A Study of Real Area of Contact for Tire/Road Interface

Author(s):  
Jeremy J. Dawkins ◽  
Sameer G. Shah ◽  
Robert L. Jackson

This paper investigates some of the modeling techniques available for predicting the real area of contact between two surfaces. These models are then applied to an idealized case of a rubber block in contact with a rough surface representing a tire on the road. A description of how the models work is presented. The various contact models are compared and analyzed. Qualitatively the models compare very well. Several models also compare well quantitatively.

Author(s):  
Yilei Zhang ◽  
Sriram Sundararajan

Autocorrelation Length (ACL) is a surface roughness parameter that provides spatial information of surface topography that is not included in amplitude parameters such as Root Mean Square roughness. This paper presents a statistical relation between ACL and the real area of contact, which is used to study the adhesive friction behavior of a rough surface. The influence of ACL on profile peak distribution is studied based on Whitehouse and Archard’s classical analysis, and their results are extended to compare profiles from different surfaces. With the knowledge of peak distribution, the real area of contact of a rough surface with a flat surface can be calculated using Hertzian contact mechanics. Numerical calculation shows that real area of contact increases with decreasing of ACL under the same normal load. Since adhesive friction force is proportional to real area of contact, this suggests that the adhesive friction behavior of a surface will be inversely proportional to its ACL. Results from microscale friction experiments on polished and etched silicon surfaces are presented to verify the analysis.


Author(s):  
W. Everett Wilson ◽  
Robert L. Jackson

The current work considers the multiscale nature of surface roughness in a new model that predicts the real area of contact and surface separation, both as functions of load. By summing the distance between the two surfaces at all scales, a model of surface separation as a function of dimensionless load is also obtained. A previous rough surface multiscale contact model was based on stacked elastic-plastic spheres. This work uses stacked 3-D sinusoids to represent the asperities in contact at each scale of the surface. The results are also compared to several other existing rough surface contact models and experimental results. It appears that the statistical and multiscale models make different assumptions when considering surface separation. The statistical model does not consider the effect of deformation on the mean surface height, but the multiscale model does (the location of the mean height will change as the surface deforms). When deformation is included and the surface separation becomes zero, the surfaces must also come into complete contact.


1995 ◽  
Vol 117 (4) ◽  
pp. 607-611 ◽  
Author(s):  
C. P. Hendriks ◽  
M. Visscher

Theoretical models describing the contact of rough surfaces have been developed for at least three decades. Experimental verification, however, has not been straightforward up till now, since current measurements suffer from large inaccuracies, often 100 percent or worse. In this paper a new method, based on autofocus techniques, is applied with an accuracy better than 15 percent. Measurements are presented for the contact of a rough polyurethane specimen in contact with a smooth glass plate. It was not yet possible to conclude whether the real area of contact is proportional to the contact load, but the results show the forming of contact agglomerations, which becomes significant at 10 percent real area of contact. Asperity interaction appears to be important, even at low loads. However, one or both of these facts are often not considered in present contact models, questioning their reliability.


1984 ◽  
Vol 106 (1) ◽  
pp. 26-34 ◽  
Author(s):  
Bharat Bhushan

The statistical analysis of the real area of contact proposed by Greenwood and Williamson is revisited. General and simplified equations for the mean asperity real area of contact, number of contacts, total real area of contact, and mean real pressure as a function of apparent pressure for the case of elastic junctions are presented. The critical value of the mean asperity pressure at which plastic flow starts when a polymer contacts a hard material is derived. Based on this, conditions of elastic and plastic junctions for polymers are defined by a “polymer” plasticity index, Ψp which depends on the complex modulus, Poisson’s ratio, yield strength, and surface topography. Calculations show that most dynamic contacts that occur in a computer-magnetic tape are elastic, and the predictions are supported by experimental evidence. Tape wear in computer applications is small and decreases Ψp by less than 10 percent. The theory presented here can also be applied to rigid and floppy disks.


Worldview ◽  
1976 ◽  
Vol 19 (9) ◽  
pp. 4-9
Author(s):  
Mark A. Bruzonsky

The real crunch for Israel will probably come during 1977 if Ford is elected—it will be delayed by only a few months if a Democratic candidate wins.” So writes Wolf Blitzer, editor of the “Jewish lobby's” Washington publication Near East Report, in a recent issue of the Jerusalem Post.With the same sense of urgency Abba Eban insists that “Time is of the essence, and unhappily for us, time is running out. We ought to grasp the central issues now and involve the United States in resolving them.” He and a growing number of his colleagues fear that should Israel not choose to “cooperate” with the U.S., the Americans might run right over Israel on the road to Geneva and some form of imposed settlement.


Complexity ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-17
Author(s):  
Yongchao Song ◽  
Jieru Yao ◽  
Yongfeng Ju ◽  
Yahong Jiang ◽  
Kai Du

In order to solve the problems of traffic object detection, fuzzification, and simplification in real traffic environment, an automatic detection and classification algorithm for roads, vehicles, and pedestrians with multiple traffic objects under the same framework is proposed. We construct the final V view through a considerate U-V view method, which determines the location of the horizon and the initial contour of the road. Road detection results are obtained through error label reclassification, omitting point reassignment, and so an. We propose a peripheral envelope algorithm to determine sources of vehicles and pedestrians on the road. The initial segmentation results are determined by the regional growth of the source point through the minimum neighbor similarity algorithm. Vehicle detection results on the road are confirmed by combining disparity and color energy minimum algorithms with the object window aspect ratio threshold method. A method of multifeature fusion is presented to obtain the pedestrian target area, and the pedestrian detection results on the road are accurately segmented by combining the disparity neighbor similarity and the minimum energy algorithm. The algorithm is tested in three datasets of Enpeda, KITTI, and Daimler; then, the corresponding results prove the efficiency and accuracy of the proposed approach. Meanwhile, the real-time analysis of the algorithm is performed, and the average time efficiency is 13 pfs, which can realize the real-time performance of the detection process.


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