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  • JOURNAL ARTICLE
    Bekas DG, Sharif-Khodaei Z, Aliabadi MHF, 2018,

    An Innovative Diagnostic Film for Structural Health Monitoring of Metallic and Composite Structures

    , SENSORS, Vol: 18, ISSN: 1424-8220
  • JOURNAL ARTICLE
    Fu H, Sharif Khodaei Z, Aliabadi MH, 2018,

    An Event-Triggered Energy-Efficient Wireless Structural Health Monitoring System for Impact Detection in Composite Airframes

    , IEEE Internet of Things Journal

    IEEE In this paper, a low-power high-response wireless structural health monitoring system (WSHMS) is designed, implemented and experimentally evaluated for impact detection in composite airframes. Due to the rare, random and transitory nature of impacts, an event-triggered mechanism is adopted for allowing the system to exhibit low power consumption when no impact occurs and high performance when triggered. System responsiveness, robustness and energy efficiency are considered and modelled. Based on system requirements and functions, several modules are designed, including filtering, impact detecting, local processing and wireless communicating modules. The system was implemented on a printed circuit board. The response time is about 12 us with an average current lower than 1 mA when the impact activity is lower than 0.1%. The system exhibits high robustness to ambient vibration noises and is also capable of accurately and responsively capturing multiple sensing input channels (up to 24 channels). This work presents a low-latency energy-aware WSHMS for impact detection of composite structures. It can be adapted to monitor of other rare, random and ephemeral events in many Internet of Things applications.

  • CONFERENCE PAPER
    Goossens S, De Pauw B, Geernaert T, Salmanpour MS, Khodaei ZS, Thienpont H, Berghmans Fet al., 2018,

    Aerospace-grade compatible surface mounted optical fibre sensor for structural health monitoring of composite structures

    © 2018 The Author(s). We suggest a robust optical fibre sensor package and its installation method for structural health monitoring purposes on carbon fibre reinforced polymer structures with potential to meet aerospace standards.

  • JOURNAL ARTICLE
    Li J, Khodaei ZS, Aliabadi MH, 2018,

    Dynamic dual boundary element analyses for cracked Mindlin plates

    , INTERNATIONAL JOURNAL OF SOLIDS AND STRUCTURES, Vol: 152, Pages: 248-260, ISSN: 0020-7683
  • JOURNAL ARTICLE
    Morse L, Khodaei ZS, Aliabadi MH, 2018,

    Reliability based impact localization in composite panels using Bayesian updating and the Kalman filter

    , MECHANICAL SYSTEMS AND SIGNAL PROCESSING, Vol: 99, Pages: 107-128, ISSN: 0888-3270
  • JOURNAL ARTICLE
    Dafydd I, Khodaei ZS, 2017,

    Laser Vibrometer imaging of delamination interaction with Lamb waves using a chirp excitation method

    , Key Engineering Materials, Vol: 754 KEM, Pages: 375-378, ISSN: 1013-9826

    © 2017 Trans Tech Publications, Switzerland. One method that has shown great potential in visualising and characterising the interaction of guided waves with damage in composites is Laser Vibrometry. A Laser Doppler Vibrometer (LDV) can be used to produce 2D wavefield images of guided Lamb waves but a single scan is very time consuming and normally multiple scans are required at various frequencies in order to determine the best input signal. This paper demonstrates the use of a chirp excitation method requiring only a single scan and a post-processing algorithm to obtain results corresponding to any narrowband signal within the frequency range of the chirp signal. The method was used on an artificially delaminated composite panel and showed that the S0 mode, dominant at higher frequencies, mainly caused mode conversions whilst the A0 mode, dominant at lower frequencies, mainly caused a change in phase and amplitude across the delamination.

  • CONFERENCE PAPER
    De Toro Espejel JF, Khodaei ZS, 2017,

    Lightning strike simulation in composite structures

    , Pages: 181-184, ISSN: 1013-9826

    © 2017 Trans Tech Publications, Switzerland. Lighting strike is one of the critical threats to the safety of composite aircrafts during flight. This work reports on numerical simulation of lightning strike in composite structures. Different modelling techniques using the commercial software ABAQUS, together with damage models are studied to find the most appropriate one in comparison to experimental results. Once the numerical model is validated, the effect of insertion of carbon nanotubes (CNTs) and metallic mesh in the composite is investigated. It is concluded that inserting CNTs in the top layer of the composite can improve its lightning strike protection noticeably.

