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A combined lumped parameter, finite element (FE) and boundary element (BE) model is developed to predict the whine noise from rear axle. The hypoid geared rotor system, including the gear pair, shafts, bearings, engine and load, is represented by a lumped parameter model, in which the dynamic coupling between the engaging gear pair is represented by a gear mesh model condensed from the loaded tooth contact analysis results. The lumped parameter model gives the dynamic bearing forces, and the noise radiated by the gearbox housing vibration due to the dynamic bearing force excitations is calculated using a coupled FE-BE approach. Based on the predicted noise, a new procedure is proposed to tune basic rear axle design parameters for better sound quality purpose. To illustrate the salient features of the proposed method, the whine noise from an example rear axle is predicted and tuned.

A general time-varying nonlinear dynamic model of a hypoid gear pair for rear axle applications is proposed. The dynamic model considers time-varying mesh position, line of action, mesh stiffness, mesh damping and backlash nonlinearity. Based on the model, dynamic analysis is conducted to study the effect of mean load, mesh damping and mesh parameter variations on dynamic mesh force response and the interaction between them and backlash nonlinearity. Numerous nonlinear phenomena such as tooth impacts and jump discontinuities are revealed by computational results.

As the drive to make automobiles more noise and vibration free continues, it has become necessary to analyze transient events as well as periodic and random phenomena. Averaging of transient events requires a repeatable event as well as an available trigger event. Knowing the exact event time, the data can be post-processed by re-sampling the time scale to capture the recorded event at the proper instant in time to allow averaging. Accurately obtaining the event time is difficult given the sampling restrictions of current data acquisition hardware. This paper discusses the ideal hardware needed to perform this type of analysis, and provides analytical examples showing the transient averaging improvements using time scale re-sampling. These improvements are applied to noise source identification of a single transient event using an arrayed microphone technique. With this technique, the averaging is performed using time delays between potential sources and microphones in the array.

In partly autonomous driving such as level 2 or level 3 automatic driving from SAE international classification, the switching of the driving right between the human driver and the machine plays an important role in the driving process of vehicle [1]. In this paper, the data collected from vehicle states and the driving behavior of drivers is completed via a simulator and self-report questionnaires. A fuzzy analytic network process (Fuzzy-ANP) model is developed to evaluate the driving capability of the drivers in real time from vehicle states due to its direct inherent link to the change of the driving state of drivers Moreover, in this model, the idea of group decision and multi-index fusion is adopted. The questionnaire is required to identify the experimental results from the simulator. The results show that the proposed Fuzzy-ANP model can evaluate the driving capability of the participants in real time accurately.

The design optimization of vehicle body structure is addressed to reduce interior noise and improve customer satisfaction in this paper. The structural-acoustic model is developed by using finite element method. The frequency response of structural-acoustic system is computed by modal analysis method. The optimization problem is constructed to minimize the sound pressure level in the right ear of the driver. The sensitivity analysis is carried out to find the key panels to be optimized as design variables and improve the efficiency of optimization computation. Response Surface Method (RSM) is utilized to develop the surrogate model and optimize the vehicle Noise Vehicle and Harshness (NVH) behavior. A 9dB reduction of sound pressure level (SPL) in the right era of the driver is obtained through geometric optimization for panels. Furthermore, the topology optimization model is developed to search the optimal layout of constrained layer damping treatments in the front floor.

The design optimization of vehicle body structure is addressed to reduce interior noise and improve customer satisfaction in this paper. The structural-acoustic model is established and the response of sound pressure in frequency domain is obtained by using finite element method. The minimization of sound pressure near the driver's right ear depends on the geometry of vehicle body structure and the layout of damping treatments. The panel participation analysis is performed to find out the key panels as design variables and improve the efficiency of optimization computation. Response Surface Method (RSM) is utilized to optimize the vibro-acoustic properties of vehicle body structure instead of complex structural-acoustic coupling finite element model. Geometric optimization problem of panels is described and solved to minimize the interior noise in vehicle.

In order to measure the noise of auto shock absorbers, a test bench used to detect piston-rod vibration responses of shock absorbers and measuring analyzer named SANTS-I were developed. The vibration response data was detected by bench tests, which shows that there are high-frequency violent peaks on the sine curve of piston-rod oscillating with relative low frequency. In order to explain the interior work dynamic mechanism of shock absorbers, a schematic Micro-process Dynamic Model with 10 steps particularly divided extension and compression stroke in more detail, and dynamic differential equations for each step were presented and discussed. Furthermore, numerical simulation for the inner impacts interaction between piston and damping fluid of hydraulic shock absorber was realized by ADINA software, by the establishment of a gas-liquid two-phase finite element model.

