Search Results

This paper describes a feasibility study of the acoustic holographic method to identify a noise source on an operating vehicle. A new acoustical holography method applicable to identification of a nonstationary noise source was assessed and developed. Based on the new method, a measurement system was made and applied to quantification of the noise source in the vehicle. The method was evaluated first for source identification capablity and confirmed by loudspeakers. The experimental approach was then applied to identify the location of vehicle tire noise under various steady state conditions. In this paper, an identification method of noise sources with relatively high power level is presented and the relationship between locations of tire noise sources under various operating conditions investigated.

This paper describes the application of an acoustic intensity measurement method to high-frequency interior noise. Technical problems in applying an averaging technique via surface scanning to high-frequency interior noise were conquered, and detailed quantitative contribution analysis of interior surfaces was made possible. Based on the analysis of a small passenger car, the effectiveness of additional noise control treatment can be roughly estimated, and an acoustic confort of the car was improved by a minimum additional treatment required.

This paper describes a system modeling technique for predicting passenger compartment “boom” for a specific car design prior to the building of a prototype vehicle. Since “boom” — defined here as auditory response in the 20 Hz to 80 Hz frequency range — is dependent on body panel vibrations as well as air acoustic properties, three-dimensional finite element models of both body and air are constructed. These models are incorporated in existing vehicle models which include powertrain and chassis representations of the type previously used for performing shake and harshness analyses. To avoid non-symmetric mass and stiffness matrices, a modal method using auxilliary variables is utilized to couple the acoustic and body models. Included in the paper are discussions of modeling issues unique to structural acoustic simulation as well as several examples of studies in which sound pressure level response to realistic inputs is predicted and reduced by simulated design modifications.

Knock control systems based on engine block vibrations analysis are widely adopted in passenger car engines, but such approach shows its main limits at high engine speeds, since knock intensity measurement becomes less reliable due to the increased background mechanical noise. For small two wheelers engines, knock has not been historically considered a crucial issue, mainly due to small-sized combustion chambers and mixture enrichment. Due to more stringent emission regulations and in search of reduced CO2 emissions, an effective on-board knock controller acquires today greater importance also for motorcycle applications, since it could protect the engine when different fuel types are used, and it could significantly reduce fuel consumption (by avoiding lambda enrichment and/or allowing higher compression ratios to be adopted). These types of engines typically work at high rotational speeds and the reduced signal to noise ratio makes knock onset difficult to identify.

A design procedure is presented which utilizes (1) the active control technologies such as Flutter Mode Control, Gust Load Alleviation and Maneuver Load Control to relax the strength and stiffness requirements on wing structure, and (2) structural optimization to derive the minimum weight composite wing structures satisfying the relaxed structural requirements. The design procedure is applied to the preliminary design study of a Supersonic Commercial Transport configuration with laminated composite wing structure. Four design configurations are compared. Maximum of about 30% structural weight reduction was achieved from the quasi-isotropic design. Also some insights on the characteristics of the Supersonic Commercial Transport configuration are discussed.

Adaptive control enables more productive use of high speed numerically controlled milling machines. With adaptive control, machines are programmed for optimum material removal, with the controller automatically reducing the material feed rate when heavy load conditions are encountered. The authors outline advantages of adaptive control and describe their testing technique for determining appropriate values for making maximally effective use of adaptive control.

This paper develops an adaptive idle speed control strategy for a V2, 1000 cc four-stroke, water-cooled, port injection SI engine. In order to verify the proposed strategy, the non-dimensional engine model including charging and torque dynamics is established in Matlab/Simulink software based on previously experimental verification. The integration of dynamics above will be a multi-input-single-output (MISO) system, which inputs are throttle angle and spark advance angle, and the output is engine speed. The proposed adaptive controller is developed on the model-based structure. The system parameters are updated by recursive least square (RLS) method so the system is able to represent the actual operation. The updated system parameters adjust control gain by derivation of closed-loop gain and pole placement.

The paper presents the estimator design procedures for automotive power train systems based on the adaptive Kalman filter. The Kalman filter adaptation is based on a simple and robust algorithm that detects sudden changes of power train variables. The adaptive Kalman filter has been used to estimate the SI engine load torque and air mass flow, and also the tire traction force and road condition. The presented experimental results indicate that proposed estimators are characterized by favorable response speeds and good noise suppression abilities.

Modeling the combustion process of a diesel-biodiesel fuel spray in a 3-dimensional (3D) computational fluid dynamics (CFD) domain remains challenging and time-consuming despite the recent advancement in computing technologies. Accurate representation of the in-cylinder processes is essential for CFD studies to provide invaluable insights into these events, which are typically limited when using conventional experimental measurement techniques. This is especially true for emerging new fuels such as biodiesels since fundamental understanding of these fuels under combusting environment is still largely unknown. The reported work here is dedicated to evaluating the Adaptive Local Mesh Refinement (ALMR) approach in OpenFOAM® for improved simulation of reacting biodiesel fuel spray. An in-house model for thermo-physical and transport properties is integrated to the code, along with a chemical mechanism comprising 113 species and 399 reactions.

