Wyniki wyszukiwania - BazTech

1

Fakty i mity o wzmacnianiu konstrukcji żelbetowych na zginanie przy użyciu materiałów kompozytowych FRP

Kotynia Renata

Materiały Budowlane

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2020

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nr 5

26--30

PL

W artykule przedstawiono konfrontację obowiązujących zasad projektowania wzmocnienia konstrukcji żelbetowych materiałami kompozytowymi FRP z podważającymi je tezami, które z uwagi na błędne założenia prowadzą do mylnych wniosków. Wyjaśnienie mechanizmów zniszczenia w kontekście zasad projektowych ma na celu uniknięcie upowszechniania błędnych teorii w środowisku inżynierów budownictwa.

EN

The paper presents confrontation of existing design guidelines of strengthening reinforced concrete structures using FRP materials with undermining theses, which due to incorrect assumptions lead to misleading solutions. Explanation of failure mechanisms in the context of design guidelines aims to avoid dissemination of confusing theories in the civil engineering community.

2

Tensile Damage Mechanism of 3-D Angle-Interlock Woven Composite using Acoustic Emission Events Monitoring

Ma Q., Wang K., Wang S. D., Liu H., Jin B. C., Jin L. M., Ma P.

Autex Research Journal

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2018

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Vol. 18, no. 1

46--50

EN

The quasi-static tensile damage behavior of one type of layer-to-layer 3-Dimensional Angle-interlock Woven Composite (3DAWC) was tested and analyzed in this paper. Incorporated with the acoustic emission (AE) events monitoring, the mechanical behavior of the 3DAWC under tensile loading condition was characterized. The Load-Extension curve, Load/AE events-Time curves occurred during the entire testing process and tensile damage modes were recorded to characterize and summarize the mechanical properties and damage mechanism of the 3DAWC subjected to tensile loading. It was found that the tensile damage of the 3DAWC could be summarized into 3 steps. And each step has a distinct primary damage mode. Moreover, the resin cracks, resin-yarn interface debonding and yarn breakages were the main damage modes for the 3DAWC.

3

Analiza doświadczalna wpływu przestrzennego zbrojenia na nośność i przemieszczenie belki żelbetowej

Babiński W., Stolarski A.

Materiały Budowlane

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2016

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nr 2

32--35

PL

W artykule przedstawiono wyniki badań doświadczalnych modeli belek żelbetowych z przestrzennym, ortogonalnym układem zbrojenia, który składa się z prętów podłużnych oraz połączonych z nimi prętów poprzecznych pionowych i poziomych. Wyniki te wskazują na odmienny mechanizm zniszczenia belek w porównaniu z elementami ze zbrojeniem tradycyjnym.

EN

The paper presents results of experimental studies of reinforced concrete beam models with spatial orthogonal reinforcement system. The system of reinforcement consists of longitudinal rods and connected with them vertical and horizontal transverse bars. The experimental results indicate a different failure mechanism of the beams as compared to behavior of the elements with the traditional reinforcement.

4

Schematy zniszczenia elementów konstrukcji szkieletowych budynków drewnianych

Baszeń M., Malesza J.

Materiały Budowlane

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2013

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nr 4

41--42

EN

In the paper are discussed damage mechanisms of structural elements in light wood-framed buildings. The paper presents informations about experimental tests over wall and floor elements. During these tests the specimen were destroyed and the graphic presentation of the damage mechanisms are included in the article. In the paper also is discussed the numerical model which allows to calculate stress and displacements in analyzed elements.

5

Metodyka i wyniki badań doświadczalnych ceglanych nadproży łukowych

Nowak R., Orłowicz R.

Materiały Budowlane

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2013

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nr 3

94--95

EN

Two models of brick arched lintels and two arch models were put to the test of single concentrated force in the middle of the span and in the most sensitive spot. Value of the concentrated force, value of the horizontal force and the displacement were registered. The dependence of the construction strength (in comparison with the strength of the arched lintel to the strength of the arch) were compared to the placement of concentrated force. Analytical numerical research where carried out with help of limit tension stress criterion, then results where compared to the results of fundamental research.

6

Three-dimensional analysis of a tensile test on a propellant with digital volume correlation

Hild F., Fanget A., Adrien J., Maire E., Roux S.

