11/09/2026
By Thomas Dugan

The Francis College of Engineering, Department of Mechanical Engineering, invites you to attend a master’s thesis defense by Willoughby Kahalin Cheney, titled “High-Efficiency Reduced-Order Models of Microstructured Media with Edge Dynamics.”

Details

  • Date: Thursday, Nov. 19, 2026
  • Time: 10 a.m. – noon
  • Location: Falmouth 311
  • Virtual: Zoom meeting - meeting ID: 995 3745 9190

Committee members

  • Alireza V. Amirkhizi, Advisor, Professor, Mechanical Engineering, UMass Lowell
  • Scott E. Stapleton, Professor, Mechanical Engineering, UMass Lowell
  • Reza Abedi, Associate Professor, Mechanical Engineering, University of Tennessee Space Institute
  • Weidi Wang, Adjunct Professor, Mechanical Engineering, UMass Lowell

Abstract

Cellular resonator-based mechanical metamaterials can be used to create microstructured media that interact efficiently with stress waves. However, modeling finite arrays of these structures in the time domain can be computationally intensive when standard finite element analysis is used, because each cell must be represented with sufficient detail and resolution.

This thesis develops a reduced-order model that replaces mechanical resonators with effective discrete inertial and structural elements. The model is compared with a continuum model using standard finite element analysis. The research demonstrates that reduced-order-model accuracy in the time domain depends in part on the boundary effects introduced between the monolithic and metamaterial regions.

To address these edge dynamics and improve the model’s performance, the parameters of the exterior cells are modified using a genetic algorithm while the interior-cell parameters remain unchanged. This approach significantly improves the model’s ability to represent the behavior of the systems under study. The results show that separating the dynamics of exterior and interior reduced-order-model cells can support rapid, high-accuracy analysis of arrays with different dimensions and loading histories.

The research also develops a frequency-domain reduced-order model and compares it with a corresponding continuum model. By optimizing the exterior cells to improve the scattering response, the study obtains generalized reduced-order-model properties that can be applied to finite arrays. These boundary-cell optimizations provide physical insight into the rapid analysis of finite metamaterial arrays and support more efficient modeling and design of complex systems, including graded metamaterial structures.