Core materials for composites manufacturing when high stiffness and low weight is required.
Benefits of Core Materials
Increasing stiffness, decreasing weight, and improving mechanical performance make sandwich composites very popular.
A weight reduction for projects that use Core Materials includes:
- Lower fuel consumption
- Increased speed
- Increase in load capacity
- Reduction in carbon footprint
In engineering theory, a panel’s stiffness is proportional to its thickness cube. Adding a low-density core material can significantly increase the composite’s stiffness with a minimal weight penalty.
A variety of core materials offers a variety of densities, sizes, weights, life spans, physical characteristics, and costs, allowing users to choose the best material for any particular application. Honeycomb and PVC foam is the most commonly used high-quality core materials.
Core materials are the best and most appropriate materials for a composites application requiring high stiffness and low weight. As a result of these unique properties, core materials are extensively used in sandwich composites, primarily for aerospace, marine, wind energy, transportation, and industrial applications.
Structured composite sandwich materials consist of two thin and strong skins attached to a lightweight, softer core. Each skin consists of an isotropic material or a fibre-reinforced composite laminate. These skins provide the bending stiffness and in-plane shear strength and absorb axially, bending, and in-plane shear loads. To prevent the faces from sliding over each other, the core needs to be stiff enough to maintain their relative positions when loaded and strong sufficient to maintain their relative positions when sheared.
It is necessary to use an adhesive between the facings and the core to force them to cooperate and act as integral structural members. Structural member. Epoxies, modified epoxies, or epoxy polyamides are commonly used as adhesives. Under static or dynamic conditions, the adhesive’s toughness measures its ability to withstand loads to separate the facing from the core. Although each component is relatively weak and flexible, they create a solid structure when combined in a sandwich panel.
Our Range of Core Materials
Primary Types of Core Materials
In aerospace, marine, military, construction, sports, and automotive industries, honeycomb is widely used because of its high strength-to-weight ratio. Honeycomb is manufactured with aramid fibre paper. The Honeycomb Core is then shaped into a honeycomb structure.
This structure resembles a bee’s honeycomb. The hexagonal cells are coated with heat-resistant phenolic resin to improve mechanical properties and gain some stability. A Honeycomb structure provides excellent strength and efficiency while reducing the component’s weight. For this reason Honeycomb is a highly effective Core Material.
Honeycomb core materials are also manufactured with other aramid paper, plain paper, metal (aluminium), and plastic such as polypropylene. Honeycomb core materials are also made with fibreglass and carbon fibre reinforced plastics. For more information on the Honeycomb Core Materials, visit the Honeycomb product page.
Polyvinyl chloride foam, or PVC foam, as it is more commonly known, is made from a polymer, polyvinyl chloride (or PVC) and is filled with air bubbles. Polymer and air bubbles create a consistent material with a high volume and a low weight. Most resins can be used with PVC Foam. These resins include Epoxy, Vinylester, and others and all kinds of Fibre Reinforcement, such as Carbon, Aramid, Kevlar, and Fibreglass.
PVC foam comes in two forms: cross-linked or rigid and linear or ductile. Due to its excellent physical properties, PVC Foam is used in marine construction due to its low water absorption. Still, it is also used in transportation, aerospace, military, wind and industrial markets.
Secondary Types of Core Materials
The structure of Plywood is similar to that of honeycomb. This material is easy to find, less expensive than other core materials, and easy to work with. Plywood is a wood product widely used in construction. Due to its high strength, resistance to cracking, shrinkage and twisting, it is used instead of wood. Additionally, marine Plywood is much better at resisting moisture. However, all wood cores are susceptible to moisture, and if not enclosed in Epoxy Resin, they may rot.
Another common wood used for cores is balsa wood. This wood has a very low density and some water resistance. In addition, it provides good thermal insulation and good acoustic absorption, and it easily forms without a lot of expensive or technical equipment. Due to its very high minimum density, balsa wood is often used when weight saving is not as significant.
Polyurethane (PU) foams have good mechanical properties but may be prone to delamination with age. Additionally, this foam has reasonably raised temperature and good acoustic absorption properties. A machine can be used to achieve the required shapes.
Pseudo cores are not usually considered one hundred per cent core material; they are thin, low-density materials used to reduce the density of a single skin laminate. The polyester nonwovens Coremat and Spheretex, for instance, contain microspheres and volumized glass. In fibre reinforced laminates, pseudo cores are used as a thin core to increase stiffness while only adding a few grams of weight.
Thermoplastic polyethene-terephthalate (PET) is lightweight and recyclable. This foam offers excellent strength, is temperature resistant, and is low in impact resistance.
Also known as Styrofoam, polystyrene can be a low-cost core material. Polystyrene consists of expanded (EPS) and extruded (XPS.) It is relatively light and has low water absorption compared to other core material foams, such as polyurethane. The windsurf and surfboard industries use Styrofoam extensively (almost all surfboards and wind surfboards contain this material.) Styrofoam can be CNC machined and is an excellent material for prototyping and shaping.