Sourav Banerjee - Academia.edu (original) (raw)

Papers by Sourav Banerjee

Journal of Composites Science

It is always challenging to provide appropriate material properties for a composite progressive f... more It is always challenging to provide appropriate material properties for a composite progressive failure model. The nonstandard percentage reduction method that is commonly used to degrade the material constants with micro-scale defects generates tremendous uncertainty in failure prediction. The constitutive matrix is composed of multiple material constants. It is not necessary that all constants degrade either equally or linearly due to a certain state of material defects. With this very concern in mind, this article presents a guideline for using a quantified perturbation for each coefficient appropriately. It also presents distribution of effective material properties (EMPs) in unidirectional composite materials with different states of defects such as voids. Irrespective of resin transfer molding (RTM) or chemical vapor infiltration (CVI) processes, manufacturers’ defects such as voids of different shapes and sizes are the most common that occur in composite materials. Hence, it ...

SPIE Proceedings, 2017

Primary objective of the work is to design, fabrication and testing of a 3-dimensional Mechanical... more Primary objective of the work is to design, fabrication and testing of a 3-dimensional Mechanical vibration test bed. Vibration testing of engineering prototype devices in mechanical and industrial laboratories is essential to understand the response of the envisioned model under physical excitation conditions. Typically, two sorts of vibration sources are available in physical environment, acoustical and mechanical. Traditionally, test bed to simulate unidirectional acoustic or mechanical vibration is used in engineering laboratories. However, a device may encounter multiple uncoupled and/or coupled loading conditions. Hence, a comprehensive test bed in essential that can simulate all possible sorts of vibration conditions. In this article, an electrodynamic vibration exciter is presented which is capable of simulating 3-dimensional uncoupled (unidirectional) and coupled excitation, in mechanical environments. The proposed model consists of three electromagnetic shakers (for mechanical excitation). A robust electrical control circuit is designed to regulate the components of the test bed through a self-developed Graphical User Interface. Finally, performance of the test bed is tested and validated using commercially available piezoelectric sensors.

Directional guiding, passing or stopping of elastic waves through engineered materials have many ... more Directional guiding, passing or stopping of elastic waves through engineered materials have many applications to the engineering fields. Recently, such engineered composite materials received great attention by the broader research community. In elastic waves, the longitudinal and transverse motion of material particles are coupled, which exhibits richer physics and demands greater attention than electromagnetic waves and acoustic waves in fluids. Waves in periodic media exhibit the property of Bragg scattering and create frequency band gaps in which the energy propagation is prohibited. However, in addition to the Bragg scattering, it has been found that local resonance of artificially designed resonators can also play a critical role in the generation of low-frequency band gaps. It has been found that negative effective mass density and negative effective elastic modulus are created by virtue of the local resonators and are correlated with the creation of the frequency band gaps that can be artificially perturbed. In this paper, the authors present a novel anisotropic design of metamaterial using local split-ring resonators of multiple-length scales. Unlike traditional metamaterials, multiple split rings of different dimensions are embedded in a polymer matrix. Considering the complexity of the proposed material, it is extremely difficult to find the dynamic response of the material using analytical methods. Thus, a numerical simulation was performed in order to find frequency band gaps. Simultaneously, correlation between the band gaps and negative effective mass density and negative effective elastic modulus was verified. Both unidirectional split rings and bidirectional chiral split rings were studied. The effects of discontinuity in the rings at larger scales were compared with the dynamic characteristics of full rings in the proposed metamaterial. Application of such metamaterials will be primarily for vibration isolation and impact mitigation of structures. The proposed configuration is based on unit dimension and is, thus, dimensionless. The concept can be easily commutable between macro-scale structures for low-frequency applications and micro-scale MEMS devices for high-frequency applications.

Journal of Composites Science

Material properties at the vicinity of the cut-outs in composites are not entirely defect-free. T... more Material properties at the vicinity of the cut-outs in composites are not entirely defect-free. The nteraction of multiple cutouts like rivet holes, the repercussion of their configuration on crack propagation, and ultimate strength were predicted using Peridynamic method and the results are reported in this article. The effect of microscale defects at the vicinity of the cutouts on macroscale damage propagation were shown to have quantifiable manifestation. This study focused on two to four holes in unidirectional composite plates with 0°, 45°, and 90° fiber directions, while the vicinity of a hole was considered degraded. Numerical results were validated using quantitative ultrasonic image correlation (QUIC) and the tensile test. Both the experimental and numerical results confirmed that the strength of the horizontal configuration is higher than the vertical in the plates with two holes. Furthermore, the square configuration was found to be stronger than the diamond configuration...

