Dynamical properties of flax fibre reinforced PA11 over a large frequency range

Abstract This paper reports the characterisation of the dynamic behaviour of a flax fibre reinforced polyamide 11 biocomposite. The film stacking and hot pressing process is used to obtain composite plates. Quasi-static tests are conducted to get information on the Young's moduli and Poisson's ratios. The aim of the present study is to identify the storage modulus and the loss factor over a wide range of frequencies. For this purpose, an inverse method inspired from the Force Analysis Technique and based on the local equation of motion is used. The out-of-plane displacements of suspended vibrating plates are measured by a laser Doppler vibrometer. Together with the plate thickness, material density and Poisson's ratios, the measured displacements constitute the inputs of the identification method. Additional tests on Dynamic Mechanical Analysis are conducted to compare the results of the two methods. A good correlation of the results is obtained. The storage modulus can be identified by the inverse method up to a frequency of 10 kHz and is rather constant, but the loss factor is not obtained with a good accuracy.