Quality assessment and damage detection in nanomodified adhesively-bonded composite joints using inkjet-printed interdigital sensors

Bekas, D.G.; Khodaei, Zahra Sharif; Baltzis, D.; Aliabadi, M.H.; Paipetis, Alkiviadis S.

doi:10.1016/j.compstruct.2019.01.008

Cited by 24 publications

(13 citation statements)

References 42 publications

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“…The results indicated that the mean size decreased after the addition of the CNTs in the shell wall ( Figure 2 ). As was also observed in the literature [ 6 , 7 ], smaller microcapsules were produced after the incorporation of nanoparticles, due to the reduced number of collisions between the smaller droplets. The outer UF shell of the microcapsules with a rougher surface were thicker than those of the microcapsules with smoother surfaces.…”

Section: Resultssupporting

confidence: 74%

“…Multifunctional composites represent a state-of-the-art technology, since they are capable of simultaneously performing two or more functions [ 1 ]. Among their functionalities, such as energy harvesting [ 2 , 3 , 4 ] and structural health monitoring (SHM) [ 5 , 6 , 7 , 8 ], self-healing is being vigorously studied [ 9 , 10 ]. Self-healing can be intrinsic [ 11 , 12 , 13 , 14 ] or extrinsic, with the incorporation of vascules [ 15 ] or capsules [ 16 ] inside the material.…”

Section: Introductionmentioning

confidence: 99%

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Healing Efficiency of CNTs-Modified-UF Microcapsules That Provide Higher Electrical Conductivity and EMI Shielding Properties

et al. 2021

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In this study, the effect of the addition of multi-walled carbon nanotubes (MWCNTs), at three percentages, into the urea-formaldehyde (UF) shell-wall of microcapsules on the healing efficiency is reported. The modified shell-wall created a conductive network in semi-conductive epoxies, which led to an improvement of the electromagnetic interference shielding effectiveness (EMI SE); utilizing the excellent electrical properties of the CNTs. The microcapsule’s mean diameter and shell wall were examined via scanning electron microscopy (SEM). Thermal stability was evaluated via thermogravimetric analysis (TGA). The healing efficiency was assessed in terms of fracture toughness, while the electrical properties were measured using impedance spectroscopy. The measurements of the EMI SE were carried out in the frequency range of 7–9 GHz. The derived results indicated that the incorporation of the CNTs resulted in a decrease in the mean size of the microcapsules, while the thermal stability remained unchanged. In particular, the introduction of 0.5% w/v CNTs did not affect the healing efficiency, while it increased the initial mechanical properties of the epoxy after the incorporation of the self-healing system by 27%. At the same time, it led to the formation of a conductive network, providing electrical conductivity to the epoxies. The experimental results showed that the SE increased on average 5 dB or more after introducing conductive microcapsules.

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Section: Resultssupporting

confidence: 74%

Section: Introductionmentioning

confidence: 99%

Healing Efficiency of CNTs-Modified-UF Microcapsules That Provide Higher Electrical Conductivity and EMI Shielding Properties

et al. 2021

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“…Aircraft SHM is one of the scenarios where great attention has been drawn, especially when composite materials are widely adopted nowadays [11]. In order to detect damage at an early stage and to prevent catastrophic failures, many monitoring methodologies using various types of sensors have been investigated, including those using strain gauges, accelerometers, ultrasonic sensors, passive acoustic sensors and fibre optical sensors [12,13,14,15,16]. Among them, piezoelectric transducers (PZTs) have been widely used, due to their advantages in structural compactness, installation convenience and high sensitivity.…”

Section: Introductionmentioning

confidence: 99%

An energy-efficient cyber-physical system for wireless on-board aircraft structural health monitoring