International Journal of Solids and Structures, 2006

The Journal of the Acoustical Society of America, 2006

The Journal of the Acoustical Society of America, 2006

International Journal of Solids and Structures, 2007

Distributed Point Source Method (DPSM) is a semi-analytical technique that can be used to calcula... more Distributed Point Source Method (DPSM) is a semi-analytical technique that can be used to calculate the ultrasonic field (pressure, velocity and displacement fields in a fluid, or stress and displacement fields in a solid) generated by ultrasonic transducers. So far the technique has been used to model ultrasonic fields in homogeneous and multilayered fluid structures, and near a fluid-solid interface when a solid half-space is immersed in a fluid. In this paper, the method is extended to model the ultrasonic field generated in a homogeneous isotropic solid plate immersed in a fluid. The objective of this study is to model the generation of guided waves in a solid plate when ultrasonic beams from transducers of finite dimension strike the plate at different critical angles. DPSM results for a solid half-space problem are compared with the finite element predictions to show the superiority of the DPSM technique. The predicted results are also compared with the experimental visualization of the mode patterns of Lamb waves propagating in a glass plate obtained from stroboscopic photoelastic method. Experimental and theoretical results show good qualitative agreement. The DPSM technique is then applied to study the mode patterns in aluminum plates immersed in water.

Sensors

Surface acoustic waves (SAWs) are the guided waves that propagate along the top surface of a mate... more Surface acoustic waves (SAWs) are the guided waves that propagate along the top surface of a material with wave vectors orthogonal to the normal direction to the surface. Based on these waves, SAW sensors are conceptualized by employing piezoelectric crystals where the guided elastodynamic waves are generated through an electromechanical coupling. Electromechanical coupling in both active and passive modes is achieved by integrating interdigitated electrode transducers (IDT) with the piezoelectric crystals. Innovative meta-designs of the periodic IDTs define the functionality and application of SAW sensors. This review article presents the physics of guided surface acoustic waves and the piezoelectric materials used for designing SAW sensors. Then, how the piezoelectric materials and cuts could alter the functionality of the sensors is explained. The article summarizes a few key configurations of the electrodes and respective guidelines for generating different guided wave patterns ...

Sensors

The effect of a self-pulsing non-equilibrium plasma discharge on piezoelectric PVDF nanofiber mem... more The effect of a self-pulsing non-equilibrium plasma discharge on piezoelectric PVDF nanofiber membrane was investigated. The plasma discharge was generated in air with a DC power source, with a discharge current of 0.012 mA, a nominal interelectrode separation of 1 mm, and discharge voltage of ~970 V. In a continuous fabrication process, the electrospinning method was used to generate thin nanofiber membrane with a flow rate of 0.7–1 mL h−1 and 25–27 kV voltage to obtain the nanofiber with high sensitivity and a higher degree of alignment and uniformity over a larger area. Plasma treatment was applied on both single layer and multi-layer (three layers) nanomembranes. In addition, simultaneously, the nanofiber membranes were heat-treated at a glass transition temperature (80–120 °C) and then underwent plasma treatment. Fourier-transform infrared (FTIR) spectroscopy showed that the area under the curve at 840 and 1272 cm−1 (β phase) increased due to the application of plasma and diffe...

Crystals

Simultaneous occurrence of Dirac-like cones at the center of the Brillouin zone (Г) at two differ... more Simultaneous occurrence of Dirac-like cones at the center of the Brillouin zone (Г) at two different energy states is termed Dual-Dirac-like cones (DDC) in this article. The occurrence of DDC is a rare phenomenon. Thus, the generation of multiple Dirac-like cones at the center of the Brillouin zone is usually non-manipulative and poses a challenge to achieve through traditional accidental degeneracy. However, if predictively created, DDC will have multiple engineering applications with acoustics and vibration. Thus, the possibilities of creating DDC have been identified herein using a simple square periodic array of tunable square phononic crystals (PnCs) in air media. It was found that antisymmetric deaf bands may play critical roles in tracking the DDC. Hence, pivoting on the deaf bands at two different energy states, an optimized tuning parameter was found to achieve Dirac-like cones at two distinct frequency states, simultaneously. Orthogonal wave transport identified as key Dir...

