Nonlinear wave dynamics of continuum phononic materials with periodic rough contacts

Controlling mechanical wave propagation is crucial for addressing technological and environmental challenges. These include preventing the vibration-induced structural failure of civil and energy infrastructure, enhancing noise-cancellation and imaging technologies, and developing novel acoustic devices for protective gears and nondestructive evaluation. Phononic materials, which are engineered materials with periodic building blocks, exhibit wave characteristics superior to that of traditional materials and therefore have the potential to revolutionize our ability to control waves. However, the current understanding of their functionality is primarily limited to the linear regime, despite the prevalent occurrence of large deformations and nonlinear mechanical responses in real-world materials. Recent research has explored the nonlinear behavior of phononic materials through granular crystals and soft metamaterials, extending the analysis beyond the linear regime. However, these studies primarily examined either discrete nonlinearity in the form of spring-mass chains or continuous nonlinearities in continuous periodic materials. Consequently, there remains an open fundamental question of how waves propagate in continuum phononic materials with discrete (or local) nonlinearities. Addressing this question may reveal new opportunities to control the global nonlinear wave response of phononic materials via local nonlinearities and discrete-continuum coupling. This dissertation introduces and investigates nonlinear continuum phononic materials featuring geomaterial microstructures, particularly, micro-cracks as local nonlinearities. The nondestructive evaluation of geomaterials has shown that micro-cracks display highly nonlinear responses because of rough features on their contacting surfaces, known as rough contacts. Despite their rich nonlinear responses, rough contacts have not yet been explored in the context of engineered periodic media. Thus, this research develops a fundamental understanding of (1) the influence of the periodic arrangement of rough contacts on wave propagation and (2) the role of local contact nonlinearity between successive continuum layers in shaping nonlinear wave responses. To achieve this, extensive numerical analyses were conducted to study wave responses in these phononic materials for varying levels of contact nonlinearity, from weak to strong, including friction. Additionally, pilot experimental studies of acoustic characterization of base materials and ultrasonic wave propagation through rough contact have been conducted, which serves as a foundation for the future realization of these materials. The research reveals atypical wave signatures with no analogs in linear theory and provides insight into the underlying physics behind their emergence. Specifically, the study reports energy transfer between frequencies through harmonic generation, self-demodulation, and wave mixing, propagation of localized traveling waves in the form of stegotons, energy localization through acoustic resonances, and generation of eigenstrains from memory-dependent responses. These properties are further exploited to demonstrate novel wave propagation control via tunable vibration filtering, tunable spectral energy transfer, broadband nonreciprocal wave propagation, adaptive energy absorption, compact energy propagation, and acoustically-governed programmability, and surface reconfigurability. Preliminary measurements suggest that complex mechanisms at rough contacts such as nonlinear normal force-displacement relationship due to asperity deformation, and eigenstrain generation and energy dissipation due to interface sliding in a physical system may be captured through ultrasonic measurements. Overall, this dissertation offers a new perspective on the potential of nonlinear continuum phononic materials with local nonlinearity for wave control and manipulation, which could have significant implications for enhancing structural integrity and innovations in acoustic technology.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Mechanical Engineering

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2023

Author dc:creator

• Patil, Ganesh U.

Contributors dc:contributor

• Matlack, Kathryn H
• Vakakis, Alexander F
• Dunn, Alison C
• Elbanna, Ahmed

• Nonlinear Waves
• Phononic Materials
• Contact Nonlinearity
• Rough Contacts
• Friction
• Phononic Crystals
• Metamaterials
• Hysteresis
• Solitary Waves
• Nonreciprocity
• Band Gaps
• Wave Mixing
• Resonances
• Programmability
• Wave Propagation
• Periodic Materials
• Contact Clapping
• Contact Sliding
• Wave Dynamics
• Stegotons
• Eigenstrains

Statement dc:rights

• Copyright 2023 Ganesh Patil

Language dc:language

en, eng

Handle dc:identifier

https://hdl.handle.net/2142/121942

OAI record oai:identifier

https://www.ideals.illinois.edu/oai-pmh?verb=GetRecord&metadataPrefix=etdms&identifier=oai%3Awww.ideals.illinois.edu%3A2142%2F121942