Prof. Darryll J. Pines Profile

Prof. Darryll J. Pines

Program Manager at Univ of Maryland College Park

SPIE Involvement:

Author

Publications (32)

Proceedings Article | 27 March 2018 Presentation + Paper

Structural health monitoring of a composite F/A-18 wing section using a sparse piezoelectric transducer array

Jacob McCullum, Byungseok Yoo, Darryll Pines, Norman Wereley

Proceedings Volume 10598, 105980F (2018) https://doi.org/10.1117/12.2299845

KEYWORDS: Transducers, Structural health monitoring, Ferroelectric materials, Composites, Sensors, Signal attenuation, Waveguides, Inspection, Ultrasonics, Skin

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Proceedings Article | 12 April 2017 Paper

A magnetostrictive phased array sensor using a nickel comb patch for guided Lamb wave-based damage detection

Byungseok Yoo, Darryll Pines

Proceedings Volume 10168, 101683O (2017) https://doi.org/10.1117/12.2260345

KEYWORDS: Magnetic sensors, Nickel, Magnetism, Phased arrays, Damage detection, Sensors, Anisotropy, Waveguides, Transducers, Ultrasonics, Ferroelectric materials, Imaging arrays, Actuators, Signal processing

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Proceedings Article | 8 March 2014 Paper

Galfenol-based directional magnetostrictive patch transducer for guided Lamb wave techniques

Byungseok Yoo, Suok-Min Na, Alison Flatau, Darryll Pines

Proceedings Volume 9061, 906146 (2014) https://doi.org/10.1117/12.2046601

KEYWORDS: Transducers, Ferroelectric materials, Nickel, Magnetostrictive materials, Actuators, Magnetism, Aluminum, Sensors, Wave propagation, Receivers

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Proceedings Article | 26 September 2007 Paper

Fiber optic sensors monitoring transmission ring gears

Chris Baldwin, Jason Kiddy, Paul Samuel, Joseph Coker, Darryll Pines

Proceedings Volume 6758, 675808 (2007) https://doi.org/10.1117/12.733905

KEYWORDS: Sensors, Fiber Bragg gratings, Fiber optics sensors, Planets, Multiplexing, Damage detection, Detection and tracking algorithms, Diagnostics, Planetary systems, Algorithm development

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Proceedings Article | 19 May 2005 Paper

A smart composite patch for the repair of aircraft structures

Kelah Wakha, Paul Samuel, Darryll Pines

Proceedings Volume 5767, (2005) https://doi.org/10.1117/12.600532

KEYWORDS: Sensors, Composites, Aluminum, Finite element methods, Aerospace engineering, Chemical elements, Actuators, Smart sensors, Aircraft structures, Nondestructive evaluation

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Recent interest in bonded composite patch repair technology for aerospace systems is because this method can be carried out at a reduced cost and time and can easily be applied to complex geometric structures. This paper details the development of a dual stiffness/energy sensor for monitoring the integrity of a composite patch used to repair an aluminum structural component. The smart sensor has the ability to predict the elastic field of a given host structure based on the strain state of two sub-sensors integrated into the structure. The present study shows the possibility of using the sensor to deduce the local instantaneous host stiffness. Damaged structures are characterized by a reduction in their elastic stiffness that evolve from microstructural defects. A local smart sensor can be developed to sense the local average properties on a host. In this paper, sensors are attached to a structure and a modified Eshelby's equivalent inclusion method is used to derive the elastic properties of the host. An analytical derivation and a sensitivity analysis for the quasistatic application is given in a papers by Majed, Dasgupta, Kelah and Pines. A summary of the derivation of the dynamic Eshelby tensor is presented. This is of importance because damage detection in structures undergoing vibratory and other motions present a greater challenge than those in quasistatic motion. An in-situ health monitoring active sensor system for a real structure (an aluminum plate with an attached repair patch) under close-to real lifecycle loading conditions is developed. The detection of the onset of any damage to the structure as well as the repair patch and the subsequent monitoring of the growth of this damage constitute important goals of the system. Both experimental and finite element methods were applied. Experimental results are presented for tests of the aluminum plate with the repair patch under monotonic quasi-static and dynamic loading vibratory conditions. In summary, the study shows that smart bonded composite repair patches are very effective in the repair of thin aluminum structures since they are able to determine the integrity of the repair structure as well as the repair patch.

