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Technical Paper

Modeling and Experimental Verification of Vibration and Noise Caused by the Cavity Modes of a Rolling Tire under Static Loading

2011-05-17
2011-01-1581
Tire cavity noise refers to the vehicle noise due to the excitation of the acoustic modes of a tire air cavity. Although two lowest acoustic modes are found to be sufficient to characterize the cavity dynamics, the dynamical response of these two modes is complicated by two major factors. First, the tire cavity geometry is affected by the static load applied to the tire due to vehicle weight. Second, the excitation force from the tire-road contact changes position as the tire rotates. In this paper, we first develop dynamic equations for the lowest cavity modes of a rotating tire under the static load. Based on the model, we obtain the forces transmitted to the wheel from the tire resulting from the random contact force between the tire and the road surface. The transmitted forces along the fore/aft direction and the vertical direction show two peaks at frequencies that are dependent both on the tire static load and on the vehicle speed.
Technical Paper

Determination of Interior NVH Levels from Tire/Wheel Variations using a Monte Carlo Process

2011-05-17
2011-01-1580
Variability in design (e.g. tolerance), material, manufacturing, or other sources of variation causes significant variation in vehicle noise, vibration and harshness (NVH) response. This leads to a higher percentage of produced vehicles with higher levels of NVH leading to higher number of warranty claims and loss of customer satisfaction, which are proven costly to the original equipment manufacturers (OEM). Measures must be taken to insure less warranty claims and higher levels of customer satisfaction. As a result, original equipment manufacturers have implemented design for variation in the design process to secure an acceptable (or within specification) response. We will focus on some aspects of design variations in a tire/wheel assembly that should be considered in the design process. In particular, certain materials (e.g. rubber) are known to have variation in stiffness that is either unavoidable or proven costly if tighter control is desired.
Journal Article

Challenges for Tire Noise Evaluation on Common Pavements

2011-05-17
2011-01-1582
Developing common methods of noise evaluation and facilities can present a number of challenges in the area of tire/pavement noise. Some of the issues involved include the design and construction of pavements globally, the change in pavement over time, and variation in the noise produced with standard test tires used as references. To help understand and address these issues for airborne tire/pavement noise, acoustic intensity measurement methods based on the On-board Sound Intensity (OBSI) technique have been used. Initial evaluations have included measurements conducted at several different proving grounds. Also included were measurements taken on a 3m diameter tire noise dynamometer with surfaces replicating test track pavements. Variation between facilities appears to be a function of both design/construction and pavement age. Consistent with trends in the literature, for smooth asphalt surfaces, the newest surface produced levels lower than older surfaces.
Journal Article

Tire and Road Input Modeling for Low-Frequency Road Noise Prediction

2011-05-17
2011-01-1690
This paper presents a modeling method for prediction of low-frequency road noise in a steady-state condition where rotating tires are excited by actual road profile undulation input. The proposed finite element (FE) tire model contains not only additional geometric stiffness related to inflation pressure and axle load but also Coriolis force and centrifugal force effects caused by tire rotation for precise road noise simulation. Road inputs act on the nodes of each rib in the contact patch of the stationary tire model and move along them at the driving velocity. The nodes are enforced to displace in frequency domain based on the measured road profile. Tire model accuracy was confirmed by the spindle forces on the rotating chassis drum up to 100Hz where Coriolis force effect should be considered. Full vehicle simulation results showed good agreement with the vibration measurement of front/rear suspension at two driving velocities.
Technical Paper

Road Noise TPA Simplification for Improving Vehicle Sensitivity to Tire Cavity Resonance Using Helium Gas

2009-05-19
2009-01-2092
Transfer Path Analysis (TPA) is an established tool that can be used to determine path contributions for road noise transmission (e.g. suspension links, sub-frame bushings, etc.) in passenger vehicles. However, due to the large number of paths and the presence of multiple partially-correlated sources in a road noise problem, TPA can be nearly impractical to implement as an experimental diagnostic tool. A simplified approach to Road Noise TPA is desirable to reduce test and analysis times in this era of shortening development cycles. It has been previously established that helium gas can be used to significantly alter the frequency of a tire’s acoustic cavity resonance [1]. Helium is used to “eliminate” excitation sources at the frequencies of tire cavity resonances, thereby reducing the number of paths to consider and simplifying a complex multi-reference TPA down to a single-reference TPA problem.
Technical Paper

A Three-Dimensional Ring-Based Structural Tyre Model: Development and Validation

2009-05-19
2009-01-2105
This paper presents the development of a structural model for passenger car tyres, based on a three-dimensional flexible ring on an elastic foundation. The ring represents the belt and the elastic foundation represents the tyre sidewall. The tyre model, which is implemented as a finite element model, is valid below the first treadband axial bending mode and includes a definition of the wheel flexibility and air cavity. The eigenfrequencies predicted by the model are within 5% of the measured eigenfrequencies. The model is validated by comparing predicted with measured responses for both an unloaded and loaded tyre.
Technical Paper

