Fatigue Performance of Aramid Hybrid Ropes in Offshore Lifting
How TechIce® Extends Bend-Over-Sheave Life Beyond Conventional Fiber and Steel
Lift-line integrity offshore depends on more than tensile strength. Differences in weight, stiffness, and damping determine how a rope behaves under dynamic loads. In deep-water operations with Active Heave Compensation, fatigue life becomes the critical performance measure. Each bend and recovery introduces micro-damage that defines the usable lifetime of any rope. To quantify this behavior, TechIce® underwent cyclic bend-over-sheave (CBoS) testing that replicated the motion, tension, and temperature profiles of deep-sea lifting, demonstrating fatigue performance that surpasses previous fiber-rope limitations.
Measuring what endurance really means
CBoS testing provides a controlled method to replicate the complex bending and loading cycles experienced offshore. Each pass over the sheave subjects the rope to tension, curvature, and friction comparable to active-heave and repetitive-lift operations. Over time, the resulting data shows how temperature, tension, and strand interaction govern fatigue life. Steel ropes have long been measured this way, yet experience shows that ISO 4309’s visual criteria overlook the damage that starts internally. Our goal was to understand how a hybrid construction – a rope with HMPE-covered Technora® strands – would respond under identical conditions and whether the results would match the theory. The test campaign took place at NORCE’s Mechatronics Innovation Lab in Grimstad, reproducing offshore motion under controlled laboratory conditions. Each rope was wound over paired sheaves at a D-over-d ratio between 20 and 27, running under a safety factor of 2.5 to 3 and an ambient temperature of 43°C. No active cooling was used; heat could build naturally. TechIce® and DynIce®, both 30 mm ropes, were cycled at 100 mm/s under continuous strain monitoring, up to failure or a maximum of 50,000 cycles. Steel reference data from Vennemann’s 2008 tests provided context at the same load factor, where grease boiled off and hidden breaks formed as temperature climbed beyond 150°C. Testing continued, either until failure or data indicated it was imminent.
Endurance that rewrites the fatigue curve
TechIce® showed a fatigue pattern unlike any rope seen before. Cycle counts passed 30,000, then 40,000, before the first signs of wear appeared. The TechIce rope did not fail, and the run was deliberately stopped at 49,768 cycles and 50,374 cycles, respectively, across two separate tests. DynIce® failed at 27,585 under the same conditions.
Fig 1. Elongation and strain during CBoS testing at 43°C ambient. TechIce® maintained structural stability and limited strain growth over time, completing 49,768 cycles without failure, whereas DynIce® ruptured after 27,585 cycles.
The difference was both endurance and behavior. The fatigue curve of TechIce® flattened, showing slower degradation as heat and tension stabilized – an effect linked to reduced creep and stabilized tension typical of aramid-core behavior.
CBoS fatigue life data
Fig 2. CBoS fatigue life data for Technora®, DynIce®, TechIce®, and steel wire rope (Warrington-Seale 6 × 36) under comparable D/d and safety-factor conditions. Data points marked with arrows indicate tests stopped prior to failure, where remaining strength was measured (η = 0.xx in the legend shows residual strength as a percentage of the initial rope strength). TechIce® exhibits a markedly higher cycle life and a flatter fatigue trend, confirming slower degradation and extended endurance relative to both HMPE and steel references.
Thermal measurements confirmed the same trend. At 43°C ambient, TechIce® surface temperatures stayed between 60 and 64°C, while DynIce climbed close to 90°C. The hybrid structure explained it: HMPE strand covers limited inter-strand friction, while the Technora® core resists creep and heat. Steel wire tested by Vennemann (2008) at the same safety factor exceeded 150°C and failed internally. TechIce® showed mild wear of the outer protective jacket, while the remaining breaking strength after 49,768 cycles was 66 %MBL.
Real-world performance under pressure
Field results mirrored the laboratory data. On the Ocean Guardian vessel, two 6,200-meter TechIce® ropes have operated for more than two years in full active-heave-compensated service without downtime. Deck temperatures regularly exceed 40°C, yet the ropes run without cooling on Parkburn’s self-fleeting capstan winch integrated with Scantrol’s mTrack AHC system. According to Stabbert Maritime’s engineering team, spooling remains consistent and performance unchanged. At Favelle Favco’s onshore yard, identical behavior was recorded: 600 hoists at D/d 22 with 87% strength retained after testing. In both cases, fatigue followed the same stable pattern observed in CBoS trials.
From data to design confidence
CBoS testing builds understanding, as each result adds to a fatigue curve that can be linked to actual load histories, turning test cycles into lifetime models. This supports the development of predictive modeling approaches comparable to those used for steel wire ropes, in line with IMCA’s lifetime and fatigue management framework. Steel ropes still depend on inspection to find failure after it starts. TechIce® makes fatigue visible in data long before it appears on the surface. Research presented at IMCA and Stuttgart Ropedays highlights ongoing work toward more predictive lifetime modeling, exploring correlations between rope exposure, load, and bending cycles. These insights contribute to safer planning and improved reliability offshore. The hybrid Technora® and HMPE construction has a density about one-eighth that of steel, which substantially reduces rope weight. This reduction allows smaller winches and cranes to handle the same load with less power and lower structural stress. Without grease or corrosion, deck equipment stays clean, and maintenance becomes periodic rather than continuous. The thermal stability of TechIce® removes the need for cooling systems, even in 40°C conditions. Together, these factors extend the working depth and efficiency of offshore lifting, turning material performance into operational capability. TechIce® changes what engineers can expect from a lifting rope. The data proves both endurance and control. Fatigue becomes measurable, predictable, and consistent across conditions. That level of reliability transforms rope performance into engineering assurance: a measurable foundation for safe, efficient offshore lifting.
References
- Cornelissen, B.; Waage, D.; Magnússon, J. Cost-effective replacement of steel wire hoisting ropes: the TechIce® heat-resistant synthetic fiber rope, 8th International Stuttgart Ropedays, 2025.
- Nordgård-Hansen, E.; Hauge, E. Rope Testing at Elevated Temperatures – Test Results, NORCE Mechatronics Innovation Lab, Grimstad, 2024.
- Vennemann, O.; Frazer, I. Installation of Subsea Structures in Deep and Ultra Deep Water Using Steel Wire Rope Deployment Systems, D.O.T. XXI Conference, Perth, 2008.
- IMCA Seminar Proceedings, Fatigue Testing of Large Diameter Multi-Strand Wire Ropes for Offshore Installation Tasks, Kuala Lumpur, 2008.
- Parkburn–Scantrol–Hampidjan TechIce® Rope Case: Ocean Guardian, SOS Magazine, May 2025.
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