Analytical modelling of the orientation dependency of 3D printed SHCC at increasing levels of scale

Abstract

3D printable strain hardening cementitious composites (3DP-SHCC) stand out for their high ductility and increase in tensile strength after initial cracking. Due to the printing process, which includes the pumping and extruding of the material, the fibres are not uniformly orientated in the material but have an orientation dependency due to the specific printing process applied. Three different cases for the fibre orientation distribution functions are presented with increasing levels of relation to the printing process. These three cases have been used in a micro-mechanical model to verify with experimental stress-crack opening results (single crack). Furthermore, a spring model is used to give insight into the potential to develop pseudo strain hardening behaviour (multiple cracking) in various printing directions. The method is also used to model the experimentally obtained spread in uni-axial tensile dogbone test results. From these experimental dogbone tests, average stress-strain relations are determined in two directions. Finally, a multi-layer method is used on the component level to validate the use of these average stress-strain relations for modelling the bending behaviour of printed elements in multiple directions.