Wyniki wyszukiwania - BazTech

1

Flexural Buckling Resistance of Stiffeners Reinforcing Wall of a Steel Silo

Marcinowski Jakub

Civil and Environmental Engineering Reports

|

2023

|

Vol. 33, no. 3

89--98

EN

Stiffeners reinforcing silo’s wall made from corrugated sheets are main structural elements sustaining meridional forces evoked by shear forces, source of which is friction of the material stored inside silo. Buckling resistance of stiffeners can be assessed by the method recommended in PN-EN 1993-4-1:2009/A1-2017-08E and in the draft of the Eurocode prEN 1993-4-1:2022. This method consists in determination of stiffener’s resistance treated as a column resting on elastic substrate which is the susceptible wall of the silo. It means that it was assumed that the stiffness of the sheeting resists buckling displacements normal to the silo wall. The procedure recommended in mentioned Eurocodes requires determination of stiffness coefficient K on the basis of the flexibility of an equivalent arch of the span equal to the double circumferential separation between adjacent stiffeners. The stiffness coefficient K was derived in the paper using classical mechanics methods and its value was compared to the one given in mentioned Eurocodes. Careful comparative analyses resulted in the identification of errors in one of the Eurocode formulae, which could result in a significant misestimation of the buckling resistance of the stiffeners. The proposed amendment led to a full correspondence between the final formula for K derived in the paper and that proposed in the referenced Eurocodes. The errors found were reported to the coordinator of the CEN working group updating EN 1993-4-1.

2

Fatigue Strength of Thin-Walled Rectangular Elements in the State of Post-Critical Deformation

Mazurek Przemysław

Advances in Science and Technology. Research Journal

|

2019

|

Vol. 13, no 2

84--91

EN

The paper presents the results of numerical analyses and static experimental testing of thin-walled rectangular elements subject to post-critical deformation under shear conditions. The deliberations concerned the elements made of aluminium alloy and the model material. The obtained stress distribution was used to conduct a numerical simulation of the fatigue strength for a metal plate and testing under cyclic load conditions for both types of models.

3

The influence of geometric imperfections on the stability of three-layer beams with foam core

Wstawska I.

Archives of Mechanical Technology and Materials

|

2017

|

Vol. 37

65--69

EN

The main objective of this work is the numerical analysis (FE analysis) of stability of three-layer beams with metal foam core (alumina foam core). The beams were subjected to pure bending. The analysis of the local buckling was performed. Furthermore, the influence of geometric parameters of the beam and material properties of the core (linear and non-linear model) on critical loads values and buckling shape were also investigated. The calculations were made on a family of beams with different mechanical properties of the core (elastic and elastic-plastic material). In addition, the influence of geometric imperfections on deflection and normal stress values of the core and the faces has been evaluated.

4

Selected Problems of Determining Critical Loads in Sructures with Stable Post–Critical Behaviour

Czapski P., Kubiak T.

Mechanics and Mechanical Engineering

|

2016

|

Vol. 20, nr 2

79--95

EN

This paper presents selected cases of inapplicability of theory based methods of determining critical loads in thin – walled, composite tubes. 8th layered composite tubes with square cross-section were being subjected to static compression and in order to register experimental data two measuring equipment were employed: strain-gauges and Digital Image Correlation system ARAMIS R. When measurement data were collected five different theory based methods were applied in order to determine critical loads. Cases where it was impossible to apply certain methods or some doubts about correctness of the results occurred were presented and analyzed. Moreover in cases where it was possible, the theory was equivalently transformed, in such a way to fit experimental data and calculate the critical loads.

5

Buckling Analysis of Cold Formed Silo Column

Rejowski K., Iwicki P.

Mechanics and Mechanical Engineering

|

2016

|

Vol. 20, nr 2

109--120

EN

The paper is devoted to stability analysis of different models of steel cold formed silo column. The steel cylindrical silos are often composed of corrugated walls and vertical open-sectional columns uniformly placed along the silo circumference. Both the whole 3D silo, a simplified model consisting of one column with a part of the silo walls, and a single column resting on elastic foundation provided by the silo walls were analyzed. Linear buckling analyses were carried out using commercial FE package ABAQUS. Axisymmetric and non-axisymmetric loads imposed by a bulk solid following Eurocode 1 were considered. The calculated buckling loads of 1D column model were compared with the permissible one given by Eurocode 3 and with results found for the whole silo and a single column on elastic foundation modeled by shell elements.

