Monitoring Poisson’s ratio of glass fiber reinforced composites as damage index using biaxial Fiber Bragg Grating sensors

Yılmaz, Çağatay; Akalın, Çağdaş; Kocaman, Esat Selim; Suleman, Afzal; Yıldız, Mehmet

doi:10.1016/j.polymertesting.2016.05.009

Cited by 22 publications

(9 citation statements)

References 14 publications

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“…The TDR increases linearly with compressive and tensile shear strains. This is a different trend compared to the behaviour reported in the literature for 0°/90° FRP laminates 13,14 and ±40°/90°laminates. 15 For multidirectional laminates with 0-degree and off-angle plies under tensile loading, such an increase was shown.…”

Section: Resultscontrasting

confidence: 89%

Correction factors for in-plane shear strength and stiffness testing of flat angle-ply composite laminates with high Poisson’s ratios

Sieberer

Schagerl

2022

Polymers and Polymer Composites

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In this paper, a method to obtain correction factors for in-plane shear properties in fibre-reinforced polymers with high Poisson’s ratio under biaxial load conditions and at high loads is presented. Experimental testing shows the deviations from classical laminate theory for such cases. The transverse deformation ratio is a general form of Poisson’s ratio and, for a ±45° angle-ply laminate, increases with strain. This effect is shown to exist for long and short test specimens, where significant biaxiality in the stress state is present. Reasons for this include fibre rotation at higher loads in tensile load conditions, and matrix plasticity and damage initiation. Test results show that the expanded formulas compensate errors in shear strength calculation of angle-ply laminates which arise from using nominal parameters with standard formulas. The results are also applicable to structures under biaxial load and when transverse contraction is inhibited, e.g. in shear panels. Further potential uses are in the presence of high shear strains and to detect the onset of damage under shear loading.

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Section: Resultscontrasting

confidence: 89%

Correction factors for in-plane shear strength and stiffness testing of flat angle-ply composite laminates with high Poisson’s ratios

Sieberer

Schagerl

2022

Polymers and Polymer Composites

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“…Any change in bragg wavelength due to thermal and/or mechanical strains can be written as equation (1): where Pe is strain-optic coefficient of fiber, normalΔεitalicapp is applied mechanical strain on fiber, αf is thermal expansion coefficient of fiber, normal ξ is thermo-optic coefficient of fiber and normalΔT is the temperature variance during measurements. Since temperature does not change very significantly during conventional tensile tests and any possible temperature variation due to failure is momentarily, second term of the above equation can be ignored and change in Bragg wavelength will be only a function of mechanical strain (Yilmaz et al., 2016). Due to their capability of non-invasive internal measurements, two single mode fiber optic gratings purchased from Technica were used with Bragg wavelengths of λ B = 1550 nm and λ B = 1540 nm.…”

Section: Materials Experimental Procedures and Smoothing Element Anal...mentioning

confidence: 99%

“…Tensile specimen were cut according to ASTM D3039, however as already devised by authors (Yilmaz et al., 2016), an L-shaped specimen was prepared to enable the ingress of FBG sensors into the laminated specimen. Specimens were cut precisely to ensure that the position of FBG sensors was just at the midpoint of the gauge length area.…”

Section: Materials Experimental Procedures and Smoothing Element Anal...mentioning

confidence: 99%

Damage growth and failure detection in hybrid fiber composites using experimental in-situ optical strain measurements and smoothing element analysis

Tabrizi

Kefal

Zanjani

et al. 2021

International Journal of Damage Mechanics

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In previous study the failure initiation and development in hybrid fiber laminates was successfully monitored and determined. In current investigation a novel damage monitoring approach is proposed for hybrid laminates by combining different optical strain measurement techniques namely digital image correlation (DIC), fiber Bragg grating sensors (FBG) and infrared thermography (IRT) with smoothing element analysis (SEA). This viable experimental procedure eliminates the effects of global/local nature of optical strain measurement systems on heterogeneous damage accumulation and is a two-step approach. First, all optical sensing systems together with conventional strain gauges are utilized concurrently to indicate the differences in the measured strains and monitor damage accumulation under tensile loading. This demonstrates how failure events disturb the measurement capabilities of optical systems, which can cause a miscalculation of hybrid effect in hybrid-fiber laminates. The second step involves the utilization of SEA algorithm for discretely measured DIC displacements to predict a realistic continuous displacement/strain map and rigorously mitigate the inherent noise of the full field optical system. Remarkably, for large deformation states in hybrid composites, the combination of SEA/DIC enables early prediction of susceptible damage zones at stress levels 30% below material strength.

