Temperature influence on tire/road noise measurements: recently collected data and discussion of various issues related to standard testing procedures

Air, road, and tire temperatures substantially affect tire/road noise emission. For measuring purposes, one would like to normalize measurements to a reference temperature by means of a reliable correction procedure. Current studies show that temperature effects remain an important source of uncertainty in tire/road noise measurements and tire testing, even after applying the correction terms provided in the various standards. This seems to be the case for the measurement methods used in OBSI, CPX, SPB, and various regulations or directives based on ECE R117. This paper examines a new dataset consisting of 7.5 million temperature measurements aimed at contributing to a better understanding of temperature effects and the ways they relate to air, road, and tire temperatures. It is assumed that tire temperatures are the most relevant for noise corrections; therefore, special studies are made for how tire temperatures relate to air and road (test surface) temperatures. A profound analysis is provided on how these relationships vary over different day times, seasons, and climatic regions. Based on this analysis, the authors provide suggestions for improvement of temperature normalization in current tire/road noise and tire testing standards. Special considerations are devoted to measurements on test tracks having ISO 10844 reference surfaces.

PLANTABILIDADE E DISTRIBUIÇÃO LONGITUDINAL DE SEMENTES DE ALGODÃO COM DIFERENTES CONJUNTOS DISCO-ANEL EM DOSADOR MECÂNICO

PLANTABILIDADE E DISTRIBUIÇÃO LONGITUDINAL DE SEMENTES DE ALGODÃO COM DIFERENTES CONJUNTOS DISCO-ANEL EM DOSADOR MECÂNICO ALDIR CARPES MARQUES FILHO1, LUIZ HENRIQUE MENCK RUSCONI1, PAULO ROBERTO ARBEX SILVA1 1 Departamento de Engenharia Rural, Universidade Estadual Paulista, UNESP/Botucatu, av. Universitária, 3780, Altos do Paraíso, 18610-034, Botucatu, São Paulo, Brasil) [email protected]; [email protected]; [email protected] RESUMO: A tecnologia em semeadura ou “plantabilidade” é um tema bastante abordado na atualidade e representa a adoção de boas práticas na implantação de lavouras agrícolas. Entre diversos fatores que afetam a qualidade de semeadura está a escolha do conjunto disco e anel dosadores de sementes, como fator de interferência direta na distribuição longitudinal das plantas. Este trabalho teve como objetivo avaliar a interferência da aplicação de dois conjuntos disco-anel de tamanhos diferentes na distribuição longitudinal das sementes na cultura do algodão. O ensaio foi realizado em sistema simulador de semeadura, pertencente ao Núcleo de Ensaios de Máquinas e Pneus Agroflorestais, no Grupo de Plantio Direto (GPD) da UNESP/Botucatu. Os resultados do trabalho mostraram que a seleção adequada do conjunto disco-anel afeta a qualidade da semeadura, sendo que o tratamento T2 apresentou acréscimo de 5% nas falhas e redução de 1% em espaçamentos aceitáveis para a cultura do algodão em semeadura mecânica, assim o percentual de falhas representou um total de 5500 falhas de deposição na lavoura por cada hectare de cultivo. Recomenda-se o uso do conjunto disco-anel T1 (6mm) por ter apresentado os melhores resultados para a variedade de sementes utilizada no experimento. Palavras-chave: mecanização, tecnologia em semeadura, Gossypium hirsutum L. PLANTABILITY AND LONGITUDINAL DISTRIBUTION OF COTTON SEEDS WITH DIFERENTS DISC - RING SET IN MECHANICAL DOSER ABSTRACT: Sowing technology, or “Plantability” is a topic that is widely discussed today and represents the adoption of good practices in the implantation of agricultural crops. Among several factors that affect the quality of planting, the choice of the disc/ring set directly interferes in the longitudinal distribution of plants. This work aimed to evaluate the interference of the application of two disc / ring sets of different sizes in the longitudinal distribution of seeds in cotton crop. Test carried out in a sowing simulator system belonging to the Agroforestry Machinery and Tire Testing Center and the no tillage group (GPD), UNESP/Botucatu. The results of our research showed that the correct selection of the disk-ring set affects the quality of the sowing, and the T2 treatment showed an increase of 5% in the failures and a reduction of 1% in acceptable spacing for the cotton culture in mechanical sowing, as well as the percentage of failures represented 5500 failures of deposition in the field for each hectare of cultivation. It is recommended to use the T1 disk-ring set (6mm) as it has shown the best results for the variety of seeds used in the experiment. Keywords: mechanization, sowing technology, Gossypium hirsutum L

