Modelling of fracture processes in laminate composite plates with embedded delamination

Tashkinov, Mikhail

doi:10.3221/igf-esis.39.23

Cited by 8 publications

(5 citation statements)

References 37 publications

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“…12. Effective resistance G Reff curves for delamination embedded in 0 • 4 //0 • 24 laminate (open symbols) and in 0 • 4 //90 • 20 /0 • 4Some qualitative verification of the obtained results can be made by comparing them against the results of the numerical analysis presented in the open literature[23,38]. However, this comparison is limited to delamination growth…”

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confidence: 71%

Archive of Mechanical Engineering

Czarnocki

Zagrajek

2020

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Growth stability analysis of embedded delaminations with the use of FE node relocation procedure and effective resistance curve conceptEmbedded delamination growth stability was analysed with the help of the FEM combined with a specially developed procedure for node relocation to obtain a smooth variation of the SERR components along the delamination contour. The procedure consisted in the replacement of the actual material with the very compliant fictitious one and the displacement of the delamination front nodes by the previously determined distance in a local coordinate system. Due to this loading, the new delamination front was created. Subsequently, the original material was restored. Evolution under inplane compression of three initially circular delaminations of diameters d = 30, 40 and 50 mm embedded in thin laminates of two different stacking sequences, i.e., 0 • 4 //0 • 24 and 0 • 4 //90 • 20 /0 • 4 were considered. It was found that the growth history and the magnitude of the load that triggers unstable delamination growth depended mainly on the combined effects of the initial delamination size, delamination contour, out of plane post-buckling geometry of the disbonded layers, reinforcement arrangement, and magnitude and variation of the SERR components along the delamination contour. To present the combined effect of these features, an original concept of the effective resistance curve, G Reff , was introduced.

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confidence: 71%

Archive of Mechanical Engineering

Czarnocki

Zagrajek

2020

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“…The issues in predicting the bearing capacity of structures and products made of composites remain unresolved. Therefore, it is necessary to understand how the locations and geometric parameters of defects influence the material and its mechanical properties [1][2][3][4][5][6]. Composite materials are widely used in various fields, which determines the importance of their study.…”

Section: Introductionmentioning

confidence: 99%

The Analysis of Stress Raisers Affecting the GFRP Strength at Quasi-Static and Cyclic Loads by the Theory of Critical Distances, Digital Image Correlation, and Acoustic Emission

et al. 2023

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The purpose of this work is to analyze the stress-raisers that affect the tensile strength and fatigue resistance of GFRP parts using the point and line methods of the theory of critical distances (TCD) to obtain a quantitative measure of the defect size that can be tolerated by the composite before it fails. In the course of the work, a method combining TCD and the Weibull function was developed. In the course of the work, GFRP structural fiberglass for electrical purposes was tested under uniaxial quasi-static and cyclic loading with digital image correlation (DIC) and acoustic emission (AE), as well as a numerical simulation of deformation. The studied specimens were plain (without a stress-raiser) and notched (V-shaped) with different notch root radii and depths. The results were used to determine the material critical distances. In this case, two approaches to TCD were used: line (LM) and point (PM) methods. To analyze the experimental results, finite element modeling was applied using the ANSYS software package. As a result, the linearized maximum principal stresses were obtained on the central line passing through the top of the stress raiser. Thus, the values of the critical distances of the material were determined by PM and LM. Based on the data obtained, the sizes of permissible defects in the studied fiberglass were established that do not affect the tensile and fatigue strength of the material. The paper illustrates the cumulative energy, peak amplitudes, and distributions of the frequency of the spectral maximum of acoustic emission signals obtained after the destruction of specimens by fatigue test. Evolutions of deformation fields on the specimen surface were recorded using a Vic-3D contactless optical video system and the DIC.

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“…Due to the very complex damages to composite structures with holes, all failure models contain approximated solutions or suggestions that have been more or less confirmed by experimental observations [14][15][16][17][18][19]. Therefore, experimental methods are required to improve models and confirm their results.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of the Sensitivity of Various Reinforcement Patterns for Structural Carbon Fibers to Open Holes during Tensile Tests

2021

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This paper is devoted to the experimental study of polymeric composite specimens, with various types of reinforcement, in order to evaluate the breaking strength of specimens with open holes when undergoing uniaxial compression and tensile tests. Four types of interlaced 3D woven preforms were considered (orthogonal, orthogonal combined, with pairwise inter-layer reinforcement, and with pairwise inter-layer reinforcement and a longitudinal layer), with a layered preform used for comparison. Tensile tests of solid specimens without a hole, under ASTM D 3039, and of specimens with an open hole, under ASTM D 5766, were carried out using the Instron 5989 universal electromechanical testing system. Movements and strains on the specimen surface were recorded using a Vic-3D contactless optical video system and the digital images correlation method (DIC). For all the series of carbon fiber tension specimens, strain and stress diagrams, mechanical characteristics, and statistical processing for 10 specimens were obtained. The paper evaluated deformation fields for certain points in time; the obtained fields showed an irregular distribution of deformation and dependency on types of reinforcing fibers. A coefficient of strength variation is introduced, which is defined as a ratio of the ultimate stress limits obtained on solid samples with and without open holes. Within the framework of ASTM D 5766, when calculating the ultimate stress, the hole is not taken into account, and the paper shows that for certain structures a hole cannot be excluded. The hole size must not be neglected when calculating the ultimate stress.

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Modelling of fracture processes in laminate composite plates with embedded delamination

Cited by 8 publications

References 37 publications

Archive of Mechanical Engineering

Archive of Mechanical Engineering

The Analysis of Stress Raisers Affecting the GFRP Strength at Quasi-Static and Cyclic Loads by the Theory of Critical Distances, Digital Image Correlation, and Acoustic Emission

Evaluation of the Sensitivity of Various Reinforcement Patterns for Structural Carbon Fibers to Open Holes during Tensile Tests

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