Trusses

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Matthew R. Begley - One of the best experts on this subject based on the ideXlab platform.

  • design and mechanical properties of elastically isotropic Trusses
    Journal of Materials Research, 2018
    Co-Authors: Ryan M. Latture, Matthew R. Begley, Frank W. Zok
    Abstract:

    The present article addresses design of stiff, elastically isotropic Trusses and their mechanical properties. Isotropic Trusses are created by combining two or more elementary cubic Trusses in appropriate proportions and with their respective nodes lying on a common space lattice. Two isotropic binary compound Trusses and many isotropic ternary Trusses are identified, all with Young’s moduli equal to the maximal possible value for isotropic strut-based structures. In finite-sized Trusses, strain elevations are obtained in struts near the external free boundaries: a consequence of reduced nodal connectivity and thus reduced constraint on strut deformation and rotation. Although the boundary effects persist over distances of only about two unit cell lengths and have minimal effect on elastic properties, their manifestations in failure are more nuanced, especially when failure occurs by modes other than buckling (yielding or fracture). Exhaustive analyses are performed to glean insights into the mechanics of failure of such Trusses.

  • periodic truss structures
    Journal of The Mechanics and Physics of Solids, 2016
    Co-Authors: Frank W. Zok, Ryan M. Latture, Matthew R. Begley
    Abstract:

    Abstract Despite the recognition of the enormous potential of periodic Trusses for use in a broad range of technologies, there are no widely-accepted descriptors of their structure. The terminology has been based loosely either on geometry of polyhedra or of point lattices: neither of which, on its own, has an appropriate structure to fully define periodic Trusses. The present article lays out a system for classification of truss structure types. The system employs concepts from crystallography and geometry to describe nodal locations and connectivity of struts. Through a series of illustrative examples of progressively increasing complexity, a rational taxonomy of truss structure is developed. Its conceptual evolution begins with elementary cubic Trusses, increasing in complexity with non-cubic and compound Trusses as well as superTrusses, and, finally, with complex Trusses. The conventions and terminology adopted to define truss structure yield concise yet unambiguous descriptions of structure types and of specific (finite) Trusses. The utility of the taxonomy is demonstrated by bringing into alignment a disparate set of ad hoc and incomplete truss designations previously employed in a broad range of science and engineering fields. Additionally, the merits of a particular compound truss (comprising two interpenetrating elementary Trusses) is shown to be superior to the octet truss for applications requiring high stiffness and elastic isotropy. By systematically stepping through and analyzing the finite number of structure types identified through the present classification system, optimal structures for prescribed mechanical and functional requirements are expected to be ascertained in an expeditious manner.

Frank W. Zok - One of the best experts on this subject based on the ideXlab platform.

  • design and mechanical properties of elastically isotropic Trusses
    Journal of Materials Research, 2018
    Co-Authors: Ryan M. Latture, Matthew R. Begley, Frank W. Zok
    Abstract:

    The present article addresses design of stiff, elastically isotropic Trusses and their mechanical properties. Isotropic Trusses are created by combining two or more elementary cubic Trusses in appropriate proportions and with their respective nodes lying on a common space lattice. Two isotropic binary compound Trusses and many isotropic ternary Trusses are identified, all with Young’s moduli equal to the maximal possible value for isotropic strut-based structures. In finite-sized Trusses, strain elevations are obtained in struts near the external free boundaries: a consequence of reduced nodal connectivity and thus reduced constraint on strut deformation and rotation. Although the boundary effects persist over distances of only about two unit cell lengths and have minimal effect on elastic properties, their manifestations in failure are more nuanced, especially when failure occurs by modes other than buckling (yielding or fracture). Exhaustive analyses are performed to glean insights into the mechanics of failure of such Trusses.

  • periodic truss structures
    Journal of The Mechanics and Physics of Solids, 2016
    Co-Authors: Frank W. Zok, Ryan M. Latture, Matthew R. Begley
    Abstract:

    Abstract Despite the recognition of the enormous potential of periodic Trusses for use in a broad range of technologies, there are no widely-accepted descriptors of their structure. The terminology has been based loosely either on geometry of polyhedra or of point lattices: neither of which, on its own, has an appropriate structure to fully define periodic Trusses. The present article lays out a system for classification of truss structure types. The system employs concepts from crystallography and geometry to describe nodal locations and connectivity of struts. Through a series of illustrative examples of progressively increasing complexity, a rational taxonomy of truss structure is developed. Its conceptual evolution begins with elementary cubic Trusses, increasing in complexity with non-cubic and compound Trusses as well as superTrusses, and, finally, with complex Trusses. The conventions and terminology adopted to define truss structure yield concise yet unambiguous descriptions of structure types and of specific (finite) Trusses. The utility of the taxonomy is demonstrated by bringing into alignment a disparate set of ad hoc and incomplete truss designations previously employed in a broad range of science and engineering fields. Additionally, the merits of a particular compound truss (comprising two interpenetrating elementary Trusses) is shown to be superior to the octet truss for applications requiring high stiffness and elastic isotropy. By systematically stepping through and analyzing the finite number of structure types identified through the present classification system, optimal structures for prescribed mechanical and functional requirements are expected to be ascertained in an expeditious manner.