An Experimental Study of Longitudinal Tire Relaxation Constants for Vehicle Traction Dynamics Modeling

Existing literature on vehicle traction dynamics were reviewed for a variety of vehicle and tire dynamic models, some of which consider the pneumatic tires’ relaxation as a property of vehicle transient dynamics. In general, unlike the lateral relaxation counterpart, the longitudinal tire relaxation characteristics were mostly overlooked in tire transient dynamics modeling. As a continuation of the analytical study published in the 2018 DSCC Proceedings, the co-authors of this paper present an experimental study of the longitudinal tire relaxation characteristics of a Continental MPT 81 tire. Experimental results were obtained by conducting tests on an MTS Flat-Trac LTR tire testing machine. The experimental data is analyzed to investigate longitudinal tire relaxation characteristics as they relate to changes of tire conditions. The goal is to verify and refine the existing models suggested in the literature; as well as, discuss advantages and disadvantages of different test procedures and tire testing equipment. In particular, the paper investigates the longitudinal tire relaxation constant variation due to changes of wheel velocity, tire inflation pressure, and sine oscillations of tire slippage in the time and frequency domains. The paper concludes on the influence of the longitudinal tire relaxation constants on the tire/vehicle traction dynamics modeling.

Tire Lateral Vibration Considerations in Vehicle-Based Tire Testing

ABSTRACT Vehicle-based tire testing can potentially make it easier to reparametrize tire models for different road surfaces. A passenger car equipped with external sensors was used to measure all input and output signals of the standard tire interface during a ramp steer maneuver at constant velocity. In these measurements, large lateral force vibrations are observed for slip angles above the lateral peak force with clear peaks in the frequency spectrum of the signal at 50 Hz and at multiples of this frequency. These vibrations can lower the average lateral force generated by the tires, and it is therefore important to understand which external factors influence these vibrations. Hence, when using tire models that do not capture these effects, the operating conditions during the testing are important for the accuracy of the tire model in a given maneuver. An Ftire model parameterization of tires used in vehicle-based tire testing is used to investigate these vibrations. A simple suspension model is used together with the tire model to conceptually model the effects of the suspension on the vibrations. The sensitivity of these vibrations to different operating conditions is also investigated together with the influence of the testing procedure and testing equipment (i.e., vehicle and sensors) on the lateral tire force vibrations. Note that the study does not attempt to explain the root cause of these vibrations. The simulation results show that these vibrations can lower the average lateral force generated by the tire for the same operating conditions. The results imply that it is important to consider the lateral tire force vibrations when parameterizing tire models, which does not model these vibrations. Furthermore, the vehicle suspension and operating conditions will change the amplitude of these vibrations and must therefore also be considered in maneuvers in which these vibrations occur.

Comprehensive Study of the Performance of Winter Tires on Ice, Snow, and Asphalt Roads: The Influence of Tire Type and Wear

ABSTRACT This work presents a comprehensive study of the performance of winter tires on snow, ice, and asphalt. A set of 77 different winter tires were carefully selected for the study. Of these, 27 were new and 50 were worn from real traffic use. All three tire types for winter conditions (Nordic, European, and studded) were represented. All tires have been tested using a mobile tire-testing device for snow and asphalt and using a stationary tire-testing facility for ice. Both devices recorded the tire forces and motions, enabling a close to complete stationary characterization of the tires. In addition, 42 of the tires were tested on a passenger car, where brake performance was evaluated for the three different road conditions. This enables a comparative study of performance between tire types and wear for various winter road conditions. The results suggest that the recorded data represent real vehicle performance. Some conclusions from the measurements are that the effect of wear is consistent between the tire groups and that the performance degradation is most noticeable on studded tires on ice and on European tires on snow.

A ‘smart tire’ for estimating the tire force and the extents of the influences of specific factors

This paper describes an intelligent device for detection of the mechanical characteristics of a tire and its test method. When deformation of the operating tire occurs, by tracking the displacements of fluorescent marker points with a camera, a neural network algorithm is applied to obtain the tire forces. The FTire model is used to fit the experimental curves obtained by measuring the mechanical properties in order to compare whether the test data agree with the actual motion law of the tire. The proposed system bypasses the use of a tire-testing machine and a six-component sensor to measure the force and the torque, and it can achieve real-time measurement and computation without isolating the tire and the vehicle. The proposed method is simple, possesses a compact structure, is easy to operate, and has low costs.