6

Rozpoznawanie przyczyn wyboczeń torów

Bałuch H., Nowosińska I.

Przegląd Komunikacyjny

|

2015

|

Nr 9

102--103

PL

Wyboczenia torów należą do największych zagrożeń bezpieczeństwa ruchu kolejowego. Zmiany klimatyczne zachodzące w ostatnich latach, głównie rosnące ocieplenie, mogą wpłynąć na wzrost tego zagrożenia. Badaniom stateczności toru bezstykowego poświęcono bardzo dużo poważnych prac naukowych, nieliczne są natomiast prace dotyczące przyczyn już zaistniałych wyboczeń, ograniczone zwykle do opisów tych przypadków, które doprowadziły do wykolejeń. Wyboczenia, które nie spowodowały żadnych następstw są ze zrozumiałych powodów szybko likwidowane i słabo udokumentowane. Rozpoznawanie przyczyn każdego z nich mogłoby stanowić cenny materiał umożliwiający zmniejszenie tego zagrożenia.

EN

Tracks buckling are among the greatest threats to the safety of rail traffic. Climate changes in recent years, mainly the increasing warmth, can affect the growth of this threat. A lot of scientific research papers have been devoted to stability tests of long welded tracks, whereas there are a few papers on the reasons for tracks buckling, usually limited to descriptions of those cases which led to derailments. Cases of buckling, which have not caused any consequences are understandably quickly liquidated and poorly documented. Identifying the causes of each of them could provide valuable material which allows to reduce of this threat.

7

Inelastic stability analysis of uniaxially compressed flat rectangular isotropic CCSS plate

Ibearugbulem O. M., Eziefula U. G., Onwuka D. O.

International Journal of Applied Mechanics and Engineering

|

2015

|

Vol. 20, no. 3

637--645

EN

This study investigates the inelastic stability of a thin flat rectangular isotropic plate subjected to uniform uniaxial compressive loads using Taylor-Maclaurin series formulated deflection function. The plate has clamped and simply supported edges in both characteristic directions (CCSS boundary conditions). The governing equation is derived using a deformation plasticity theory and a work principle. Values of the plate buckling coefficient are calculated for aspect ratios from 0.1 to 2.0 at intervals of 0.1. The results compared favourably with the elastic stability values and the percentage differences ranged from -0.353% to -7.427%. Therefore, the theoretical approach proposed in this study is recommended for the inelastic stability analysis of thin flat rectangular isotropic plates under uniform in-plane compression.

8

Structural stability and reliability of the underground steel tanks with the Stochastic Finite Element Method

Kamiński M., Świta P.

Archives of Civil and Mechanical Engineering

|

2015

|

Vol. 15, no. 2

593--602

EN

The main aim is to present the Stochastic perturbation-based Finite Element Method analysis of the stability and also reliability of the underground steel vertical cylindrical structure of the waste container. This thin walled structure with constant cross-sectional thickness is loaded with subsoil pressure, snow and surface as well as dead loads and we look for the critical pressure value, when stability loss would be observed; it is done to design in the probabilistic context the safety margins. We employ to achieve this goal the Finite Element Method program ROBOT and computer algebra system MAPLE to get the analytical polynomial functions relating the critical pressure and random design parameters – shell thickness and its Young's modulus as well as to provide all probabilistic calculations. We determine up to the fourth order probabilistic characteristics of the structural response assuming that the input random parameters have Gaussian probability functions truncated to the positive values only. Finally, the reliability index is calculated according to the first order method using a difference in-between critical pressure and maximum tensile stress determined in this structure to verify its durability according to the demands of EU engineering codes.

9

3D Buckling Analysis of a Truss with Horizontal Braces

Iwicki P., Krajewski M.

