Martin Pieter Vlasblom

Predicting the Creep Lifetime of HMPE Mooring Rope Applications

Under constant loading HMPE fibers and ropes show an irreversible deformation (creep) behavior that is strongly dependent upon load and temperature. This paper presents an updated model that seeks to accurately predict the creep rate at various temperature ranges and to estimate creep life of HMPE on fiber level, and demonstrates the apparent validity of this model to rope applications regardless of rope construction. The model may thus serve as design tool for long-term loading conditions as are found in offshore mooring operations

Development of HMPE Fiber for Permanent Deepwater Offshore Mooring

For a number of years, the creep performance of standard High Modulus Polyethylene (HMPE) fiber types has limited their use in synthetic offshore mooring systems. In 2003, a low creep HMPE fiber was introduced and qualified for semi-permanent MODU moorings. This paper reports on the introduction of a new High Modulus Polyethylene fiber type with significantly improved creep properties compared to other HMPE fiber types, which, for the first time, allows its use in permanent offshore mooring systems, for example for deep water FPSO moorings. Industry guidelines and standards mentioning HMPE creep are briefly discussed, and results on fiber and rope creep experiments reported. Laboratory testing has shown that ropes made with the new fiber type retain the properties characteristic of HMPE such as high static strength and stiffness and yarn-on-yarn abrasion resistance. Link to download paper: https://www.onepetro.org/conference-paper/OTC-23333-MS

Airborne Wind Energy Tethers with High-Modulus Polyethylene Fibers

Airborne Wind Energy tethers are a critical component in many AWE systems. There are many diverse systems that are currently under development, this chapter focusses on tethers for the so called pumping Yo–Yo system. In these systems the tether is the critical component for transfer of kinetic energy from kite to ground station. Given the desired hardware and performance expectations, this chapter provides a first estimation of the tether dimensions for a tether made of HMPE fibers. Especially creep and bending fatigue considerations are described for long term performance checks. Other conditions that may influence the longevity of the tether are briefly mentioned, but since firm testing data is lacking, it is recommended to perform these checks on case by case basis.

Tension endurance of HMPE fiber ropes

Tension-tension fatigue tests on high modulus polyethylene fibers show that fatigue lifetime is governed by plastic deformation failure. This insight is further evaluated on small ropes and via a simple to implement dynamic shift factor, time-to-failure under dynamic conditions is shown to be predicted based on static creep failure. Basis of the shift factor is the time spend under load and gives excellent predictions when no additional heating-up is introduced during the test. This makes DSM Dyneemas Performance Model, for static creep prediction, also capable to predict dynamic tension-tension failure.