Slotted Waveguide Stress Concentration Factor


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American Institute of Aeronautics and Astronautics


Sharp turns or corners within a structure lead to local failures well before the rest of the structure due to the creation of stress concentrations. For a load-bearing waveguide, these occur at the corners of the slots. After modeling a test waveguide, a bivariate curve fit was created to model these stress concentrations, based on four configurations for a single slot length, then refined into a trivariate form based on an expanded eight cases across two slot lengths. Once properly formatted, the integration of the bivariate function into an optimization allowed stress concentration to be estimated at the slot corners within a coarse low-fidelity model, rather than the high-fidelity model otherwise required, following the expected behavior and acting as a verification case. Implementation of the full trivariate form into a design optimization enabled use of the concentration factor to estimate the critical stress. The study showed that the inset copper waveguide could not be loaded from the outset, and that an offset of the copper waveguide could avoid overloading it.