KRAIBON® – elastomers as the perfect supplement
for fiber reinforced plastics
KRAIBON® for the lightweight construction sector.
KRAIBON® is a thin film made of non-cross-linked rubber that hardens within the component laminate in the same production process. A hybrid material occurs that combines the best of both worlds – fiber composite compounds and elastomer compounds.
By integrating elastomer in the composition of FRP it is possible to achieve an alternating structure of hard and soft material that combines the good mechanical properties of the FRP with the good “elastic” properties of the elastomer. The main areas of application are improved acoustics and impact and splintering behavior.
The decisive advantages are direct integration of the elastomers in the normal manufacturing process for FRP components and a direct connection between elastomer and FRP without additional bonding agents. This innovative technology is used selectively in industries such as automotive construction, wind power, aeronautics, rail vehicles and medical technology.
Acoustics – featherlight damping for composites
Lightweight construction is a key issue in modern vehicle production processes. However, at the same time, lightweight construction must also take the comfort requirements of customers into account.
Loud and uncomfortable vehicles are hard to sell. There are various solutions to adress Noise, Vibration, Harshness (NVH), however, as basis, heavyweight mats are used. It is clear, that ‘heavyweight’ clashes with the concept of ‘lightweight construction’.
The acoustic behavior of composite components can be significantly improved through the use of KRAIBON®. Studies show that KRAIBON® exceeds the structure-borne sound damping of alubutyl and that it does so at a fraction of the weight.
Advantages of KRAIBON®:
- Through inlaying modified elastomers, the CFRP loss can be significantly increased.
- The damping achieved through KRAIBON® layers in CFRP is greater than the damping of CFRP with alubutyl.
- The area weight of KRAIBON® layers is significantly lower than of alubutyl.
- With KRAIBON®, the performance, i.e. the ratio of max. loss factor and area weight, can be increased by approx. 600 % in comparison with alubutyl.
Impact protection for composites
Impact damage is a critical issue in connection with CFRP components. In the automotive and aerospace industries, damage caused by the impact of larger particles is a real concern. The wind energy sector on the other hand is working on developing solutions to protect the equipment against small particles that are the cause of sand and rain erosion.
Whatever the size of the particle, impacts can cause huge damage to CFRP parts, depending of course on the impact energy. Impacts also reduce the stability of the component and can affect its aerodynamics. In the worst case, impacts can lead to total failure.
With the integration of KRAIBON® a clear enhancement of damage tolerance can be achieved without necessitating an increase in weight or cost.
In the graphic below, the component with KRAIBON® can either be designed for higher loads or for constant impact tolerance.
The end result is a lighter and more cost-effective product.
The original laminate was designed for damage/energy tolerance at point 1. By integrating two layers of KRAIBON point 2 is reached. At this point, the laminate is slightly heavier and only inappreciably more expensive due to the additional KRAIBON, but the damage tolerance is three-times as high as the original and the component is more resistant.
This provides various options for the user. If a sturdier component is needed, the choice in this example falls on two layers. If, however, the original tolerance is sufficient (point 1), one or more layers of carbon can be removed.
This means less weight and lower costs, as KRAIBON is lighter and less expensive than carbon.Point 3 represents a combination of the options “better, lighter, less expensive”. In the past, several components have already been realized, which achieve all three attributes simultaneously.
Drop tower test: FEM model
Splintering protection for composites
When breaking, carbon fibre compounds can shatter, producing tiny splinters and dangerous sharp edges. This results in an increased risk of injury, for example to passengers or pedestrians in the event of a car accident. This risk can be eliminated by integrating a rubberized fabric such as KRAIBON® into the material.
KRAIBON® not only increases the impact strength, but also can improve shattering and splintering characteristics. Therefore it offers a future for composites which previously was not possible.
With the simple integration of into your composites, splintering and shattering resistance is significantly improved. In addition, we also offer solutions where KRAIBON® can remarkably enhance energy absorption.
Crash-test: conventional layup
Crash-test: layup with KRAIBON®
Hybrid composites – CFRP – KRAIBON® – Metal
Hybrid material combinations of metal and carbon open up a highly attractive field in the area of composite material construction. Through the combination of these two materials, components that are lighter than pure metal, and significantly more affordable than CFRP components are possible.
A clear weakness of these composites is the bonding agents that are conventionally used. They are moderately effective in compensating for differences in the materials, and can cause a weakening of the component. KRAIBON® offers an innovative, high-performance alternative to conventional bonding agents.
When metal is combined directly with carbon using a bonding agent, contact corrosion can occur. Through use of KRAIBON®, an insulating layer is inserted between the two materials, which prevents corrosion and considerably extends the service life of the component.
A large variance in thermal expansion of the two materials occurs through the variable temperatures during production, painting processes and in the end application. This results in stresses in the material composite. KRAIBON® compensates for these stresses significantly better than conventional bonding agents and retains an excellent adhesion to both materials.
A hybrid component of aluminum and CFRP, 1000 mm in length, is manufactured at 150 °C. At –30 °C the length of the aluminum component is approx. 996 mm, the length of the CFRP proportion is 1000 mm. On the edge an adhesive layer of 0.3 mm must compensate a length difference of 2 mm. Thus it is elongated by approx. 566 %.
KRAIBON® in hybrid material combinations provides very good adhesion, greater flexibility, and – particularly for crashrelevant applications – significantly better energy absorption and thus safety reserves.