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Vehicle to Vehicle Communication use case performance heavily relies on market penetration rate. The more vehicles support a use case, the better the customer experience. Enabling these use cases with acceptable quality on vehicles without built-in navigation systems, elaborate map matching and highly accurate sensors is challenging. This paper introduces a simulation framework to assess system performance in dependency of vehicle positioning accuracy for matching approach path traces in Decentralized Environmental Notification Messages (DENMs) in absence of navigation systems supporting map matching. DENMs are used for distributing information about hazards on the road network. A vehicle without navigation system and street map can only match its position trajectory with the trajectory carried in the DENM.

Vehicle fire investigators often use the existence of burn patterns, along with the amount and location of fire damage, to determine the fire origin and its cause. The purpose of this paper is to study the effects of ventilation location on the interior burn patterns and burn damage of passenger compartment fires. Four similar Ford Fusion vehicles were burned. The fire origin and first material ignited were the same for all four vehicles. In each test, a different door window was down for the duration of the burn test. Each vehicle was allowed to burn until the windshield, back glass, or another window, other than the window used for ventilation, failed, thus changing the ventilation pattern. At that point, the fire was extinguished. Temperatures were measured at various locations in the passenger compartment. Video recordings and still photography were collected at all phases of the study.

This paper discusses the optimization of an automotive hydraulic steering pump pulley design for improved in-vehicle pump NVH performance. Levels of steering pump whine noise heard inside a vehicle were deemed objectionable. Vehicle and component transfer path analyses indicated that the dominant noise path for the whine noise was airborne in nature. Subsequent experimental modal analysis indicated that the steering pump pulley was a major contributor to the amount of radiated noise produced by the pump/pulley system. CAE analysis was used to further analyze the dynamic behavior of the pulley and develop an optimized design with decreased noise radiation efficiency. The results predicted with the CAE analysis were verified in-vehicle, resulting in a vehicle with acceptable steering pump whine noise performance.

Sunroof is placed in certain high-end vehicles to give user a better driving experience. All automakers are searching alternatives to reduce weight and cost in the vehicle, in which sunroofs are also impacted. Some alternatives are already applied, as a honeycomb paper used in some sunshades that presents benefits, as less weight and with a good cost reduction. Although, due the reduced weight for this part produced in this material, it shows more susceptibility to reproduce the vibration that vehicle propagates in movement, especially in bad condition roads. The sunroof assembly is dependent of the roof reinforcement and roof skin, but in this special case, the validation could be done in the components itself because the interaction of the sunshades is directly dependent of the other sunroof parts, as rails and front frame.

Squeak and rattle are two undesirable occurrences during component operation and during vehicle driving condition, resulting in one of the top complains from costumers. One common grievance could happen during the user exterior handle operation and during side door closing. The exterior handle system during the operation could generate a squeak between interface parts, if materials and geometric tolerances was not been carefully designed. Also, vibration generated during door closing effort, might generate squeak between parts since the reinforcement for exterior handle touches the outer sheet metal internally. For this reason several guidelines might be included to avoid potential noise condition for this system during vehicle lifetime as correct material reduce friction between parts, taking into consideration the geometric condition between parts. Plus, coupling system on handles two pieces should also be evaluated to avoid squeak during use.

The influence of the pin/main bearing journal diameters and the counter weight orientation to crankshaft axial vibration were examined using a fully flexible finite element engine model. The simulation, performed with AVL/Excite, incorporates modal contributions of all interfacing engine components and enables the study of interactions among the components. The simulation successfully predicted crankshaft axial vibration and was validated by measurements. The correlated CAE model was used to study modifications in crankshaft pin and main bearing journal diameters and in the orientation of the crankshaft counter weights. Design direction on how to minimize axial vibration was provided.

In this paper, a new technology for the design of silent transaxles is developed, where topography optimization is adopted and an artificial parameter called β is proposed as an objective function, representing an upper bound of the surface velocity. The strategy of the optimization is to minimize β while getting the surface velocities less than β. as the constraints. A numerical example of reducing transaxle's radiated noise by using the new optimization technology is given in the paper. In the example, an entire Ford transaxle system was modeled numerically, where most internal components were included. First a modal frequency velocity analysis was conducted. Then an acoustic power analysis based on the Acoustic Transfer Vector (ATV) was carried out. Finally, a topography optimization based on the β - method for the transaxle was performed to minimize the radiated noise.