After an initial reduction, the composite strength undergoes a dormant state that builds up insid... more After an initial reduction, the composite strength undergoes a dormant state that builds up inside the material, we call material memory. At that stage the distributed damage accumulates at the intrinsic length scales. However, such state does not affect the global strength of the materials. There is no experimental tool that can quantify such material state. Here, we introduce a precursor to damage quantifi cation technique by bridging the gap between multiscale modeling and multiscale sensing. We propose a recently developed parameter called “damage entropy”. It is derived from the understanding of micromorphic behavior of materials where deformation is expressed as sum of macroscopic continuous deformation and internal microscopic deformation. The characteristic length scale evolves during the fatigue life of the composite and their progressive infl uence changes in a quantifi ed sense thus increase the entropy. We obtained the quantifi ed entropy using quantitative ultrasonic im...

Energy harvesters primarily depend on on a groups of unit cells to harvest energy at broadband fr... more Energy harvesters primarily depend on on a groups of unit cells to harvest energy at broadband frequencies so that each unit cell is responsible to harvest energy at a distinct frequency. Other design complexity, space, and financial profusion are required for transferring from unit-frequency to multi-frequency energy scavenging. Also, it is very unlikely to obtain expected power output if the available vibration source doesn’t match the designed loading condition (usually, unidirectional) of the device and requires rearrangement of the base structure to have projected output. In this paper we model the unique feature of acoustic metamaterial (AM), which is not only able to harvest energy at multiple frequencies using only a unit cell device, but also able to harvest energy under a variety of uncoupled (unidirectional) and coupled (multi-directional) vibration environments with an identical base structure arrangement.

Sensors (Basel, Switzerland), 2021

The effect of a self-pulsing non-equilibrium plasma discharge on piezoelectric PVDF nanofiber mem... more The effect of a self-pulsing non-equilibrium plasma discharge on piezoelectric PVDF nanofiber membrane was investigated. The plasma discharge was generated in air with a DC power source, with a discharge current of 0.012 mA, a nominal interelectrode separation of 1 mm, and discharge voltage of ~970 V. In a continuous fabrication process, the electrospinning method was used to generate thin nanofiber membrane with a flow rate of 0.7–1 mL h−1 and 25–27 kV voltage to obtain the nanofiber with high sensitivity and a higher degree of alignment and uniformity over a larger area. Plasma treatment was applied on both single layer and multi-layer (three layers) nanomembranes. In addition, simultaneously, the nanofiber membranes were heat-treated at a glass transition temperature (80–120 °C) and then underwent plasma treatment. Fourier-transform infrared (FTIR) spectroscopy showed that the area under the curve at 840 and 1272 cm−1 (β phase) increased due to the application of plasma and diffe...

In spite of many studies concerning the potential of auditory nerve actions, the timing of neural... more In spite of many studies concerning the potential of auditory nerve actions, the timing of neural excitation in relation to basilar membrane motion is still not well understood. In this study, therefore, a Piezoelectric Artificial Basilar Membrane (PABM) is fabricated using Denton Explorer evaporator. The proposed dynamical system is made of polyvinylidene fluoride membrane on which 40 chromium electrodes were deposited with thickness close to 104 Å. The PABM sensor was tested with variable engineering parameters that contribute to its frequency selection capabilities. To characterize the frequency selectivity of the PABM, mechanical displacements were measured using a very precise high-resolution data acquisition board. When electrical and acoustic stimuli were applied, the measured resonance frequencies were in the ranges of 600to2000. These results demonstrate that the mechanical frequency selectivity of this PABM is close to the human communication frequency range (300–3000 Hz),...

Inception of damage quantification during fatigue loading has been a challenge in the field of st... more Inception of damage quantification during fatigue loading has been a challenge in the field of structural health monitoring (SHM). Interaction between intrinsic damage state and ultrasonic wave signals of composite material is not fully understood. Fiber reinforced composite materials unveils damage precursor in the form of micro crack in matrix and fiber fracture which leads to catastrophic failure of the structure. Here, in this paper tensile-tensile fatigue tests were performed on two different types of ASTM standard composite specimen. For carbon fiber reinforced composite (CFRP) specimens at a regular interval of 10,000 cycles and for glass fiber reinforced composite (GFRP) interrogation of material state during fatigue tests were performed at the interval of 1,000 cycles, until micro cracks are developed. Quantitative Ultrasonic Microscopy is performed during the same intervals. For the Carbon-Carbon composites, the non-local material properties degraded continuously during fa...