Archives of Mechanics

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2011

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Vol. 63, nr 5-6

459-478

EN

A full three-dimensional study of a tensile test on a sample made of polymerbonded propellant is presented. The analysis combines different tools, namely, X-ray microtomography of an in situ experiment, image acquisition and treatment, 3D volume correlation to measure three-dimensional displacement fields. It allows for global and local strain analyses prior to and after the peak load. By studying the correlation residuals, it is also possible to analyze the damage activity during the experiment.

7

Corrosion behaviour of the welded steel sheets used in automotive industry

Katundi D., Tosun-Bayraktar A., Bayraktar E., Toueix D.

Journal of Achievements in Materials and Manufacturing Engineering

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2010

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Vol. 38, nr 2

146-153

EN

Purpose: of this paper is to characterise the corrosion resistance in the steel sheets (Hot dip galvanizing of steel sheets) used in automotive industry. In fact, corrosion of automotive components by road salt is a widely known problem. The different parts under the car body and the interior surface of body panels suffer easily from the corrosive products deposited on roads and used mainly to melt snow. A comparison in a chemical investigation of the corrosion rate for base metals (without welding) and welded steel is required. Therefore, conformity will be accomplished between the corrosion phenomena in simulated corrosion tests and those in actual cars. Design/methodology/approach: Simulated corrosion tests, wet/humidity test and hot dust/dry cycle talk test carried on in laboratory conditions was investigated quantitatively. Dynamic behaviour of the corroded specimens have been tested dynamically to simulate under the crash test conditions. Findings: Studies carried out on the vast corroded samples have shown that the pitting corrosion damage and crack initiation sites have began and propagated generally in the HAZ in the welded steel sheets (Tailored welded blanks - TWB). Research limitations/implications: This paper contains partially results of a common research project. Some limitations exist in application of hot dust/dry cycle talk to the real open air test conditions. All of these results were carried out in the laboratory conditions. Practical implications: The problem is of extreme importance to all academic, scientific, manufacturing, maintenance and industrial societies. The outcome of the proposed study will contribute to the industrial application of ARCELOR-MITTAL. The proposed study will be benefit not only for the car industry and steel makers, but also important for the other industrial applications. The proposed research can be employed in a broad range of applications in oil and natural gas industries. This project will promote multidisciplinary research and cooperation between university and industry. Originality/value: An effective corrosion test proposed by Volvo was applied to the welded sheets (TWB) in an enclosed climatic chamber. This test is a practical and inexpensive test. Impact tensile-crash test makes it possible to analyse the corrosion damage of sheet metals under the dynamic rupture.

8

A comparative study on the damage initiation mechanism of elastomeric composites

Da Silva Botelho T., Isac N., Bayraktar E.

Archives of Computational Materials Science and Surface Engineering

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2009

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Vol. 1, nr 2

112-119

EN

Purpose: Modelling - Finite Element Analysis (FEA) of the damage initiation mechanisms in thin rubber sheet composites were carried out under static solicitation at room temperature. Natural rubber vulcanised and reinforced by carbon, NR is used in this study. Design/methodology/approach: Experimental results were compared with that of the Finite Element Analysis (FEA). Damage mechanism has been described with a threshold criterion to identify the tearing resistance, characteristic energy for tearing (T) and damage in the specimens was evaluated just at the beginning of the tearing by assuming large strain. A typical type of specimen geometry of thin sheet rubber composite materials was considered under static tensile tests conducted on the smooth and notched specimens with variable depths. In this way, the effects of the plane stress on the damage mechanism are characterized depending on the rubber materials. Findings: In this stage of this research, a finite element analysis (FEA) has been applied under the same conditions of this part in order to obtain the agreement between experimental and FEA results. The numerical modelling is a representation of a previous experimental study. The specimen is stretched more than once its initial size, so that large strains occur. A hyper elastic Mooney-Rivlin law and a Griffith criterion are chosen. The finite elements analysis was performed with ABAQUS code (V.6.4.4). The tearing energy is evaluated with contour integrals. The Griffith criterion states that a notch with an initial length will elongate of a differential length for a given strain state only if the variation of elastic energy is higher than the variation of the surface energy related to the newly created surface. Practical implications: A tearing criterion was suggested in the case of simple tension conditions by assuming large strain. In the next step of this study, a finite element analysis (FEA) will be applied under the same conditions of this part in order to obtain the agreement between experimental and FEA results. Originality/value: This study proposes a threshold criterion for the damage just at the beginning of the tearing for thin sheet rubber composites and gives a detail discussion for explaining the damage mechanisms. Comparison of FEA results with those of experimental studies gives many facilities for the sake of simplicity in industrial application.

