Finite element mesh generation for composites with ply waviness based on X-ray computed tomography

Nikishkov, Gennadiy; Nikishkov, Yuri; Makeev, Andrew

doi:10.1016/j.advengsoft.2013.01.002

Cited by 32 publications

(19 citation statements)

References 17 publications

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“…Creighton et al [9] and Sutcliffe et al [10] have captured the fiber orientation and its scattering by means of digital image analysis. Nikishkov et al [11] investigated automated FE mesh generation based on CT images.…”

Section: Wave Description and Influence Parametermentioning

confidence: 99%

Numerical and experimental investigation of out-of-plane fiber waviness on the mechanical properties of composite materials

et al. 2020

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The limited capability to predict material failure in composite materials and specifically in wavy composite layers has led to high margins of safety for the design of composite structures. Thus, the full lightweight potential of this class of materials is left unused. To understand the complex failure behavior of composite materials containing out-of-plane fiber waviness under compressive and tensile loading, a non-linear 2D material model was implemented in ABAQUS and validated with extensive experimental test data from compression and tensile tests. Each test was recorded by a stereo camera system for digital image correlation to resolve damage initiation and propagation in detail. This study has shown excellent agreement of numerical simulations with experimental data. In a virtual testing approach various parameters, i.e. amplitude, wavelength and laminate thickness, have been studied. It was found that the failure mode changed from delamination to kink shear band formation with increasing laminate thickness. The wavelength has shown minor influences compared to amplitude and laminate thickness.

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Section: Wave Description and Influence Parametermentioning

confidence: 99%

Numerical and experimental investigation of out-of-plane fiber waviness on the mechanical properties of composite materials

et al. 2020

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“…Importantly, the presence of a wrinkle defect can significantly effect the structural integrity of the as-manufactured part, in some cases leading to expensive wholesale rejection. Naturally there has been a focused research effort to develop non-destructive methods (NDT) to measure and classify wrinkles in as-manufactured parts [10][11][12][13][14]. Amongst the variety of NDT methods available, only some are suitable for investigating geometric features at the meso-scale (sub-laminate scale).…”

Section: Introductionmentioning

confidence: 99%

“…Amongst the variety of NDT methods available, only some are suitable for investigating geometric features at the meso-scale (sub-laminate scale). The most popular of these are X-ray computed tomography (XRCT) [10], ultrasonic techniques [11,12] or infrared thermography [13]. XRCT can provide fibre scale resolution in a 3D volume but it is a much slower process compared to some ultrasonic methods which sacrifice accuracy for speed by limiting resolution.…”

Section: Introductionmentioning

confidence: 99%

A Bayesian framework for assessing the strength distribution of composite structures with random defects

Sandhu

Reinarz

Dodwell

2018

Composite Structures

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This paper presents a novel stochastic framework to quantify the knock down in strength from out-of-plane wrinkles at the coupon level. The key innovation is a Markov Chain Monte Carlo algorithm which rigorously derives the stochastic distribution of wrinkle defects directly informed from image data of defects. The approach significantly reduces uncertainty in the parameterization of stochastic numerical studies on the effects of defects. To demonstrate our methodology, we present an original stochastic study to determine the distribution of strength of corner bend samples with random out-plane wrinkle defects. The defects are parameterized by stochastic random fields defined using Karhunen-Loéve (KL) modes. The distribution of KL coefficients are inferred from misalignment data extracted from B-Scan data using a modified version of Multiple Field Image Analysis. The strength distribution is estimated, by embedding wrinkles into high fidelity FE simulations using the high performance toolbox dune-composites from which we observe severe knockdowns of 74% with a probability of 1/200. Supported by the literature our results highlight the strong correlation between maximum misalignment and knockdown in coupon strength. This observations allows us to define a surrogate model providing fast assessment of predicted strength informed from stochastic simulations utilizing both observed wrinkle data and high fidelity finite element models.

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“…In order to detect any defect that may have appeared during the manufacturing process before the blades are installed in the wind farms, several non-destructive testing techniques are already in use (9) although not every technique allows the detection of wrinkles. Even though Micro-focus X-Ray Computed Tomography (Micro-CT) is the technique that provides the most detailed information for 3D characterisation of fibre orientation on small components; it is expensive and it is not a practical technique for large components (10)(11) due to the trade-off between resolution and component size. In components as large as turbine blades Micro-CT does not achieve sufficient resolution of ply boundaries (requires 20 µm voxel size or less) and, therefore, wrinkles, so other techniques must be considered.…”

Section: Introductionmentioning

confidence: 99%

Wrinkle measurement in glass-carbon hybrid laminates comparing ultrasonic techniques: A case study

Larrañaga-Valsero¹,

Smith²,

Tayong

et al. 2018

Composites Part A: Applied Science and Manufacturing

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Wrinkles, (also known as out-of-plane waviness) are, unfortunately, a common phenomenon that has caused some wind-turbine blades to unexpectedly fail in service. Being able to detect the wrinkles while in the factory will reduce the risk of catastrophic failure and characterising the wrinkles would minimise the repaired area, thus increasing the efficiency of the repair and the design. This work compares the effectiveness of three different ultrasound techniques for detecting and characterising out-of-plane wrinkles in the typical glass-carbon hybrid laminates that are used for wind-turbine blades. The tests samples were manufactured so that the laminates and the defects are representative of those used in the wind-turbine industry. Basic mechanical tests were performed to check the drop in mechanical properties due to wrinkling. The ideal probe frequency was determined as the resonance frequency of the plies using an analytical ultrasonic-propagation model. The three different ultrasound techniques used are: full-matrix capture (FMC) with the total focusing method (TFM), a commercial phased-array instrument and an immersion test with a raster-scanned single-element focused probe. When possible, severity parameters of the wrinkle were measured on the ultrasonic images and compared with the measurements of the actual sample in order to determine which method best characterises such wrinkles and which would be more appropriate to implement in an industrial environment. Not all of the techniques allowed full characterisation of out-of-plane waviness on the specimens. The FMC/TFM method gave better results whilst phased-array technology and single-element immersion testing presented more challenges. An additional enhancement to the TFM imaging was achieved using an Adapted-TFM method with an angle-dependent velocity correction.

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Finite element mesh generation for composites with ply waviness based on X-ray computed tomography

Cited by 32 publications

References 17 publications

Numerical and experimental investigation of out-of-plane fiber waviness on the mechanical properties of composite materials

Numerical and experimental investigation of out-of-plane fiber waviness on the mechanical properties of composite materials

A Bayesian framework for assessing the strength distribution of composite structures with random defects

Wrinkle measurement in glass-carbon hybrid laminates comparing ultrasonic techniques: A case study

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