David C Dunand - One of the best experts on this subject based on the ideXlab platform.

  • niti nb micro Trusses fabricated via extrusion based 3d printing of powders and transient liquid phase sintering
    Acta Biomaterialia, 2018
    Co-Authors: Shannon L. Taylor, Amaka J. Ibeh, Adam E Jakus, Ramille N Shah, David C Dunand
    Abstract:

    Abstract We present a novel additive manufacturing method for NiTi-Nb micro-Trusses combining (i) extrusion-based 3D-printing of liquid inks containing NiTi and Nb powders, solvents, and a polymer binder into micro-Trusses with 0/90° ABAB layers of parallel, ∼600 µm struts spaced 1 mm apart and (ii) subsequent heat-treatment to remove the binder and solvents, and then bond the NiTi powders using liquid phase sintering via the formation of a transient NiTi-Nb eutectic phase. We investigate the effects of Nb concentration (0, 1.5, 3.1, 6.7 at.% Nb) on the porosity, microstructure, and phase transformations of the printed NiTi-Nb micro-Trusses. Micro-Trusses with the highest Nb content exhibit long channels (from 3D-printing) and struts with smaller interconnected porosity (from partial sintering), resulting in overall porosities of ∼75% and low compressive stiffnesses of 1–1.6 GPa, similar to those of trabecular bone and in agreement with analytical and finite element modeling predictions. Diffusion of Nb into the NiTi particles from the bond regions results in a Ni-rich composition as the Nb replaces Ti atoms, leading to decreased martensite/austenite transformation temperatures. Adult human mesenchymal stem cells seeded on these micro-Trusses showed excellent viability, proliferation, and extracellular matrix deposition over 14 days in culture. Statement of Significance Near-equiatomic NiTi micro-Trusses are attractive for biomedical applications such as stents, actuators, and bone implants because of their combination of biocompatibility, low compressive stiffness, high surface area, and shape-memory or superelasticity. Extrusion-based 3D-printing of NiTi powder-based inks into micro-Trusses is feasible, but the subsequent sintering of the powders into dense struts is unachievable due to low diffusivity, large particle size, and low packing density of the NiTi powders. We present a solution, whereby Nb powders are added to the NiTi inks, thus forming during sintering a eutectic NiTi-Nb liquid phase which bonds the solid NiTi powders and improves densification of the struts. This study investigates the microstructure, porosity, phase transformation behavior, compressive stiffness, and cytocompatibility of these printed NiTi-Nb micro-Trusses.

  • Sintering of micro-Trusses created by extrusion-3D-printing of lunar regolith inks
    Acta Astronautica, 2018
    Co-Authors: Shannon L. Taylor, Katie D. Koube, Amaka J. Ibeh, Nicholas R. Geisendorfer, Adam E Jakus, Ramille N Shah, David C Dunand
    Abstract:

    Abstract The development of in situ fabrication methods for the infrastructure required to support human life on the Moon is necessary due to the prohibitive cost of transporting large quantities of materials from the Earth. Cellular structures, consisting of a regular network (truss) of micro-struts with ∼500 μm diameters, suitable for bricks, blocks, panels, and other load-bearing structural elements for habitats and other infrastructure are created by direct-extrusion 3D-printing of liquid inks containing JSC-1A lunar regolith simulant powders, followed by sintering. The effects of sintering time, temperature, and atmosphere (air or hydrogen) on the microstructures, mechanical properties, and magnetic properties of the sintered lunar regolith micro-Trusses are investigated. The air-sintered micro-Trusses have higher relative densities, linear shrinkages, and peak compressive strengths, due to the improved sintering of the struts within the micro-Trusses achieved by a liquid or glassy phase. Whereas the hydrogen-sintered micro-Trusses show no liquid-phase sintering or glassy phase, they contain metallic iron 0.1–2 μm particles from the reduction of ilmenite, which allows them to be lifted with magnets.

Ryan M. Latture - One of the best experts on this subject based on the ideXlab platform.