  • JOURNAL ARTICLE
    Geraci G, Aliabadi MH, 2017,

    Micromechanical boundary element modelling of transgranular and intergranular cohesive cracking in polycrystalline materials

    , ENGINEERING FRACTURE MECHANICS, Vol: 176, Pages: 351-374, ISSN: 0013-7944
  • CONFERENCE PAPER
    Lambinet F, Khodaei ZS, 2017,

    Smart patch repair with low profile PVDF sensors

    , Pages: 359-362, ISSN: 1013-9826

    © 2017 Trans Tech Publications, Switzerland. Bonded repair of composite structures still remains a major concern for the airworthiness authorities because of the uncertainty about the repair quality. This work, investigates the applicability of conventional Structural Health Monitoring (SHM) techniques for monitoring of bonded repair with ring-shaped low profile sensors. A repaired composite panel has been sensorized with two Ring-Shaped Polyvinylidene fluoride piezopolymer Sensors (RSPS) and a piezoelectric (PZT) transducer. An electromechanical impedance (EMI) and Lamb wave analysis have been carried out to check the sensitivity of these sensors to detect an artificially introduced damage simulating a disbond of the repair. The state of the repair have been successfully monitored and reported by both methods.

  • CONFERENCE PAPER
    Lambinet F, Sharif Khodaei Z, 2017,

    Damage detection in composite skin stiffener with hybrid PZT-FO SHM system

    , Pages: 367-370, ISSN: 1013-9826

    © 2017 Trans Tech Publications, Switzerland. A hybrid piezoelectric (PZT)/fibre optic diagnostic system has been developed for damage detection in built up composite structures. The hybrid system uses PZT transducers to actuate the structure and fibre optic (FO) sensors to capture the propagating wave. The diagnostic system will then have the advantages of both PZT and FO sensors. The applicability of the system is then tested for detecting an artificial damage at a skin/stiffener interface of a thick composite structure. The response of the FO sensors is then compared to PZT sensors and presented.

  • CONFERENCE PAPER
    Mallardo V, Sharif Khodaei Z, Aliabadi MH, 2017,

    Sensor optimization for impact detection: A Bayesian approach

    , Pages: 1855-1865

    © 2018 International Center for Numerical Methods in Engineering. All rights reserved. A Bayesian optimization strategy resulting in optimal sensor locations for impact localization under operational conditions is developed and presented. The impact detection methodology is based on developing meta-models utilizing artificial neural network (ANN) through the recorded sensor signals generated by various impact events. The novelty of the proposed method is to include the probability of one or more sensors failing under operation as well as non-uniform probability of impact occurrence in the structure. Finally, the proposed optimization algorithm is applied to a composite stiffened panel.

  • JOURNAL ARTICLE
    Salmanpour MS, Khodaei ZS, Aliabadi MH, 2017,

    Guided wave temperature correction methods in structural health monitoring

    , JOURNAL OF INTELLIGENT MATERIAL SYSTEMS AND STRUCTURES, Vol: 28, Pages: 604-618, ISSN: 1045-389X
  • JOURNAL ARTICLE
    Salmanpour MS, Khodaei ZS, Aliabadi MH, 2017,

    Transducer placement optimisation scheme for a delay and sum damage detection algorithm

    , STRUCTURAL CONTROL & HEALTH MONITORING, Vol: 24, ISSN: 1545-2255
  • JOURNAL ARTICLE
    Salmanpour MS, Khodaei ZS, Aliabadi MH, 2017,

    Instantaneous Baseline Damage Localization Using Sensor Mapping

    , IEEE SENSORS JOURNAL, Vol: 17, Pages: 295-301, ISSN: 1530-437X
  • JOURNAL ARTICLE
    Salmanpour MS, Khodaei ZS, Aliabadi MHF, 2017,

    Impact Damage Localisation with Piezoelectric Sensors under Operational and Environmental Conditions

    , SENSORS, Vol: 17, ISSN: 1424-8220
  • JOURNAL ARTICLE
    Sharif Khodaei Z, Yue N, Aliabadi MH, 2017,

    Damage detectability model of pitch-catch configuration in composite plates.

