Nonlinear Coarse-graining Models for 3D Printed Multi-material Biomimetic Composites

TL;DR

This paper introduces a nonlinear coarse-graining method for predicting the mechanics of complex 3D printed biomimetic composites, enabling efficient design and optimization of advanced architected materials with predictable properties.

Contribution

A novel nonlinear coarse-graining approach using foam-based constitutive equations for modeling 3D printed biomimetic composites is developed and validated against experimental data.

Findings

Coarse-grained predictions closely match full-field strain measurements.

The method accurately predicts fracture behavior of complex bio-inspired designs.

Inverse coarse-graining successfully optimized microarchitecture of a 3D-printed femur.

Abstract

Bio-inspired composites are a great promise for mimicking the extraordinary and highly efficient properties of natural materials. Recent developments in voxel-by-voxel 3D printing have enabled extreme levels of control over the material deposition, yielding complex micro-architected materials. However, spatial complexity makes it a formidable challenge to find the optimal distribution of both hard and soft phases. To address this, a nonlinear coarse-graining approach is developed, where foam-based constitutive equations are used to predict the mechanics of biomimetic composites. The proposed approach is validated by comparing coarse-grained finite element predictions against full-field strain distributions measured using digital image correlation. To evaluate the degree of coarse-graining on model accuracy, pre-notched specimens decorated with a binarized version of a renowned painting were modeled. Subsequently, coarse-graining is used to predict the fracture behavior of bio-inspired composites incorporating complex designs, such as functional gradients and hierarchical organizations. Finally, as a showcase of the proposed approach, the inverse coarse-graining is combined with a theoretical model of bone tissue adaptation to optimize the microarchitecture of a 3D-printed femur. The predicted properties were in exceptionally good agreement with the corresponding experimental results. Therefore, the coarse-graining method allows the design of advanced architected materials with tunable and predictable properties.