Numerical simulation of 3D printed ultra high-performance concrete using the lattice discrete particle model

The Lattice Discrete Particle Model (LDPM) is highly effective in capturing the fracture behavior of concrete, especially at the scale where significant material heterogeneities, such as coarse aggregates, dominate.This model constructs a meso-structure of concrete using a stochastic approach to generate spherical particles.This process is guided by several key parameters, including cement content, water-to-cement ratio, and the size range of aggregates, from the largest to the smallest.Delaunay tetrahedralization is employed to establish the lattice framework, targeting the centers of aggregates, which results in formation of polyhedral cells surrounding each aggregate particle through a 3D domain tessellation.LDPM is integrated into Project Chrono, an open-source multi-physics simulation engine and implemented as a user element code in Abaqus.In this study, mechanical characterization of the 3D printed concrete samples will be investigated.A 3D scanner is utilized to ensure accurate geometric representation of the printed sample geometries, which are then imported into the FreeCAD preprocessor for meso-structure generation.The simulations of various mechanical tests are conducted, such as unconfined compression and three-point bending tests, with the ability to apply loads at different orientations relative to the printing direction.The model's accuracy is validated by comparing the simulation results with experimental data, ensuring that it can accurately capture the behavior of 3D printed ultra-high-performance concrete under different loading conditions.