Simultaneous topology and toolpath optimization for layer-free multi-axis additive manufacturing of 3D composite structures

Abstract

Composite materials are extremely common in nature, with organic structures freely distributing and orienting anisotropic material properties in 3D to achieve a high degree of efficiency and functionality. Human-made composite structures do not leverage the same design thinking; they are frequently designed specifically for isotropic performance and with little geometric complexity due to limitations imposed by the manufacturing processes. While additive manufacturing (AM) provides unprecedented geometric flexibility, it typically deposits material in a series of stacked 2D layers (despite the moniker of “3D printing”); it does not enable the same freedoms of material placement and orientation seen in nature. Multi-axis (e.g., robotically-enabled) AM enables true 3D part fabrication such that material anisotropy can be advantageously oriented to enhance part performance (e.g., aligning fiber reinforcement to anticipated load paths), but existing methodologies separate the design of part geometry from its multi-axis printing toolpath. This paper presents a novel design and manufacturing workflow that integrates design optimization and multi-axis AM to algorithmically create optimal part topologies concurrently with their printing toolpaths. The workflow is aware of manufacturing and design considerations to maximize part performance while simultaneously guaranteeing multi-axis printability. Material is placed through an optimized, layer-free process to significantly improve the performance of additively manufactured composite structures. The design workflow is validated by optimizing, fabricating, and mechanically evaluating multi-axis structures and demonstrated a 56.9 % improvement in structural efficiency relative to a conventional, layer-wise AM process.