This paper provides several examples of silicon “micromachined” semiconductor sensors with which the authors are involved for aerospace condition monitoring. This and related work in MEMS (Micro Electro Mechanical Systems) has the potential to revolutionize condition monitoring in aerospace condition and “health monitoring” by (1) moving “smart” electronics out to the sensor chip itself and (2) combining a vast quantity and types of, not only electronic, but micromechanical sensing schemes into the silicon chip . Precisely formed cantilevers, gears, valves, microplumbing and even micro motors of the cross-section of a human hair can be fabricated on a single silicon microchip. Silicon is an excellent mechanical material with a yield strength several times that of stainless steel. Also silicon has excellent thermal properties , whereas compatible silicon dioxide (which we typically use in connection with silicon microelectronics patterning) is virtually a thermal insulator.

Computer programs and models are playing an increasing role in simulating vehicle crashworthiness, dynamic, and fuel efficiency. To maximize the effectiveness of these models, the validity and predictive capabilities of these models need to be assessed quantitatively. For a successful implementation of Computer Aided Engineering (CAE) models as an integrated part of the current vehicle development process, it is necessary to develop objective validation metric that has the desirable metric properties to quantify the discrepancy between multiple tests and simulation results. However, most of the outputs of dynamic systems are multiple functional responses, such as time history series. This calls for the development of an objective metric that can evaluate the differences of the multiple time histories as well as the key features under uncertainty.

Vehicle electronics and sensor systems have become indispensable parts in providing safety, comfort, personal communication mobility and many other advanced functions in today's vehicles. As a result, reliability requirements for these critical parts have become extremely important. To meet these requirements, more advanced technologies and tools for degradation monitoring and failure prevention are needed. Currently, the development of diagnostics and prognostics techniques, which employ accurate degradation quantification by appropriate sensor selection, location decision, and feature selection and feature fusion, still remains a vital and unsolved issue. This paper addresses several realistic concerns of failure prevention in vehicle electronics and sensor systems. A unified monitoring and prognostics approach that prevents failures by analyzing degradation features, driven by physics-of-failure, is suggested as a general framework to overcome the unsolved challenge.

Practical issues to consider when making measurements for Nearfield Acoustical Holography (NAH) analysis are addressed. These include microphone spacing and placement from the test surface, number of microphones and array size, reference microphone number and placement, and filtering of the data. NAH has become an accepted analysis tool so that several commercial packages are available. Its application is limited to test surfaces that are fairly planar, lending itself well to tire testing, front of dash testing, engine face testing, etc. In order to achieve accurate NAH results, the measurement and analysis process must be clearly understood on a practical level. Understanding the advantages and limitations of NAH and the measurement parameters required of it will allow the user to determine if NAH is applicable to a particular test object and environment.

The compressor surge line of automotive turbochargers can limit the low-end torque of an engine. In order to determine how close the compressor operates to its surge limit, the Hurst exponent of the pressure signal has recently been proposed as a criterion. The Hurst exponent quantifies the fractal properties of a time series and its long-term memory. This paper evaluates the outcome of applying Hurst exponent based criterion on time-resolved pressure signals, measured simultaneously at different locations in the compression system. Experiments were performed using a truck-sized turbocharger on a cold gas stand at the University of Cincinnati. The pressure sensors were flush-mounted at different circumferential positions at the inlet of the compressor, in the diffuser and volute, as well as downstream of the compressor.

Turbochargers are commonly used in automotive engines to increase the internal combustion engine performance during off design operation conditions. When used, a most wide operation range for the turbocharger is desired, which is limited on the compressor side by the choke condition and the surge phenomenon. The ported shroud technology is used to extend the operable working range of the compressor, which permits flow disturbances that block the blade passage to escape and stream back through the shroud cavity to the compressor inlet. The impact of this technology on a speed-line at near optimal operation condition and near surge operation condition is investigated. A numerical study investigating the flow-field in a centrifugal compressor of an automotive turbocharger has been performed using Large Eddy Simulation. The wheel rotation is handled by the numerically expensive sliding mesh technique. In this analysis, the full compressor geometry (360 deg) is considered.

