Dr. Hongfei Zhu Profile

Dr. Hongfei Zhu

at Purdue Univ

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Author

Publications (5)

Proceedings Article | 18 April 2022 Presentation + Paper

Electrode spacing-induced signal filtering for transient piezoresistivity

J. Hernandez, H. Zhu, F. Semperlotti, T. Tallman

Proceedings Volume 12046, 120460B (2022) https://doi.org/10.1117/12.2612903

KEYWORDS: Nanocomposites, Multifunctional materials, Electrodes, Structural health monitoring, Resistance, Composites, Sensors, Electronic filtering, Epoxies, Wave propagation

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Nanofiller-modified composites have shown much potential for structural health monitoring (SHM) and nondestructive evaluation (NDE) because they exhibit self-sensing behavior via the piezoresistive-effect. To date, the piezoresistive effect has been used predominantly in isolation for cases of (quasi-)static loading. There is a comparative lack of work that investigates the piezoresistive-effect under mechanically dynamic conditions. This is important because combined piezoresistive-elastodynamic approaches could leverage the relationship between electrode geometry/topology and piezoresistive information carried in elastic waves. In other words, the question of how certain factors of electrode design, such as spacing between electrode pairs, impacts the measured piezoresistive signal has been little explored within the context of elastodynamics. Addressing this gap in the state of the art may yield insights into multiphysics approaches to SHM and NDE which seamlessly marry conductivity and vibration-based techniques. To this end, a simple prismatic carbon nanofiber (CNF)-modified epoxy rod was manufactured. Piezoresistive measurements were taken as a function of time by way of normalized resistance measurements between surface mounted electrodes. An electromagnetic shaker was employed to inject highly controlled one-dimensional stress waves into the CNF-modified epoxy rod. It was found that surface mounted piezoresistive measurements were able to accurately reconstruct the profile of propagating subsurface wave packets across the length of the rod. Transmission and propagation of the wave packets were extrinsically validated with the shaker force sensor and an external laser vibrometer (LV) system, respectively. Furthermore, artificial signal filtering was achieved by changing the distance between the electrode pairs. Lastly, the dispersion curves were constructed from piezoresistive measurements and extrinsically validated. Results from this preliminary investigation seeks to lay the foundational work for a new multiphysics SHM tool, piezoresistivity-coupled elastodynamics, that aims to provide an unparalleled level of understanding into material dynamic properties from direct electrical interrogation.

Proceedings Article | 18 April 2022 Presentation

Vibration analysis of a pre-strained shape memory alloy beam

Qianlong Zhang, Hongfei Zhu, Fabio Semperlotti

Proceedings Volume PC12046, PC120460C (2022) https://doi.org/10.1117/12.2612262

KEYWORDS: Shape memory alloys, Vibrometry, Beam shaping, Vibration control, Temperature metrology, Structured optical fibers, Structural engineering, Signal attenuation, Finite element methods, Complex systems

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Proceedings Article | 1 April 2016 Paper

Anomalous refraction of guided waves via embedded acoustic metasurfaces

Hongfei Zhu, Fabio Semperlotti

Proceedings Volume 9805, 98051F (2016) https://doi.org/10.1117/12.2218915

KEYWORDS: Refraction, Acoustics, Waveguides, Wavefronts, Solids, Phase shifts, Numerical simulations, Structural engineering, Wave propagation, Interfaces, Aluminum

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Proceedings Article | 27 March 2015 Paper

Design of embedded acoustic lenses in plate-like structures based on periodic acoustic black holes

Hongfei Zhu, Fabio Semperlotti

Proceedings Volume 9435, 94350K (2015) https://doi.org/10.1117/12.2084245

KEYWORDS: Acoustics, Phase velocity, Metamaterials, Wave propagation, Lenses, Collimation, Wave plates, Dispersion, Ultrasonics, Wavefronts

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Proceedings Article | 8 March 2014 Paper

A passively tunable acoustic metamaterial lens for damage detection applications

H. Zhu, F. Semperlotti

Proceedings Volume 9061, 906107 (2014) https://doi.org/10.1117/12.2045531

KEYWORDS: Acoustics, Metamaterials, Ultrasonics, Lens design, Wave propagation, Waveguides, Transducers, Damage detection, Finite-difference time-domain method, Aluminum

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