Student Name: Silvia Caggese

Advisor: Dr. Dimitri Mavris

Milestone: MS Thesis Final Examination (Defense)

Degree Program: Aerospace Engineering

Title: A Continuous Engine Attachment Methodology for Gradient-Based Aerostructural Optimization, with Application to the Athena Wing

Abstract: Unconventional aircraft configurations, such as the Athena developed by the Aerospace Systems Design Laboratory for the NASA AACES 2050 initiative, have few or no previous designs to guide the engine position, which must therefore be searched together with the structural sizing. Gradient-based optimization with adjoint derivatives is suited to this search, but it requires the engine position to be a continuous design variable, while finite-element models of the wing usually attach the engine through rigid elements to a fixed set of nodes. This thesis develops a continuous engine attachment for gradient-based aerostructural optimization, and uses it to study the structural trade-offs of engine placement on the Athena wing. The proposed sliding kernel attachment is based on the linearized MELD transfer scheme. A smooth spanwise weighting function moves the engine load with the engine and shares it among the rib corners of the pylon strip, conserving force, moment and virtual work. Its derivatives with respect to the engine coordinates are combined with the adjoint sensitivities of the coupled analysis, assembled in OpenMDAO with TACS and a vortex lattice method, so that the engine coordinates become design variables together with the structural sizing. The attachment is verified on the Simple Transonic Wing benchmark. Force, moment and virtual work are conserved to machine precision, the outputs vary continuously with the engine position, and the total derivatives agree with finite differences within 1.6 × 10⁻⁶. For engine positions aligned with a rib station, the results match those of an RBE3 attachment within 0.2% for the global quantities and 1.4% for the local failure index. A structural optimization with the engine position as a design variable reaches the same wingbox mass within 0.004% from different starting points, but without other trade-offs it moves the engine close to the tip. The framework is then applied to the Athena wing, in a structural and in an aerostructural optimization. The pylon weight, the vertical tail required with one engine inoperative, and the interference drag between nacelle and wing are included as penalties in the objective.

Date and time: 2026-11-18, 10:00 AM - 12:00 PM

Location: Collaborative Visualization Environment (CoVE) Weber Space Science and Technology Building (SST II)

Committee:
Dr. Dimitri Mavris (advisor), School of Aerospace Engineering
Dr. Graeme J. Kennedy, School of Aerospace Engineering
Dr. Christian Perron, School of Aerospace Engineering
Dr. Heriberto David Solano Sarmiento, School of Aerospace Engineering
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