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“…In recent decades, significant progress has been made in different forms of SHM technologies for various material and structural systems [ 4 , 5 ]. The SHM of simple and complex structural topologies (e.g., shell models with surface cracks [ 6 , 7 ]) made of isotropic materials (e.g., steel/aluminum structures [ 2 , 3 , 8 ]) or orthotropic materials (e.g., multilayered composite and sandwich structures [ 9 , 10 ]) are studied under static and dynamic loading conditions. Particularly, damage, delamination, and fatigue in laminated composite and foam-core sandwich structures were identified using embedded fiber optic sensors [ 11 , 12 , 13 ].…”

Section: Introductionmentioning

confidence: 99%

A Comparative and Review Study on Shape and Stress Sensing of Flat/Curved Shell Geometries Using C0-Continuous Family of iFEM Elements

Abdollahzadeh

Kefal

Yıldız

2020

Sensors

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In this study, we methodologically compare and review the accuracy and performance of C0-continuous flat and curved inverse-shell elements (i.e., iMIN3, iQS4, and iCS8) for inverse finite element method (iFEM) in terms of shape, strain, and stress monitoring, and damage detection on various plane and curved geometries subjected to different loading and constraint conditions. For this purpose, four different benchmark problems are proposed, namely, a tapered plate, a quarter of a cylindrical shell, a stiffened curved plate, and a curved plate with a degraded material region in stiffness, representing a damage. The complexity of these test cases is increased systematically to reveal the advantages and shortcomings of the elements under different sensor density deployments. The reference displacement solutions and strain-sensor data used in the benchmark problems are established numerically, utilizing direct finite element analysis. After performing shape-, strain-, and stress-sensing analyses, the reference solutions are compared to the reconstructed solutions of iMIN3, iQS4, and iCS8 models. For plane geometries with sparse sensor configurations, these three elements provide rather close reconstructed-displacement fields with slightly more accurate stress sensing using iCS8 than when using iMIN3/iQS4. It is demonstrated on the curved geometry that the cross-diagonal meshing of a quadrilateral element pattern (e.g., leading to four iMIN3 elements) improves the accuracy of the displacement reconstruction as compared to a single-diagonal meshing strategy (e.g., two iMIN3 elements in a quad-shape element) utilizing iMIN3 element. Nevertheless, regardless of any geometry, sensor density, and meshing strategy, iQS4 has better shape and stress-sensing than iMIN3. As the complexity of the problem is elevated, the predictive capabilities of iCS8 element become obviously superior to that of flat inverse-shell elements (e.g., iMIN3 and iQS4) in terms of both shape sensing and damage detection. Comprehensively speaking, we envisage that the set of scrupulously selected test cases proposed herein can be reliable benchmarks for testing/validating/comparing for the features of newly developed inverse elements.

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Monitoring Poisson’s ratio of glass fiber reinforced composites as damage index using biaxial Fiber Bragg Grating sensors

Cited by 22 publications

References 14 publications

Correction factors for in-plane shear strength and stiffness testing of flat angle-ply composite laminates with high Poisson’s ratios

Correction factors for in-plane shear strength and stiffness testing of flat angle-ply composite laminates with high Poisson’s ratios

Damage growth and failure detection in hybrid fiber composites using experimental in-situ optical strain measurements and smoothing element analysis

A Comparative and Review Study on Shape and Stress Sensing of Flat/Curved Shell Geometries Using C0-Continuous Family of iFEM Elements

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