Optimal Design and Additive Manufacturing of Functionally Graded Shell-Based PH Steel Metamaterials
Abstract
We propose to develop the scientific understanding that will enable optimal design and scalable additive manufacturing of a novel c) from 17-4 PH steel. We will deliver (i) a computational strategy for optimal design of LPBF-fabricated functionally graded shell-metamaterials that are far superior to traditional truss-based lattices, and (ii) a fabrication approach that allows local control of plastic deformation mechanisms in 17-4 PH steel thin-wall structures. While LPBF is an ideal technique for fabrication of lattice materials for critical structural applications, we argue that existing lattice designs have not taken advantage of two unique benefitsof this additive manufacturing process: (i) the ability to fabricate almost arbitrarily complextopologies and (ii) the opportunity to locally tailor the mechanical properties of the constituent material. The overarching goal of the proposed research project is to develop the scientific understanding in metallurgy, mechanics and topology optimization that is required to realize these advances and develop physically heterogeneous shell-metamaterials with unprecedented combinations of properties. Building upon exceptional results recently demonstrated by the PI on the mechanical efficiency of shell and plate-based metamaterials, we propose to: (1) fully elucidate the interplays among processing parameters, microstructural evolution and mechanical properties in LPBF-processedshell-metamaterials using a combination of numerical and experimental techniques, and establish effective processing windows; (2) harness these complex interplays to locally control martensite/austenite ratio and precipitate formation to either eliminate or amplify property gradients across the build; (3) combine mechanical models with experiments to achieve a full mechanistic understanding of the non-linear deformation and failure behavior of these shell-based metamaterials; (4) capitalize on the extensive (experimentally driven) database to infer, through the application of data analytics, property uncertainty and gradation models as well as their as sociated length scales and (5) develop novel non-linear stochastic topology optimization algorithms that benefit from fully validated models of the mechanics to id LPBF process. To demonstrate the power of this novel design/fabrication approach for DoD-relevant applications,r we will develop shell-metamaterials with optimal specific energy absorption under large plastic deformation, by ensuring simultaneous progression of plasticity throughout the material. Importantly, this cannot be achieved by traditional optimization of the metamaterial architecture, but requires local tuning of the yield strength and the strain hardening behavior of the material. By assembling a highly interdisciplinary team across three universities, with expertise in metallurgy, processing science, additive manufacturing, mechanical behavior of metamaterials,stochastic modeling and topology optimization, we will guarantee that the impact of this project extend well beyond the field of mechanical metamaterials. Elucidating the science underlying local microstructural control in PH steels fabricated by LPBF will dramatically affect the additive manufacturing of structural and functional materials for nearly any DoD application; at the sametime, establishing novel computational design processes, where the marriage between geometrical complexity (e.g. 3D shell-based topologies) and local property control provides a significantly wider design space, is expected to leapfrog the field of additively manufactured metamaterials in a variety of DoD applications.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jun 09, 2021
- Source ID
- N000142112570
Entities
People
- Lorenzo Valdevit
Organizations
- Office of Naval Research
- United States Navy
- University of California, Irvine