Wyniki wyszukiwania - Biblioteka Nauki

1

Buckling of I-core sandwich panels

100%

Taczała M. , Banasiak W.

Journal of Theoretical and Applied Mechanics

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2004

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tom Vol. 42 nr 2

335-348

EN

Necessity of optimisation of ship hull structural mass calls for application of innovative materials and structural components. One option is based on using structural components with internal structure. The considered sandwich panels are composed of two plates stifenned by vertical ribs (I-core) or ribs of different shape (V-core). Such panels are applied as the ship hull structural components, replacing the conventional stiffened panels. They are subject to typical loadings acting in the ship hull; tension, compression and lateral loading. Analysis of stability of sandwich panels subject to compressive loading is presented in the paper. Stabilities of conventional and innovative ship panels were compared. Influence of the filling foam was also investigated.

PL

Optymalizacja masy kadłuba okrętowego wymaga zastosowania innowacyjnych materiałów i elementów konstrukcyjnych. Możliwe jest wykorzystanie elementów konstrukcyjnych ze strukturą wewnętrzną. Analizowane w pracy panele składają się z dwóch płyt usztywnionych żebrami pionowymi (I-core) lub żebrami innego kształtu (V-core). Panele takie stosowane są jako elementy konstrukcyjne kadłuba okrętowego zastępując konwencjonalne usztywnione panele. Poddane są one obciążeniu występującemu w kadłubie statku: rozciąganiu, ściskaniu i obciążeniu poprzecznemu. W pracy przedstawiono analizę stateczności sandwiczowych paneli typu I-core i V-core poddanych ściskaniu. Porównano stateczność konwencjonalnych i innowacyjnych paneli okrętowych. Zbadano także wpływ piany wypełniającej panele typu I-core.

2

Elastic buckling of a porous beam

80%

Magnucki K. , Stasiewicz P.

Journal of Theoretical and Applied Mechanics

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2004

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tom Vol. 42 nr 4

859-868

EN

The work deals with the problem a straight beam of a rectangular cross-section pivoted at both ends and loaded with a lengthwise compressive force. The beam is made of an isotropic porous material. Its properties vary through thickness of the beam. The modulus of elesticity is minimal on the beam axis and assumes maximum values at its top and bottom surfaces. The principle of stationarity of the total potential energy enables one to define a system of differential equations that govern the beam stability. The system is analytically solved, which leads to an explicit expression for the critical load of the compressed beam. Results of the solution are verified on an example beam by means of the Finite Element Method (COSMOS).

PL

Przedmiotem pracy jest prosta belka o przekroju prostokątnym, podparta przegubowo na obu końcach, obciążona wzdłużną siłą ściskającą. Belka wykonana jest z materiału izotropowego porowatego. Właściwości tego materiału są zmienne na wysokości belki. Na osi belki moduł sprężystości jest najmniejszy, natomiast na powierzchniach górnej i dolnej największy. Z zasady stacjonarności całkowitej energii potencjalnej wyznaczono układ równań różniczkowych stateczności belki. Uklad ten rozwiązano analitycznie i zapisano w postaci zamkniętej wyrażenie na obciążenie krytyczne ściskanej belki. Wyniki tego rozwiązania zweryfikowano dla przykładowej belki za pomocą metody elementów skończonych (System COSMOS).

3

The Influence of Composite Lay-Up on the Stability of a Structure with Closed Section

80%

Różyło P. , Dębski H.

Advances in Science and Technology. Research Journal

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2022

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tom Vol. 16, no 1

260--265

EN

This paper presents a study on the stability of a composite structure with a closed section. The research was carried out solely based on numerical simulations using the finite element method. ABAQUS software was used to conduct numerical simulations, which allowed to determine the values of critical loads, as well as the corresponding forms of buckling. As part of the research, the influence of composite material arrangement of layers on the stability of the structure was analyzed. The study was conducted on a composite material, which is a carbon-epoxy composite (CFRP). The obtained research results will be verified in subsequent studies by the results of experimental tests.

