DuPont thermoplastic elastomer helps keep marine devices afloat

PUBLISHED: 11 Dec 14

The TFI technology includes an energy damper , extruded in DuPont™ Hytrel® TPC-ET
and shown in red in the photograph,,within the mooring lines to reduce the forces along
the whole tether with potential to reduce mooring costs
The TFI technology includes an energy damper , extruded in DuPont™ Hytrel® TPC-ET and shown in red in the photograph,,within the mooring lines to reduce the forces along the whole tether with potential to reduce mooring costs

DuPont Performance Polymers and Ireland-based Technology from Ideas (TFI) collaborated to develop a novel way to allow moored devices to move with the sea, which dramatically reduces peak loads up to 70% and improves durability of mooring lines that tether and protect high-value marine devices, such as wave energy devices and fish farms.

The new Dynamic Tethers wave protection system replaces chain and rope mooring, which pulls taut, rattles and wears quickly as it moves against the sea. It incorporates an energy-damping bellow that acts similar to a "shock absorber", which delivers high load and fatigue resistance to protect devices from harsh sea wave conditions, designed to stay slightly taut and respond smoothly when stretched to its limit, while dramatically reducing wear and tear, improving stability, reliability and positioning and lowering cost.

The energy-damping bellow is extruded by Radius Systems Ltd. In Banbridge, Ireland using DuPont™ Hytrel® TPC-ET polyester thermoplastic elastomer and a tensile elastomer element made of a soft material with low stiffness which deliver the low force response of the system with elongations of up to 250% of the original length, while withstanding repeated low-force events (>3.5 million cycles per year). The energy-dampening bellow is 1.2 meters (nearly 4 ft) long, 250 mm (nearly 10 inches) in diameter and weighs 20 kg (44 lb) and is engaged as the tether reaches its maximum extension and is designed to deliver a specific targeted smooth response as it compresses.

The new tethers are being monitored at a number of installations in Europe and are expected to be commercially available in early 2015. "The design takes advantage of the elasticity and flex fatigue of Hytrel®," said Mark Hazel, technical specialist for DuPont Performance Polymers. "We adapted our technology for constant velocity joint (CVJ) boots, which are a mainstay in the automotive industry, and developed a highly functional bellow to handle the extreme load conditions and meet the demanding overall performance requirements of the marine industry."

"The key to develop such wave protection system is to ensure excellent fatigue resistance coupled with high performance over time in sea water. Hytrel® thermoplastic elastomer was selected over competitive materials due to its excellent load recovery performance." added Noel Halloran, TFI's CEO.

In the development process, TFI provided the load deflection curve for a quarter-scale model and DuPont's computer-aided engineering (CAE) experts used their design knowledge from automotive shock-absorbing bellows to create a Hytrel® bellow with corrugations of different pitch that compress at different rates to give increasing stiffness as the compression progresses. Advanced finite-element analysis (FEA) techniques were used to ensure the design met the performance specification.

DuPont de Nemours International SA, Switzerland
Tel: + 41 22 717 5419

More news from this company:
DowDuPont Transportation & Advanced Polymers introduces Kalrez® 9600 perfluoroelastomer parts
Schneider Electric selects DuPont™ Zytel® for development of smart housing in high current connected air circuit breaker
DowDuPont Specialty Products announces DuPont™ Zytel® and Hytrel® capacity expansion
Collaboration between DuPont and Regina leads to the launch of Regina E-F.A.S.T.
DuPont Electronics & Communications and Holst Centre extend collaboration
Judges Announced for the 29th DuPont Awards for Packaging Innovation
DuPont announces new guide to non-halogenated flame-retardant polymers for the electrical and electronics industry
DuPont Performance Materials launches operations at Europe's first Zytel® HTN polymer production facility
DuPont™ Vespel® polyimide bushings precisely guide connecting rods in MAHLE's electrical wastegate actuators
DuPont Performance Materials starts operations at Shenzhen, China
New intake system from DuPont™ Zytel® PLUS to save space and boost performance
DuPont Performance Materials celebrates new investment in its Centre of Excellence at Meyrin
DuPont Performance Polymers adds new processing facilities to Asia-Pacific assets
DuPont performance Polymer Advisor tool saves time, reduces risk
New DuPont™ Vamac® AEM takes the heat