Dynamic Stability of a Structurally Damped Delaminated Beam Using Higher Order Theory

Pölöskei, Tamás; Szekrényes, András

doi:10.1155/2018/2674813

Cited by 5 publications

(1 citation statement)

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“…As the composite materials play important role in the industrial applications [11], the strong adhesion between the laminated layers is essential and must remain reliable even at high strains and high stresses [15]. Presence and propagation of a delamination in lightweight composite materials [35,38] can significantly decrease the load bearing capability of the structure [7,26,28], modify the dynamic properties [6,20,27,39,40], and furthermore, they can easily lead to sudden and catastrophic failure of the brittle mechanical system. Thus, the description [22,36] and the avoidance [10,59] of an interlaminar failure, which may take place because of low-velocity impact [5,24], blast loading [32,37], manufacturing defects [16][17][18] and free edge effects [13], are inevitable from engineering point of view.…”

Section: Introductionmentioning

confidence: 99%

Fracture and mode mixity analysis of shear deformable composite beams

Kiss

Szekrényes

2019

Arch Appl Mech

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To analyse delaminated composite beams with high accuracy under mixed-mode I/II fracture conditions first-, second-, third-and Reddy's third-order shear deformable theories are discussed in this paper. The developed models are based on the concept of two equivalent single layers and the system of exact kinematic conditions. To deduce the equilibrium equations of the linearly elastic system, the principle of virtual work is utilised. As an example, a built-in configuration with different delamination position and external loads are investigated. The mechanical fields at the delamination tip are provided and compared to finite element results. To carry out the fracture mechanical investigation, the J -integral with zero-area path is introduced. Moreover, by taking the advantage of the J -integral, a partitioning method is proposed to determine the ratio of mode-I and mode-II in-plane fracture modes. Finally, in terms of the mode mixity, the results of the presented evaluation techniques are compared to numerical solutions and previously published models in the literature.Keywords Delamination · Energy release rate · Mixed-mode I/II fracture · J -integral · Higher-order beam theories IntroductionAs the composite materials play important role in the industrial applications [11], the strong adhesion between the laminated layers is essential and must remain reliable even at high strains and high stresses [15]. Presence and propagation of a delamination in lightweight composite materials [35,38] can significantly decrease the load bearing capability of the structure [7,26,28], modify the dynamic properties [6,20,27,39,40], and furthermore, they can easily lead to sudden and catastrophic failure of the brittle mechanical system. Thus, the description [22,36] and the avoidance [10,59] of an interlaminar failure, which may take place because of low-velocity impact [5,24], blast loading [32,37], manufacturing defects [16][17][18] and free edge effects [13], are inevitable from engineering point of view.The application of the linear elastic fracture mechanics is one possibility to characterise the interlaminar fracture resistance of conventional high performance composites with inherent brittleness [8,9]. The critical value of the energy release rate G c , which can be considered as a material property, is suitable to characterise the strength of an interface layer between two elastic plies [19]. Like any other material parameters, mechanical tests must be carried out to be determined. In the case of fracture mechanical investigation, as linear elastic fracture mechanics works only if the location, size andshape of the crack are known, the experiments must be B. Kiss (B) · A. Szekrényes

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Section: Introductionmentioning

confidence: 99%

Fracture and mode mixity analysis of shear deformable composite beams

Kiss

Szekrényes

2019

Arch Appl Mech

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On the dynamic stability of delaminated composite beams under free vibration

2022

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This work deals with the analysis of the free vibration problem of elastic delaminated composite beams. The work mainly consists of a model development and improvement stage based on the first-order shear deformable beam theory. A general model is developed taking the bending-extensional coupling into account. The specified problem is a built-in beam with free end, and one of the novelties of this work is the consideration of the fact that a built-in beam cannot be fixed rigidly in reality. Thus, a Winkler-type elastic foundation is applied along the built-in length. The total potential energy and the governing equations of the delaminated and intact parts of the beam are also captured. The problem is solved in two ways: analytically and numerically by using the finite element method, respectively. Applying the developed models the natural frequencies, mode shapes as well as the stress resultants are determined. The comparison of natural frequencies to those measured experimentally shows that the built-in length resting on Winkler-type elastic foundation influences significantly the agreement between model and experiment. In the final stage, the parametric excitation phenomenon taking place in the delaminated part is analyzed using a local model and the harmonic balance method. The dynamic buckling is characterized by some stability diagrams, and it is shown that the applied model is very sensitive to the frequency leading to somewhat controversial critical amplitudes compared to measurements.

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Mechanics of delaminated composite beams subjected to retarded follower force with multiple time delay

Szekrényes

2024

Acta Mech

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In this work the problem of a delaminated composite cantilever beam subjected to a retarded periodically changing follower axial force is taken into consideration. The equation of motion is deduced based on a previous work including finite element discretization in space. On the other hand the delayed system is captured by the Chebyshev polynomials of the first kind in the time domain. The most important aspect of the model is that multiple time delay is considered, i.e., the principal period of the parametric excitation is not equal to the delay. Under these conditions the stability of the system is investigated using the Floquet theory and the unit circle criterion. The stability diagrams are determined for large number of cases focusing essentially on the effect of delamination on the stable domains. The main conclusion is that although the delamination length and thicknesswise position does not have an essential effect on the stability domains, the definite offset of the limit curves may be observed. In contrast, the relation of time delay and principal period influences substantially the shape and nature of limit curves on certain parameter planes.

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Dynamic Stability of a Structurally Damped Delaminated Beam Using Higher Order Theory

Cited by 5 publications

References 45 publications

Fracture and mode mixity analysis of shear deformable composite beams

Fracture and mode mixity analysis of shear deformable composite beams

On the dynamic stability of delaminated composite beams under free vibration

Mechanics of delaminated composite beams subjected to retarded follower force with multiple time delay

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