Influence of climatic conditions on the occurrence of wheel track deformation on asphalt paved roads

When the car moves, a vertical, longitudinal and transverse dynamic force is generated, where there is a link between the road cover and the wheel. Repeated loads from vehicles and the impact of climatic factors lead to deformation in the pavement and pavement of the road. In deformation and deformation, the geometric dimensions and durability of the road pavement are lost. Disturbances-loss of dimensions and loss of durability of parts of the construction is understood. In practice, all types of deformation and distortion are often regarded as a drawback of road conditions [1].

Fractal Characteristics of Transverse Crack Propagation on CRTSII Type Track Slab

Objectives of this study are to examine influence of the surface crackles fractal characteristics of CRTSII track slab on its propagation velocity and stress intensity factor (SIF) and to improve the service performance of track slab. In this paper, fractal dimension D of transverse crack on the surface of CRTSII track slab was calculated by image processing, digital image technology, and box-counting method. Based on the fractal structure of transverse crack on track slab surface, a fractal transverse crack propagation model was established. The impact of fractal effect on the surface crack propagation velocity and SIF of CRTSII track slab was analyzed quantitatively. The fractal dimension D of transverse crack is 1.0652 on the surface of CRTSII track slab. The actual measured crack propagation velocity V0 on the surface of the track slab can be corrected as the true crack propagation velocity V. When the V0/Cr=0.899<1, the SIF K′L1.0652,t,V of transverse dynamic fractal crack propagation on the surface of track slab has been equal to 0, and the V0 is always lower than Rayleigh wave velocity. In addition, the true attenuation rate of SIF for CRTSII track slab surface transverse dynamic crack propagation is faster than the actual measured value.

Longitudinal and Transversal Behavior of Multifilament Yarn Subjected to Longitudinal Load Using Image Analysis

The understanding of textile yarns behavior is of paramount relevance for the textile industry, mainly for technical applications. This describes the research work to introduce an alternative method for both yarns diameter and volumetric measurement using image analysis. Its main goal is to better describe the transverse dynamic behavior of multifilament yarns when submitted to tensile loads. Methods for measuring yarns diameter found in the literature are described and discussed. The proposed method presents significant advantages allowing the possibility to perform tests without interruption, as well as the ability to generate a greater amount of data, providing more accurate results. Longitudinal tensile tests using two types of multifilament polyamide yarns were performed and their actual dynamic behavior is analyzed using the experimental results.

Intelligent parameter identification for bridge cables based on characteristic frequency equation of transverse dynamic stiffness

Determining the cable force and other parameters of cables is important for condition assessment of cable-stayed structures. This study proposes a frequency characteristic equation of transverse dynamic stiffness for cables; this equation is suitable for measuring the vibrations to evaluate the primary factors that influence the accuracy of cable parameter identification. Further, a cable parameter identification method based on the particle swarm optimization algorithm is proposed. The method is suitable for a cable system of arbitrary length and with moderate sag especially when the measurement quality of the modal frequencies of cables is poor. Both numerical case studies and a cable vibration test proved that the proposed method can identify parameters with high accuracy for cables of any length and for cases requiring low-frequency measurement. Moreover, structural modal order information is not required. The extreme case is that only one order frequency can achieve highly accurate result in this way. The proposed method is suitable for parameter identification of short cables, hanger cables, and parallel strand cables, which are commonly applicable in engineering applications.