Proceedings Article | 9 May 2005 Paper

Damage assessment of an isolation system

Liming Salvino, Darryll Pines, Frederick Costanzo, John Przybysz

Proceedings Volume 5768, (2005) https://doi.org/10.1117/12.599940

KEYWORDS: Damage detection, Optical isolators, Time-frequency analysis, Time metrology, Phase measurement, Data modeling, Structural health monitoring, Data centers, Mathematical modeling, Signal detection

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Proceedings Article | 29 July 2004 Paper

Active periodic struts for gearbox support system

Saeed Asiri, Amr Baz, Darryll Pines

Proceedings Volume 5386, (2004) https://doi.org/10.1117/12.540675

KEYWORDS: Actuators, Wave propagation, Lawrencium, Control systems, Matrices, Signal attenuation, Lithium, Tunable filters, Optical filters, Control systems design

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Proceedings Article | 21 July 2004 Paper

Detecting structural damage using adaptive feature extraction from transient signals

Liming Salvino, Erik Rasmussen, Darryll Pines

Proceedings Volume 5394, (2004) https://doi.org/10.1117/12.541401

KEYWORDS: Composites, Phase measurement, Signal detection, Time metrology, Time-frequency analysis, Inspection, Damage detection, Feature extraction, Visualization, Optical inspection

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Proceedings Article | 5 August 2003 Paper

Sensitivity of Hilbert magnitude and phase to structural damage

Darryll Pines, Liming Salvino

Proceedings Volume 5056, (2003) https://doi.org/10.1117/12.483491

KEYWORDS: Diagnostics, Wave propagation, Sensors, Time series analysis, Wave mechanics, Signal analyzers, Smart structures, Aerospace engineering, Algorithm development, Environmental sensing

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Proceedings Article | 5 August 2003 Paper

Multifunctional piezoelectric stiffness/energy sensor for monitoring the health of structures

Kelah Wakha, Majeed Majed, Abhijit Dasgupta, Darryll Pines

Proceedings Volume 5056, (2003) https://doi.org/10.1117/12.483465

KEYWORDS: Sensors, Ferroelectric materials, Aluminum, Finite element methods, Diagnostics, Active sensors, Chemical elements, Solids, Structural health monitoring, Aerospace engineering

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Proceedings Article | 1 August 2003 Paper

Signal processing and damage detection in a frame structure excited by chaotic input force

Liming Salvino, Darryll Pines, Michael Todd, Jonathan Nichols

Proceedings Volume 5049, (2003) https://doi.org/10.1117/12.484012

KEYWORDS: Damage detection, Time-frequency analysis, Time metrology, Phase measurement, Algorithm development, Signal processing, Feature extraction, Structural health monitoring, Detection and tracking algorithms, Data modeling

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Proceedings Article | 15 July 2002 Paper

Design and development of a biomimetic device for micro air vehicles

Felipe Bohorquez, Darryll Pines

Proceedings Volume 4701, (2002) https://doi.org/10.1117/12.474688

KEYWORDS: Fermium, Frequency modulation, Aerodynamics, Micro unmanned aerial vehicles, Actuators, Kinematics, Prototyping, Computer aided design, Magnetism, Biomimetics