4

Numerical identification of material parameters for microbuckling analysis of fiber reinforced polymer matrix composites

80%

Romanowicz M.

Computer Methods in Materials Science

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2014

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tom Vol. 14, No. 2

108--113

EN

This research focuses on studying the effect of material parameters upon the compressive response of a unidirectional fiber reinforced polymer matrix composite. To investigate this effect, the finite element method and a periodic unit cell model of unidirectional composite with an initial fiber waviness and inelastic behavior of the matrix were used. The sensitivity of the compressive strength to the hydrostatic pressure, the flow rule and the fiber misalignment angle were presented. The model was verified against an analytical solution and experimental data. The results of this study indicate that a micromechanical model with correctly identified material parameters provides a useful alternative to theoretical models and experimentation.

PL

W pracy badano wpływ parametrów materiałowych na wytrzymałość na wzdłużne ściskanie kompozytu jednokierunkowo wzmocnionego. W tym celu wykorzystano metodę elementów skończonych oraz komórkę elementarną kompozytu z początkową imperfekcją włókien i plastyczną matrycą. Analizowano zmianę krzywej ściskania kompozytu w wyniku zmiany tarcia wewnętrznego matrycy, prawa plastycznego płynięcia matrycy oraz początkowej imperfekcji włókien. W celu identyfikacji wymienionych parametrów materiałowych wykorzystano badania doświadczalne oraz istniejące modele analityczne. Wyniki badań pokazują, że model numeryczny jest skuteczną alternatywą w analizie mikro-wyboczenia kompozytów polimerowych wzmocnionych ciągłym włóknem.

5

Numerical analysis of the critical state of thin-walled structure with Z-profile cross section

80%

Różyło P. , Łukasik D.

Advances in Science and Technology. Research Journal

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2017

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tom Vol. 11, no 1

194--200

EN

The object of the study was a thin-walled profile with Z-shaped cross section made of the carbon-epoxy composite. The material model was prepared based on the implemented orthotropic properties. The purpose of the study was to determine the value of the critical load at which buckling occurs, the form of buckling and operating characteristics in critical condition. In order to achieve this numerical analysis were carried out. Additionally, the effects of the modification in arrangement of layers of the laminate to the stability and strength of thin-walled composite structures was presented. Numerical studies were carried out using commercial simulation software - ABAQUS®. Within the FEM research, both forms of buckling and the associated critical load, dependent on the configuration the layers of the composite were achieved. The analysis of the obtained results allowed the evaluation of the structure’s work in relation to the level of energy consumption or rigidity estimation. In the paper only numerical simulations of the critical state were conducted.

6

A unit-cell approach to prediction of the microbuckling strength of composites with non-uniform fiber imperfections under combined axial compression and in-plane shear

80%

Romanowicz M.

Journal of Theoretical and Applied Mechanics

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2019

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tom Vol. 57 nr 2

303--316

EN

A new micromechanical model for predicting the failure locus of long fiber composites under combined axial compression and in-plane shear is proposed. The model is based on a periodic unit cell with centrally located imperfections. Predictions of the compressive behavior for various biaxial loading ratios are made. The role of distribution of fiber imperfections in predicting the biaxial strength is discussed. The failure locus calculated from the new model is found to be in good agreement with experimental data available in the literature and less conservative than that from the periodic model with uniform imperfections.

7

Analysis Of Frame Stability As Safety Requirement

80%

Holka H. , Kukliński M.