Many decisions need to be made when test track data is used to set up Squeak & Rattle evaluations of subsystems or components. These decisions are judgment-based so different people with different backgrounds and experience levels will make different decisions - few of which can be called right or wrong - but they are different which causes problems. Squeak & Rattle evaluation has become more scientific in recent years as subjective evaluation has been replaced by quantitative methods like N10 Loudness and shakers have become quiet. It is the authors' contention that the variations caused by different judgment calls can no longer be tolerated. Therefore a methodical process was developed which assures that different people will get the same results from the same set of test track data.

A laboratory experiment is designed to examine the clunk phenomenon. A static torque is applied to a driveline system via the mass of an overhanging torsion bar and electromagnet. Then an applied load may be varied via attached mass and released to simulate the step down (tip-out) response of the system. Shaft torques and torsional and translational accelerations are recorded at pre-defined locations. The static torque closes up the driveline clearances in the pinion/ring (crown wheel) mesh. With release of the applied load the driveline undergoes transient vibration. Further, the ratio of preload to static load is adjusted to lead to either no-impact or impact events. Test A provides a ‘linear’ result where the contact stiffness does not pass into clearance. This test is used for confirming transient response and studying friction and damping. Test B is for mass release with sufficient applied torque to pass into clearance, allowing the study of the clunk.

The objective of this study was to identify and gain an understanding of the origins of noise in a commercial excavator cab. This paper presents the results of two different tests that were used to characterize the vibration and acoustic characteristics of the excavator cab. The first test was done in an effort to characterize the vibration properties of the cab panels and their associated contribution to the noise level inside the cab. The second set, of tests, was designed to address the contribution of the external airborne noise produced by the engine and hydraulic pump to the overall interior noise. This paper describes the test procedures used to obtain the data for the signature analysis, operational deflection shapes (ODS), and sound diagnosis analysis. It also contains a discussion of the analysis results and an inside look into the possible contributors of key frequencies to the interior noise in the excavator cab.

Sensory jury testing was utilized to characterize vibration levels perceived by the operator, with respect to levels measured using instrumentation, in order to develop a tool for the evaluation of vibration at the operator interfaces. Details of the jury testing and jury data processing method are highlighted as well as the refinement of vibration characterization for a specific application. The vibration at user interface locations of both snowmobiles and ATVs was measured along with subjective feedback from a panel of jurists. Statistical analysis was performed on the jury data to provide both a qualitative and quantitative number to represent the opinion of the jury. Correlations were developed between the measured levels of vibration and the opinions of the jury. Finally, a set of correlation functions suitable for design predictions was developed.

This paper describes a study to demonstrate the feasibility of developing an acoustic encapsulation to reduce airborne noise from a commercial diesel engine. First, the various sources of noise from the engine were identified using Nearfield Acoustical Holography (NAH). Detailed NAH measurements were conducted on the four sides of the engine in an engine test cell. The main sources of noise from the engine were ranked and identified within the frequency ranges of interest. Experimental modal analysis was conducted on the oil pan and front cover plate of the engine to reveal correlations of structural vibration results with the data from the NAH. The second phase of the study involved the design and fabrication of the acoustical encapsulation (noise covers) for the engine in a test cell to satisfy the requirements of space, cost and performance constraints. The acoustical materials for the enclosure were selected to meet the frequency and temperature ranges of interest.

This work is focused on the computer aided engineering noise and vibration control area (CAE-NVH), which is one of the most important in the automobile industry. The reason for that relevancy is that the noise and vibration effects can be directly perceived by the costumer. The vibration of the seats and steering wheel, as well as audible noises are some examples of factors that can cause discomfort to the driver. During the early design of a car, the systems are designed in a way to reach a good modal management level in order to avoid resonance problems. The finite element models, used to predict these resonances, are normally generated using only deterministic values for the model parameters such as stiffnesses, thicknesses and masses. However, these properties have an uncertainty due to the manufacturing process which is, in most cases, not taken into consideration during the design.

Global acoustic sensitivity analysis [1] is a technique used to identify structural modifications to a component that can reduce the total radiated power of a vibrating structure or the sound pressure levels at specified field points. This report describes the use of global sensitivity analysis within SYSNOISE to determine what structural changes are required to reduce radiated noise from flexible structures in an open duct system. The technique can help optimize design parameters that define the behavior of a flexible structure such as shell thickness and Young's Modulus. The sensitivity analysis approach consists of separately evaluating structural and acoustic sensitivities. A structural finite element model (FEM) of an open duct system is used to compute the sensitivity of the structural response to changes in thickness. A boundary element model (BEM) is then used to relate changes in the calculated acoustic response to changes in the structural design variables.