9

Modelling of damage initiation mechanism in rubber sheet composites under the static loading

Da Silva Botelho T., Isac N., Bayraktar E.

Journal of Achievements in Materials and Manufacturing Engineering

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2007

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Vol. 22, nr 2

55-58

EN

Purpose: Modelling - Finite Element Analysis (FEA) of the damage initiation mechanisms in thin rubber sheet composites were carried out under static solicitation at room temperature. Natural rubber wulcanised and reinforced by carbon, NR is used in this study. Design/methodology/approach: Experimental results were compared with that of the Finite Element Analysis (FEA). Damage mechanism has been described with a threshold criterion to identify the tearing resistance, characteristic energy for tearing (T) and damage in the specimens was evaluated just at the beginning of the tearing by assuming large strain. Typical specimen geometry of thin sheet rubber composite materials was considered under static tensile tests conducted on the smooth and notched specimens with variable depths. Findings: This stage of this research, a finite element analysis (FEA) has been applied under the same conditions of this part in order to obtain the agreement between experimental and FEA results. The numerical modelling is a representation of a previous experimental study. The specimen is stretched more than once its initial size, so that large strains occur. A hyper elastic Mooney-Rivlin law and a Griffith criterion are chosen. Practical implications: A tearing criterion was suggested in the case of simple tension conditions by assuming large strain. In the next step of this study, a finite element analysis (FEA) will be applied under the same conditions of this part in order to obtain the agreement between experimental and FEA results. Originality/value: This study proposes a threshold criterion for the damage just at the beginning of the tearing for thin sheet rubber composites and gives a detail discussion for explaining the damage mechanisms. Comparison of FEA results with those of experimental studies gives many facilities for the sake of simplicity in industrial application.

10

Damage mechanisms of Ti-Al intermetallics in three point ultrasonic bending fatigue

Bayraktar E., Xue H., Bathias C.

Journal of Achievements in Materials and Manufacturing Engineering

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2007

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Vol. 24, nr 1

153-161

EN

Purpose: Damage mechanisms of two phases (alpha2-Ti3Al and gamma-Ti-Al) intermetallics alloy are investigated at room temperature in a new developed resonance type 3- point (3P) fatigue bending test device at a frequency of 20 kHz. Design/methodology/approach: Manufacturing and analysis of composition of this alloy were carried out in advanced materials laboratory by collaborating with aircraft design engineering department for non-ferrous metal research centre in China. All of the 3P- fatigue bending were carried out at the stress ratios of R=0.1, R=0.5, R=0.7 mainly in gigacycle regime. Findings: Damage mechanisms were compared in static and dynamic test conditions. The geometries of static tensile test and ultrasonic fatigue test specimens have been calculated by analytical or numerical method as discussed in detail formerly. This paper gives further results and more complicate discussion on this study particularly on the crack formation and the role of the different parameters on the damage mechanisms of this alloy. Damage analysis was made by means of optical (OM) and Scanning Electron Microscopies (SEM). Research limitations/implications: Paper gives results and more complicate discussion on the crack formation and the role of the different parameters on the damage mechanisms of this alloy. Originality/value: This study proposes a new methodology for fatigue design and a new idea on the criterion for the damage under very high cycle fatigue regime. The results are well comparables for the specimens under real service conditions. This type of study gives many facilities for the sake of simplicity in industrial application.

11

Modelling of brittle damage nucleation by means of

Nowak K.