Journal of Polish CIMAC

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2009

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tom Vol. 4, no 3

41-48

EN

This work is an analysis of an accident that occurred in a warehouse during loading of a new multi-level storing frame. The frame was designed in a professional design office with aid of computer program. It is of great importance to carry out checking procedures at various steps of the computerized design process. In this article two different methods were applied in order to calculate the critical buckling force. Then the results were compared. The Euler’s and the Rayleigh’s method yielded convergent results. The both methods proved that the critical buckling force would be exceeded if the frame was fully loaded. Since the frame began to incline when it was loaded only in 80%, other reasons of buckling must also be considered. Although we can’t eliminate designer’s mistake, it is more probable, that the buckling resistance of the frame was reduced by inappropriate operation of hydraulic stackers. The photographs show that the construction was so tightly loaded with palettes, that the overloading was the most probable cause of the catastrophe. The bending moment originated during the loading process could also reduce the buckling resistance of the construction.

8

FEM analysis of critical loads plate with cut-out

80%

Falkowicz K. , Ferdynus M. , Wysmulski P.

Applied Computer Science

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2015

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tom Vol. 11, no 2

43--49

EN

The work presents the original conception of thin-walled plate element with the cut-out of irregular shape for use as a elastic or bearer element. The influence of geometrical parameters and the shape of the cut-out on the value of the critical load of the structure was researched. To discrete model and to perform numerical calculations used commercial program ABAQUS. Numerical calculations constitued own solution problem of compression structure and are the initial stage of research on work construction in elastic postcritical field with forced torsional-bending form of loss of stability was performed.

9

Risks and Implications for Decision-Making Processes Associated with Existing Design Codes or Their Non-Existence

80%

Błachut J. , Sala D.

Decision Making in Manufacturing and Services

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2018

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tom Vol. 12, no. 1-2

5--15

EN

The buckling phenomenon is a perplexing and unresolved issue in many safety critical structures; as a result, it has been heavily regulated. The existence of regulations would normally benefit modern decision-making tools. But there are various obstacles coming from real-life situations. In order to illustrate the above and draw awareness to the problem, the paper chooses the buckling of shells and discusses (i) the case of an internally pressurized dome found in a plane’s fuselage that failed during a routine flight, (ii) a case where advances in structural mechanics challenge the existing design codes (i.e., metallic domes in pressure vessels), and (iii) a case of extracting rich seabed resources where efficient buoyancy units are required. In the last-mentioned case, the paper points towards the use of advanced Carbon Fiber Plastics (CFRPs) and illustrates this by a failed CFRP dome manufactured from a woven fabric (a topic still within the research sphere of activities). Cases of several other industrial failures caused by buckling are also provided. Finally, the paper highlights the risks to the decision-making processes due to the growing tendencies of eliminating the records of disastrous events from public domains through confidentiality arrangements and the erosion of the existing human know-how.

10

Buckling of Compressed Thin-Walled Composite Structures with Closed Sections

80%

Różyło P. , Rosłaniec K. , Kuciej M.

Advances in Science and Technology. Research Journal

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2023

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tom Vol. 17, no 6

63--72

EN

The subject of the study was thin-walled composite structures, which were made of carbon-epoxy composite. The structures were characterized by a closed square cross-sectional shape. In the research paper, stability tests of axially compressed thin-walled composite structures were carried out in order to determine the critical state of the structures. Experimental tests were carried out on a universal testing machine, using a system for optical measurement of deformation of structures. Numerical simulations were carried out using the finite element method. The research made it possible to evaluate the work of the structure in the buckling state from a qualitative and quantitative point of view.

11

Prediction of Buckling Behaviour of Composite Plate Element Using Artificial Neural Networks

80%

Falkowicz K. , Kulisz M.

Advances in Science and Technology. Research Journal

|

2024

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tom Vol. 18, no 1

231--243

EN

This article presents the use of Artificial Neural Networks (ANNs) to analysis of the composite plate elements with cut-outs which can work as a spring element. The analysis were based on results from numerical approach. ANNs models have been developed utilizing the obtained numerical data to predict the composite plate’s flexural-torsional form of buckling as natural form for different cut-outs and angels configurations. The ANNs models were trained and tested using a large dataset, and their accuracy is evaluated using various statistical measures. The developed ANNs models demonstrated high accuracy in predicting the critical force and buckling form of thin-walled plates with different cut-out and fiber angels configurations under compression. The combination of numerical analyses with ANNs models provides a practical and efficient solution for evaluating the stability behaviour of composite plates with cut-outs, which can be useful for design optimization and structural monitoring in engineering applications.

