A new theory of slow dynamics: Mechanistic diffusion model

Document Type

Article

Publication Date

12-2-2020

Department

Department of Engineering Fundamentals

Abstract

Wave propagation through damaged heterogeneous materials (e.g., stone, cement, metals) elicits a broad range of physical behaviors, which includes a transient nonlinear modulus softening known as slow dynamics. Slow dynamic behaviors may provide new capability for identifying the presence of damage in materials that are traditionally difficult to inspect. Yet, to date, no verified physical justification for the presence of slow dynamic behavior exists and no single model accounts for all experimental observations. In this work, we propose a new theory for slow dynamic behaviors based on a mechanistic multi-physics diffusion model, and we evaluate the theory using a new experiment. Our results demonstrate that the new theory provides a physical mechanism for slow dynamic behaviors that aligns well with existing experimental observations, and the experiment enables measurement of a new physical quantity that correlates with transient nonlinear modulus softening. These results can be used to create new techniques of measuring slow dynamics for improved detection of damage in heterogeneous materials.

Publication Title

The Journal of the Acoustical Society of America

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