Characterisation Of Bio.docx

Characterisation of bio-based Composites for Simulation of the mechanical properties Summary description of the project

With increasing environmental awareness the use of renewable reinforcement fibres -such hemp, jute or regenerated cellulose- increasingly comes to the fore. The mechanical properties of glass fibre reinforced composites are already reachable with the natural fibre reinforcement whereby their structures and properties deviate significantly to those of conventional reinforcement fibres Due to the significantly lower bending stiffness not only their spatial orientation in the matrix, but also the orientation of the natural fibres itself is important. Furthermore, in addition to the usual variations in properties of natural fibres, the fibre length, the fibre-matrix adhesion and a possible thermal degradation during processing and their quantitative impact on the microstructure and micromechanics are unknown. Accordingly, a simulation of the mechanical properties and the failure behavior of the bio-composite materials is not possible. In this subproject the so far only integral considered bio-composites will be investigated with regard to their micromechanics and the results should be used for modeling and simulation of the composites. This simulation is necessary for a transfer of the properties to complex components, in order to ensure a safe and reliable material behavior. The boundary conditions required for the simulation are determined quantitatively and are included in the sub-projects C2 and C3.

Current status of the project

One of the main goals of the sub-project is the simulation and modeling of the mechanical properties regarding safe and reliable materials to expand the fields of application of alternative resources in technical areas. Especially the low flexural stiffness and the non-linear alignment of cellulose fibres currently only allow an inadequate statement of the underlying micromechanics in natural fibre reinforced composites. In order to determine this quantitatively, the influent factors are currently identified and investigated. These include: • Fibre orientation and spatial orientation of the natural fibres with microscopy and CT images • Fibre strength and influence of the thermal degradation with tensile tests on single fibres and fibre bundles • Fibre-matrix adhesion by pull-out tests of single fibres • Fibre lengths and their distribution by dynamic fibre analysis • Usual fluctuations in properties of natural fibres • Quantitative influence on the microstructure and micromechanics •Investigation of crack propagation by means of static and dynamic test procedures The aim is to simulate the composite characteristics and their transfer to complex parts in order to avoid an unpredictable failure of the natural fibre-reinforced plastics and to ensure a reliable material behavior.