Khodaei

Aliabadi

2019

Mechanical Systems and Signal Processing

Self Cite

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In this paper, an energy-efficient cyber physical system using piezoelectric transducers (PZTs) and wireless sensor networks (WSN) is proposed, designed and experimentally validated for on-board aircraft structural health monitoring (SHM). A WSN is exploited to coordinate damage detection using PZTs distributed on the whole aircraft. An active sensing methodology is adopted for PZTs to evaluate the structural integrity in a pitch-catch manner. The system configuration and operation principle are discussed in the first place. Then, the detailed hardware design was introduced. The proposed system is not only characterized as low-power, high-compactness and wireless, but also capable of processing actuating-sensing signals at megahertz, generating actuating signals with great flexibility, handling multiple actuating-sensing channels with marginal crosstalk. The design was implemented on a 4-layer printed circuit board (8 × 6.5 cm) and evaluated on a large-scale composite fuselage. A 5 MHz sampling rate for actuating and 1.8 MHz for sensing (8 channels) were realized, and the accuracy was validated by comparing the results with those from an oscilloscope. The crosstalk issue caused by actuation on sensing channels is properly addressed using a 2-stage attenuation method. An ultra-low current (81.7 µA) was measured when no detection was required; the average current was 0.45 mA with a detection rate of twice per hour, which means the system can continuously work for up to 12.6 months for 2 AA batteries. Eventually, an example of damage detection is provided, showing the capability of such a system in SHM.

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“…Two of the main sensor technologies that have received attention are Piezoelectric (PZT) transducers and Fibre optic (FO) sensors due to their many advantages, either used individually [ 15 , 16 ] or in combination [ 17 , 18 , 19 , 20 , 21 , 22 ]. There are other sensor technologies for bondline monitoring which have been recently developed [ 23 , 24 , 25 ] and hence have lower maturity than PZT and FO sensors, in particular, in harsh operational environments such as aircraft structures. In a hybrid system the advantages of utilising PZTs as actuators is combined together with the advantages of the FO sensors which have high sensitivity to strain, low weight, ability to compensate temperature, possibility of multiplexing and immunity from electromagnetic interference [ 20 , 26 ].…”

Section: Introductionmentioning

confidence: 99%

Development of Hybrid Piezoelectric-Fibre Optic Composite Patch Repair Solutions

Lambinet

Khodaei

2021

Sensors

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This paper proposes a hybrid structural health monitoring (SHM) solution for a smart composite patch repair for aircraft structures based on piezoelectric (PZT) and fibre optic (FO) sensors to monitor the integrity of a the bondline and detect any degradation. FO sensors are used to acquire guided waves excited by PZT transducers to allow the advantages of both sensor technologies to be utilised. One of the main challenges of guided wave based detection methodologies is to distinguish the effect of temperature on the propagating waves, from that of an existing damage. In this research, the application of the hybrid SHM system is tested on a composite step sanded repair coupon under operational condition (temperature variation) representative of an aircraft for the first time. The sensitivity of the embedded FO sensor in recording the strain waves is compared to the signals acquired by PZT sensors under varying temperature. A novel compensation algorithm is proposed to correct for the effect of the temperature on the embedded FO sensor spectrum in the hybrid set-up. The repaired specimen is then impacted with a drop mass to cause barely visible impact damage (BVID). The hybrid SHM system is then used to detect the damage, and its diagnosis results are compared to a PZT only based smart repair solution. The results show promising application of the hybrid solution for monitoring bondline integrity as well as highlighting challenges of the embedding of FO sensors for a reliable and repeatable diagnosis.

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Quality assessment and damage detection in nanomodified adhesively-bonded composite joints using inkjet-printed interdigital sensors

Cited by 24 publications

References 42 publications

Healing Efficiency of CNTs-Modified-UF Microcapsules That Provide Higher Electrical Conductivity and EMI Shielding Properties

Healing Efficiency of CNTs-Modified-UF Microcapsules That Provide Higher Electrical Conductivity and EMI Shielding Properties

An energy-efficient cyber-physical system for wireless on-board aircraft structural health monitoring

Development of Hybrid Piezoelectric-Fibre Optic Composite Patch Repair Solutions

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