Characterisation and mathematical modelling of nonlinear mechanical behaviour of 3D printed short carbon fibre reinforced composites

Short carbon fibre reinforced plastic composites (SCFRP) that can be used in 3D printing exhibit excellent properties such as high specific strength and modulus, fatigue resistance, and efficient production at a lower cost. However, in the process of 3D printing, short carbon fibres tend to be distributed along the axial direction of the printed filament when they flow in the nozzle, leading to anisotropy and dispersity at the macro level. This brings difficulties to the design and application of materials. This paper developed a novel fix point iteration method based on classical laminate theory and Euler's integral method to accurate predict the nonlinear mechanical behaviour of SCFRP and verified via experiments. Results showed that the predicted curve and experimental data were in excellent agreement with only a 5 % error for 0 degrees/90 degrees laminate under uniaxial tensile loading. The accuracy of strength prediction for the -45 degrees/45 degrees laminate was improved and stabilised with the introduction of the fix point iteration method. These findings provide a useful framework for predicting the mechanical properties of the short fibre reinforced composited prepared by 3D printing.