Nonlinear interaction between time-varying hypoid gear mesh and bearing support is investigated in this study. Mesh parameters are time-varying due to complex tooth profile of hypoid gear. Bearing stiffness is formulated based on real geometry and instantaneous orbital position of rolling elements. Linear model is firstly analyzed to study the modal frequency and mode shape variations under different stiffness ratio between gear mesh and bearing support. Then, nonlinear analysis is conducted to compare the differences between linear and nonlinear dynamic response based on specific nonlinear conditions of geared rotor system. It is found that the coupling between hypoid gear mesh and bearing support can be either strong or weak depending on the ratio between mesh stiffness along line-of-action (LOA) and bearing stiffness in radial direction. Parametric studies indicate that dynamic mesh force is sensitive to bearing clearance for certain stiffness ratio.

A multi-point hypoid gear mesh model based on 3-dimensional loaded tooth contact analysis is incorporated into a coupled multi-body dynamic and vibration hypoid gear model to predict more detailed dynamic behavior of each tooth pair. To validate the accuracy of the proposed model, the time-averaged mesh parameters are applied to linear time-invariant (LTI) analysis and the dynamic responses, such as dynamic mesh force, dynamic transmission error, are computed, which demonstrates good agreement with that predicted by single-point mesh model. Furthermore, a nonlinear time-varying (NLTV) dynamic analysis is performed considering the effect of backlash nonlinearity and time-varying mesh parameters, such as mesh stiffness, transmission error, mesh point and line-of-action. Simulation results show that the time history of the mesh parameters and dynamic mesh force for each pair of teeth within a full engagement cycle can be simulated.

Current powertrain active noise control (ANC) systems are not sufficient enough to track the fast engine speed variations, and yield consistent convergence speeds for individual engine order such that a balanced noise reduction performance can be achieved over a broad frequency range. This is because most of these ANC systems are configured with the standard filtered-x least mean squares (FxLMS) algorithm, which has an inherent limitation in the frequency-dependent convergence behavior due to the existence of secondary path model (electro-acoustic path from the input of control loudspeaker to the output of monitoring error microphone) in the reference signal path. In this paper, an overview is given first to compare several recently modified FxLMS algorithms to improve the convergence speed for harmonic responses such as eigenvalue equalization FxLMS (EE-FXLMS) and normalized reference LMS (NX-LMS) algorithms.

Compression molded SMC composed of chopped carbon fiber and resin polymer which balances the mechanical performance and manufacturing cost presents a promising solution for vehicle lightweight strategy. However, the performance of the SMC molded parts highly depends on the compression molding process and local microstructure, which greatly increases the cost for the part level performance testing and elongates the design cycle. ICME (Integrated Computational Material Engineering) approaches are thus necessary tools to reduce the number of experiments required during part design and speed up the deployment of the SMC materials. As the fundamental stage of the ICME workflow, commercial software packages for SMC compression molding exist yet remain not fully validated especially for chopped fiber systems. In the present study, SMC plaques are prepared through compression molding process.

The formation of fuel film in the combustion cylinder affects the mixing process of the air and the fuel, and the process of the combustion propagation in engines. Some models of film evaporation have been developed to predict the evaporation behavior of the film, but rarely experimental results have been produced, especially when the temperature is high. In this study, the evaporation behavior of the film of different species of oil and their blends at different temperature are observed. The 45 μL films of isooctane, 1-propanol, 1-butanol, 1-pentanol, and their blends were placed on a quartz glass substrate in the closed temperature-controlled chamber. The shape change of the film during evaporation was monitored by a high-speed camera through the window of the chamber. First, the binary blends film of isooctane and one of the other three oils were evaporated at 30 °C, 50 °C, 70 °C and 90 °C.

Road load data is an essential input to evaluate vehicle durability and strength performances. Typically, load case of pothole impact constitutes the major part in the development of structural durability. Meanwhile, misuse conditions like driving over a curb are also indispensable scenarios to complement impact strength of vehicle structures. This paper presents a methodology of establishing Multi-body Dynamics (MBD) full vehicle model in Adams/Car to acquire the road load data for use in durability and strength analysis. Furthermore, load level between durability and misuse conditions of the same Impact road was also investigated to explore the impact due to different driving maneuvers.

Due to the design of lightweight, high speed driveline system, the coupled bending and torsional vibration and rotordynamics must be considered to predict vibratory responses more realistically. In the current analysis, a lumped parameter model of the propeller shaft is developed with Timoshenko beam elements, which includes the effect of rotary inertia and shear deformation. The propeller shaft model is then coupled with a hypoid gear pair representation using the component mode synthesis approach. In the proposed formulation, the gyroscopic effect of both the gear and propeller shaft is considered. The simulation results show that the interaction between gear gyroscopic effect and propeller shaft bending flexibility has considerable influence on the gear dynamic mesh responses around bending resonances, whereas the torsional modes still dominate in the overall frequency spectrum.