The building blocks of lightweight structures are continually evolving as our industry innovates.
TRB Lightweight Structures uses prepreg and infusion technologies, processing carbon, glass, and aramid fabrics in a wide range of woven and unidirectional formats. We have strong relationships with prepreg manufacturers and some of our sandwich panels are produced with proprietary prepreg resin systems which were developed specifically for TRB. We use both vacuum bagging and press molding processes to cure fiber-reinforced plastic (FRP) panels and components.
Most of the core in use at TRB is made from honeycomb. We specify aluminium for the majority of our projects, and we process Nomex, plastic honeycomb and other core materials when required.
LIGHT AS A FEATHER, STRONG AS STEEL
* Images courtesy of Ten Cate Advanced Composites
Adhesives are an integral component of composite structures. When specified and applied correctly, they can provide fatigue strength, shock absorption, protection against galvanic corrosion, sealing against fluid transfer, and improved damping characteristics of a mechanical system. Adhesives enable us to bond heat-sensitive materials, dissimilar materials, and materials which would otherwise distort or weaken with the heat of welding.
Importance of Adhesives
Adhesives are critical in composite structures where mechanical fasteners such as rivets add unwanted weight or an unwanted surface profile and where welding is typically not possible. Correct application of an adhesive depends on proper surface preparation, understanding cure times, using the right heat and pressure, and establishing rigid process control. Decades of experience at TRB helps us achieve consistent results.
Many applications require a sandwich structure which is often the best way to take advantage of the physical properties of the component materials. We build sandwich panels out of all of the above materials. For those building their own structures, we offer standard or custom panels in a variety of configurations and thickness.
Thermoset materials find wide uses in the aerospace industry, for structural material as well as aircraft interiors. They are also used on the highest-performing automobiles where weight reduction is critical.
A thermosetting plastic is a polymer that cures, generally through heat or a chemical reaction, and cannot be remoulded or reheated. The resins are generally liquid prior to curing and extruded through fabrics such as carbon fibre or glass.
Thermosets can be expensive and difficult to work with, but because they retain their strength even when heated, they are well-suited to the production of long-lasting components and shapes which must retain their dimensions over time and at higher temperatures. Thermoset materials are generally stronger than thermoplastic materials. They are more brittle, however, and because they can’t be remolded (they are “set”), they are not thought to be recyclable.
Thermoplastics are the material of choice within much of the automotive industry due to cost and recyclability.
Thermoplastic material softens when heated and strengthens when cooled. Thermoplastics can be cycled through heating, shaping and cooling multiple times without causing chemical change. They are generally easier to work with and less expensive than thermosets and they can generally be recycled numerous times, but they will not exhibit the same strength as thermosets.
Commercial and Aerospace grades of Aluminium Honeycomb are available. We hold extensive stock and we cut and expand our honeycomb on demand to specification. AAC commercial grade honeycomb is made from 3003 alloy aluminum foil. AAA core is a structural aerospace grade aluminum honeycomb available in 5052 and 5056 alloys in a range of densities.
Flex Core Honeycomb
Where highly contoured sandwich panels are required we employ Flex-Core® aluminium honeycomb. Flex-Core® honeycomb is made from either 5052 or 5056 aluminium alloy foil and is available in two cell sizes. It has unique cell configurations that permit small radii of curvature without deformation of the cell walls or loss of mechanical properties.
Highly contoured sandwich panels are often required in leading edges and flaps, nacelles, fairings, doors and access covers, and other parabolic, spherical and cylindrical shapes.
Flex-Core® is available in the following configurations:
5052/F80 – .0013N Density 4.3
5052/F80 – .0025N Density 8.0
5056/F80 – .0014N Density 4.3
For lighter weight when the crush strength of aluminium isn’t required, we use ANA Aerospace grade and ANC Commercial grade core materials manufactured from Nomex® paper sheets which are coated and bonded together with a high modulus phenolic resin.
For composite sandwich panels, foam has good performance characteristics and popularity of foam as a core material is growing. The right product can give good compressive strength, impact tolerance, chemical resistance, a uniform bonding surface, and burn characteristics that meet stringent specifications. Another advantage is that they can be easier to machine than honeycomb. Typical foam cores that are used in composite applications come from Airex, Sabic, and DIAB.