Thermal cycling of (heated) fibre metal laminates

Müller, Bernhard; Hagenbeek, Michiel; Sinke, J.

doi:10.1016/j.compstruct.2016.05.020

Cited by 29 publications

(37 citation statements)

References 20 publications

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“…It was based on an earlier reported one 37,38 with integrated structured light projector (LightCrafter™ DLP3000 by Texas Instruments 24 ). Three spatially-distributed shearing cameras, the laser with beam expansion optics and the projector were placed in a cross configuration using an Alufix modular fixture system imaging lenses and the shearing devices are based on Michelson interferometers 40,41 .…”

Section: D Shape Shearography System Prototypementioning

confidence: 99%

3D shape shearography with integrated structured light projection for strain inspection of curved objects

Anisimov

Groves

2015

SPIE Proceedings

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Shearography (speckle pattern shearing interferometry) is a non-destructive testing technique that provides full-field surface strain characterization. Although real-life objects especially in aerospace, transport or cultural heritage are not flat (e.g. aircraft leading edges or sculptures), their inspection with shearography is of interest for both hidden defect detection and material characterization. Accurate strain measuring of a highly curved or free form surface needs to be performed by combining inline object shape measuring and processing of shearography data in 3D. Previous research has not provided a general solution. This research is devoted to the practical questions of 3D shape shearography system development for surface strain characterization of curved objects. The complete procedure of calibration and data processing of a 3D shape shearography system with integrated structured light projector is presented. This includes an estimation of the actual shear distance and a sensitivity matrix correction within the system field of view. For the experimental part a 3D shape shearography system prototype was developed. It employs three spatially-distributed shearing cameras, with Michelson interferometers acting as the shearing devices, one illumination laser source and a structured light projector. The developed system performance was evaluated with a previously reported cylinder specimen (length 400 mm, external diameter 190 mmm) loaded by internal pressure. Further steps for the 3D shape shearography prototype and the technique development are also proposed.

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Section: D Shape Shearography System Prototypementioning

confidence: 99%

3D shape shearography with integrated structured light projection for strain inspection of curved objects

Anisimov

Groves

2015

SPIE Proceedings

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“…Hence, the main focus of this research is on the analysis of thermal strains and stresses in FMLs, which are caused by the local embedded heating. This paper supplements the previous conducted researches on FMLs and GLARE, which addressed the temperature dependent material characteristics, residual stresses, the temperature distribution, the long‐term behaviour, and thermal fatigue effects of GLARE and FMLs . This research includes the experimental measuring of the surface strains caused by the embedded heating and numerical modelling of the stress–strain state and temperature distributions.…”

Section: Introductionmentioning

confidence: 81%

“…The through‐the‐thickness assessment of the stress–strain state and temperature distributions were done supplementary to the two‐dimensional strain and temperature mapping of the measurements. Secondly, the model was used to predict stress–strain state and temperature distributions for a heating curve on the basis of expected de‐icing conditions . This regime was defined as the de‐icing regime.…”

Section: Numerical Analysesmentioning

confidence: 99%

“…These stand‐alone research questions are out of the scope of this paper. The experimental assessment of the thermal cycling was reported earlier . The value of this research is in the coupling of the experimental results on the surface behaviour characterisation (strain, temperature) with the numerical analysis revealing the through‐the‐thickness information on the temperature distributions and stress–strain state during the embedded heating of GLARE.…”

Section: Introductionmentioning

confidence: 99%

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Analysis of thermal strains and stresses in heated fibre metal laminates

Anisimov

Müller

Sinke

et al. 2018

Strain

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Current trends in aircraft design are to increase the economic efficiency by integrating different features in multifunctional materials. One strategy is to embed resistance heater elements between glass‐fibre epoxy layers in (heated) fibre metal laminates and to use them as anti or de‐icing devices in leading edges of wings. Heated glass fibre reinforced aluminium (GLARE) is an example of such a multifunctional material where heating functionality was added to the (certified) structural feature of GLARE. As heated fibre metal laminates are an innovative and rather new material, the possible (local) effects of embedded heating on the stress–strain state have not yet been investigated. This research couples experimental characterisation of heated GLARE surface behaviour and numerical modelling analysis to investigate the surface and the through‐the‐thickness strain‐stress state and temperature distributions due to the embedded heating. For the experimental part, the surface strains and the temperatures of a developed specimen were measured in a slow heating regime (temperature increase from 22.7 to 39.4 °C within 120 s) using, respectively, a developed shearography instrument and thermocouples with an infrared camera. Then a numerical model of heated GLARE was developed and verified with experimental results. Further, the numerical model was used to predict strains, stresses, and temperatures during a temperature increase similar to that used for de‐icing in a real operation (temperature increase from −25 to 86.7 °C within 4.8 s).

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“…Figure 1). The thermal cycling tests were conducted using a specifically designed thermal cycling setup which uses Peltier elements for cooling and/or heating 11,12 . Thus, the samples were exposed in total approximately 24, 48, and 72 hours above 70 °C as regards to the 0 °C to 120 °C after 4000, 8000, and 12000 thermal cycles respectively.…”

Section: Dimensions and Thermal Loadingmentioning

confidence: 99%

Monitoring chemical degradation of thermally cycled glass-fibre composites using hyperspectral imaging

et al. 2016

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Nowadays, the application of glass-fibre composites in light-weight structures is growing. Although mechanical characterizations of those structures are commonly performed in testing, chemical changes of materials under stresses have not yet been well documented. In the present work coupon tests and Hyperspectral Imaging (HSI) have been used to categorise possible chemical changes of glass-fibre reinforced polymers (GFRP) which are currently used in the aircraft industry. HSI is a hybrid technique that combines spectroscopy with imaging. It is able to detect chemical degradation of surfaces and has already been successfully applied in a wide range of fields including astronomy, remote sensing, cultural heritage and medical sciences. GFRP specimens were exposed to two different thermal loading conditions. One thermal loading condition was a continuous thermal exposure at 120°C for 24h, 48 h and 96h, i.e. ageing at a constant temperature. The other thermal loading condition was thermal cycling with three different numbers of cycles (4000, 8000, 12000) and two temperature ranges (0°C to 120°C and -25°C to 95°C). The effects of both conditions were measured using both HSI and interlaminar shear (ILSS) tests. No significant changes of the physical properties of the thermally cycled GFRP specimens were detected using interlaminar shear strength tests and optical microscopy. However, when using HIS, differences of the surface conditions were detected. The results showed that the different thermal loading conditions could be successfully clustered in different colours, using the HSI linear unmixing technique. Each different thermal loading condition showed a different chemical degradation level on its surface which was indicated using different colours.

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Thermal cycling of (heated) fibre metal laminates

Cited by 29 publications

References 20 publications

3D shape shearography with integrated structured light projection for strain inspection of curved objects

3D shape shearography with integrated structured light projection for strain inspection of curved objects

Analysis of thermal strains and stresses in heated fibre metal laminates

Monitoring chemical degradation of thermally cycled glass-fibre composites using hyperspectral imaging

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