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Schultz, Ryan

Publications and source records attributed to Schultz, Ryan.

At least 91 records · Page 5
All sourcesNASA NTRSDOE OSTI
DOE OSTI2019

Minimizing Transuranic Waste Generated in Hot Cells at Oak Ridge National Laboratory Through Use of a Non-Destructive CO2 Pellet Cleaning System

Wastes generated in shielded hot cells containing materials contaminated with transuranic (TRU) waste present unique problems in waste disposal at Department of Energy (DOE) sites. Reduction of the TRU waste footprint is desirable from a disposal cost perspective due to constraints with RH waste processing and a lack of space availability at the WIPP. Segregation of waste through a pelletized CO2 system provides a viable method this goal.

Ford, Mark↗
DOE OSTI2018

Using a Dynamic Substructuring Approach to Model the Effects of Acoustic Damping in Coupled Acoustic-Structure Systems

Acoustic-structure coupling can substantially alter the frequency response of air-filled structures. Coupling effects typically manifest as two resonance peaks at frequencies above and below the resonant frequency of the uncoupled structural system. In this study, a dynamic substrucuring approach is applied to a simple acoustic-structure system to expose how the system response depends on the damping in the acoustic subsystem. Parametric studies show that as acoustic damping is increased, the frequencies and amplitudes of the coupled resonances in the structural response undergo a sequence of changes. For low levels of acoustic damping, the two coupled resonances have amplitudes approximating the corresponding in vacuo resonance. As acoustic damping is increased, resonant amplitudes decrease dramatically while the frequency separation between the resonances tends to increase slightly. When acoustic damping is increased even further, the separation of the resonant frequencies decreases below their initial separation. Finally, at some critical value of acoustic damping, one of the resonances abruptly disappears, leaving just a single resonance. Counterintuitively, increasing acoustic damping beyond this point tends to increase the amplitude of the remaining resonance peak. Finally, these results have implications for analysts and experimentalists attempting to understand, mitigate, or otherwise compensate for the confounding effects of acoustic-structure coupling in fluid-filled test structures.

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DOE OSTI2018

Acoustoelasticity Testing: Changing Boundary Conditions and Damping

A series of modal tests were performed on an acoustoelastic system to explore how changes to the air and structural components affect the acoustoelastic coupling. This work is a continuation of previous experimental and analytical efforts. Here, the test method and perturbations were much more controlled than in previous tests, resulting in more refined data. Outputs of interest here are the coupled system modes as well as the resulting frequency response for various perturbations of the coupled system. Perturbations explored in this work include mass loading the structure, changing the air damping, and changing the air boundary conditions. Results of these tests indicate that simply adding damping to the air component, using foam or other absorptive material, is not sufficient to fully decouple the system. Rather, it is preferred to employ a change to the air boundary conditions, in the form of volume inclusions or scatterers, to prevent formation of the acoustic coupled mode.

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DOE OSTI2018

Modeling and Measurement of a Tunable Acoustoelastic System

Acoustoelastic coupling occurs when a hollow structure's in-vacuo mode aligns with an acoustic mode of the internal cavity. The impact of this coupling on the total dynamic response of the structure can be quite severe depending on the similarity of the modal frequencies and shapes. Typically, acoustoelastic coupling is not a design feature, but rather an unintended result that must be remedied as modal tests of structures are often used to correlate or validate finite element models of the uncoupled structure. Here, however, a test structure is intentionally designed such that multiple structural and acoustic modes are well-aligned, resulting in a coupled system that allows for an experimental investigation. First, coupling in the system is identified using a measure termed the magnification factor. Next, the structural-acoustic interaction is measured. Modifications to the system demonstrate the dependency of the coupling on changes in the mode shape and frequency proximity. This includes an investigation of several practical techniques used to decouple the system by altering the internal acoustic cavity, as well as the structure itself. These results show that acoustic absorption material effectively decoupled the structure while structural modifications, in their current form, proved unsuccessful. Readily available acoustic absorptive material was effective in reducing the coupled effects while presumably adding negligible mass or stiffness to the structure.

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