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Rosen, David W.

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Author: Johnston, Scott R. × Item Type: Publication ×

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    Analysis of Mesostructure Unit Cells Comprised of Octet-truss Structures
    (Georgia Institute of Technology, 2006-08) Johnston, Scott R. ; Rosen, David W. ; Reed, Marques ; Wang, Hongqing Vincent
    A unit truss finite element analysis method allowing non-linear deformation is employed to analyze a unit cell comprised of n3 octet-truss structures for their stiffness and displacement compared to their relative density under loading. Axial, bending, shearing, and torsion effects are included in the analysis for each strut in the octet-truss structure which is then related to the mesostructure level (unit cell). The versatility of additive manufacturing allows for the fabrication of these complex unit cell truss structures which can be used as building blocks for macro-scale geometries. The finite element calculations are compared to experimental results for samples manufactured on a Stereolithography Apparatus (SLA) out of a standard resin.
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    Design of a Graded Cellular Structure For an Acetabular Hip Replacement Component
    (Georgia Institute of Technology, 2006-08) Johnston, Scott R. ; Rosen, David W. ; Wang, Hongqing Vincent
    The state-of-the-art porous coatings become more and more popular in uncemented prostheses to make bone grow into implants for biological fixation. In this paper, graded cellular structures are proposed for uncemented prostheses to enhance stability on implant-bone interfaces. As an example study, the authors develop a new acetabular implant with gradient porosity for hip replacement. A gradient porous acetabular component with cellular structure could match the bone’s elasticity. Material is adaptively distributed from high porosity at the bone-implant interface to solid metal at the joint’s articulating surface. The new acetabular prosthesis would replace metal-on-polyethylene bearing with metal-on-metal bearing for less wear. The design problem of acetabular component is formulated and a requirement list is elaborated. A detailed design of the prosthesis with a graded cellular structure is presented. The design concept is validated with a comparison to the existing products according to the design requirements.
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    Design of General Lattice Structures for Lightweight and Compliance Applications
    (Georgia Institute of Technology, 2006-07) Rosen, David W. ; Johnston, Scott R. ; Reed, Marques
    The primary goal is to design parts with lattice mesostructure and demonstrate that they have better structural and/or compliance performance, per weight, than parts with bulk material, foams, or other mesostructured approaches. Mesostructure refers to features within a part that have sizes between micro and macro-scales, for example, small truss structures, honeycombs, and foams. The versatility of additive manufacturing allows for the fabrication of these complex unit cell lattice structures which can be used as building blocks for macro-scale geometries. A method and software system have been developed to synthesize lattice mesostructure parts and compliant mechanisms in 2D and 3D. Underlying the synthesis method is a new analytical model of unit lattices, used to compose larger structures. Axial, bending, shearing, and torsion effects are included in the analysis for each strut in the lattice structure which is then related to the mesostructure level (unit cell). A unit lattice finite element analysis method allowing nonlinear deformation is employed to analyze a unit cell comprised of n[3] unit structures for their stiffness and displacement compared to their relative density under loading. Aerospace and biomedical applications are demonstrated.