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An airport runway frictional coefficient measuring vehicle is the important ground support equipment which is essential to the aircraft safety of taking off and landing. The modeling method of the measuring vehicle affects the measure result directly. The bond-graph modeling method is used to model the hanging system and measuring system of the measuring vehicle, the surface roughness of the runway produced by power spectral density and the discrete Fourier inverse transformation is utilized as the input excitation. The validity of the system models is verified based on the simulation.

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It is rather difficult for engineers to apply many of the fatigue damage models for requiring a knee point, material-dependent coefficient, or extensive testing, and some of them are only validated by a fatigue test of two-stage loading rather than higher-stage loading. In this paper, we propose a new model of fatigue cumulative damage in variable amplitude loading, which just requires the information of the S-N curve determined from the fatigue experiment. Specifically, the proposed model defines a stress equivalent transformation way to translate the damage of one stress to another stress through simple calculation. Experimental data of fatigue including two-, three-, and four-block loading verify the superiority of the proposed model by comparing it with the Miner model and Manson model. The results show that the proposed model can be generalized to any type of loading and presents a better prediction. Therefore, the advantage of the proposed model can be easily used by an engineer.