Mesoscopic analysis and prediction of in-situ effect in FFF 3D printing CFRP/GFRP

Abstract

The inadequate computational methodologies for fused filament fabrication (FFF) 3D printing components, particularly in addressing interlayer characteristics, have hindered their widespread engineering applications. This paper presents a novel computational framework for in-situ effect determination, which identifies transverse tensile strength and shear strength (Y, S) through exhaustive search matching experimental ultimate tensile strength data, with the converged solutions being determined as authentic in-situ effect values (Y_is, S_is). Based on this method, the in-situ effect distribution patterns and calculation methods for FFF 3D printing carbon fiber reinforced polymer (CFRP) and glass fiber reinforced polymer (GFRP) laminates are investigated under both pure matrix tensile failure mode and matrix tensile-shear coupling failure mode. The meso-structure indicates that, unlike conventional composite materials, the distinctive FFF 3D printing process diminishes the impact of adjacent layers on clustered plies in thin-layer structures. Consequently, the in-situ effect increases with clustered plies thickness. In terms of numerical prediction, this work refines the traditional empirical formula to account for the specific characteristics of FFF 3D printing composites. As a result, the improved model achieves regression values of 0.88 (CFRP) and 0.72 (GFRP) for transverse in-situ tensile strength, and 0.99 (CFRP) and 0.98 (GFRP) for in-situ shear strength, respectively.