Journal of Nondestructive Evaluation, Diagnostics and Prognostics of Engineering Systems

The understanding of strength recovery behavior under a dynamic loading environment provides a gu... more The understanding of strength recovery behavior under a dynamic loading environment provides a guidance for optimizing the design of composite structures for in-service applications. Although established for metals, the quantification of strength recovery in carbon fiber-reinforced viscoelastic composites is still an area under active research. This study aims to understand the effects of fatigue loading rates on the damage behaviors of stress-relaxed carbon fiber-based composites. Hence, the time-dependent strength recovery in woven composites is quantified experimentally using two mutually exclusive approaches under identical fatigue loading environments. In the first approach, the strength recovery is quantified by the dissipated non-linearity in Lamb wave propagation due to the damage state of the composite materials. This is quantified and shown coupled with second- and third-order non-linear parameters. In the second approach, ultrasonic acoustic pressure waves are utilized to...

Applied Sciences

In this paper, a novel method to quantify the incubation of damage on piezoelectric crystal is pr... more In this paper, a novel method to quantify the incubation of damage on piezoelectric crystal is presented. An intrinsic length scale parameter obtained from nonlocal field theory is used as a novel measure for quantification of damage precursor. Features such as amplitude decay, attenuation, frequency shifts and higher harmonics of guided waves are commonly-used damage features. Quantification of the precursors to damage by considering the mentioned features in a single framework is a difficult proposition. Therefore, a nonlocal field theory is formulated and a nonlocal damage index is proposed. The underlying idea of the paper is that inception of the damage at the micro scale manifests the evolution of damage at the macro scale. In this paper, we proposed a nonlocal field theory, which can efficiently quantify the inception of damage on piezoelectric crystals. The strength of the method is demonstrated by employing the surface acoustic waves (SAWs) and longitudinal bulk waves in Li...

IEEE/ASME Transactions on Mechatronics

A high percentage of failures in sensors and devices employed in harsh industrial environments an... more A high percentage of failures in sensors and devices employed in harsh industrial environments and airborne electronics is due to mechanical vibrations and shocks. Therefore, it is of paramount importance to test equipment reliability and ensure its survival in long missions in the presence of physical fluctuations. Traditional vibration testbeds employ unidirectional acoustic or mechanical excitations. However, in reality, equipment may encounter uncoupled (unidirectional) and/or coupled (multidirectional) loading conditions during operation. Hence, to systematically characterize and fully understand equipment's behavior, a testbed capable of simulating a wide variety of vibration conditions is required. The primary objective of this study is design, fabrication, and testing of an acousto electrodynamic three-dimensional (3-D) vibration exciter (AEVE 3-D), which simulates coupled and decoupled (with unpowered arms) 3-D acoustic and/or 3-D mechanical vibration environments. AEVE 3-D consists of three electromagnetic shakers (for mechanical excitation) and three loud speakers (for acoustic excitation) as well as a main control unit that accurately calculates and sets the actuators’ input signals in order to generate optimal coupled and decoupled vibrations at desired frequencies. In this paper, the system's architecture, its mechanical structure, and electrical components are described. In addition, to verify AEVE 3-D's performance, various experiments are carried out using a 3-D piezoelectric energy harvester and a custom-made piezoelectric beam.

Structural Health Monitoring

In this article, experimental verification and validation of a peridynamics-based simulation tech... more In this article, experimental verification and validation of a peridynamics-based simulation technique, called peri-elastodynamics, are presented while simulating the guided Lamb wave propagation and wave–damage interaction for ultrasonic nondestructive evaluation and structural health monitoring applications. Peri-elastodynamics is a recently developed elastodynamic computation tool where material particles are assumed to interact with the neighboring particles nonlocally, distributed within an influence zone. First, in this article, peri-elastodynamics was used to simulate the Lamb wave modes and their interactions with the damages in a three-dimensional plate-like structure, while the accuracy and the efficacy of the method were verified using the finite element simulation method (FEM). Next, the peri-elastodynamics results were validated with the experimental results, which showed that the newly developed method is more accurate and computationally cheaper than the FEM to be use...

