Simplified elastic wave modeling in seven-wire prestressed parallel strands

This paper considers elastic wave propagation in seven-wire parallel strands. Under a transverse distributed force, the stress state of seven-wire strands is derived from the Hertzian theory, which is regarded as the prestress state for the dynamic analysis. According to the wave finite element method, the elastodynamic equation with prestress is discretized corresponding to harmonic wave motion. Firstly, the results are verified by the semi-analysis finite element method. Then, dispersion properties in seven-wire parallel strands are computed and compared to those of double cylindrical rods. Besides, the results from parallel strands and helical strands indicate that wave propagation in the former is significantly different from that in the latter. For the deep understanding of wave characteristics, the displacement vectors are used to identify the propagating modes. It is found that there is only one torsional-like mode which rotates with a twist center in the whole region. Meanwhile, it is found that the variation of prestress has large influence on the torsional-like mode for low frequencies, but little on propagating modes for high frequencies. In addition, there appears the notch frequency and the effect of prestress on it is discussed in detail. The notch frequency decreases with the rising of the prestress in a certain range.