finite element shape optimization, face a daunting task of handling cylindrical parts like a pusher for a crimp. The shape vectors generated by any of the existing methods/tools cannot constrain nodes to move in a circular path. Since the pusher is not a complete cylinder and the loading is only along axial direction, shape optimization was performed after flattening out the cylindrical pusher. The existing shape optimization tools could now be applied to the flat plate. A numerical interpolation method, based on ‘Autodv’, has been used to generate shape vectors. Both weight and stresses have been brought down and the final design was verified with solid finite element analysis.

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.

NASA has long recognized the advantages of providing improved information interfaces to EVA astronauts and has pursued this goal through a number of development programs over the past decade. None of these activities or parallel efforts in industry and academia has so far resulted in the development of an operational system to replace or augment the current extravehicular mobility unit (EMU) Display and Controls Module (DCM) display and cuff checklist. Recent advances in display, communications, and information processing technologies offer exciting new opportunities for EVA information interfaces that can better serve the needs of a variety of NASA missions. Hamilton Sundstrand Space Systems International (HSSSI) has been collaborating with Simon Fraser University and others on the NASA Haughton Mars Project and with researchers at the Massachusetts Institute of Technology (MIT), Boeing, and Symbol Technologies in investigating these possibilities.

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 combustion process after auto-ignition is investigated. Depending on the non-uniformity of the end gas, auto-ignition could initiate a flame, produce pressure waves that excite the engine structure (acoustic knock), or result in detonation (normal or developing). For the “acoustic knock” mode, a knock intensity (KI) is defined as the pressure oscillation amplitude. The KI values over different cycles under a fixed operating condition are observed to have a log-normal distribution. When the operating condition is changed (over different values of λ, EGR, and spark timing), the mean (μ) of log (KI/GIMEP) decreases linearly with the correlation-based ignition delay calculated using the knock-point end gas condition of the mean cycle. The standard deviation σ of log(KI/GIMEP) is approximately a constant, at 0.63. The values of μ and σ thus allow a statistical description of knock from the deterministic calculation of the ignition delay using the mean cycle properties

Two critical milestones that must be achieved during concept design are 1) definition of a product architecture that meets performance, producibility, and strategic objectives, and 2) estimation of the integration risk in each candidate concept. This paper addresses these issues by describing the role played by the producibility members of an Integrated Product Team (IPT) during concept design. Our focus is on the execution of the what we call the “chain method”, which illustrates the structure of function delivery in a concept in a simple pictorial way and helps the IPT to understand the advantages or disadvantages of using a modular or an integral product architecture. The producibility members play a central role in capturing and evaluating the chains for different candidate concepts and decompositions.

In this paper we investigate the optimal forming of conical cups of AL 2008-T4 through the use of real-time process control. We consider a flat, frictional binder the force of which can be determined precisely through closed-loop control. Initially the force is held constant throughout the forming of the cup, and various levels of force are tested experimentally and with numerical simulation. Excellent agreement between experiment and simulation is observed. The effects of binder force on cup shape, thickness distribution, failure mode and cup failure height are investigated, and an “optimal” constant binder force is determined. For this optimal case, the corresponding punch force is recorded as a function of punch displacement and is used in subsequent closed-loop control experiments. In addition to the constant force test, a trial variable binder force test was performed to extend the failure height beyond that obtained using the “optimal” constant force level.

Draw beads are widely utilized as a mechanism for providing proper restraining force to a sheet in a forming operation. In this paper, numerical simulations using the nonlinear finite element method are conducted to model the process of drawing a sheet through various draw bead configurations to study the mechanics of draw bead restraint. By examing the sensitivity of the draw bead restraining force due to the change of the draw bead penetration, the work shows that the penetration has the potential to be a very good element for varying and controlling restraining force during the process. A closed-loop feedback control of draw bead penetration using a proportional-integral controller is achieved by the combination of the original finite element simulation and a special element which links penetration to a pre-defined restraining force trajectory.

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.

The design objective of the Spicer S400-S axle program was to develop a light weight, lower torsional vibration, long life tandem drive axle for the heavy truck industry. This was accomplished with the incorporation of a number of new product features and technical advancements, both in design and manufacturing. These include: reduced standouts for improved interaxle driveline angles use of finite element analysis fixed pinion mounting optimization of lube flow and direction of lubrication optimized gear design for improved strength and noise reduction. This paper focuses on these features and also on the development process for the axle, including the use of simultaneous engineering. Utilizing simultaneous engineering, the S400-S was developed from concept to full production in fifteen months.

Enhanced information management techniques made available through emerging Information Technology platforms hold a promise of providing significant improvements in both the effectiveness and efficiency of developing complex products. Determining actual management implementations that deliver on this promise has often proven elusive. Work in conjunction with the Lean Aircraft Initiative at MIT has revealed a straight forward use of Information Technology that portends significant cost reductions. By integrating previously separate types of data involved in the process of product development, engineers and designers can make decisions that will significantly reduce ultimate costs. Since the results presented are not specific to particular technologies or manufacturing processes, the conclusions are broadly applicable.

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.

Microalloyed (MA) steels have been developed as economical alternatives to the traditional quenched and tempered (QT) steels. The physical metallurgy principles underlying their basic composition-processing-microstructure-property interrelationships have been reviewed in the first part of the review. In this second part of the review, mechanical properties as well as fabrication properties, such as mahinability, weldability, and formability, are discussed. Flat products (such as strips, sheets, and plates), long products (including bars, rods, sections/profiles), and forging articles made of MA steels are investigated. Since most engineering components made of these steels are subjected to cyclic loading, fatigue and fracture performance of MA steels and their comparison with the QT steels are also evaluated in this review.

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 sampling system was developed to measure the evolution of the speciated hydrocarbon emissions from a single-cylinder SI engine in a simulated starting and warm-up procedure. A sequence of exhaust samples was drawn and stored for gas chromatograph analysis. The individual sampling aperture was set at 0.13 s which corresponds to ∼ 1 cycle at 900 rpm. The positions of the apertures (in time) were controlled by a computer and were spaced appropriately to capture the warm-up process. The time resolution was of the order of 1 to 2 cycles (at 900 rpm). Results for four different fuels are reported: n-pentane/iso-octane mixture at volume ratio of 20/80 to study the effect of a light fuel component in the mixture; n-decane/iso-octane mixture at 10/90 to study the effect of a heavy fuel component in the mixture; m-xylene and iso-octane at 25/75 to study the effect of an aromatics in the mixture; and a calibration gasoline.