Journal of Composites Science

It is always challenging to provide appropriate material properties for a composite progressive f... more It is always challenging to provide appropriate material properties for a composite progressive failure model. The nonstandard percentage reduction method that is commonly used to degrade the material constants with micro-scale defects generates tremendous uncertainty in failure prediction. The constitutive matrix is composed of multiple material constants. It is not necessary that all constants degrade either equally or linearly due to a certain state of material defects. With this very concern in mind, this article presents a guideline for using a quantified perturbation for each coefficient appropriately. It also presents distribution of effective material properties (EMPs) in unidirectional composite materials with different states of defects such as voids. Irrespective of resin transfer molding (RTM) or chemical vapor infiltration (CVI) processes, manufacturers’ defects such as voids of different shapes and sizes are the most common that occur in composite materials. Hence, it ...

SPIE Proceedings, 2017

Primary objective of the work is to design, fabrication and testing of a 3-dimensional Mechanical... more Primary objective of the work is to design, fabrication and testing of a 3-dimensional Mechanical vibration test bed. Vibration testing of engineering prototype devices in mechanical and industrial laboratories is essential to understand the response of the envisioned model under physical excitation conditions. Typically, two sorts of vibration sources are available in physical environment, acoustical and mechanical. Traditionally, test bed to simulate unidirectional acoustic or mechanical vibration is used in engineering laboratories. However, a device may encounter multiple uncoupled and/or coupled loading conditions. Hence, a comprehensive test bed in essential that can simulate all possible sorts of vibration conditions. In this article, an electrodynamic vibration exciter is presented which is capable of simulating 3-dimensional uncoupled (unidirectional) and coupled excitation, in mechanical environments. The proposed model consists of three electromagnetic shakers (for mechanical excitation). A robust electrical control circuit is designed to regulate the components of the test bed through a self-developed Graphical User Interface. Finally, performance of the test bed is tested and validated using commercially available piezoelectric sensors.

Directional guiding, passing or stopping of elastic waves through engineered materials have many ... more Directional guiding, passing or stopping of elastic waves through engineered materials have many applications to the engineering fields. Recently, such engineered composite materials received great attention by the broader research community. In elastic waves, the longitudinal and transverse motion of material particles are coupled, which exhibits richer physics and demands greater attention than electromagnetic waves and acoustic waves in fluids. Waves in periodic media exhibit the property of Bragg scattering and create frequency band gaps in which the energy propagation is prohibited. However, in addition to the Bragg scattering, it has been found that local resonance of artificially designed resonators can also play a critical role in the generation of low-frequency band gaps. It has been found that negative effective mass density and negative effective elastic modulus are created by virtue of the local resonators and are correlated with the creation of the frequency band gaps that can be artificially perturbed. In this paper, the authors present a novel anisotropic design of metamaterial using local split-ring resonators of multiple-length scales. Unlike traditional metamaterials, multiple split rings of different dimensions are embedded in a polymer matrix. Considering the complexity of the proposed material, it is extremely difficult to find the dynamic response of the material using analytical methods. Thus, a numerical simulation was performed in order to find frequency band gaps. Simultaneously, correlation between the band gaps and negative effective mass density and negative effective elastic modulus was verified. Both unidirectional split rings and bidirectional chiral split rings were studied. The effects of discontinuity in the rings at larger scales were compared with the dynamic characteristics of full rings in the proposed metamaterial. Application of such metamaterials will be primarily for vibration isolation and impact mitigation of structures. The proposed configuration is based on unit dimension and is, thus, dimensionless. The concept can be easily commutable between macro-scale structures for low-frequency applications and micro-scale MEMS devices for high-frequency applications.

Journal of Composites Science

Material properties at the vicinity of the cut-outs in composites are not entirely defect-free. T... more Material properties at the vicinity of the cut-outs in composites are not entirely defect-free. The nteraction of multiple cutouts like rivet holes, the repercussion of their configuration on crack propagation, and ultimate strength were predicted using Peridynamic method and the results are reported in this article. The effect of microscale defects at the vicinity of the cutouts on macroscale damage propagation were shown to have quantifiable manifestation. This study focused on two to four holes in unidirectional composite plates with 0°, 45°, and 90° fiber directions, while the vicinity of a hole was considered degraded. Numerical results were validated using quantitative ultrasonic image correlation (QUIC) and the tensile test. Both the experimental and numerical results confirmed that the strength of the horizontal configuration is higher than the vertical in the plates with two holes. Furthermore, the square configuration was found to be stronger than the diamond configuration...