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This paper presents the design and development of a pitching and plunging (flapping) mechanism for small-scale flight. In order to harness the unsteady lift mechanisms, used by most insects, a biologically inspired flapping/pitching device in conjunction with a rotary wing concept was developed and built. This mechanism attempts to replicate some of the aerodynamic phenomena that enhance the performance of small fliers, replacing the periodic translational motion with a unidirectional circular motion while actively flapping and pitching the rotor blades. In order to find the appropriate combination of phase, amplitude, frequency and rotational speed that leads to enhancement in lift, the device requires uncoupled independent pitch and flap actuation systems to permit the complete mapping of the parameter space. In the device under consideration the phase shift between the flapping and the pitching oscillations can be adjusted from 0 to 360 degrees over a wide range of rotational speeds. Maximum flapping and pitching amplitudes of +/- 23 degree(s) and +/- 20 degree(s) respectively can be attained. Linear displacements of two coaxial shafts are translated into the flapping and pitching motion of the rotor blades. The mechanism was designed to minimize the actuation stroke so that smart materials and conventional actuators such as motors and cams could be used. Kinematic analysis as well as experimental tests were performed. Using a customized test stand thrust and torque produced by the rotor were measured at different angles of attack, in steady-state and under periodical pitching actuation. The results showed that hover efficiency was considerably increased for a range of thrust coefficients. The device was developed based on the University of Maryland's rotary wing Micro Air vehicle (MAV) the MICOR (MIcro COaxial Rotorcraft), an electrically driven 100 g coaxial helicopter. It is anticipated that active flapping and/or pitching could be implemented in the prototype to improve its aerodynamic performance. The present paper will discuss the design and development process of a rotating/pitching/flapping mechanism for MAVs. Test results indicate that unsteady pitching motion can be used to include the aerodynamic effect of delayed stall. Performance measurements confirm that unsteady pitching motion improves efficiency in hover.

Proceedings Article | 15 July 2002 Paper

Health monitoring of one-dimensional structures using empirical mode decomposition and the Hilbert-Huang transform

Darryll Pines, Liming Salvino

Proceedings Volume 4701, (2002) https://doi.org/10.1117/12.474653

KEYWORDS: Wavelets, Signal processing, Diagnostics, Time-frequency analysis, Signal analyzers, Fourier transforms, Wavelet transforms, Associative arrays, Analytical research, Sensors

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Proceedings Article | 28 June 2002 Paper

Detecting multiple damage types/locations in a civil building structure model

Jun Ma, Darryll Pines

Proceedings Volume 4696, (2002) https://doi.org/10.1117/12.472551

KEYWORDS: Damage detection, Structural dynamics, Inspection, Wave propagation, Actuators, Digital signal processing, Modal analysis, Iron, Smart structures, Aerospace engineering

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Proceedings Article | 16 August 2001 Paper

Feasibility of a linear phased acoustic array for health monitoring of gears

Adrian Hood, Darryll Pines

Proceedings Volume 4327, (2001) https://doi.org/10.1117/12.436538

KEYWORDS: Acoustics, Teeth, Fourier transforms, Sensors, Phased arrays, Beam steering, Neodymium, Planetary systems, Free space, Linear filtering

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Proceedings Article | 16 August 2001 Paper

Near-field effects of damage

Ashish Purekar, Darryll Pines

Proceedings Volume 4327, (2001) https://doi.org/10.1117/12.436580

KEYWORDS: Wave propagation, Scattering, Near field, Laser scattering, Sensors, Damage detection, Phase shifts, Matrices, Beam propagation method, Image segmentation

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Proceedings Article | 30 July 2001 Paper

Detecting damage in a building structure model under seismic excitation

Jun Ma, Darryll Pines

Proceedings Volume 4330, (2001) https://doi.org/10.1117/12.434111

KEYWORDS: Damage detection, Systems modeling, Iron, Interfaces, Actuators, Digital signal processing, Earthquakes, Data modeling, Smart structures, Aerospace engineering

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Proceedings Article | 22 June 2000 Paper

Effects of tooth damage on spur gear vibrations

Donald Richards, Darryll Pines

Proceedings Volume 3985, (2000) https://doi.org/10.1117/12.388834

KEYWORDS: Teeth, Systems modeling, Servomechanisms, Sun, Antimony, Thulium, Computer simulations, Aerospace engineering, Nomenclature, Smart materials

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Proceedings Article | 22 June 2000 Paper

Vibration separation methodology for planetary gear health monitoring

Paul Samuel, Darryll Pines

Proceedings Volume 3985, (2000) https://doi.org/10.1117/12.388828

KEYWORDS: Sensors, Planets, Teeth, Continuous wavelet transforms, Wavelets, Sun, Diagnostics, Algorithm development, Polonium, Signal analyzers