  • design and mechanical properties of elastically isotropic Trusses
    Journal of Materials Research, 2018
    Co-Authors: Ryan M. Latture, Matthew R. Begley, Frank W. Zok
    Abstract:

    The present article addresses design of stiff, elastically isotropic Trusses and their mechanical properties. Isotropic Trusses are created by combining two or more elementary cubic Trusses in appropriate proportions and with their respective nodes lying on a common space lattice. Two isotropic binary compound Trusses and many isotropic ternary Trusses are identified, all with Young’s moduli equal to the maximal possible value for isotropic strut-based structures. In finite-sized Trusses, strain elevations are obtained in struts near the external free boundaries: a consequence of reduced nodal connectivity and thus reduced constraint on strut deformation and rotation. Although the boundary effects persist over distances of only about two unit cell lengths and have minimal effect on elastic properties, their manifestations in failure are more nuanced, especially when failure occurs by modes other than buckling (yielding or fracture). Exhaustive analyses are performed to glean insights into the mechanics of failure of such Trusses.

  • periodic truss structures
    Journal of The Mechanics and Physics of Solids, 2016
    Co-Authors: Frank W. Zok, Ryan M. Latture, Matthew R. Begley
    Abstract:

    Abstract Despite the recognition of the enormous potential of periodic Trusses for use in a broad range of technologies, there are no widely-accepted descriptors of their structure. The terminology has been based loosely either on geometry of polyhedra or of point lattices: neither of which, on its own, has an appropriate structure to fully define periodic Trusses. The present article lays out a system for classification of truss structure types. The system employs concepts from crystallography and geometry to describe nodal locations and connectivity of struts. Through a series of illustrative examples of progressively increasing complexity, a rational taxonomy of truss structure is developed. Its conceptual evolution begins with elementary cubic Trusses, increasing in complexity with non-cubic and compound Trusses as well as superTrusses, and, finally, with complex Trusses. The conventions and terminology adopted to define truss structure yield concise yet unambiguous descriptions of structure types and of specific (finite) Trusses. The utility of the taxonomy is demonstrated by bringing into alignment a disparate set of ad hoc and incomplete truss designations previously employed in a broad range of science and engineering fields. Additionally, the merits of a particular compound truss (comprising two interpenetrating elementary Trusses) is shown to be superior to the octet truss for applications requiring high stiffness and elastic isotropy. By systematically stepping through and analyzing the finite number of structure types identified through the present classification system, optimal structures for prescribed mechanical and functional requirements are expected to be ascertained in an expeditious manner.

Haydn N. G. Wadley - One of the best experts on this subject based on the ideXlab platform.

  • pyramidal lattice truss structures with hollow Trusses
    Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2005
    Co-Authors: Douglas T. Queheillalt, Haydn N. G. Wadley
    Abstract:

    A method for fabricating pyramidal lattice structures with hollow metallic Trusses has been explored. A periodic diamond hole pattern sheet consisting of 304L stainless steel hollow tubes was made by an alternating collinear lay-up process followed by vacuum brazing. The array was then folded at the nodes to create a periodic pyramidal cellular metal lattice and was then bonded to face sheets by a second vacuum brazing process. The out-of-plane compression properties of this hollow truss lattice structure have been investigated and compared to a similar lattice made with the solid Trusses. In both cases, the peak strength is found to be governed by inelastic truss buckling. The compressive strength of a hollow lattice with a relative density of 2.8% was approximately twice that of a solid pyramidal lattice of similar relative density. The increased strength resulted from an increase in the buckling resistance of hollow Trusses because of their higher radius of gyration.

  • Cellular metal lattices with hollow Trusses
    Acta Materialia, 2005
    Co-Authors: Douglas T. Queheillalt, Haydn N. G. Wadley
    Abstract:

    Cellular metal lattice truss structures are being investigated for use as multifunctional load supporting structures where their other functionalities include thermal management, dynamic load protection and acoustic damping. A simple method for making lattice structures with either solid or hollow Trusses is reported. The approach involves laying up collinear arrays of either solid wires or hollow cylinders and then alternating the direction of successive layers. The alternating collinear assembly is metallically bonded by a brazing process. The dimensions of the cylinders, the wall thickness of hollow truss structures and the spacing between the Trusses enable independent control of the cell size and the relative density of the structure. The process has been used to create stainless steel lattices with either square or diamond topologies with relative densities from 0.03 to 0.23. The through thickness elastic modulus of these lattice truss structures is found to be proportional to relative density. The square topology has twice the stiffness of the diamond oriented Trusses. The peak compressive strengths of both topologies are similar and is controlled by plastic buckling. The structural efficiency of hollow truss structures with a fixed cell size is approximately proportional to the relative density unlike equivalent structures made from solid Trusses whose peak strength has been predicted to scale with the cube of the relative density. The experimental data for hollow Trusses lie between predictions for Trusses with built-in and pin-jointed nodes consistent with experimental observations of constrained node rotation. The use of hollow Trusses increases the resistance to buckling offsetting the usually rapid drop in strength as the relative density decreases in cellular systems where truss buckling controls failure. The low relative density hollow truss structures reported here have the highest reported specific peak strength of any cellular metal reported to date.