Composite materials with thermoplastic matrices and a reinforcement of natural fibers are increasingly regarded as an alternative to glass fiber-reinforced composites. The substitution of the traditionally used reinforcing glass fibers by natural fibers such as flax, kenaf, or cotton can lead to a reduction of the component's weight and furthermore to a significant improvement of specific properties like impact strength, crash behaviour, or sound absorption. One of the major fields of application for such materials can be found in structural components for the automotive industry. Product examples are door trim panels, headliners, or back panels. At present the processing of such materials into structural parts usually takes place by thermal compression molding. Semiproducts (so-called hybrid fleeces) are employed, which are generated by carding or air-laid processes and subsequent mechanical bonding. This paper presents a survey and latest developments on the material, processing technologies, and fields of applications. Furthermore, acoustical investigations on cotton-based composite materials are presented.

Composite materials and layered structures based on natural plant fibers are increasingly regarded as an alternative to glass fiber reinforced parts. One of their major field of application can be found in structural components for the automotive industry. Product examples are door trim panels or instrument panels. For such applications an utmost impact strength is required in order to implement a maximum of passenger safety by a good crash behavior. The paper describes the effects of several material parameters such as fiber fineness or fleece composition as well as the impact of the process conditions on this important composite characteristic.

With increasing demand for automobiles in the global market, and a simultaneous pressure to address the issue of sustainability, there is continuing need for the incorporation of natural fiber based materials into automotives. The focus of recent research has been to produce compostable cotton fiberbased composites that can be safely disposed off after their intended use without polluting the atmosphere, in an environmentally safe manner. It is evident from studies being done jointly at the University of Tennessee, University of Bremen, Germany and USDA, New Orleans, that by suitably combining cotton and other natural cellulosic fibers, with an appropriate biodegradable binder fiber in the right combination a moldable nonwoven fabric can be produced. Results from these studies addressing the structure and properties of the composites, with respect to their suitability for automotive applications are discussed.

In thermobonded nonwovens, the design of the bond point geometry is of major importance to the desired mechanical behavior. Despite the geometry´s significance the selection is subject to a trial and error approach. This paper describes a numerical method for the prediction of the nonwovens tensile behavior depending on the bond point geometry and process parameters. The tensile behavior of thermobonded nonwovens is modeled in a numerical model using the Finite Element Method (FEM). The approach covers the influence of the shape and size of the bonded area as well as the properties of the nonwoven. The influence of the technological parameters during the bonding process such as process temperature and pressure, are also covered. The solidified area within the bond point is represented using solid elements. The connection between the bonded areas is modeled using link elements, representing the connecting fibers. This approach covers the nonlinear behavior caused by the fiber material properties and geometry. Sets of fibers are combined into fiber bundles in order to reduce the numerical effort. The fiber orientation within the nonwoven is taken into account in order to represent the different fiber distributions caused by the nonwovens production techniques. The mechanical properties of fibers and fiber bundles are taken from experimental data and are mapped onto the model. The model is verified using experimental data from tensile testing.