Mechanics and Mechanical Engineering

|

2013

|

Vol. 17, nr 1

49–-58

EN

The present research is devoted to the study of out–of–plane buckling of a truss with horizontal braces. The truss is a model of real roof truss scaled by factor 1/4. A linear buckling and a non–linear analysis with geometric and material non–linearity were carried out. The truss buckling and limit load for different stiffnesses and number of braces are found. Numerical analysis are verified by experiment. Threshold bracing stiffness condition for full bracing of the truss is proposed.

10

Modelling of an imperfect column having variable cross-sections and non-symmetric responses in tension and compression

Rahman M. A., Chowdhuri A. K.

International Journal of Applied Mechanics and Engineering

|

2012

|

Vol. 17, no. 2

439-457

EN

The behavior of a column having variable rectangular cross-sections has been modelled assuming that the column material has non-symmetric responses both in tension and compression. For this purpose, a powerful numerical scheme, based on the finite difference technique, has been devised and used to trace the load-deflection curves (equilibrium configuration paths) of a column that has highly non-linear stress-strain curves which are non-symmetric both in tension and compression. The appearance of the critical load, that causes enormous deflections with an infinitesimall increase in the loading parameters, is determined from those load-deflection curves. The devised method can be used to calculate buckling loads of any column with material and geometric nonlinearities. To make the study realistic an initial shape imperfection has been included and its effect on the column's response has also been discussed in detail. A comparison shows a good agreement between results based on the devised numerical scheme and those obtained from experiments for a specific case and other available studies.

11

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

|

2010

|

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.

12

Investigation of Fabric Behaviour in Bias Extension at Low Loads

Naujokaitytė L., Strazdienė E., Domskienė J.

Fibres & Textiles in Eastern Europe

|

2008

|

Vol. 16, no. 5 (70)

59--63

EN

Shear deformations are the most significant mode of deformation during draping or forming processes. The bias extension test can be used to trace the parameters describing fabric shear. In this research the image analysis method in combination with an bias extension test were used for characterisation of the specimen buckling point and surface irregularity changes during uni-axial extension. Buckling point dependence on stiffener concentration was recorded. Shear angle values were obtained by an optical method. Particular focus was placed on the methods capability to distinguish fabrics of similar structure and those that differ in the bending rigidity parameter, which is changed by the PVA stiffener concentration. Shear angle dependence on the load and extension is presented. Shear parameters obtained from the bias extension test were proved to correlate with the shear parameters obtained by well known methods.

PL

Deformacje pod wpływem sił ścinających są najważniejszym rodzajem deformacji podczas układania tkanin lub formowania ich kształtu. Testy skośnego rozciągu mogą być stosowane dla określenia parametrów opisujących naprężenia ścinające w tkaninach. W pracy wykorzystano analizę obrazu podczas skośnego rozciągu dla scharakteryzowania wyboczenia próbek i nieregularności ich powierzchni podczas jednoosiowego rozciągania. Określano zależność wyboczenia od sztywności materiału. Kąty sił ścinających zostały określone metodą optyczną. Szczególną uwagę poświęcono opracowaniu metody określenia możliwości rozróżniania tkanin o podobnej strukturze oraz wyodrębnienia tych, które różnią się parametrami sztywności zginania. Przedstawiono zależność kąta ścinania od wartości obciążenia i wydłużenia. Otrzymane wyniki badań dobrze korelowały z wynikami badan prowadzonych innymi metodami.

13

Investigation of Fabric Shear Behaviour

Domskienė J., Strazdienė E.

Fibres & Textiles in Eastern Europe

|

2005

|

Vol. 13, no. 2 (50)

26--30

EN

The shear behaviour of fabrics and the phenomenon of buckling is analysed during the uniaxial tension of a bias cut specimen. The image analysis method is proposed to define critical shearing conditions and to analyse the deformation processes of bias-stretched fabric. The critical tension load, critical elongation and critical shear angle are defined on the basis of a grey-scale value I variation in the images of the fabric specimen. It is found that the dispersal of a grey-scale value CV can be used to estimate the surface waviness of stretched fabric. It is shown that a simple uniaxial tension experiment supplemented by image analysis can be used not only to define the shear parameters of a fabric but also to explain fabric behaviour in greater depth due to analysis of the buckling phenomenon.