An analytical model is developed to describe the torsional responses of the powertrain system. The model is used to analyze system equilibrium, free vibration, forced and self-excited vibrations. The equations of motion are linearized about the equilibrium to determine natural frequencies and mode shapes of the torsional modes. The forced responses of the system are investigated by including the excitations of gas combustion forces and inertia torques induced by the reciprocating motions of the piston and connecting rod. The self-excited vibration induced by negative damping behavior of clutch torque capacity is studied. For an example rear-wheel drive powertrain considered, the free vibration analyses show the natural frequencies and the associated mode shapes. The forced and the self-excited vibrations for the transmission gearset and the driveline components are examined. Experimental measurements from a test powertrain are used to confirm the theoretical predictions.

Vehicle sensitivity to brake induced vehicle vibration has been one of the key factors impacting overall vehicle quality. This directly affects long term customer satisfaction. The objective of this investigation is to understand the sensitivities of a given suspension, and steering system with respect to brake induced vehicle vibration, and develop possible solutions to this problem. Design of experiment methods have been used for this chassis system sensitivity study. The advantage of applying the design of experiment methodology is that it facilitates an understanding of the interactions between the hardware components and the sensitivity of the system due to the component change. The results of this investigation have indicated that the friction of suspension joints may affect vehicle system response significantly.

High mileage NVH performance is one of the major concerns in vehicle design for long term customer satisfaction. Elastomeric bushings and brake rotors are key chassis components which tend to degrade as vehicle mileage accumulates with time. The degradation of these components normally causes the overall degradation of vehicle NVH performance. In the current paper two categories of problems are addressed respectively: road-induced vibration due to bushing degradation, and brake roughness due to rotor wear. A system integration approach is used to derive the design strategies that can potentially make the vehicle more robust in these two NVH attributes. The approach links together bushing degradation characteristics, brake rotor wear characteristics, the design of experiment (DOE) method, and CAE modeling in a systematic fashion. The concept and method are demonstrated using a production vehicle.

Thermocouples are commonly used to measure exhaust gas temperature during automotive engineering experiments. In most cases, the raw measurements are used directly as an absolute indication of the actual exhaust gas temperature. However, in reality, the signal from a TC is only an indication of its own tip temperature. The TC indicated tip temperature can deviate significantly from the actual gas temperature due to factors such as thermal capacitance of the tip itself, and heat transfer to the exhaust pipe wall through conduction and radiation. A model has been developed that calculates the effects of these factors to provide an estimate of the actual exhaust gas temperature. Experiments were performed to validate the model under both transient and steady state engine dynamometer conditions utilizing three popular sizes of TCs. Good correlation among predictions for various TC sizes confirms the model's accuracy.

In today's competitive automobile environment with shorter vehicle development time and fewer prototypes/tests, CAE is becoming very crucial for vehicle development. Seat is a critical system of automobiles for customer satisfaction because seat provides support, safety, and comfort especially NVH for vehicle occupants. In this paper, the effects of seat system on body and vehicle NVH were studied. How the seat system affected body and vehicle NVH, and how seat to floor coupling affected vehicle NVH were investigated. Two groups of finite element body models, body-on-frame and unitized body, were used for this study to ensure the effect of body architecture was included in this study. In the baseline body models, the seats were represented by detailed finite element models. Then, several versions of body models were built by modeling seats in different finite element representations.

In order to remain competitive in the current challenging automotive industry, there is a great demand for a common design that can be used across different platforms. Such common design can not only lower the cost due to the high volume production, but also significantly reduces the design development time. However, how to meet different programs' unique requirements by the same design remains as a challenge. In the case of a seat design, it is important that the seat natural frequencies are separated from the full vehicle system's resonant frequencies to avoid the possible alignment causing the seat vibration issue. This paper describes a method of how to design a mass damper that not only separates the seat modes from the vehicle's specific resonant frequency range but also reduces the seat back vibration amplitude significantly. The response surface based optimization method is used to tune the elastic mass damper parameters to meet the program's specific requirements.