12

Temperature Effect on Buckling Properties of Thin-Walled Composite Profile Subjected to Axial Compression

80%

Falkowicz K. , Kuciej M. , Święch Ł.

Advances in Science and Technology. Research Journal

|

2024

|

tom Vol. 18, no 3

305--313

EN

This study investigates the influence of temperature variations on the buckling properties of thin-walled omega-profiles fabricated from carbon-epoxy composite materials. Utilizing a MTS testing machine, compression tests were conducted on these profiles at temperatures ranging from -20°C to 80°C, in 20°C increments. The primary objective was to assess how temperature fluctuations impact the buckling load and load-bearing capacity of these composite profiles under axial compression. The experimental setup allowed for precise measurement of load-displacement and load-deflection characteristics, and the critical load at which buckling initiation occurred. Observations revealed that the buckling resistance of the profiles exhibited a complex dependence on temperature. At lower temperatures, the composite material demonstrated enhanced stiffness and strength, marginally increasing buckling resistance. Conversely, at elevated temperatures, a noticeable degradation in mechanical properties was observed, leading to a reduced buckling load and altered failure modes. To complement the experimental findings, a comprehensive finite element (FE) analysis was conducted for sample in room temperature. The FE model, developed to replicate the experimental conditions closely, employed an eigenvalue-based approach to predict the buckling initiation and progression accurately. The presented results are the results of only preliminary tests and they will be expand about more samples number as well as to determine material properties for various temperatures.

13

Buckling and initial post-buckling behaviour of thin-walled elliptic shells under bending

80%

Królak M. K. , Kołakowski Z.

Mechanics and Mechanical Engineering

|

2002

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tom Vol. 6, nr 1

63-71

EN

The problem of the buckling and the initial post-buckling equilibrium paths of thin-wailed cylindrical and elliptic shells subjected to bending has been tarried out. 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.

14

Numerical and experimental investigations of embedded delamination growth caused by compressive loading

80%

Bajurko P. , Czarnocki P.

Journal of Theoretical and Applied Mechanics

|

2014

|

tom Vol. 52 nr 2

301--312

EN

The paper deals with growth analysis of initially circular delaminations embedded in carbon-epoxy laminate plates subjected to compressive loading. Three different reinforcement lay-ups yielding different elastic laminate properties were considered. The numerical results were supplemented with experimental ones. The reasonably good agreement between the numerical predictions and experimental results was found. It was shown that variation in elastic properties of sub-laminates separated by delaminations significantly affected the way the delaminations propagated.

15

Buckling of cylindrical shells under external pressure in a Hamiltonian system

80%

Sun J. , Xu X. , Lim C. W.

Journal of Theoretical and Applied Mechanics

|

2014

|

tom Vol. 52 nr 3

641--653

EN

In this article, the elastic buckling behavior of cylindrical shells under external pressure is studied by using a symplectic method. Based on Donnell’s shell theory, the governing equations which are expressed in stress function and radial displacement are re-arranged into the Hamiltonian canonical equations. The critical loads and buckling modes are reduced to solving for symplectic eigenvalues and eigenvectors. The buckling solutions are mainly grouped into four categories according to the natures of the buckling modes. The effects of geometrical parameters and boundary conditions on the buckling loads and modes are examined in detail.

16

The Influence of Composite Lay-Up and the Shape of the Closed Section on the Stability of the Structure

80%

Czajka B. , Różyło P.

