Wyniki wyszukiwania - BazTech

1

Experimental investigation of Euler’s elastica: in-situ SEM nanowire post-buckling

Manecka-Padaż Aleksandra, Jenczyk Piotr, Pęcherski Ryszard B., Nykiel Anna

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2022

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Vol. 70, nr 6

art. no. e143648

EN

An in-situ nanoindenter with a flat tip was employed to conduct buckling tests of a single nanowire with simultaneous SEM imaging. A series of SEM images allowed us to calculate deflection. The deflection was confronted with the mathematical model of elastica. The post-buckling behaviour of nanowires is conducted in the framework of the nonlinear elasticity theory. Results show the significant effect of geometrical parameters on the stability of buckled nanowires.

2

Stability and failure of thin-walled composite structures with a square cross-section

Czajka Błażej, Różyło Patryk, Dębski Hubert

Applied Computer Science

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2022

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Vol. 18, no 2

43--55

EN

This paper is devoted to the analysis of the stability and load-carrying capacity of thin-walled composite profiles in compression. The specimens reflect elements made of carbon fibre reinforced laminate (CFRP). Thin-walled columns with a square cross-section were made from 4 layers of composite in 3 different combinations of layer arrangements. Advanced numerical analyses have been carried out. In the first stage of the study, a buckling analysis of the structure was performed. In further numerical simulations, two advanced models were used simultaneously: the Progressive Failure Analysis (PFA) and the Cohesive Zone Model (CZM). The results showed significant differences between the critical load values for each layer configuration. The forms of buckling and the areas of damage initiation and evolution were also dependent on the applied layup.

3

Asymptotic analysis of the clamped-pinned elastica

Singh P., Goss V. G. A.

Archives of Mechanics

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2018

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Vol. 70, nr 4

317--336

EN

Asymptotic solutions for the clamped-pinned elastica when the displacement of the pinned end is small (immediately after buckling) and when it approaches its limiting displacement (when the force in the rod tends to infinity) are presented. Simple leading order relationships describing the force as a function of the pinned end’s displacement are derived. Those approximate the force-displacement behaviour of the clamped-pinned elastica for small and limiting end displacements. All our results are valid for the clamped-pinned elastica in any mode.

4

Post–Buckling State of Rectangular Plate Stiffened by Denselly Arranged Ribs. Numerical Analysis and Experimental Investigation

Kopecki H., Święch Ł.

Mechanics and Mechanical Engineering

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2013

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Vol. 17, nr 1

71--87

EN

The paper presents results of comparative experimental examinations and numerical analyses of rectangular plates subjected to shear treated as a skin of half–monocoque aircraft structure. There were considered: the plate without stiffeners 2 mm thick and structure with 1 mm thickness, stiffened by 15 integral ribs. Results of nonlinear numerical FEM analyses and experimental investigations with use of 3D DIC method were compared to ones conducted for smooth plate with equivalent mass. It was documented that introduction of sub–stiffening significant influence on both the form of deformation and distribution of stress in the structure. For smooth plate low cycle fatigue test was conducted.

5

An analytical approach to large amplitude vibration and post-buckling of functionally graded beams rest on non-linear elastic foundation

Yaghoobi H., Torabi M.

Journal of Theoretical and Applied Mechanics

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2013

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Vol. 51 nr 1

39--52

EN

In this paper, non-linear vibration and post-buckling analysis of beams made of functionally graded materials (FGMs) rest on a non-linear elastic foundation subjected to an axial force are studied. Based on Euler-Bernoulli beam theory and von-Karman geometric non-linearity, the partial differential equation (PDE) of motion is derived.Then, this PDE problem is simplified into an ordinary differential equation problem by using the Galerkin method. Finally, the governing equation is analytically solved using the variational iteration metod (VIM). The results from the VIM solution are compared and shown to be in excellent agreement with the available solutions from the open literature. Some new results for the non-linear natural frequencies and buckling load of functionally graded (FG) beams, such as effects of vibration amplitude, elastic coefficients of foundation, axial force, end supports and material inhomogenity are presented for future references.