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Proceedings Article | 20 April 2000 Paper

Concept of dereverbation and its application to damage detection in civil structures

Jun Ma, Darryll Pines

Proceedings Volume 3988, (2000) https://doi.org/10.1117/12.383133

KEYWORDS: Chemical elements, Damage detection, Wave propagation, Systems modeling, Superposition, Nondestructive evaluation, Device simulation, Motion models, Smart structures, Aerospace engineering

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Proceedings Article | 9 June 1999 Paper

Modeling damage in tapered flexbeams

Ashish Purekar, Darryll Pines

Proceedings Volume 3668, (1999) https://doi.org/10.1117/12.350712

KEYWORDS: Chemical elements, Bessel functions, Wave propagation, Spectral models, Composites, Differential equations, Beam propagation method, Damage detection, Finite element methods, Data modeling

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Proceedings Article | 9 June 1999 Paper

Multifunctional sensor for simultaneous measurement of structureborne sound and vibration

Adrian Hood, Darryll Pines

Proceedings Volume 3668, (1999) https://doi.org/10.1117/12.350690

KEYWORDS: Sensors, Ferroelectric polymers, Acoustics, Electrodes, Amplifiers, Etching, Calibration, Vibration control, Capacitance, Data modeling

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Proceedings Article | 18 May 1999 Paper

Damage detection in a framed building structure

Jun Ma, Darryll Pines

Proceedings Volume 3671, (1999) https://doi.org/10.1117/12.348681

KEYWORDS: Damage detection, Wave propagation, Sensors, Motion models, Systems modeling, Inspection, Nondestructive evaluation, Smart materials, Modal analysis, Actuators

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Interest in infrastructure health monitoring and damage detection has received a considerable amount of attention over the past two decades. Previous approaches to non- destructive evaluation of structures to assess their integrity typically involved some form of human interaction. Recent advances in smart materials and structures technology has resulted in a renewed interest in developing advanced self-diagnostic capability for assessing the state of a structure without any human interaction. The goal is to reduce human interaction while at the same time monitor the integrity of a structure. With this goal in mind, many researchers have made significant strides in developing damage detection methods for civil structures based on traditional modal analysis techniques. These techniques are of the well suited for structures which can be modeled by discrete lumped-parameter elements where the presence of damage leads to some low frequency change in the global behavior of the system. On the other hand small defects such as cracks are obscured by modal approaches since such phenomena are high frequency effects not easily discovered by examining changes in modal mass, stiffness or damping parameters. This is because at high frequency modal structural models are subject to uncertainty. This uncertainty can be reduced by increasing the spatial order of discrete model, however, this increases the computational effort of modal-based damage detection schemes. On the other hand, wave propagation models of structures have higher spatial order model fidelity. Thus, they are better suited for detecting and global wave propagation models to detect damage in a discrete model of a farmed building structure, consisting of discrete structural elements. Simulated damage in the form of mass or stiffness loss is used to determine the effect on the resonant and incident wave response of the structure. Examination of the incident transfer function response of the structure reveals the loading path of the damaged element.

Proceedings Article | 27 July 1998 Paper

Detecting delamination damage in composite rotorcraft flexbeams using the local wave response

Ashish Purekar, Kodanate Lakshmanan, Darryll Pines

Proceedings Volume 3329, (1998) https://doi.org/10.1117/12.316922

KEYWORDS: Composites, Wave propagation, Scattering, Sensors, Structural dynamics, Epoxies, Damage detection, Actuators, Laser scattering, Data modeling

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Proceedings Article | 17 June 1998 Paper

Damage assessment in a bolted lap joint

Philip Lovell, Darryll Pines

Proceedings Volume 3325, (1998) https://doi.org/10.1117/12.310600

KEYWORDS: Scattering, Laser scattering, Sensors, Interfaces, Structural dynamics, Nondestructive evaluation, Bridges, Actuators, Chemical elements, Wave propagation