International Journal of Solids and Structures, 2006

The Journal of the Acoustical Society of America, 2006

The Journal of the Acoustical Society of America, 2006

International Journal of Solids and Structures, 2007

Distributed Point Source Method (DPSM) is a semi-analytical technique that can be used to calcula... more Distributed Point Source Method (DPSM) is a semi-analytical technique that can be used to calculate the ultrasonic field (pressure, velocity and displacement fields in a fluid, or stress and displacement fields in a solid) generated by ultrasonic transducers. So far the technique has been used to model ultrasonic fields in homogeneous and multilayered fluid structures, and near a fluid-solid interface when a solid half-space is immersed in a fluid. In this paper, the method is extended to model the ultrasonic field generated in a homogeneous isotropic solid plate immersed in a fluid. The objective of this study is to model the generation of guided waves in a solid plate when ultrasonic beams from transducers of finite dimension strike the plate at different critical angles. DPSM results for a solid half-space problem are compared with the finite element predictions to show the superiority of the DPSM technique. The predicted results are also compared with the experimental visualization of the mode patterns of Lamb waves propagating in a glass plate obtained from stroboscopic photoelastic method. Experimental and theoretical results show good qualitative agreement. The DPSM technique is then applied to study the mode patterns in aluminum plates immersed in water.

Sensors

Surface acoustic waves (SAWs) are the guided waves that propagate along the top surface of a mate... more Surface acoustic waves (SAWs) are the guided waves that propagate along the top surface of a material with wave vectors orthogonal to the normal direction to the surface. Based on these waves, SAW sensors are conceptualized by employing piezoelectric crystals where the guided elastodynamic waves are generated through an electromechanical coupling. Electromechanical coupling in both active and passive modes is achieved by integrating interdigitated electrode transducers (IDT) with the piezoelectric crystals. Innovative meta-designs of the periodic IDTs define the functionality and application of SAW sensors. This review article presents the physics of guided surface acoustic waves and the piezoelectric materials used for designing SAW sensors. Then, how the piezoelectric materials and cuts could alter the functionality of the sensors is explained. The article summarizes a few key configurations of the electrodes and respective guidelines for generating different guided wave patterns ...

Sensors

The effect of a self-pulsing non-equilibrium plasma discharge on piezoelectric PVDF nanofiber mem... more The effect of a self-pulsing non-equilibrium plasma discharge on piezoelectric PVDF nanofiber membrane was investigated. The plasma discharge was generated in air with a DC power source, with a discharge current of 0.012 mA, a nominal interelectrode separation of 1 mm, and discharge voltage of ~970 V. In a continuous fabrication process, the electrospinning method was used to generate thin nanofiber membrane with a flow rate of 0.7–1 mL h−1 and 25–27 kV voltage to obtain the nanofiber with high sensitivity and a higher degree of alignment and uniformity over a larger area. Plasma treatment was applied on both single layer and multi-layer (three layers) nanomembranes. In addition, simultaneously, the nanofiber membranes were heat-treated at a glass transition temperature (80–120 °C) and then underwent plasma treatment. Fourier-transform infrared (FTIR) spectroscopy showed that the area under the curve at 840 and 1272 cm−1 (β phase) increased due to the application of plasma and diffe...

Crystals

Simultaneous occurrence of Dirac-like cones at the center of the Brillouin zone (Г) at two differ... more Simultaneous occurrence of Dirac-like cones at the center of the Brillouin zone (Г) at two different energy states is termed Dual-Dirac-like cones (DDC) in this article. The occurrence of DDC is a rare phenomenon. Thus, the generation of multiple Dirac-like cones at the center of the Brillouin zone is usually non-manipulative and poses a challenge to achieve through traditional accidental degeneracy. However, if predictively created, DDC will have multiple engineering applications with acoustics and vibration. Thus, the possibilities of creating DDC have been identified herein using a simple square periodic array of tunable square phononic crystals (PnCs) in air media. It was found that antisymmetric deaf bands may play critical roles in tracking the DDC. Hence, pivoting on the deaf bands at two different energy states, an optimized tuning parameter was found to achieve Dirac-like cones at two distinct frequency states, simultaneously. Orthogonal wave transport identified as key Dir...