PL

W pracy przedstawiono analizę drgań nieliniowych i zjawisk następujących po wyboczeniu w belkach wykonanych z funkcjonalnych materiałów gradientowych (FGMs), spoczywających na nieliniowo sprężystym podłożu i jednocześnie poddanych osiowemu ściskaniu. Na podstawie teorii Eulera-Bernoulliego oraz przy uwzględnieniu geometrycznej nieliniowości von Karmana wyprowadzono cząstkowe równanie różniczkowe ruchu takich układów. Równanie to sprowadzono do postaci różniczkowej zwyczajnej za pomocą metody Galerkina. Na koniec, rozwiązano je analitycznie poprzez zastosowanie iteracyjnej metody wariacyjnej (VIM), a uzyskane rozwiązanie porównano z innymi, już istniejącymi i znanymi w literaturze, stwierdzając doskonałą zgodność. Otrzymano również nowe rezultaty w postaci określenia wpływu amplitudy drgań, sprężystości podłoża, wartości siły osiowej, rodzaju podparcia brzegów oraz niejednorodności materiału na częstości własne i obciążenie krytyczne belek gradientowych.

6

Experimental study on ultimate strength of CK20 steel cylindrical panels subjected to compressive axial load

Shariati M., Sedighi M., Saemi J., Eipakchi H. R., Allahbakhsh H. R.

Archives of Civil and Mechanical Engineering

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2010

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Vol. 10, no 2

117-130

EN

In this paper, the effects of the length, sector angle and boundary conditions on the buckling load and postbuckling behaviour of cylindrical panels have been studied, experimentally. The compressive axial load has been applied on the panels using servo-hydraulic machine and different boundary conditions have been prepared by suitable fixtures. The presented results can be used in designing of these structures.

PL

W pracy przedstawiono eksperymentalne wyniki wpływu długości i kąta sektora próbek oraz warunków brzegowych na siłę wyboczenia oraz ich zachowanie się po wyboczeniu. Badania przeprowadzono na maszynie hydraulicznej, gdzie za pomocą odpowiednich uchwytów uzyskano różne warunki brzegowe. Przedstawione wyniki mogą być wykorzystane w projektowaniu struktur cylindrycznych.

7

Buckling and initial post-buckling behaviour of thin-walled shell and plate structures

Królak M., Kołakowski Z.

International Journal of Applied Mechanics and Engineering

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2002

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Vol. 7, no 2

491-512

EN

The problem of critical states and initial post-buckling equilibrium paths of thin-walled girders (beam-columns) built of plate and/or shell elements subjected to compression and bending has been solved. Plate and shell elements can be made of multi-layer orthotropic materials. The problem has been solved within the first order approximation of Koiter's asymptotic theory, using the transition matrix method. The results of numerical calculations have been presented in the form of plots.

8

The alleviation of post-buckled displacements and non-linear stresses within laminated plates using SMA actuators

Thompson S. P., Loughlan J.

Applied Mechanics and Engineering

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2000

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Vol. 5, no 1

269-282

EN

Restoration forces, associated with embedded activated pre-strained shape memory alloy wires, have successfully been employed to enhance the post-buckling behaviour of various laminated plate structures. An extensive experimental and numerical programme has been conducted, of which, results will be presented. The manufacturing methodology of the hybrid SMA/carbon/epoxy plates is outlined. Such specimens feature 0.4 mm diameter shape memory alloy wires located within tubing at desired locations. Numerical thermal analysis has been employed to predict the non-uniform temperature profile, attributed to shape memory alloy activation through resistive heating, within the laminates. Structural finite element analysis has been employed to determine the hybrid plates adaptive response while under the influence of the uniaxial compressive load, in excess of its critical buckling value. It is shown that, utilizing the considerable control authority generated, even for a small actuator volume fraction, the out-of-plane displacement of the post-buckled laminates can be significantly reduced. Such displacement alleviation allows for the load redistribution away from the specimens unloaded edges. With the increase in use of composite materials within aerospace platforms, it is envisaged that the hybrid adaptive SMA/laminate configuration will extend the operational performance over conventional materials and structures, particularly when the structure is exposed to an elevated temperature.