    , Key Engineering Materials, Vol: 754, ISSN: 1013-9826

    Detectability of damage using Lamb waves depends on many factors such as size and severity of damage, attenuation of the wave and distance to the transducers. This paper presents a detectability model for pitch-catch sensors configuration for structural health monitoring (SHM) applications. The proposed model considers the physical properties of lamb wave propagation and is independent of damage detection algorithm, which provides a generic solution for probability of detection. The applicability of the model in different environmental and operational conditions is also discussed.

  • CONFERENCE PAPER
    Yue N, Khodaei ZS, Aliabadi MH, 2017,

    Damage detectability model of pitch-catch configuration in composite plates

    , Pages: 387-390, ISSN: 1013-9826

    © 2017 Trans Tech Publications, Switzerland. Detectability of damage using Lamb waves depends on many factors such as size and severity of damage, attenuation of the wave and distance to the transducers. This paper presents a detectability model for pitch-catch sensors configuration for structural health monitoring (SHM) applications. The proposed model considers the physical properties of lamb wave propagation and is independent of damage detection algorithm, which provides a generic solution for probability of detection. The applicability of the model in different environmental and operational conditions is also discussed.

  • CONFERENCE PAPER
    De Luca A, Sharif-Khodaei Z, Aliabadi MH, Caputo Fet al., 2016,

    Numerical simulation of the Lamb wave propagation in impacted CFRP laminate

    , 2nd International Symposium on Dynamic Response and Failure of Composite Materials, (Draf), Publisher: ELSEVIER SCIENCE BV, Pages: 109-115, ISSN: 1877-7058
  • CONFERENCE PAPER
    De Luca A, Sharif-Khodaei Z, Caputo F, 2016,

    Determination of the impact location and damage characterization based on guided waves

    , Pages: 10-13, ISSN: 1013-9826

    © 2016 Trans Tech Publications, Switzerland. The aim of this paper is to understand the effects of the damage criteria modelling on the training phase (performed by means of Finite Element simulations) of an artificial neural network (ANN) enabled to locate impacts onto a CFRP laminate. The developed FE models have been also used to investigate the intra-laminar damage mode, which, among different ones, has the most effects on the residual strength of the panel.

  • JOURNAL ARTICLE
    Khodaei ZS, Aliabadi MH, 2016,

    A Multi-Level Decision Fusion Strategy for Condition Based Maintenance of Composite Structures

    , MATERIALS, Vol: 9, ISSN: 1996-1944
  • CONFERENCE PAPER
    Khodaei ZS, Aliabadi MH, 2016,

    An optimization strategy for best sensor placement for damage detection and localization in complex composite structures

    , Pages: 2999-3008

    In this paper an optimization strategy based on providing maximum area coverage (MAC) resulting in optimal sensor placement for damage localization in complex composite structures is proposed. The proposed optimization algorithm is uses genetic algorithm to minimize the defined fitness function based on geometrical and physical constraints of the structure, rather than probability of detection of the damage detection algorithm. The proposed fitness function is applicable to any damage detection technique based on ultrasonic guided wave in pitch catch configurations and is readily up-scalable to any structure. The optimization algorithm is then applied to a full wing demonstrator of an aircraft.

  • JOURNAL ARTICLE
    Mallardo V, Khodaei ZS, Aliabadi FMH, 2016,

    A Bayesian Approach for Sensor Optimisation in Impact Identification

    , MATERIALS, Vol: 9, ISSN: 1996-1944
  • JOURNAL ARTICLE
    Salmanpour MS, Khodaei ZS, Aliabadi MH, 2016,

    Airborne Transducer Integrity under Operational Environment for Structural Health Monitoring

    , SENSORS, Vol: 16, ISSN: 1424-8220
  • CONFERENCE PAPER
    Salmanpour MS, Sharif Khodaei Z, Aliabadi MH, 2016,

    Towards real-time structural health monitoring damage detection without user input

