Monitoring multiple damage mechanisms in crack‐patched structures using optical infrared thermography

Martens, Ulrike; Schröder, Kai‐Uwe

doi:10.1111/ffe.13388

Cited by 5 publications

(4 citation statements)

References 31 publications

(71 reference statements)

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“…Reference measurements of the crack length are carried out by infrared thermography [41,42] . The thermographic camera ImageIR 8380 S from InfraTec GmbH, Dresden, Germany is used.…”

Section: Fatigue Testsmentioning

confidence: 99%

Integration of eddy current sensors into repair patches for fatigue reinforcement at rivet holes

Schmid

Martens

Schomburg

et al. 2021

Strain

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Fatigue cracks at rivet holes occur at advanced service life of aircrafts due to cyclic loading. As a repair method, adhesively bonded stiffener patches enhance the fatigue life of the structure by delaying crack initiation and reducing crack growth. Combining a crack sensor with a repair patch to a sensor‐based stiffener patch allows crack growth reduction and monitoring at the same time. This paper presents a feasibility study on the integration of eddy current sensors into carbon fibre reinforced plastic (CFRP) repair patches. To this end, a specific patch design is developed, and samples are manufactured by ultrasonic fabrication. The performance of the patches is investigated in fatigue tests in terms of ‘crack reinforcement’ and ‘crack detection.’ Both requirements are met. The undertaking of future efforts to tailor the sensor‐based repair patch concept to an individual application in aircraft maintenance seems reasonable.

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“…Reference measurements of the crack length are carried out by infrared thermography [41,42] . The thermographic camera ImageIR 8380 S from InfraTec GmbH, Dresden, Germany is used.…”

Section: Fatigue Testsmentioning

confidence: 99%

Integration of eddy current sensors into repair patches for fatigue reinforcement at rivet holes

Schmid

Martens

Schomburg

et al. 2021

Strain

Self Cite

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“…Supposing that a peak magnitude x eq = x 0 appears at the frequency ω = ω 0 and a value x eq = x 1 (somewhat less than the peak magnitude) is at frequency ω = ω 1 (ω 1 < ω 0 ). Then the three system parameters k eq , m eq , c eq can be determined by equations ( 8) and (9):…”

Section: The Equivalent System For Parameters Evaluationmentioning

confidence: 99%

“…Generally, there are two kinds of methods that can be used for assessing the curing condition of the composite repair patch, which are non-destructive testing (NDT) and structural health monitoring (SHM). The NDT techniques, such as acoustic emission [8], infrared thermal imaging [9], and ultrasonic testing [10], are often used for inspecting initial damage inside structures to eliminate the safety hazards. However, these NDT approaches are usually performed off-line, which are difficult to obtain the curing condition of epoxy resin in real-time.…”

Section: Introductionmentioning

confidence: 99%

Curing monitoring of bonded composite patch at constant temperature with electromechanical impedance and system parameters evaluation approach

Zhu¹,

Wen²,

Chen³

et al. 2021

Smart Mater. Struct.

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As one of cost-effective maintenance methods, bonded composite patch repair has been receiving more and more attention in the engineering community since past decades. However, realizing real-time monitoring for curing process of bonded repair patch is difficult for most current techniques. In our work, a method based on electromechanical impedance and system parameters evaluation for structural health monitoring issues was developed, which could implement the online monitoring throughout whole curing process. Compared with the dynamic thermomechanical analysis results, the experiment data matches well. It demonstrates that the proposed approach can effectively monitor the curing process of composite repair patch at a constant temperature of 120 °C. Hence, the presented approach in this paper is expected to be a novel, robust, and real-time monitoring method for structural maintenance with the composite patch.

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“…With the increasing demand for the performance of composite structures, many structural health monitoring (SHM) methods are required to be incorporated into life-cycle monitoring plans to obtain higher optimal quality [9]. Accordingly, a number of sensing and measurement technologies have emerged such as optical fiber sensing [10][11][12][13], ultrasonic sensing [14][15][16][17], electromechanical impedance [18][19][20], thermometers [21,22], and pressure transducers [23,24]. According to these sensing technologies, they enable one to follow manufacturing parameters such as the progress of the reaction, the residual stress, the development of the resin complex modulus, and the events during the curing cycle such as gelation and vitrification.…”

Section: Introductionmentioning

confidence: 99%

Real-Time Life-Cycle Monitoring of Composite Structures Using Piezoelectric-Fiber Hybrid Sensor Network

Liu

Yan

et al. 2021

Sensors

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In this paper, an in situ piezoelectric-fiber hybrid sensor network was developed to monitor the life-cycle of carbon fiber-reinforced plastics (CFRPs), from the manufacturing phase to the life in service. The piezoelectric lead-zirconate titanate (PZT) sensors were inserted inside the composite structures during the manufacturing process to monitor important curing parameters, including the storage modulus of resin and the progress of the reaction (POR). The strain that is related to the storage modulus and the state of resin was measured by embedded fiber Bragg grating (FBG) sensors, and the gelation moment identified by the FBG sensors was very close to those determined by dynamic mechanical analysis (DMA) and POR. After curing, experiments were conducted on the fabricated CFRP specimen to investigate the damage identification capability of the embedded piezoelectric sensor network. Furthermore, a modified probability diagnostic imaging (PDI) algorithm with a dynamically adaptive shape factor and fusion frequency was proposed to indicate the damage location in the tested sample and to greatly improve the position precision. The experimental results demonstrated that the average relative distance error (RDE) of the modified PDI method was 68.48% and 46.97% lower than those of the conventional PDI method and the PDI method, respectively, with an averaged shape factor and fusion frequency, indicating the effectiveness and applicability of the proposed damage imaging method. It is obvious that the whole life-cycle of CFRPs can be effectively monitored by the piezoelectric-fiber hybrid sensor network.

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Monitoring multiple damage mechanisms in crack‐patched structures using optical infrared thermography

Cited by 5 publications

References 31 publications

Integration of eddy current sensors into repair patches for fatigue reinforcement at rivet holes

Integration of eddy current sensors into repair patches for fatigue reinforcement at rivet holes

Curing monitoring of bonded composite patch at constant temperature with electromechanical impedance and system parameters evaluation approach

Real-Time Life-Cycle Monitoring of Composite Structures Using Piezoelectric-Fiber Hybrid Sensor Network

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