ECOCOMP 2013, International Conference on Sustainable Materials, Polymers and Composites edition:5 location:Edinburg, UK date:3-4 July 2013
As of today, a major lack of data on natural fibre durability properties, such as fatigue behaviour and impact resistance, which limits the use of these fibres for structural applications. This study seeks to assess and compare the mechanical properties and fatigue behaviour of flax fibre reinforced composites for various architectures which is later on compared to glass fiber. Sample were processed using Resin Transfer Moulding (RTM) process to obtain high quality samples. Quasi-static tensile test were carried to obtain the stiffness and ultimate tensile strength (UTS) of flax/epoxy composites. This data is crucial to understand the effect of architecture on the intrinsic properties of a biocomposites part. UTS values vary from 248 MPa for the unidirectional composite (UD) to 85 MPa for the chopped strand mat (MAT) as well as 190 MPa for twill 2x2 weave (TW) and 120MPa for plain weave (PW), at an equivalent fibre volume fraction of 40%. These values (So) are later used to carry on the fatigue testing. Tension–tension fatigue tests with a ratio of R = 0.1 at a frequency of 5Hz as well as loading level (S/So) varying from 0.3 to 0.9 UTS, were conducted at 22oC room temperature. Results showed that at comparable normalised stresses, MAT flax composites has a comparable life as PW glass preforms and can resist more than 1x106 cycles at 0.3 load level. As well, flax PW has an enhanced fatigue performance compared to glass with the first being able to sustain around 100 000 thousand cycle and the second only 20 000 cycles at a 0.65 load level. This results may help widens the application domain of possible application with flax fibre in replacement of glass by flax.