21 st International Conference on Composite Materials Xi’an, 20-25 th August 2017 DUCTILITY OF PLATELET COMPOSITES INSPIRED BY NACRE DESIGN Anil R. Ravindran 1 , Raj B. Ladani 2 , Shuying Wu 3 , Adrian P. Mouritz 4 and Chun H. Wang 5 1 Sir Lawrence Wackett Aerospace Research Centre, School of Engineering, RMIT University, Melbourne, VIC 3001, Australia Email: anil.ravindran@rmit.edu.au web page: http://www.rmit.edu.au 2 Sir Lawrence Wackett Aerospace Research Centre, RMIT University, Email: raj.ladani@rmit.edu.au. web page: http://www.rmit.edu.au 3 School of Mechanical and Manufacturing Engineering, University of New South Wales, Kensington, NSW 2052, Australia Email: shuying.wu@unsw.edu.au . web page: http://www.unsw.edu.au 6 Sir Lawrence Wackett Aerospace Research Centre, School of Engineering, RMIT University, Email: adrian.mouritz@rmit.edu.au web page: http://www.rmit.edu.au 5 School of Mechanical and Manufacturing Engineering, University of New South Wales, Kensington, NSW 2052, Australia Email: chun.h.wang@unsw.edu.au. web page: http://www.unsw.edu.au Keywords: Carbon fibre, nacre-mimetics, pseudo-ductility, tensile strength, z-pins ABSTRACT Platelet composite design inspired by nacre microstructure has attracted wide interest as a means to improve toughness of materials. A systematic comparative numerical and experimental study is described in this paper to identify the relationship between ply-overlap length and strain ductility. Larger ply overlap length is found to retain 45% and 93%, respectively, of the tensile strength and failure strain of the continuous fibre composite counterpart. A relatively small pseudo-ductility strain of 1.07% was observed. Analytical modelling studies towards these were conducted on platelet or discontinuous fibre reinforced epoxy composites with varying aspect ratio and tiling configurations. Results suggest that the staggering of the neighbouring ply terminations resulted in an increased tensile strength whereas aligning the ply-termination for each second consecutive ply leads to the increase in strain-to-failure. The incorporation of z-pin reinforcements (stainless steel, copper and carbon fibre/BMI) through-the- thickness of the platelet composite was investigated. The shear-induced work hardening of the metal pins further enhances the pseudo-ductile strain and strength simultaneously; supplementing the shear lag process between the ply overlaps. 1 INTRODUCTION