PL

Wpływ obciążeń ścinających i zjawisko wyboczenia były analizowane podczas osiowego obciążenia próbki wyciętej skośnie z materiału. Metoda komputerowej analizy obrazu została zastosowana dla badania procesu deformacji skośnie wyciętej próbki. Krytyczne obciążenie, krytyczne wydłużenie i krytyczny kąt ścinania zostały zdefiniowane na podstawie wartości szarej skali i zmian obrazu próbki. Stwierdzono, że znajomość wartości szarej skali może być wykorzystana dla określenia sfalowania powierzchni rozciąganej próbki. Pokazano, że prosty eksperyment osiowego rozciągania próbki, uzupełniony analizą obrazu może być zastosowany nie tylko do zdefiniowania parametrów ścinania materiału tekstylnego, ale również dzięki przeprowadzonej analizie, dla wytłumaczenia zjawiska wyboczenia zachowania się próbki w jej głębszych warstwach.

14

Evaluating the Bending Rigidity of Flat Textiles with the Use of an Instron Tensile Tester

Kocik M., Żurek W., Krucińska I., Geršak J., Jakubczyk J.

Fibres & Textiles in Eastern Europe

|

2005

|

Vol. 13, no. 2 (50)

31--34

EN

The purpose of this work is to verify the possibility of using an Instron tensile tester for evaluating those mechanical properties of flat textile fabrics which are responsible for their handle properties. A method of evaluating the bending rigidity of woven fabrics was developed. The method consists in axially compressing samples fixed at both ends and placed in a vertical position, which leads to their buckling. The bending rigidity was determined on the basis of the critical maximum force occurring at buckling, and the curvature of the buckled sample which appears as result of the action of this force. The results obtained by this method were compared with those obtained with the use of the FAST system. The good compatibility of both these methods was proved by the correlation coefficients.

PL

Przedstawiana praca miała na celu sprawdzenie możliwości wykorzystania maszyny wytrzymałościowej firmy Instron do oceny właściwości mechanicznych, odpowiedzialnych za chwyt płaskich wyrobów włókienniczych. Opracowano metodę oceny sztywności zginania tkanin, polegającą na ściskaniu osiowym pasków tkaniny, prowadzącym do wyboczenia próbek zamocowanych w położeniu pionowym. Zaproponowano sposób określenia długości wyboczeniowej próbek na podstawie kształtu wykresu siły w funkcji długości skrócenia próbki. Sztywność zginania określono na podstawie maksymalnej siły przy ściskaniu oraz kształtu krzywizny próbki, powstałej pod wpływem tej siły. Otrzymane wyniki porównano z wynikami otrzymanymi za pomocą systemu FAST. Wykazano dobrą zgodność obydwu metod, o czym świadczy współczynnik korelacji.

15

Projektowanie mostów stalowych : komentarz do prENV 1993-2: 1997

Czudek H.

Prace Instytutu Badawczego Dróg i Mostów

|

1998

|

nr 1-2

43-80

PL

Komentarz do Eurokodu prENV 1993-2: 1997 "Projektowanie mostów stalowych" składa się z dwóch części. W pierwszej części przedstawiono te zagadnienia projektowe związane ze stanami granicznymi użytkowania i nośności, które wymagają korzystania z innych Eurokodów lub norm europejskich. Zagadnienia te dotyczą przede wszystkim wyboczenia, także wyboczenia giętno-skrętnego, zmęczenia, odkształcenia ścinania (tzn. shear lag), miarodajnej długości efektywnej przy obliczaniu wytrzymałości elementu, obliczania łączników. W drugiej części przedstawiono teorię wyboczenia cienkich blach, opartą na liniowej teorii wyboczenia cienkich płyt oraz na zachowaniu się płyt w obszarze nadkrytycznym (wg von Karmana). Na zakończenie podano przykład obliczenia smukłości granicznych dwuteownika poddanego czystemu zginaniu.

EN

This elaboration presents principles and rules defined in prENV 1994-2: 1997 which should be applied in design of composite bridge structures. Basis of this design, material characteristic, strength criteria as well as serviceability and ultimate limit states were described. More exactly were described these pronciples which at presently used design methods have not been (or have been rather rerely) taken into account. It concerns particularly: the conjunction with use of studs, the fatigue strength, the limit states and the use of prestress.