Influence of Elastic Modulus on the Dynamic Response of Polyester Mooring Under a Large Axial Stretch

Owing to the particularity of a polyester fiber material, the polyester mooring undergoes large axial tensile deformation over long-term use. Large axial tensile deformation significantly impacts the dynamic response of the mooring system. In addition, the degrees of large axial tension caused by different elastic moduli are also different, and the force on the mooring line is also different. Therefore, it is of great significance to study the influence of elastic modulus on the dynamic results of the mooring systems under large axial tension. Conventional numerical software fails to consider the axial tension deformation of the mooring. Based on the theory of slender rods, this paper derives the formula for large axial tension using the method of overall coordinates and overall slope coordinates and provides the calculation programs. Considering a polyester mooring system as an example, the calculation program and numerical software are used to calculate and compare the static and dynamic analyses to verify the reliability of the calculation program. To make the force change of the mooring obvious, the elastic moduli of three different orders of magnitude are compared and analyzed, and the dynamic response results after large axial tension are compared. This study concludes that the change in the elastic modulus of the polyester mooring changes the result of the vertex tension by generating an axial tension. The smaller the elastic modulus, the larger the forced oscillation motion amplitude of the top point of the mooring line, the more obvious the axial tension phenomenon, and the smaller the force on the top of the polyester mooring.