
The most prominent application area remains in nonstructural parts with randomly oriented fibers in the automotive and construction industry and is mainly driven by the lower price and environmental concerns rather than the reinforcing effect of the fibers ( Karus and Kaup, 2002 Parikh et al., 2002 Dunne et al., 2016). However, dissemination is still limited ( Staiger et al., 2008).

Natural fiber–reinforced plastics (NFRP) have become increasingly important in recent years, and especially, flax fiber–reinforced composites are increasingly used for applications subject to higher mechanical loads, such as sports equipment and higher loaded construction materials ( Misra et al., 2011 Alkbir et al., 2016 More, 2021 Rahman, 2021). The analysis of the fatigue behavior of, e.g., glass fiber–reinforced plastics (GFRP) under cyclic loading has been researched for a long time ( Bledzki and Gassan, 1998 Keusch et al., 1998 Bernasconi et al., 2007 Towo and Ansell, 2008a Lemanski and Sutcliffe, 2010 Shahzad et al., 2019). This is even more important if the relatively young material group of natural fiber–reinforced composites in structural components is intended to be used.

Overall, the hybrid material shows significantly better static bending and impact characteristics than flax and considerably better fatigue properties than the glass fiber-reinforced composite making the hybrid material attractive for an application in an axle tie.įor the mechanical design of fiber-reinforced components, it is essential to consider and understand the fatigue behavior of this type of material. The flax/glass component’s fatigue strength ranged between the flax values and the glass fiber-reinforced composites. Results based on a finite element method also demonstrate better fatigue properties at an increased number of load cycles for flax-based composites than the glass fiber-reinforced component. The hybrid materials tend to show a higher fatigue strength than the glass type from approximately 2 × 10 5 load cycles. From about 7³ to 8³ loading cycles, the flax laminate was found to have higher fatigue strength than the glass fiber-reinforced composite. A total of 10 6 load cycles were carried out. Therefore, the fatigue behavior of flax, glass, and hybrid flax/glass composites was investigated in the high cycle fatigue range. For such an application, the investigation of fatigue strength is of particular importance. Additionally, a hybrid material made of flax and glass was produced for a demonstrator component (an axle tie of a narrow-gauge railway).

A novel type of staple fiber yarn made from flax tow with almost unidirectional fiber orientation and a quasi-unidirectional fabric was developed for composite applications. The most common studies in the literature are those analyzing fatigue life under cyclic loading for flax fiber-reinforced composites. 3NOVACOM Verstärkte Kunststoffe GmbH, Aachen, Germany.2Fraunhofer-Institut für Werkstoffmechanik IWM, Freiburg, Germany.1The Biological Materials Group, Biomimetics, Faculty 5, Hochschule Bremen - HSB - City University of Applied Sciences, Bremen, Germany.Nina Graupner 1*, Jörg Hohe 2*, Michael Schober 2, Benedikt Rohrmüller 2, David Weber 1, Lisa Bruns 3, Albert Bruns 3 and Jörg Müssig 1