As the material for the swing arms of motorcycles, aluminum is becoming popular to reduce their weight in recent years. Usually their cast body and pipe arms are welded together. The new “weld-free swing arms” introduced in this paper, the adhesive and bolts are adopted for joining, and forged arms are used instead of the pipe. As advantages of forged arms, engineers are capable to design freely and styling designers to take fine key elements in consideration. The adhesive coupling has many advantages listed below: * Better appearance: No welding bead * Cost reduction: Less man hour and simplified jigs * Improved dimensional precision: No thermal strain caused by welding * Improved swing arm performance: Light and strong * Upgraded work environment Elimination of unpleasant elements * Easy work: No special skills * Predictable strength: No variation by welder's skill

Automotive manufacturers are facing stronger and stronger pressure to optimize all aspects related to fuel consumption of cars, and aerodynamic drag makes no exception, due to increasing government enforcing rules for the reduction of the emissions and the increasing influence of aerodynamic performance on fuel consumption with WLTC and RDE driving cycles. Nowadays, CFD simulation is a common tool across automotive industries for the assessment and the optimization of vehicle resistance in the design phase. The full power of these numerical methods of studying many design variants in advance of experimental testing, however, can be fully exploited when coupled with optimization techniques, always keeping into account constraints and aesthetical demands. On the other hand, a massive use of CFD optimization can lead to unaffordable computational efforts or a limitation of the design exploration space.

Important parameters in designing regenerable adsorption beds for spacecraft life support systems are defined. Typical applications include synthetic zeolite, which is used for carbon dioxide removal; and silica gel, which dehumidifies the atmospheric gas prior to passing it through the zeolite beds. Bed performance is evaluated from correlated test data. A linearized solution of the dymanic mass transfer equations is presented, which provides a simplified method of bed design. This method is used to find the optimum design for a typical four bed regenerable, isothermal, carbon dioxide removal system. Results of this simplified analysis are compared with those of a detail digital computer study. This comparison indicates that the simplified method predicts system weight approximately 10% higher than the detailed evaluation.

Civil aircraft manufacturers are close behind the military in adopting advanced composites for new aircraft. This paper focuses on the reasons this move is occurring and reviews the status of adaptations of advanced composites to civil aircraft.

This paper reviews NASA's progress in research directed toward providing the technology necessary for the application of advanced control systems and displays to general aviation aircraft, and its plans for this effort in the future. Flight evaluations of such systems as wing levelers, fluidic autopilots, yaw dampers, and angle of attack displays have been made, and test conditions and major results of some of this work are reported. Potentially valuable systems evaluated thus far are an attitude command control system and a flight-director display. As presently configured, both are prohibitively expensive for use in general aviation, however, and efforts are under way to apply technology to the goal of reducing their cost. Perhaps the most promising development in this area is called separate-surface stability augmentation, and plans for its implementation and flight testing are described.

The purpose of this paper is to illustrate how advanced predictive analysis techniques are playing a key role in the design and development of automotive gaskets. Several 2D modeling techniques are demonstrated to highlight how this type of analysis can help in the simultaneous design of gasket features and the associated tooling and manufacturing procedures. The use of 3D Finite Element (FE) analyses in the evaluation of the sealed system is the most powerful predictive tool available to the gasket engineer and engine designer alike. The techniques shown here illustrate their invaluable use in predicting fundamental system design parameters, such as the sealing pressure distribution over the gasket and engine structure deformation, in particular bore distortion.

The front bumper of a current production vehicle, which is made of hot-stamped 15B21 aluminized steel, was studied for mass and cost reductions using the Advanced High Strength Stainless Steel product NITRONIC® 30 (UNS Designation S20400) manufactured by AK Steel Corporation. This grade of stainless steel offers a combination of high ductility and strength, which was utilized to significantly modify the design of the bumper beam to incorporate geometry changes that improved its stiffness and strength. The structural performance of the bumper assembly was evaluated using LS-Dyna-based CAE simulations of the IIHS 40% Offset Full-Vehicle Impact at 40 mph with a deformable barrier, and the IIHS Full Width Centerline 6 mph Low-Speed Impact. Optimization of the bumper beam shape and gauge was performed using a combination of manual design iterations and a multi-objective optimization methodology using LS-Opt.

Most applications for Dual Phase hot rolled steel have been large components like frame members that yield significant weight savings. Difficulties in secondary forming have limited the range of parts produced. One area with good potential is noise-vibration-harshness components (NVH), since such parts tend to be heavy gauge. Significant weight reduction should be possible through thinner steel without compromising design requirements, also potentially reducing cost as well. Fatigue properties of Dual Phase also match well with these applications. We have successfully produced a multi-stage deep drawn cup for an engine mount using DP590/600 from different steel sources, demonstrating this material can be used for a new group of applications.

The potential of advanced high strength steels such as TRIP versus conventional HSLA350 steel in achieving improved durability with weight savings is explored in the case of a shock tower assembly. Through a computational approach a linear analysis and a nonlinear analysis are performed. The nonlinear analysis takes into account the effect of geometry, material and contact nonlinearities. The results from both the linear and nonlinear analysis are used to predict fatigue lives. It is shown that the advanced steel grades, in particular, TRIP steels, can offer superior resistance to fatigue loading conditions while offering an opportunity to reduce the weight of the component.

The challenges of ever increasing combustion engine complexity coupled with the introduction of new and ever more stringent emissions regulations place a unique strain on the time available during the base engine hardware development and calibration phase of the product development cycle. Considering state of the art gasoline engine architecture (dual variable valve timing, direct injection with turbocharger) it is common to have at least 12 degrees of freedom as system inputs. The understanding of interactions and inter-dependencies of these inputs is therefore key in optimising the performance of the engine. MAHLE Powertrain has developed a process using a global Design of Experiment (DoE) technique based on Gaussian processes that can be used to accurately model and optimise many aspects of an engine’s performance.

The paper deals with an application of advanced simulation methods to modeling of hydrogen fueled engines. Two models have been applied - 0-D algorithm and CFD. The 0-D model has been based on GT-Power code. The CFD model has been based on Advanced Multizone Eulerian Model representing general method of finite volume. The influence of main engine parameters, e.g. air excess, spark timing, compression ratio, on NOx formation and engine efficiency has been investigated. Both models have been calibrated with experimental data. Examples of results and comparison with experiments are shown. The means of reducing NOx formation are discussed.