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Pavement texture plays a vital role in the development of both pavement friction and tire wear. Hence, knowledge of the effect of texture parameters on friction and tire wear will certainly assist pavement engineers in designing pavements that improve tire life without compromising the all-important skid-resistance. This paper describes the second stage of a research project undertaken to identify the fundamental texture properties that are associated with friction and wear. A analytical methodology for computer modeling of pavement texture formulated during the previous stage is now applied to model actual pavement surfaces made of asphalt and concrete. The pavement surface profiles measured by a SURTRONIX 3+ profilometer in two perpendicular directions are converted to Auto Regressive Moving Average (ARMA) models. Then, these models are used to graphically regenerate the pavement surface using a Fast Fourier Transform (FFT) technique.

Although there are established methods to measure both tire-pavement friction and pavement texture, friction has not been adequately related to pavement surface texture properties. Therefore, a study has been initiated at the University of South Florida to investigate the dependence of tire-pavement friction on pavement texture. A significant development in the first phase of the study is the formulation of a computer-based methodology that can model the 3-D random roughness of a surface with a given Mean Texture Depth (MTD) as measured by the Grease Patch Test. Examination of synthesized surfaces reveals that the MTD of a random surface is almost an invariant along a given pavement. The same procedure is extended to obtain the frequency spectrum of the generated surface using Fast Fourier Transformation. Finally, the basis of a new analytical approach that can utilize the above frequency spectrum to predict the hysteresis friction of a pavement with random roughness, is illustrated.

Knowledge of the tire-wheel interface pressure distribution is necessary for aircraft wheel design and analysis. A finite element code, ANTWIL, has been developed recently which makes tractable the determination of the tire-wheel interface loads from experimentally obtained strains. Motivated by computational considerations, ANTWIL employs an asymmetrically loaded axisymmetric finite element model. Previously reported results have shown numerically that the axisymmetric assumption is well-justified. Data from a strain-roll test conducted at Wright-Patterson Air Force Base for an F-16 Block30 main landing gear wheel were obtained and analyzed via ANTWIL to recover the associated tire-wheel interface loads. Strain comparisons are shown to illustrate the validity of the recovered loads. Comparison of the load profiles for radial and bias ply tires is given and discussed.

Knowledge of the tire-wheel interface pressure distribution is necessary for aircraft wheel design and analysis. A finite element code, ANTWIL, has been developed recently which makes tractable the determination of the tire-wheel interface loads from experimentally obtained strains. ANTWIL employs an asymmetrically loaded axisymmetric finite element model. This assumption is motivated by computational considerations. Herein three-dimensional finite element models of the F-16, Block 50, main landing gear wheel are developed using the commercial CAE Aries package. One of the models is a detailed representation of the actual wheel; the other is a similar three dimensional model but with the asymmetries removed. A comparison of strain responses from these models is used to validate the axisymmetric assumption on which the ANTWIL code is based. “Experimental” strains obtained from the three-dimensional analysis were used as input to ANTWIL to perform the load recovery.

Current phase of the study was undertaken to examine tensile fatigue behavior of cord-rubber composites representing bias tire carcass under various frequencies up to the level which closely simulates loading during high-speed take-off of aircraft. At a given stress amplitude, the use of higher cyclic frequency was found to affect strain response and heat build-up characteristics of composites significantly. The lower level of initial strain observed at higher frequency stems clearly from strain rate dependence of deformation of rubber matrix composites. The temperature profile of the specimens subjected from 20 to 30 Hz loading showed that hysteretic heating under these conditions may lead to thermal fatigue failure as well as chemical degradation influencing both fiber-matrix adhesion strength and matrix strength.