Organizational Unit:
Daniel Guggenheim School of Aerospace Engineering
Daniel Guggenheim School of Aerospace Engineering
Permanent Link
Research Organization Registry ID
Description
Previous Names
Parent Organization
Parent Organization
Organizational Unit
Includes Organization(s)
Organizational Unit
Organizational Unit
Organizational Unit
Organizational Unit
Organizational Unit
ArchiveSpace Name Record
Publication Search Results
Now showing
1 - 5 of 5
-
ItemDesign and manufacturing of conformal ablative heatshields(Georgia Institute of Technology, 2019-06-10) Sidor, Adam ThomasConformal ablators, first introduced in the early 2000s under the NASA Hypersonics Project, are a type of rigid ablative thermal protection system that uses flexible, rather than rigid, fibrous substrates. These materials are impregnated with resin in a mold to yield a part that is close to the final geometry and requires little post-process machining (a near net shape part). The lack of fiber connectivity through the thickness enables the TPS to tolerate larger strains than comparable rigid substrate ablators facilitating larger tiles and installation on most aeroshells without strain isolation. Reduced part count and simplified integration drive reductions in labor, cost and complexity –advancements which are enabling for planetary and human missions. Conformal ablators are currently fabricated using an open liquid impregnation process adapted from a technique developed for Lightweight Ceramic Ablators, such as Phenolic Impregnated Carbon Ablator, which leads to design and manufacturing inefficiencies. This work advanced a new manufacturing technique for conformal ablators, vacuum infusion processing, that reduces resin consumption and streamlines clean up. The closed process also eliminates an expensive atmosphere-controlled oven or vacuum chamber. A design methodology, centered around a simulation of the mold filling process, was developed to tailor a conformal ablative heatshield to vacuum infusion processing. A constitutive model, combining properties of individual components, was formulated to estimate the properties of the composite TPS material. The methodology leverages this model, integrated with material selection, tile layout, and the mold filling simulation, to automate a conceptual conformal heatshield design. The approach allows rapid iteration on TPS composition and manufacturing constraints.
-
ItemMulti-physics high resolution topology optimization for aerospace structures(Georgia Institute of Technology, 2019-03-28) Chin, Ting WeiAdvancements in multimaterial additive manufacturing have the potential to enable the creation of topology optimized structures with both shape and material tailoring. These are extremely useful in creating designs for multi-physics applications where engineering experience may be lacking. These include designing aerospace structures that are subjected to elevated temperature environment, where mechanical and thermal loads are present or designing structures for strength and avoiding low natural frequency resonance. Multi-physics analysis and multimaterial design parametrization present additional complexity and technical challenges to overcome for large-scale designs. Design and analysis using large-scale uniform meshes is computationally expensive due to the large number of degrees of freedom (DOFs). The same mesh resolution can be created through adaptive mesh refinement such that it has fewer DOFs. However, due to the complexity in creating these adaptive meshes, especially for higher order 3D designs, they are mostly confined to 2D topology optimization. Large-scale multimaterial design through Discrete Material Optimization (DMO) also results in numerous partition of unity constraints and a multimaterial design space that has more local minima than an equivalent single material design space. This work presents new techniques for obtaining large-scale 3D multimaterial, multi-physics designs. Adaptive mesh refinement and higher order design parametrization are introduced to obtain smooth features. The multi-physics capabilities of the method are demonstration in the form of thermoelastic topology optimization. Multimaterial designs using adaptive mesh refinement as well as higher order design parametrization with steady-state thermoelastic topology optimization are presented. Novel technique to accelerate large-scale natural frequency-constrained topology optimization design is also presented.
-
ItemAdjoint-based aeroelastic optimization with high-fidelity time-accurate analysis(Georgia Institute of Technology, 2018-12-18) Jacobson, Kevin EdwardA methodology is proposed for adjoint-based sensitivities of steady and time-accurate aeroelastic analysis with high-fidelity models based on computational fluid dynamics and structural finite element modeling. The proposed methodology allows for aerodynamic, structural, and aeroelastic constraints to be formulated, and expressions for sensitivities with respect to aerodynamic, structural, and geometric design variables are derived and verified. Additionally, two types of explicit aeroelastic constraints are presented: flutter constraints based on the matrix pencil method and gust response constraints based on the field velocity method. Optimizations based on the proposed methodology and explicit aeroelastic constraints are demonstrated with two-dimensional and three-dimensional aerospace problems.
-
ItemRapid determination of mass and stiffness distribution on primary skin-stiffener structures(Georgia Institute of Technology, 2016-07-20) Noevere, August T.In modern conceptual/preliminary design of aerospace vehicles it is common for a large number of concepts and configurations to be rapidly explored. For each configuration, the structures discipline is responsible for determining an internal structural arrangement and detailed component design that minimizes mass while supporting external loads and other requirements. The proposed research presents a methodology suited for rapid design of structures which is capable of optimizing mass while easily meeting these requirements. Specifically, the methodology focuses on the stiffened panel optimization problem for metallic and composites. A change of variables is performed to allow accurate linearization of the design space, thereby greatly increasing optimization efficiency. The stiffened panel design space is recast in terms of equivalent smeared stiffness, using terms from the [ABD] stiffness matrix. This reformulation is enabled by the use of response surface equations to map the panel failure criteria (such as material failure, local buckling, etc.) to be a function of stiffness terms only. The resulting linear design space can be quickly optimized with the Simplex Algorithm. Thus, the approach is able to perform physics-based panel optimization with a level of efficiency appropriate for conceptual design studies. This approach is validated for a metallic and composite I-stiffened panel, as well as a composite laminate. Additionally, the methodology is demonstrated to couple well with the FEM-based design environment of a wing box for both metallic and composite construction. Overall, the methodology was shown to provide significant improvement in stiffened panel optimization efficiency over traditional tools while retaining accuracy within 10% of those tools.
-
ItemAeroelastic design of a lightweight distributed electric propulsion aircraft with flutter and strength requirements(Georgia Institute of Technology, 2015-04-24) An, SuiDistributed electric propulsion is a promising technology currently being considered for gen- eral aviation-class aircraft that has the potential to increase range and performance without sacrificing low-speed flight characteristics. However, the high-aspect ratio wings enabled by distributed electric propulsion make these designs more susceptible to adverse aeroe- lastic phenomena. This thesis describes the development of a gradient-based optimization framework for aircraft with distributed electric propulsion using structural and aeroelastic constraints. The governing equations for the coupled aeroelastic system form the basis of the static aeroelastic and flutter analysis. In this work, the Doublet-Lattice method is used to evaluate the aerodynamic forces exerted on the wing surface. In order to consider the impact of propeller-induced flow on aerodynamic loading, a one-way propeller-wing coupling is com- puted by superposition of the propeller induced velocity profile calculated using actuator disk theory and the wing flow field. The structural finite-element analysis is performed using the Toolkit for the Analysis of Composite Structures (TACS). The infinite-plate spline method is used to perform load and displacement transfer between the aerodynamic surface and the structural model. Instead of utilizing a conventional flutter analysis, the Jacobi-Davidson method is used to solve the governing eigenvalue problem without a reduction to the lowest structural modes, facilitating the evaluation of the gradient for design optimization. This framework is applied to different configurations with distributed electric propulsion to minimize structural weight subject to structural and aeroelastic constraints. The effect of flutter constraints, wing aspect ratio, and electric propeller quantity are compared through a series of design optimization studies. The results show that larger aspect ratio wings and more electric motors lead to heavier wings that are more susceptible to flutter. This framework can be used to develop lighter aircraft with distributed electric propulsion configuration that satisfy strength and flutter requirements.