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To say that the introduction of carbon fibers revolutionized industrial engineering might seem far-fetched at first. However, their properties speak for themselves. When produced correctly, carbon fiber composites benefit from a structural integrity and high resistance to deformity surpassing that of high-quality steel, but at a fraction of the weight. Because of this, they are extensively used in various applications, from load-bearing constructions to automotive and aerospace parts. Techniques such as Automated Fiber Placement allow for the material to be laid up quickly, resulting in large possible production volumes.
Properties and Advantages
Carbon fibers are essentially individual pieces of filament consisting of carbon atoms. The main advantages of the material are its great tensile strength, elastic modulus and very low weight. This means that force applying from either end of the filament is easily resisted without the fiber stretching or being compacted significantly.
Carbon-plastic composites do not just offer great mechanical advantages, but benefit from corrosion resistance as well. This makes them ideally suited for low-maintenance outdoor applications.
Individual filaments are relatively easy to break when applying force from any other direction, however. For this reason, the orientation of individual strands needs to be taken into consideration. Composites consisting of multiple layers of fibers are manufactured by aligning these layers to benefit from the mechanical properties of connected layers. Thus, the great tensile strength of the material works in all directions.
Since the fibers themselves are relatively flexible, layups of the material employ a form of binder as well. Epoxy resin is either applied to carbon fiber rovings before the layup process (prepreg or towpreg) or pressure-injected after the initial layup. This combination of epoxy and fiber has resulted in the creation of several high-quality composites, uniting strength, low weight and great rigidity in a single building material such as:
- Fiber-reinforced polymer, used in aerospace and automotive applications
- Unidirectional tapes for smoothly-shaped layups of high complexity
- Thermoplastic materials used for in-situ applications
Carbon is probably becoming the most frequently used type of fiber in the industrial sector, owing to its highly beneficial properties and versatility. In addition, especially fiberglass but also basalt filaments also frequently act as reinforcements for composite parts.
Using Fibers for Layup
Carbon fibers can be used in various ways. In order to create composite layups for airplane parts or similar industrial uses, the process of Automated Fiber Placement (AFP) is typically employed, meaning that continuous filaments are applied to a mold surface or preforming tool by machine. This allows for the quick manufacture of large volumes of composite materials in complex shapes.
Meanwhile, many varieties of thermoplastic tape can be applied as well. Since this variant of carbon fiber composite is pre-impregnated with plastic, it is especially useful for quick in-situ solutions. The tape simply needs to be heated, shaped and cooled down again to retain its shape until heated again.
Using methods such as the patented Compositence method of AFP – which works with pure rovings, efficiently affixing them at preform edges only – the entire process of carbon fiber layup can be completed quickly and without the costs associated with working from woven non-crimp fabric sheets. In combination with the highly flexible controller software, this also allows for large volumes of composites to be created at a consistent level of quality.
A Combination of low Weight and great Strength
Composites created by using carbon fiber materials have demonstrated remarkable structural integrity and damage resistance while remaining light at the same time. Furthermore, using high-precision Compositence manufacturing techniques, this performance-to-weight-ratio can be applied to large volumes of preforms within a short timeframe at a low cost.