Additive Manufacturing: Mechanical Behavior of Lattice Structures Produced via AM: Additive Manufacturing of Lattices - Session II
Sponsored by: TMS: Additive Manufacturing Committee, TMS: Mechanical Behavior of Materials Committee
Program Organizers: John Carpenter, Los Alamos National Laboratory; Matthew Begley, University of California, Santa Barbara; Sneha Prabha Narra, Carnegie Mellon University; Michael Groeber, Ohio State University; Isabella Van Rooyen, Pacific Northwest National Laboratory; Kyle Johnson, Sandia National Laboratories; Krishna Muralidharan, University of Arizona

Monday 2:00 PM
November 2, 2020
Room: Virtual Meeting Room 4
Location: MS&T Virtual

Session Chair: Sneha Prabha Narra, Worcester Polytechnic Institute; Isabella Van Rooyen, Idaho National Laboratory


2:00 PM  Invited
Mechanical Properties of Additively Manufactured Metal Lattices: Manyalibo Matthews1; Bradley Jared2; John Carpenter3; Benjamin Brown4; Paul Korinko5; 1Lawrence Livermore National Laboratory; 2Sandia National Laboratories; 3Los Alamos National Laboratory; 4Kansas City National Security Complex; 5Savannah River National Laboratory
    Metal additive manufacturing has enabled new applications in the area of lightweight, high stiffness metallic lattice fabrication. Load bearing properties, strength-to-weight ratio and tailored shock absorption are three mechanical benefits of the lattice structures. However, the deformation behavior of additively manufactured (AM) lattice structures is very complex and challenging to be predicted, in part because of the unique nature of AM materials. In this work, we present results of a multi-institutional effort aimed at characterizing the quasi-static and dynamic mechanical properties of metal lattices. In situ synchrotron diffraction and differential interference contrast measurements are performed with the aim of understanding the behavior of single cell Ti-5553 lattice structures under compression, which will permit improved design optimization of the lattice structures for specific applications. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

2:30 PM  
Direct Metal Laser Sintering Strategies for Fabrication of Finer Resolution Cellular Structures: Ebrahim Asadi1; Fatemeh Hejripour1; Muhammad Abdus Salam1; 1University of Memphis
    Direct Metal Laser Sintering (DMLS) is an additive manufacturing technology that is capable of fabricating net-shape intricate metallic designs such as cellular structures with tailored mechanical properties. In this talk, we present novel laser scanning strategies and their associated DMLS processing parameters to fabricate finer resolution Ti-6Al-4V cellular structures toward mimicking human cancellous bone resolution and mechanical performance. To this end, three DMLS scanning strategies with various laser power and scanning speed were defined to fabricate diamond and dodecahedron unit cells with four different cell sizes. With the constant laser spot size of 80μm, average powder size of 34μm, and layer thickness of 30μm for all the DMLS processes, the finest achieved resolution for the struts of the cellular structures are reported as 120μm in this study. Furthermore, correlations between DMLS processing parameters/scanning strategies with geometry, porosity, density, and mechanical performance of the cellular structures were comprehensively investigated and discussed.

2:50 PM  Invited
Tailoring Hierarchical Material Performance Through Process Manipulation: Bradley Jared1; Brad Boyce1; Anthony Garland1; Michael Heiden1; Scott Jensen1; David Moore1; David Saiz1; Benjamin White1; Timothy Ruggles1; 1Sandia National Laboratories
    Hierarchical materials introduce a compelling design space to achieve material and structural performance regimes that are inaccessible in bulk, homogenous materials. Numerous researchers have explored an array of geometrical constructs for tuning hierarchical material properties. The presented work, however, will explore how process inputs from laser-powder bed fusion impact the mechanical performance of 316L stainless steel octet and gyroid lattice structures. The process space within which robust lattice geometries can be fabricated will be described. Relationships between process inputs and resultant strut geometry, cell geometry and structure performance will also be presented based on fringe-project microscopy, computed tomography, metallography and quasi-static compression loading. It will be demonstrated that process inputs provide an additional degree of freedom in the design and fabrication of hierarchical materials. SNL is managed and operated by NTESS under DOE NNSA contract DE-NA0003525.

3:20 PM  
Microstructure and Mechanical Properties of Additively Manufactured Lattice Structures of Co-Cr-Mo Alloy: Bandar AlMangour; 1
    In this work, we used selective laser melting technique to build various lattice structures made of Co-Cr alloy. The mechanical properties has been assessed by considering geometrical and microstructural aspects. Higher tensile properties (e.g., elastic modulus, energy absorption) was obtained for the fcc lattice structure. However, the tested lattice structures revealed decreased ductility during tension due to notch effects and process-related microstructure. The experimental results carried out on the lattice structures demonstrate the potential to tailor the mechanical properties by adjusting the lattice structure geometry.