    , Pages: 7853-7862

    In this work a real-time damage detection platform is presented, requiring little to no user input after initial installation and set-up. Diagnostic ultrasonic signals are generated using attached piezoelectric transducers, which also serve to capture the structural response. This paper shows real-time detection in a flat CFRP panel. The necessary data acquisition and signal processing is carried out in an automated manner. A visualization of the damage map is then given as the primary output highlighting the predicted damage location. The developed system is flexible in allowing scalable deployment to cater for an increased number of transducers. The detection platform is experimentally demonstrated by real-time localization of artificial damages at various locations on a CFRP panel. This was also done under operational environment vibration loading, yielding accurate damage localization.

  • CONFERENCE PAPER
    Thiene M, Khodaei S, Aliabadi MH, 2016,

    Uncertainty analysis of active SHM system

    , Pages: 249-252, ISSN: 1013-9826

    © (2016) Trans Tech Publications, Switzerland. Structural Health Monitoring (SHM) techniques have gained an increased interest to be utilised alongside NDI techniques for aircraft maintenance. However, to take the SHM methodologies from the laboratory conditions to actual structures under real load conditions requires them to be assessed in terms of reliability and robustness. In this work, a statistical analysis is carried out for an SHM system for damage detection and characterisation in composite structures. The sensitivity of the platform to parameters such as noise, sensor failure, placement tolerances and bonding has been investigated and reported.

  • JOURNAL ARTICLE
    Thiene M, Khodaei ZS, Aliabadi MH, 2016,

    Optimal sensor placement for maximum area coverage (MAC) for damage localization in composite structures

    , SMART MATERIALS AND STRUCTURES, Vol: 25, ISSN: 0964-1726
  • CONFERENCE PAPER
    Thiene M, Khodaei ZS, Aliabadi MH, 2016,

    Statistical analysis of SHM passive sensing systems

    , Pages: 241-244, ISSN: 1013-9826

    © (2016) Trans Tech Publications, Switzerland. Structural Health Monitoring (SHM) techniques have gained an increased interest to be utilised alongside NDI techniques for aircraft maintenance. However, to take the SHM methodologies from the laboratory conditions to actual structures under real load conditions requires them to be assessed in terms of reliability and robustness. In this work, a statistical analysis is carried out for a passive SHM system capable of impact detection and identification. The sensitivity of the platform to parameters such as noise, sensor failure and in-service load conditions has been investigated and reported.

  • CONFERENCE PAPER
    Thiene M, Sharif Khodaei Z, Aliabadi MH, 2016,

    Optimal sensor placement for damage detection based on ultrasonic guided wave

    , Pages: 269-272, ISSN: 1013-9826

    © (2016) Trans Tech Publications, Switzerland. In this work a methodology for effective positioning of sensors and actuators for damage detection and characterisation is described. The novelty of the proposed methodology is that the fitness function to be optimised does not contain probability of detection (POD) which needs to be obtained for every possible sensor combination. The proposed fitness function is to provide the maximum coverage of the structure via Lamb waves and reduce the negative effects of boundary reflections. Once the fitness function is defines, genetic algorithm (GA) is used as an optimisation strategy to result in optimal sensor positioning.

  • JOURNAL ARTICLE
    Yue N, Khodaei ZS, 2016,

    Assessment of Impact Detection Techniques for Aeronautical Application: ANN vs. LSSVM

    , JOURNAL OF MULTISCALE MODELING, Vol: 7, ISSN: 1756-9737
  • CONFERENCE PAPER
    Salmanpour MS, Sharif Khodaei Z, Aliabadi MH, 2015,

    A reference free method for damage detection and location based on geometric similarity

    , Pages: 133-142

    This paper outlines a method exploiting geometrically similar areas as mutual baselines. The proposed method eliminates the need for previously recorded baseline sets and the pitfalls of changing environmental conditions between recording of signals. Through the use of instantaneously recorded baselines at the same time as the current interrogation signal and transducer calibration, it is possible to accurately predict the location of damage. The proposed transducer calibrated instantaneous baseline (TCIB) method was first applied to numerically simulated results. It was then validated experimentally for two different locations of artificial damage.

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