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This paper presents an analysis of a bolted lap joint assembly using continuum wave models to examine the scattering of flexural waves across a joint under loss of torque preload. The motivation for this work is derived from monitoring the dynamics of large buildings and bridges to assess the level of damage in bolted or riveted assemblies following a severe loading condition. In the event of such a condition, these joints can loosen or fail completely creating a potentially hazardous environment for the general public while these structures are still in service. It has been suggested that using nondestructive techniques to monitor the health of these bolted connections to determine the extent of damage can minimize such risks to the public. This paper discusses such a health monitoring approach using local mechanical impedance models to characterize the non-linear joint dynamics of a bolted assembly. As the torque on the bolted assembly is varied, the local and global response of a fixed-fixed one- dimensional structure is studied. The loss of torque load is correlated with the changes seen in the local scattering dynamics of the bolted joint. Incoming and outgoing wave dynamics at the joint are separated to compute the frequency dependent local scattering matrix of the joint and determine its affect on the global system response as the torque on the bolted assembly is varied. Analytical results using the continuum wave descriptions of the structural dynamics are compared against experimental data on a beam fixed at both ends with a bolted lap joint located at its center. Using a least squares cost function between experimental and analytical transfer function data, an effective joint stiffness is obtained. Minimizing the cost function leads to an optimal solution for a parameterized model of the joint dynamics and attempts to account for possible non-linearities such as cubic springs, deadband, stiction and hysteresis. Piezoelectric actuators are used to excite the beam in bending. Strain sensor arrays are distributed on both sides of the joint to capture the local scattering properties of the joint as a function of torque load.

Proceedings Article | 16 April 1998 Paper

Modeling damage in rotorcraft flexbeams using wave models

Kodanate Lakshmanan, Darryll Pines

Proceedings Volume 3321, (1998) https://doi.org/10.1117/12.305580

KEYWORDS: Scattering, Wave propagation, Composites, Laser scattering, Performance modeling, Matrices, Sensors, Actuators, Damage detection, Modal analysis

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Proceedings Article | 6 June 1997 Paper

Health monitoring and damage detection of a rotorcraft planetary geartrain system using piezoelectric sensors

Paul Samuel, Darryll Pines

Proceedings Volume 3041, (1997) https://doi.org/10.1117/12.275681

KEYWORDS: Wavelets, Planets, Sensors, Teeth, Wavelet transforms, Planetary systems, Time-frequency analysis, Diagnostics, Sun, Signal processing

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Proceedings Article | 6 June 1997 Paper

Detecting crack size and location in composite rotorcraft flexbeams

Kodanate Lakshmanan, Darryll Pines

Proceedings Volume 3041, (1997) https://doi.org/10.1117/12.275665

KEYWORDS: Scattering, Composites, Systems modeling, Damage detection, Error analysis, Mechanics, Structural dynamics, Wave propagation, Matrices, Laser scattering

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Proceedings Article | 6 June 1997 Paper

Damage detection of main rotor faults using a sensitivity-based approach

Jason Kiddy, Darryll Pines

Proceedings Volume 3041, (1997) https://doi.org/10.1117/12.275684

KEYWORDS: Finite element methods, Damage detection, Matrices, Composites, Algorithm development, Data modeling, Systems modeling, Detection and tracking algorithms, Inspection, Shape analysis

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Proceedings Article | 23 May 1997 Paper

Remote wireless damage detection system for monitoring the health of large civil structures

Philip Lovell, Darryll Pines

Proceedings Volume 3043, (1997) https://doi.org/10.1117/12.274643

KEYWORDS: Sensors, Data acquisition, Telecommunications, Data communications, Wireless communications, Damage detection, Computing systems, Actuators, Bridges, Smart sensors

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Proceedings Article | 1 May 1996 Paper

Hybrid distributed modal/wave sensors for structural control

Darryll Pines

Proceedings Volume 2717, (1996) https://doi.org/10.1117/12.239048

KEYWORDS: Sensors, Ferroelectric polymers, Control systems, Electrodes, Wave propagation, Transducers, Actuators, Wave sensors, Beam shaping, Structural design

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