Wave propagation and response statistics of short fibre composites from experimental estimation of material properties

Adriano T. Fabro¹; Neil S. Ferguson²; Brian R. Mace³

¹ Department of Mechanical Engineering, University of Brasilia, Brazil; ² University of Southampton, Southampton, UK; ³ Department of Mechanical Engineering, University of Auckland, New Zealand

doi:10.20906/CPS/COB-2015-1023

Resumo

Typically there is variability in the material and geometrical properties of fibre-reinforced composites and this variability is often spatially correlated. Numerical models can predict the response of such panels, but the spatially correlated nature of the variability must be represented within the model. However, characterising the variability, and especially the spatial correlation, is problematic. In this study data is first generated by an automated optical process: light transmissibility measurements are taken of a dry chopped strand mat panel. The intensity of the consequent image is post-processed to describe the fibre density as a random field using the Karhunen-Loeve decomposition. The panel is then cut into beams, from which mobility measurements are taken, providing an ensemble of mobility and natural frequency. The WKB (after Wentzel, Kramers and Brillouin) approximation, is used in order to find a suitable wave solutions for finite waveguides considering the given random field. Subsequent realisations of the random field are then used to predict the statistics of the vibration response of the beams. Numerical and experimental results show a very good agreement. This approach significantly reduces the computational time when compared to the standard FE and provides a suitable framework to account for randomness.

Palavras-chave: Fibre Reinforcement; Karhunen-Loeve Expansion; WKB approximation; Experimental Validation; Random Fields