Advances in Science and Technology. Research Journal

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2022

|

tom Vol. 16, no 2

216--224

EN

Stability tests of a thin-walled composite structure with a closed section are presented in this paper. The purpose of this paper is to conduct preliminary studies in the context of numerical simulations of critical and slightly post-buckling states. The tests were conducted based only on numerical simulations by the finite element method. Numerical simulations were conducted using ABAQUS software, which allowed to determine the values of critical loads and their corresponding buckling forms. The influence of layer arrangement on the stability of the structure was studied. Carbon-epoxy laminate (CEL) was used in the tests. It is shown that there are composite lay-ups that show more than 1.3 times higher stiffness than the other cases. The paper demonstrates the dependence of the influence of the arrangement of layers on the stability of the structure, which will provide the basis for planned experimental studies (the results require experimental verification, which will be carried out in subsequent studies).

17

Buckling behaviour of single-walled carbon nanotubes under axial loading

80%

Litak G.

Advances in Science and Technology. Research Journal

|

2017

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tom Vol. 11, no 1

208--211

EN

We investigate the behaviour of a single-walled Carbon Nanotube under axial compressive line load applied at both edges. The expected buckling response is studied by application of a molecular computation model. We formulate a global potential and search for its minimum to obtain the equilibrium configuration. The critical nanotube diameter, when local shell buckling occurs, is measured with two parameters: the value of compression loading and tube diameter.

18

Experimental and numerical analysis of the compression thin-walled composite plate

80%

Falkowicz K. , Mazurek P. , Różyło P. , Wysmulski P. , Smagowski W.

Advances in Science and Technology. Research Journal

|

2016

|

tom Vol. 10, nr 31

177--184

EN

The subject of research is a rectangular plate with a cut-out subjected to regular compression. The plate articulately supported on the short side edges, made of a composite with high strength properties. The study concerned the numerical finite element analysis linear and nonlinear stability of the structure and the experimental validation of the results. The instrument used was a numerical program ABAQUS®.

19

Exact solution for temperature-dependent buckling analysis of FG-CNT-reinforced mindlin plates

80%

Mousavi S. M. , Kolahchi R.

Advances in Science and Technology. Research Journal

|

2016

|

tom Vol. 10, nr 29

152--160

EN

This research deals with the buckling analysis of nanocomposite polymeric temperature-dependent plates reinforced by single-walled carbon nanotubes (SWCNTs). For the carbon-nanotube reinforced composite (CNTRC) plate, uniform distribution (UD) and three types of functionally graded (FG) distribution patterns of SWCNT reinforcements are assumed. The material properties of FG-CNTRC plate are graded in the thickness direction and estimated based on the rule of mixture. The CNTRC is located in a elastic medium which is simulated with temperature-dependent Pasternak medium. Based on orthotropic Mindlin plate theory, the governing equations are derived using Hamilton's principle and solved by Navier method. The influences of the volume fractions of carbon nanotubes, elastic medium, temperature and distribution type of CNTs are considered on the buckling of the plate. Results indicate that CNT distribution close to top and bottom are more efficient than those distributed nearby the mid-plane for increasing the stiffness of plates.

20

Innovative Look at the 'General Method' of Assessing Buckling Resistance of Steel Structures

80%

Czepiżak D.

Studia Geotechnica et Mechanica

|

2021

|

tom Vol. 43, nr 4

337--345

EN

Stability checking is an essential element of the dimensioning of steel frame structures. One of the stability checking methods allowed by EN 1993-1-1 is the so-called general method of assessing structural stability, based on buckling curves and relative structure slenderness λ¯op usually determined through numerical analyses. But this method is not widely used because of the limited computing capabilities of the engineering programs dedicated to static load analyses and difficulties in interpreting the results of the computations. The commonly used computer programs enable one to determine the shape of buckling and critical load amplifier αcr, from which one cannot directly determine the risk of buckling of a real structure. This paper presents a modified and innovative approach to the general method of assessing structural stability, which uses only three parameters, that is, the type of cross section, cross-section strength utilisation and αcr, to determine a member’s/structure’s bearing capacity mobilisation from the stability condition. The problem solution is presented in the form of simple formulas and legible diagrams. Finally, synthetic conclusions are formulated.