Numerical Model Describing the Early Age Behavior of 3D Printed Concrete – Work in Progress

Abstract

A numerical model used to predict the behavior of 3D printed concrete in the early age phase up until the point of collapse is presented. An incremental creep model for the material including aging and temperature effects is suggested. Furthermore, kinematic nonlinear effects are included in order to predict instability. The input parameters to the numerical model are determined through an optimization process where the displacement error between a finite element method (FEM) model and digital image correlation (DIC) measurements from an actual 3D print are minimized. A simplified (current state) version of the suggested numerical model was used to predict at how many layers a specific 3D print collapsed, with an error of 58%. This was concluded to be expected, since the numerical model is not fully implemented yet.

From analytical methods to numerical simulations: A process engineering toolbox for 3D concrete printing

“…Optimization loops used to fit the input parameters of numerical modeling should be carried out to improve the deposit modeling; digital image correlation or calorimetry tests can be used, for example, as simultaneous non-destructive or offline tests to assess the reliability of the numerical model used. This has begun to be done in the work of [134], in which the model input parameters are initially determined and then subsequently adjusted through an optimization loop minimizing the difference in the displacements predicted by the model and the measurements which could be performed by ultrasound examination or digital image correlation.…”

“…Consequently, numerical methods may be adopted to define, for instance, optimal printing speed or the minimal structuration rate without the occurrence of failure during the 3D printing process. It is interesting to note that other research groups have started to develop FEM-based numerical simulations in order to study the structural behavior of in-print structures [134,[137][138][139][140][141][142]. These studies are based on the same principles but use different criteria for plasticity and the modelling of the evolution of mechanical properties over time.…”