Prof. Darryll J. Pines Profile

Prof. Darryll J. Pines

Program Manager at Univ of Maryland College Park

SPIE Involvement:

Conference Program Committee | Conference Co-Chair | Conference Chair | Author

Publications (34)

PROCEEDINGS ARTICLE | March 27, 2018

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

Proc. SPIE. 10598, Sensors and Smart Structures Technologies for Civil, Mechanical, and Aerospace Systems 2018

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

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PROCEEDINGS ARTICLE | April 12, 2017

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

Proc. SPIE. 10168, Sensors and Smart Structures Technologies for Civil, Mechanical, and Aerospace Systems 2017

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

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PROCEEDINGS ARTICLE | March 8, 2014

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

Proc. SPIE. 9061, Sensors and Smart Structures Technologies for Civil, Mechanical, and Aerospace Systems 2014

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

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PROCEEDINGS ARTICLE | September 26, 2007

Fiber optic sensors monitoring transmission ring gears

Proc. SPIE. 6758, Photonics in the Transportation Industry: Auto to Aerospace

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

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PROCEEDINGS ARTICLE | May 19, 2005

A smart composite patch for the repair of aircraft structures

Proc. SPIE. 5767, Nondestructive Evaluation and Health Monitoring of Aerospace Materials, Composites, and Civil Infrastructure IV

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

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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 | May 9, 2005

Damage assessment of an isolation system

Proc. SPIE. 5768, Health Monitoring and Smart Nondestructive Evaluation of Structural and Biological Systems IV

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

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PROCEEDINGS ARTICLE | July 29, 2004

Active periodic struts for gearbox support system

Proc. SPIE. 5386, Smart Structures and Materials 2004: Damping and Isolation

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

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PROCEEDINGS ARTICLE | July 21, 2004

Detecting structural damage using adaptive feature extraction from transient signals

Proc. SPIE. 5394, Health Monitoring and Smart Nondestructive Evaluation of Structural and Biological Systems III

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

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SPIE Conference Volume | August 18, 2003

Smart Structures and Materials 2003: Smart Systems and Nondestructive Evaluation for Civil Infrastructures

PROCEEDINGS ARTICLE | August 5, 2003

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

Proc. SPIE. 5056, Smart Structures and Materials 2003: Smart Structures and Integrated Systems

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

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PROCEEDINGS ARTICLE | August 5, 2003

Sensitivity of Hilbert magnitude and phase to structural damage

Proc. SPIE. 5056, Smart Structures and Materials 2003: Smart Structures and Integrated Systems

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

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PROCEEDINGS ARTICLE | August 1, 2003

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

Proc. SPIE. 5049, Smart Structures and Materials 2003: Modeling, Signal Processing, and Control

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

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PROCEEDINGS ARTICLE | July 15, 2002

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

Proc. SPIE. 4701, Smart Structures and Materials 2002: Smart Structures and Integrated Systems

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

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PROCEEDINGS ARTICLE | July 15, 2002

Design and development of a biomimetic device for micro air vehicles

Proc. SPIE. 4701, Smart Structures and Materials 2002: Smart Structures and Integrated Systems

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

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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 | June 28, 2002

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

Proc. SPIE. 4696, Smart Structures and Materials 2002: Smart Systems for Bridges, Structures, and Highways

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

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SPIE Conference Volume | June 28, 2002

Smart Structures and Materials 2002: Smart Systems for Bridges, Structures, and Highways

PROCEEDINGS ARTICLE | August 16, 2001

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

Proc. SPIE. 4327, Smart Structures and Materials 2001: Smart Structures and Integrated Systems

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

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PROCEEDINGS ARTICLE | August 16, 2001

Near-field effects of damage

Proc. SPIE. 4327, Smart Structures and Materials 2001: Smart Structures and Integrated Systems

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

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PROCEEDINGS ARTICLE | July 30, 2001

Detecting damage in a building structure model under seismic excitation

Proc. SPIE. 4330, Smart Structures and Materials 2001: Smart Systems for Bridges, Structures, and Highways

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

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PROCEEDINGS ARTICLE | June 22, 2000

Effects of tooth damage on spur gear vibrations

Proc. SPIE. 3985, Smart Structures and Materials 2000: Smart Structures and Integrated Systems

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

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PROCEEDINGS ARTICLE | June 22, 2000

Vibration separation methodology for planetary gear health monitoring

Proc. SPIE. 3985, Smart Structures and Materials 2000: Smart Structures and Integrated Systems

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

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PROCEEDINGS ARTICLE | April 20, 2000

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

Proc. SPIE. 3988, Smart Structures and Materials 2000: Smart Systems for Bridges, Structures, and Highways

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

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PROCEEDINGS ARTICLE | June 9, 1999

Modeling damage in tapered flexbeams

Proc. SPIE. 3668, Smart Structures and Materials 1999: Smart Structures and Integrated Systems

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

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PROCEEDINGS ARTICLE | June 9, 1999

Multifunctional sensor for simultaneous measurement of structureborne sound and vibration

Proc. SPIE. 3668, Smart Structures and Materials 1999: Smart Structures and Integrated Systems

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

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PROCEEDINGS ARTICLE | May 18, 1999

Damage detection in a framed building structure

Proc. SPIE. 3671, Smart Structures and Materials 1999: Smart Systems for Bridges, Structures, and Highways

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

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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 | July 27, 1998

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

Proc. SPIE. 3329, Smart Structures and Materials 1998: Smart Structures and Integrated Systems

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

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PROCEEDINGS ARTICLE | June 17, 1998

Damage assessment in a bolted lap joint

Proc. SPIE. 3325, Smart Structures and Materials 1998: Smart Systems for Bridges, Structures, and Highways

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

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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 | April 16, 1998

Modeling damage in rotorcraft flexbeams using wave models

Proc. SPIE. 3321, 1996 Symposium on Smart Materials, Structures, and MEMS

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

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PROCEEDINGS ARTICLE | June 6, 1997

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

Proc. SPIE. 3041, Smart Structures and Materials 1997: Smart Structures and Integrated Systems

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

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PROCEEDINGS ARTICLE | June 6, 1997

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

Proc. SPIE. 3041, Smart Structures and Materials 1997: Smart Structures and Integrated Systems

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

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PROCEEDINGS ARTICLE | June 6, 1997

Detecting crack size and location in composite rotorcraft flexbeams

Proc. SPIE. 3041, Smart Structures and Materials 1997: Smart Structures and Integrated Systems

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

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PROCEEDINGS ARTICLE | May 23, 1997

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

Proc. SPIE. 3043, Smart Structures and Materials 1997: Smart Systems for Bridges, Structures, and Highways

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

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PROCEEDINGS ARTICLE | May 1, 1996

Hybrid distributed modal/wave sensors for structural control

Proc. SPIE. 2717, Smart Structures and Materials 1996: Smart Structures and Integrated Systems

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

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