JEC COMPOSITES MAGAZINE - Issue #72 - April/May 2012 - 36

thermoplastics

Tests have demonstrated that soaking VICTREX PEEK compounds in Skydrol hydraulic fluid at 70°C for 1000 hours results in less than a 10% change in nominal mechanical properties. Amphenol Pcd tested their injection-moulded VICTREX PEEK 450GL30 P-clamps by submerging them in aviation fuel for 12 months at room temperature. Following this immersion, there were no significant adverse effects on the properties of the clamps. The ability of the polymer to withstand the aggressive chemical assaults of jet fuel, hydraulic fluid, de-icing solution and ozone was again a key reason for the selection of a 30%-glass filled PEEK polymer, rather than a metal, for the landing gear hub caps on the Boeing 777, 787 Dreamliner and 747-8 aircraft. Another interesting aspect of Boeing’s choice was the ability of this thermoplastic to operate effectively over an extreme temperature range. Aircraft landing gear must tolerate temperatures of above 200°C when landing, and of -54°C during the flight. They must also be able to withstand the shock of repeated hard landings. VICTREX PEEK polymer meets all these needs.

the aerospace sector. The flexibility of the polymer, its excellent creep and fatigue properties and ease of high-volume manufacture to fine tolerances are all key benefits that make it an attractive option for this type of application. The major advantage over metals is again weight reduction. The result is not simply a lighter aircraft. Lighter, non-metallic impellers exhibit lower inertia and so require less rotational power to drive them, reducing energy consumption and generating cost savings. A secondary benefit is that in the event of the failure of the impeller, any debris has a lower mass than that of a metal impeller, so the debris containment structures can be lighter. Polymer blades made from VICTREX PEEK 450CA30 or 150CA30 are used in the cockpit ventilation system of the recent Airbus generation and for air delivery systems in helicopters. They have also been implemented in the oil cooling system of some Eurocopter helicopters. VICTREX PEEK 150CA30 was also the polymer of choice for the door handles installed on the recent Airbus generation. Again, the goal was to replace aluminium and achieve significant weight reduction, while equalling, the specific strength and modulus of the high-tech metal (see Graph 3). Fibre orientation in short-fibre filled polymers depends heavily on the component design and the moulding conditions used. The resulting fibre orientations in

manufactured components are likely to result in differences in the mechanical properties when the component is tested in different directions. However, only VICTREX PEEK polymer survived the rigorous testing of the development phase of the above mentioned applications.

Aerospace adopts thermoplastic pipes
The applications don’t end with primary structures. In 2011, Victrex Polymer Solutions introduced VICTREX Pipes™, a range of durable thin wall pipe and tubing products that are significantly lighter in weight than their metal equivalents. For example, a pipe with an outside diameter of 25.4 mm and a wall thickness of 1 mm weighs only 100 grams per metre. The resulting weight reduction is 33 % when compared to an aluminium pipe of the same outside diameter and 0.71 mm wall thickness. For titanium piping, there is a 45 % reduction, and for stainless steel a 68 % reduction (both with 0.51 mm wall thickness). For today’s large commercial aircraft, where extensive arrays of tubes and piping may be deployed, a weight reduction of this order is extremely significant. VICTREX Pipes™ are made from aerospace approved polymer and can be bent, flared and formed into 3-dimensional shapes, allowing for a high degree of design freedom and smart utilisation of space.

Thermoplastics for impeller blades
VICTREX PEEK polymer is also being used as a metal replacement in the production of a variety of impeller blades by

Graph 3: Specific strength vs. specific Young’s modulus comparison

Graph 4: Beam with same structural stiffness and strength at 120°C

36 jec composites magazine / No72 April - May 2012

JEC COMPOSITES MAGAZINE - Issue #72 - April/May 2012

Table of Contents for the Digital Edition of JEC COMPOSITES MAGAZINE - Issue #72 - April/May 2012