After an initial reduction, the composite strength undergoes a dormant state that builds up insid... more After an initial reduction, the composite strength undergoes a dormant state that builds up inside the material, we call material memory. At that stage the distributed damage accumulates at the intrinsic length scales. However, such state does not affect the global strength of the materials. There is no experimental tool that can quantify such material state. Here, we introduce a precursor to damage quantifi cation technique by bridging the gap between multiscale modeling and multiscale sensing. We propose a recently developed parameter called “damage entropy”. It is derived from the understanding of micromorphic behavior of materials where deformation is expressed as sum of macroscopic continuous deformation and internal microscopic deformation. The characteristic length scale evolves during the fatigue life of the composite and their progressive infl uence changes in a quantifi ed sense thus increase the entropy. We obtained the quantifi ed entropy using quantitative ultrasonic im...

Energy harvesters primarily depend on on a groups of unit cells to harvest energy at broadband fr... more Energy harvesters primarily depend on on a groups of unit cells to harvest energy at broadband frequencies so that each unit cell is responsible to harvest energy at a distinct frequency. Other design complexity, space, and financial profusion are required for transferring from unit-frequency to multi-frequency energy scavenging. Also, it is very unlikely to obtain expected power output if the available vibration source doesn’t match the designed loading condition (usually, unidirectional) of the device and requires rearrangement of the base structure to have projected output. In this paper we model the unique feature of acoustic metamaterial (AM), which is not only able to harvest energy at multiple frequencies using only a unit cell device, but also able to harvest energy under a variety of uncoupled (unidirectional) and coupled (multi-directional) vibration environments with an identical base structure arrangement.

Sensors (Basel, Switzerland), 2021

The effect of a self-pulsing non-equilibrium plasma discharge on piezoelectric PVDF nanofiber mem... more The effect of a self-pulsing non-equilibrium plasma discharge on piezoelectric PVDF nanofiber membrane was investigated. The plasma discharge was generated in air with a DC power source, with a discharge current of 0.012 mA, a nominal interelectrode separation of 1 mm, and discharge voltage of ~970 V. In a continuous fabrication process, the electrospinning method was used to generate thin nanofiber membrane with a flow rate of 0.7–1 mL h−1 and 25–27 kV voltage to obtain the nanofiber with high sensitivity and a higher degree of alignment and uniformity over a larger area. Plasma treatment was applied on both single layer and multi-layer (three layers) nanomembranes. In addition, simultaneously, the nanofiber membranes were heat-treated at a glass transition temperature (80–120 °C) and then underwent plasma treatment. Fourier-transform infrared (FTIR) spectroscopy showed that the area under the curve at 840 and 1272 cm−1 (β phase) increased due to the application of plasma and diffe...

In spite of many studies concerning the potential of auditory nerve actions, the timing of neural... more In spite of many studies concerning the potential of auditory nerve actions, the timing of neural excitation in relation to basilar membrane motion is still not well understood. In this study, therefore, a Piezoelectric Artificial Basilar Membrane (PABM) is fabricated using Denton Explorer evaporator. The proposed dynamical system is made of polyvinylidene fluoride membrane on which 40 chromium electrodes were deposited with thickness close to 104 Å. The PABM sensor was tested with variable engineering parameters that contribute to its frequency selection capabilities. To characterize the frequency selectivity of the PABM, mechanical displacements were measured using a very precise high-resolution data acquisition board. When electrical and acoustic stimuli were applied, the measured resonance frequencies were in the ranges of 600to2000. These results demonstrate that the mechanical frequency selectivity of this PABM is close to the human communication frequency range (300–3000 Hz),...

Inception of damage quantification during fatigue loading has been a challenge in the field of st... more Inception of damage quantification during fatigue loading has been a challenge in the field of structural health monitoring (SHM). Interaction between intrinsic damage state and ultrasonic wave signals of composite material is not fully understood. Fiber reinforced composite materials unveils damage precursor in the form of micro crack in matrix and fiber fracture which leads to catastrophic failure of the structure. Here, in this paper tensile-tensile fatigue tests were performed on two different types of ASTM standard composite specimen. For carbon fiber reinforced composite (CFRP) specimens at a regular interval of 10,000 cycles and for glass fiber reinforced composite (GFRP) interrogation of material state during fatigue tests were performed at the interval of 1,000 cycles, until micro cracks are developed. Quantitative Ultrasonic Microscopy is performed during the same intervals. For the Carbon-Carbon composites, the non-local material properties degraded continuously during fa...

