Characterization of tensile failure behavior of natural single fibre composite by acoustic emission technique

Abstract

In the present days among the different non-destructive testing methods Acoustic Emission is a suitable tool for detecting and evaluating and for better understanding the damage mechanism and failure behavior in composites during mechanical loading. Methodology was developed for natural single fibre tensile test with Acoustic Emission (AE) to assess or monitor the tensile failure behavior of natural single fibre especially for bamboo single fibre. Series of experiment performed with this methodology. Before the final failure of fibre during tensile test few (one or two) load drop observed from the time vs load graph. From AE parameter such as Amplitude, Energy, duration etc. significant information of corresponding to that load drops found. These AE signals from the load drop may occur from the failure such as debonding between two elementary fibre or from join of elementary fibre at edge. The value of load at first load drop was not found consistent for different sample (for a particular sample the value is 8N, Stress: 517.51 MPa). Final breaking of fibre gives saturated level AE amplitude of preamplifier (99.9 dB) for all samples. Therefore it was not possible to think up exact AE energy value for final breaking. The other AE signal of AE may occur for the micro failure mechanism. Same methodology was used for tensile test of three single fibres, which gives clear indication of load drop before the final breaking of first and second fibre. Moreover, tensile test of single fibre composite (bamboo single fibre/epoxy) was performed to identify the individual fibre and matrix failure mechanism in composites using AE technique. Experimental data from AE for SFC test shows that many of them have a clear correlation between acoustic emission amplitude and failure mechanisms in single fibre composite.