The brake judder phenomenon

The use of tire vibration modes to represent dynamics in tire models has grown significantly over the years. Initially used primarily in tire modal models to simulate low- to mid-frequency range structure-borne Noise, Vibration, and Harshness (NVH), the applications have broadened to higher frequency, air-borne NVH, and more recently to durability, ride, and braking performance simulations. The broadness and growing importance of these applications lend to having a unified understanding of tire modes and their significance to simulation quality. To this end, a naming convention using wave numbers is developed to identify and categorize modes of an unloaded tire. Background on measurement and predictive tools is presented. Finite element method models are used for interpreting the wave number concept to the 3-D mode shapes and to account for dynamics of the wheel and enclosed air cavity. The effect of tire construction changes on families of modes is discussed throughout. The intent is to simplify and improve identification and physical understanding of tire vibration modes, measurement and simulation techniques and quality, and communication among NVH specialists as well as non-NVH analysts.

Vibration Modes of Radial Tires: Measurement, Prediction, and Categorization Under Different Boundary and Operating Conditions

Vibration Modes of Radial Tires: Application to Non-rolling and Rolling Events

The importance of improving dynamic properties is growing in vehicle development, especially as tire sidewall height is reduced. In particular, accurate prediction of tire and suspension d...

Tire-Suspension-Chassis Dynamics in Rolling over Obstacles for Ride and Harshness Analysis2

Experimentelle Untersuchungen zur Interaktion zwischen Pkw-Reifen und Fahrbahn beim Bremsen

Since road roughness is an important source of vehicle vibration, a system model for NVH analysis requires a tire model which accurately predicts spindle response to road input. Most tire models currently used in the auto industry do not meet this requirement, because they are based on static stiffness of the tire and do not produce realistic response to input at the patch. This paper investigates a new modal tire model with patch input capability as a component within a vehicle system model. Comparisons are also presented between the behavior of the new tire model and a conventional spring model. To validate the performance of the tire model for NVH analysis, simulated vehicle responses to bump input are compared to chassis roll test results.

A New Tire Model for Vehicle NVH Analysis

We present a novel, straightforward method for the characterization of spatiotemporal couplings (STCs) in ultra-short laser pulses. The method employs far-field interferometry and inverse Fourier transform spectroscopy, built on the theoretical basis derived in this paper. It stands out in its simplicity: it requires few non-standard optical elements and simple analysis algorithms. This method was used to measure the space-time intensity of our 100 TW class laser and to test the efficacy of a refractive doublet as a suppressor of pulse front curvature (PFC). The measured low-order STCs agreed with ray-tracing simulations. In addition, we demonstrate a one-shot measurement technique, derived from our central method, which allows for quick and precise alignment of the compressor by pulse front tilt minimization and for optimal refractive doublet positioning for the suppression of PFC.

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Characterization of spatiotemporal couplings with far-field beamlet cross-correlation

We present a novel, straightforward method for spatiotemporal characterization of ultra-short laser pulses. The method employs far-field interferometry and inverse Fourier transform spectroscopy, built on the theoretical basis derived in this paper. It stands out in its simplicity: it requires few non-standard optical elements and simple analysis algorithms. This method was used to measure the space-time intensity of our 100 TW class laser and to test the efficacy of a refractive doublet as a suppressor of pulse front curvature (PFC). The measured low-order spatiotemporal couplings agreed with ray-tracing simulations. In addition, we demonstrate a one-shot measurement technique, derived from our central method, which allows for quick and precise alignment of the compressor by pulse front tilt (PFT) minimization and for optimal refractive doublet positioning for the suppression of PFC.

M. L. Adelberg

Papers

A New Tire Model for Vehicle NVH Analysis

Characterization of spatiotemporal couplings with far-field beamlet cross-correlation

Spatiotemporal pulse characterization with far-field beamlet cross-correlation