A Comparison of Fiber Wheel Liners on Two Different Vehicles

2009-05-19
2009-01-2106
Identical fiber wheel liners were installed on two different mid size vehicles in order to compare the noise reduction for each vehicle. The fiber liners represented material in current production. A baseline noise level was established with the existing plastic wheel liners and then comparisons were made with fiber wheel liners. Noise levels were compared in the wheel well and in the interior for similar vehicle operating conditions. For both vehicles, significant tire noise reduction at the source was measured with fiber liners compared to plastic liners. One of the vehicles also demonstrated noise reduction in the passenger cabin with fiber liners. Insight into potential explanations for these differences was provided by comparing the noise levels at different locations within the vehicles. The results show how fiber liners are an additional tool to reduce the noise in a vehicle and how the NVH design for the balance of the vehicle can leverage the NVH impact of these parts.
Journal Article

Modeling and Experimental Investigation of Tire Cavity Noise Generation Mechanisms for a Rolling Tire

2009-05-19
2009-01-2104
Tire cavity noise refers to the excitation of the acoustic mode of a tire cavity. The noise exhibits itself as sharp resonance-like peaks with frequencies typically in the range of 190-250Hz. For a rolling tire, the tire contact with the road moves relative to the tire. Furthermore, the load on the tire breaks the circular symmetry of the tire. Consequently, the peak frequency of the cavity noise shows dependence on the tire load and the vehicle speed. There are no models that simultaneously take these two factors into consideration. In this paper, we propose an analytical model and present experimental verifications of predictions on the noise peak frequency and its dependence on the tire load and vehicle speed. A wireless experimental measurement system is also presented which enables the measurement of tire cavity frequency for both non-rolling and rolling conditions.
Technical Paper

An Innovative Method of Simulating Tire Non-Uniformity Forces for Vehicle Vibration Sensitivity Measurements

2009-05-19
2009-01-2086
This paper presents an innovative method of simulating tire non-uniformity forces for vehicle vibration sensitivity tests. The method utilizes a patented mechanical device to produce a vertical or tangential force independently at a vehicle wheel spindle to simulate the excitation generated by tire non-uniformity forces. Using this device in vehicle vibration sensitivity tests, the amplitude of a vertical force can be set at a desired level without inducing a tangential force; and vice versa for a tangential force. Therefore, the vehicle vibration sensitivity to the vertical or tangential forces can be tested respectively without the confounded effect of other direction excitation. This method eliminates the time and cost associated with tire sorting and provides an effective and reliable testing approach to measure vehicle vibration sensitivity due to tire non-uniformity forces.
Technical Paper

Use of the ASTM Standard Reference Test Tire as a Benchmark for On-Board Tire/Pavement Noise Measurement

2009-05-19
2009-01-2108
There is a growing interest in using a standard reference tire for both assessing changes in test track pavement over time and rank ordering of the performance of different highway pavements. Because of longer-term availability, the ASTM Standard Reference Test Tire (SRTT) is the primary candidate for these applications. Issues of concern for the SRTT include tire-to-tire variation, the relation of the SRTT to other tires currently in use, and the “break-in” period required for stable test tires. To address tire-to-tire variability, seven SRTT’s were tested on variety of asphalt concrete (AC) and Portland cement concrete (PCC) surfaces on two occasions. These included five new tires and two that had been in use for some time. Two of the new tires were re-tested with increasing use to examine any break-in period effect.
Technical Paper

Prediction of Spindle Force Using Measured Road Forces on Rolling Tire

2009-05-19
2009-01-2107
Improvement of vehicle interior noise is desired in recent years in the modern world of the demand of low weight, good fuel economy and offering technical advantages strongly. The dynamic force transmission of rolling tires from the road surface to the spindles is a critical factor in vehicle interior noise. We focus on structure-borne noise transferred through the spindle. It is necessary for effort of the effective tire/road noise reduction to predict spindle force excited by tire/road contact. The major issues in predicting spindle forces are to clarify the distribution of road forces and how to input on the simulation model. Therefore, it is important that road forces are measured accurately on the rolling tire. First, the dynamic road forces on the rolling tire are measured by using the tri-axial force sensor directly. In efforts to reduce interior noise due to structure-borne noise, it is necessary to predict spindle forces excited by the tire/road contact.
Technical Paper

Modern Tyre Tests Support Vehicle Dynamics Calculations

2009-01-21
2009-26-0069
Nearly all the external accelerating forces acting upon a ground vehicle originate at the tyre/ground interface and are transmitted to the vehicle through its tyres. How much force is applied, how quickly, and with what sensitivity of force to tyre deflection are subjects that can fill one's entire professional career. This paper offers a look at the effect of tyre cornering stiffness upon vehicle handling stability.
Journal Article

Simulation Analysis of the Effect of Tire and Suspension Non-Linearities on the Handling Response of Rigid and Articulated Vehicles

