Experimental investigation on mechanical behavior of damaged HMPE mooring ropes under service loads

•Field tests of HMPE ropes were performed in seaweed farms to develop alternative solutions for commonly used polyethylene mooring ropes.•A new-type of experimental set-up for general fiber ropes testing is established, and a new experimental procedure is proposed.•A series of laboratory tests of residual strength and stiffness evolution of HMPE ropes are investigated.•To evaluate the impact of field service wear and tear on the HMPE mooring ropes, the field damage pattern is mimic by a cutting sub-rope method. The mechanical properties of both the cut sub-ropes and the field worn ropes are compared by analyzing the test results of their residual strength as well as the static and dynamic stiffness of the ropes. This paper investigates the residual strength and stiffness evolution characteristics of high-modulus polyethylene (HMPE) ropes used in seaweed farms service. In some cases, polypropylene (PE) ropes commonly used in seaweed farms are more prone to failure in severe marine conditions, and HMPE ropes may be a more suitable alternative. Normally, damages occur during the service life of ropes in marine environments, such as marine biofouling, corrosion and internal abrasion from fine sand infiltration into the strands. Early studies on the mechanical properties of aged ropes (due to field service) suggest that both the strength and stiffness may be affected. In addition, the damage patterns of artificially induced cutting may not faithfully replicate the damaged state of the ropes in field service marine environments. Hence, the residual strength and stiffness evolution of the aged ropes with damage induced under service loads is investigated by using experimental testing techniques of fiber ropes. Additionally, by analyzing the residual strength, as well as the static and dynamic stiffness of the new (i.e., intact) and aged HMPE ropes, the damage that occurred by artificial cutting is compared with the damage that occurred under service loads.