A Breakthrough Additive Manufacturing Method for High-Strength Lightweight 3D Micro-Architectured Materials

Carnegie Mellon University, Pittsburgh PA

Investigators

Abstract

The design and manufacture of lightweight materials having superior mechanical properties such as high strength is one of the key challenges for scientists and engineers. Current state-of-the-art materials show a drastic tradeoff between weight and strength, while manufacturing strategies for porous lightweight materials suffer from poor control over material architecture and limited material choices. This project investigates a novel additive manufacturing (AM) method that uses printing of nanoparticles to fabricate a new class of three-dimensional (3D) micro-architectured materials, which will possess the desired characteristics of low weight and high strength. The research will also incorporate multi-scale mechanical models that consider the effect of microstructures and length scales specific to AM. The research results will advance the field of AM by enabling rapid fabrication of 3D structures with custom architectures and materials that have a wide range of applications, including biomedical implants, porous membranes, tissue engineering, and energy storage. Minority and women undergraduate and graduate researchers will be recruited to work on the project and periodic activities will be carried out targeted to attract K-12 students into the manufacturing research profession. The research focuses on the investigation of a novel additive manufacturing method that involves printing of metal nanoparticles dispersed into a solvent, followed by nanoparticle sintering to realize highly intricate and controlled 3D metal architectures that are lightweight and strong. The first objective of the project is to investigate the scientific principles governing the printing process. Models will be developed that identify the role of droplet condensation, solvent evaporation, and system dynamics in the formation of the 3D architectures. The models will guide experiments that will involve printing of 3D architectures from silver, nickel, or aluminum nanoparticles dispersed into a solvent such as ethylene glycol, and using an Aerosol Jet 3D printer. The second objective of this work is to identify the micro and nanoscale deformation mechanisms governing the mechanical behavior of the metallic 3D structures. Complex 3D lattices (with up to 94% porosity) and micro-pillars will be fabricated by printing, and tested under compression and bending. Multi-scale mechanical models will be developed that consider dislocation motion, stress and strain gradients, and variability in the microstructure. The models will predict optimal 3D designs that improve strength-to-weight ratio dramatically, which will be verified through mechanical tests. The result of this project will be a novel additive manufacturing platform that can create strong lightweight structures with architectural control of over five orders of magnitudes in length scale (tens of nanometers to several millimeters), and will potentially open up new research areas in the manufacturing of 3D architectures and modeling methods for mechanical behavior of additively manufactured parts.