2011-04-12
2011-01-0962
This paper presents a simulation based analysis of the effect of various non-linearities on vehicle handling of rigid and articulated vehicles. First a description of a non-linear vehicle model is presented and non-linearities, including tires, suspension elasto-kinematics, springing and damping are discussed. Later sections present the simulations results for the effects of each non-linearity. Simulation analyses are carried out for the case of step steering maneuvers, which permit to deduce the overall vehicle model response variation in steady-state and dynamic conditions.
Journal Article

Real-time Tire Imbalance Detection Using ABS Wheel Speed Sensors

2011-04-12
2011-01-0981
This paper proposes an approach to use ABS wheel speed sensor signals together with other vehicle state information from a brake control module to detect an unbalanced tire or tires in real-time. The proposed approach consists of two-stage algorithms that mix a qualitative method using band-pass filtering with a quantitative parameter identification using conditional least squares. This two-stage approach can improve the robustness of tire imbalance or imbalances. The proposed approach is verified through vehicle testing and the test results show the effectiveness of the approach.
Technical Paper

A Technical Analysis of a Proposed Theory on Tire Tread Belt Separation-Induced Axle Tramp

2011-04-12
2011-01-0967
Recently, papers have been published purporting to study the effect of rear axle tramp during tread separation events, and its effect on vehicle handling [1, 2]. Based on analysis and physical testing, one paper [1] has put forth a mathematical model which the authors claim allows vehicle designers to select shock damping values during the development process of a vehicle in order to assure that a vehicle will not experience axle tramp during tread separations. In the course of their work, “lumpy” tires (tires with rubber blocks adhered to the tire's tread) were employed to excite the axle tramp resonance, even though this method has been shown not to duplicate the physical mechanisms behind an actual tread belt separation. This paper evaluates the theories postulated in [1] by first analyzing the equations behind the mathematical model presented. The model is then tested to see if it agrees with observed physical testing.
Journal Article

Vehicle Handling Parameter Trends: 1980 - 2010

2011-04-12
2011-01-0969
Handling and tire performance continue to evolve due to significant improvements in vehicle, electronics, and tire technology over the years. This paper examines the trends in handling and tire performance metrics for production cars and trucks since the 1980's. This paper is based on a significant number of directional response and tire tests conducted during that period. It describes ranges of these parameters and shows how they have changed over the past thirty years.
Journal Article

Steering and Handling Performance During a Full Tire Tread Belt Separation

2011-04-12
2011-01-0973
In this study, tests were performed with modified tires at the various front and rear positions on seventeen different vehicles to determine the effect of a full tire tread belt separation on a vehicle at highway speeds. The driver's steering and braking inputs were measured along with the vehicle responses during the event. The results show that the forces of a full tread belt separation generally do not force a vehicle out of a driver's control and that only small steering corrections are required to remain in the original lane of travel during the tread belt separation event. Additionally, forces due to the separating tires do not result in violent hop or tramp suspension responses during the separation event.
Technical Paper

Experimental Measurements of the Effect of Path Clearing on Hydroplaning Behavior

2011-04-12
2011-01-0975
Vehicles operating in wet conditions may experience hydroplaning of one or more tires. Proper analysis of this behavior requires accommodating the clearing of paths for the rear tires that may result from the front tires engaging the water coated surface first. An experimental program was developed to study tire/road behavior during straight line braking maneuvers on a wet surface. Wheel rpm values were measured with operating ABS via CAN bus data. The experiments allowed qualitative estimation and visualization of the effects of path clearing on rear tires.
Journal Article

Shape and Strain Measurement of Rotating Tire by Sampling Moiré Method

2011-04-12
2011-01-0995
Recently, sampling moire method was developed to analyze the phase of a one-dimensional or two-dimensional grating on an object with high accuracy. In the method, several phase-shifted moire patterns are generated from one image of the grating. In order to analyze a shape by a stereoscopic method, it is necessary to find the corresponding points between the two images of the object recorded from different two cameras. It is possible to analyze the phase of the grating using the sampling moiré method and find the corresponding points as points with the same phase. It is also possible to analyze the displacement and strain from the corresponding point before and after deformation. This method is, therefore, suitable for shape and strain distribution measurement of a moving object. In this paper, a dynamic shape and strain measurement method using the sampling moiré method is proposed and a system for the measurement is developed.
Technical Paper

Enhancement of ABS Performance through On-Board Estimation of the Tires' Response by Means of Smart Tires

2011-04-12
2011-01-0991
Active controls for braking dynamics are widely investigated in literature [1]-[8] as one of the way to improve vehicle safety and avoid collisions. Active systems commonly mounted on passenger cars like ABS/EBD, have achieved a high level of robustness towards possible changes in the tires' characteristics due to multiple causes such as: under-inflation, wear and also replacement of tires with new ones different from the first equipment series. Although these electronic control systems have been designed to be robust and no case-sensitive to such variations in tire conditions, a further improvement of their performance could be achieved by means of a continuous adaptive control.
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