Journal of Nondestructive Evaluation, Diagnostics and Prognostics of Engineering Systems

The understanding of strength recovery behavior under a dynamic loading environment provides a gu... more The understanding of strength recovery behavior under a dynamic loading environment provides a guidance for optimizing the design of composite structures for in-service applications. Although established for metals, the quantification of strength recovery in carbon fiber-reinforced viscoelastic composites is still an area under active research. This study aims to understand the effects of fatigue loading rates on the damage behaviors of stress-relaxed carbon fiber-based composites. Hence, the time-dependent strength recovery in woven composites is quantified experimentally using two mutually exclusive approaches under identical fatigue loading environments. In the first approach, the strength recovery is quantified by the dissipated non-linearity in Lamb wave propagation due to the damage state of the composite materials. This is quantified and shown coupled with second- and third-order non-linear parameters. In the second approach, ultrasonic acoustic pressure waves are utilized to...

Applied Sciences

In this paper, a novel method to quantify the incubation of damage on piezoelectric crystal is pr... more In this paper, a novel method to quantify the incubation of damage on piezoelectric crystal is presented. An intrinsic length scale parameter obtained from nonlocal field theory is used as a novel measure for quantification of damage precursor. Features such as amplitude decay, attenuation, frequency shifts and higher harmonics of guided waves are commonly-used damage features. Quantification of the precursors to damage by considering the mentioned features in a single framework is a difficult proposition. Therefore, a nonlocal field theory is formulated and a nonlocal damage index is proposed. The underlying idea of the paper is that inception of the damage at the micro scale manifests the evolution of damage at the macro scale. In this paper, we proposed a nonlocal field theory, which can efficiently quantify the inception of damage on piezoelectric crystals. The strength of the method is demonstrated by employing the surface acoustic waves (SAWs) and longitudinal bulk waves in Li...

IEEE/ASME Transactions on Mechatronics

A high percentage of failures in sensors and devices employed in harsh industrial environments an... more A high percentage of failures in sensors and devices employed in harsh industrial environments and airborne electronics is due to mechanical vibrations and shocks. Therefore, it is of paramount importance to test equipment reliability and ensure its survival in long missions in the presence of physical fluctuations. Traditional vibration testbeds employ unidirectional acoustic or mechanical excitations. However, in reality, equipment may encounter uncoupled (unidirectional) and/or coupled (multidirectional) loading conditions during operation. Hence, to systematically characterize and fully understand equipment's behavior, a testbed capable of simulating a wide variety of vibration conditions is required. The primary objective of this study is design, fabrication, and testing of an acousto electrodynamic three-dimensional (3-D) vibration exciter (AEVE 3-D), which simulates coupled and decoupled (with unpowered arms) 3-D acoustic and/or 3-D mechanical vibration environments. AEVE 3-D consists of three electromagnetic shakers (for mechanical excitation) and three loud speakers (for acoustic excitation) as well as a main control unit that accurately calculates and sets the actuators’ input signals in order to generate optimal coupled and decoupled vibrations at desired frequencies. In this paper, the system's architecture, its mechanical structure, and electrical components are described. In addition, to verify AEVE 3-D's performance, various experiments are carried out using a 3-D piezoelectric energy harvester and a custom-made piezoelectric beam.

Structural Health Monitoring

In this article, experimental verification and validation of a peridynamics-based simulation tech... more In this article, experimental verification and validation of a peridynamics-based simulation technique, called peri-elastodynamics, are presented while simulating the guided Lamb wave propagation and wave–damage interaction for ultrasonic nondestructive evaluation and structural health monitoring applications. Peri-elastodynamics is a recently developed elastodynamic computation tool where material particles are assumed to interact with the neighboring particles nonlocally, distributed within an influence zone. First, in this article, peri-elastodynamics was used to simulate the Lamb wave modes and their interactions with the damages in a three-dimensional plate-like structure, while the accuracy and the efficacy of the method were verified using the finite element simulation method (FEM). Next, the peri-elastodynamics results were validated with the experimental results, which showed that the newly developed method is more accurate and computationally cheaper than the FEM to be use...