Thermo-elastic constants of cracked symmetric laminates: A refined variational approach

Hajikazemi, M.; Sadr, M. H.; Hosseini‐Toudeshky, Hossein; Mohammadi, Bijan

doi:10.1016/j.ijmecsci.2014.08.008

Cited by 37 publications

(23 citation statements)

References 49 publications

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“…Contrary to displacement-based approaches, the approximate stress field derived with variational approaches satisfy exactly all the necessary equilibrium equations, interlaminar continuity and boundary conditions including zero-stress conditions at the free edges as well as the top and bottom surfaces of laminates. This approach was first introduced by Hashin [14] in 1985 for the analysis of cracked two-layer cross-ply laminates under uniaxial tension and further developed by many authors for analyzing cracked laminates with general lay-ups, see for example [15][16][17][18] as the most complete variational models developed so far. Kassapoglou and Lagace [10,19] were the first who applied the variational approach for analyzing stress concentrations near free edges.…”

Section: Introductionmentioning

confidence: 99%

“…Kassapoglou and Lagace [10,19] were the first who applied the variational approach for analyzing stress concentrations near free edges. The reader is referred to the recent publications [1,2,16,17] for a detailed review of the developments in variational approach for the free-edge [1,2] and matrix cracking [16,17] stress transfer problems.…”

Section: Introductionmentioning

confidence: 99%

“…Therefore, the interlaminar stress transfer problem can be reduced to a simple boundary value problem which is dependent only on the axial or transverse coordinate of the assumed laminate. For the variational free-edge stress transfer analysis [10,19] unlike the developed variational ply cracking models [15][16][17][18], this boundary value problem leads to a set of non-homogeneous differential equations as the Euler's equation(s) from the variational calculus.…”

Section: Introductionmentioning

confidence: 99%

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A variational model for free-edge interlaminar stress analysis in general symmetric and thin-ply composite laminates

Hajikazemi

Paepegem

2018

Composite Structures

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A variational model is developed to exactly determine both stress and displacement fields at free edges of general symmetric composite laminate strips under thermomechanical loads. By partitioning the total stresses in a composite with free edges into unperturbed (without free edge) and perturbation stresses and using the minimum complementary energy principle, the optimal stress and displacement fields are derived that exactly satisfy equilibrium, compatibility, boundary and continuity conditions. The paper extends the theory of stress-based variational stress transfer so that the effects of both applied traction and displacement loads can be considered. It has been also shown how the displacement field can be determined for a stress-based variational approach.The results are compared to refined finite element results. The superiority of the developed method over finite element method, both in terms of accuracy and computational efficiency, is discussed.The method is also applicable to thin-ply laminates and is computationally efficient.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A variational model for free-edge interlaminar stress analysis in general symmetric and thin-ply composite laminates

Hajikazemi

Paepegem

2018

Composite Structures

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“…The parametric excitation in delaminated plates is possible to appear, as well. 9,10,[127][128][129] subsequently in the near past.In this paper, it is shown that the phenomenon of parametric excitation can take place in free vibrating delaminated plates. Since-to the best of the author's knowledge-there is not available publication for the solution of this problem, the classical (or Kirchhoff) laminated plate theory (CLPT) is applied in this paper.…”

mentioning

confidence: 99%

“…The parametric excitation in delaminated plates is possible to appear, as well. 9,10,[127][128][129] subsequently in the near past.…”

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confidence: 99%

Natural vibration-induced parametric excitation in delaminated Kirchhoff plates

Szekrényes

2015

Journal of Composite Materials

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This paper revisits the problem of free vibration of delaminated composite plates with Lévy type boundary conditions. The governing equations are derived for laminated Kirchhoff plates including through-width delamination. The plate is divided into two subplates in the plane of the delamination. The kinematic continuity of the undelaminated part is established by using the system of exact kinematic conditions. The free vibration analysis of orthotropic simply supported Lévy plates reveals that the delaminated parts are subjected to periodic normal and in-plane shear forces. This effect induces parametric excitation leading to the susceptibility of the plates to dynamic delamination buckling during the vibration. An important aspect is that depending on the vibration mode the internal forces have a two-dimensional distribution in the plane of the delamination. To solve the dynamic stability problem the finite element matrices of the delaminated parts are developed. The distribution of the internal forces in the direction of the delamination front was considered. The mode shapes including a half-wave along the width of the plate accompanied by delamination buckling are shown based on the subsequent superimposition of the buckling eigenshapes. The analysis reveals that the vibration phenomenon is amplitude dependent. Also, the phase plane portraits are created for some chosen cases showing some special trajectories. KeywordsDelamination, free vibration, laminated plate theory, dynamic stability, parametric excitation, harmonic balance, finite element method IntroductionDelaminations are typical defects in composite and sandwich structures induced by indentations (e.g. local loading by spherical indentors), 1,2 low-velocity impact and free edge effects (normal and shear stress concentration between layers at free edges), 3-6 finally by fabrication defects. 7,8 The cracks and delaminations reduce significantly the strength and stiffness of composite laminates.9-11 The material defects also influence the dynamic behavior of the structures.12-20 One of the widely known dynamic phenomena is parametric excitation, which takes place in machine tools, 21 [73][74][75][76][77][78] and sandwich beams. 79In Burlayenko and Sadowski, 80 the foam/core debonding in sandwich plates was investigated during free vibration. However, the existence of the parametric excitation was not revealed in any of the former papers.To the best of the author's knowledge, the existence of the parametric excitation in the course of free vibration of delaminated composite beams was first revealed in Szekre´nyes 81 and was solved effectively by the FE and harmonic balance methods in Szekre´nyes.82 It was also shown that the delamination buckling takes place only if the free vibration amplitude exceeds the so-called critical amplitude at a specified point of the beam. The existence of the critical amplitude was also proved experimentally. The parametric excitation in delaminated plates is possible to appear, as well. 9,10,[127][128][129] subseq...

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Angle‐ply orientation‐dependent failure behaviors of carbon fiber reinforced polymer laminates

et al. 2021

J of Applied Polymer Sci

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This paper researches the micro‐failure behaviors of carbon fiber reinforced polymer (CFRP) laminates with different angle‐ply orientations subjected to tensile load. On the basis of the strain rates of 2.6 × 10−6 s−1 and 2.6 × 10−3 s−1, the significant difference in deformation behaviors of CFRP laminates with different angle‐ply orientations are investigated by using a miniature tensile tester. The scanning electron microscopy images are used to assess fracture damage modes of CFRP laminates, including matrix cracking, delamination, fiber‐matrix debonding, and fiber fracture, determined the “high‐low‐high” trend of the strength of laminates with the increase of ply angle. In order to analyze the crack propagation mechanism of laminates attributed to matrix micro‐crack under uniaxial tensile load, two wide applicable micro‐crack propagation models of laminates are proposed to explain the fracture damage failure behaviors of CFRP laminates with different angle‐ply orientations.

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Thermo-elastic constants of cracked symmetric laminates: A refined variational approach

Cited by 37 publications

References 49 publications

A variational model for free-edge interlaminar stress analysis in general symmetric and thin-ply composite laminates

A variational model for free-edge interlaminar stress analysis in general symmetric and thin-ply composite laminates

Natural vibration-induced parametric excitation in delaminated Kirchhoff plates

Angle‐ply orientation‐dependent failure behaviors of carbon fiber reinforced polymer laminates

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