Computer Methods in Materials Science

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2007

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Vol. 7, No. 1

150-155

EN

The main goal of the paper is to motivate damage nucleation in metals, subjected to creep conditions, on the level of material structure. In classical approach of mechanics it is achieved by introducing a scalar (or tensorial) parameter called damage variable and postulating its phenomenological evolution equation. Such an approach has been successfully used in analysis of structures under different loading circumstances, giving rise to the formation of special branch of mechanics “Continuum Damage Mechanics” (CDM). This approach reflects neither physical process that is underlying macroscopically observed phenomena, nor material structure. On the other hand, in metallurgy, the process of brittle damage formation is well recognized and described. In brief, it consists of microcraking and voids formation initiating in the triple-points and developing along grain boundaries. Therefore, it is essential to associate any description of damage formation with modelling of material structures. In the paper, it was achieved by associating deformation process with changing states of CA cells. To model time dependent behaviour of representative volume element (RVA) of material a 3D cellular automaton was developed. The process of damage formation consists of two steps in each time increment. In the first one, the tension (or compression) of RVE over an increment of deformation mesh was supposed, and then projected onto cellular automaton cells. In the second step the damage formation is controlled by the rules of an automaton. These probabilistic rules change the state of mass cell to empty for specific combination of neighbouring cells, provided this cell corresponds to grain boundary. Above procedure allows to forms microvoids or microcracs. The main rule governing cellular automaton is the mass conservation law, which enforced the number of empty cells in RVE. As the outcome from CA the damage variable is calculated as a percentage of entire damage of RVE. The entire damage is assumed to happen when the voids form a surface spanning two opposite borders of element. The procedures developed in the paper are used to modify standard FE programs through incorporating results of CA-based microstructural analysis according to the CAFE methodology. For each Gauss point of finite element the CA is running and values of state variables are exchanged between FE and CA. Strains obtained from FE are used to calculate deformation of the borders of RVE. In turn, the damage variable calculated from CA modifies the value of stress used in FE solution. In such a way multiscale description of phenomenon is proposed to obtain solution of engineering problems with sound physical background. As an example, a plate under uniform pressure working in creep condition is analysed using HKS Abaqus. Results obtained are compared with numerical solution of CDM.

PL

Zaproponowano opis nukleacji uszkodzeń dla metali pracujących w warunkach pełzania na poziomie mikrostruktury. Opisując to zjawisko w klasycznym podejściu do mechaniki wprowadza się skalarny (lub tensorowy) parametr nazywany uszkodzeniem i postuluje fenomenologiczne prawo jego rozwoju. Takie podejście jest z powodzeniem używane w analizie konstrukcji w różnych warunkach obciążenia tworząc specjalną gałąź mechaniki zwaną kontynualną mechaniką uszkodzeń. Pomimo rozwiązania szeregu ważnych technicznych problemów, takich jak oszacowanie czasu do pojawienia się pierwszego makroskopowego uszkodzenia a także dalszego rozwoju procesu pękania, podejście to nie odzwierciedla ani procesu fizycznego leżącego u podstaw makroskopowo obserwowanych zjawisk, ani struktury materiału. W niniejszej pracy proponuje się podejście wieloskalowe poprzez połączenie rozwiązania numerycznego na poziomie makroskopowym z opisem zachowania się struktury materiału na poziomie mikro przy pomocy automatów komórkowych. Otrzymane rozwiązania porównane

12

Damage initiation mechanism in rubber sheet composites during the static loading

Luong R., Isac N., Bayraktar E.

Archives of Materials Science and Engineering

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2007

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Vol. 28, nr 1

19-26

EN

Purpose: Mechanical behaviour and damage initiation mechanisms in thin rubber sheet composites were investigated under static solicitation at room temperature. Two types of rubber are used in this study; Natural rubber, NR vulcanised and reinforced by carbon black and Synthetic rubber (styrene-butadiene-rubber, SBR). Design/methodology/approach: A comprehensive study has been carried out in order to identify a threshold criterion for the damage mechanism to explain a tearing criterion for the concept of tearing energy of the elastomers and also to give a detail for the damage mechanism depending on the loading conditions. A typical type of specimen geometry of thin sheet rubber composite materials was studied under static tensile tests conducted on the smooth and notched specimens with variable depths. In this way, the effects of the plane stress on the damage mechanism are characterized depending on the rubber materials. Findings: Damage mechanisms during tensile test have been described for both of rubber types and the criteria which characterize the tearing resistance, characteristic energy for tearing (T) was explained. Damage in the specimens were evaluated just at the beginning of the tearing by means of the observations in the scanning electron microscopy (SEM). Practical implications: A tearing criterion was suggested in the case of simple tension conditions by assuming large strain. In the next step of this study, a finite element analysis (FEA) will be applied under the same conditions of this part in order to obtain the agreement between experimental and FEA results. Originality/value: This study propses a threshold criterion for the damage just at the beginning of the tearing for thin sheet rubber composites and gives a detail discussion for explaining the damage mechanisms by SEM results. This type of study gives many facilities for the sake of simplicity in industrial application.

13

Fatigue behaviour and energy dissipation of a nodular cast iron in ultrasonic fatigue loading

Xue H. Q., Bayraktar E., Bathias C.

Journal of Achievements in Materials and Manufacturing Engineering

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2006

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Vol. 18, nr 1-2

251--254

EN

Purpose: In the current research, fatigue tests of cast iron (GS51) have been conducted using the ultrasonic fatigue system and monitored by an advanced infrared imaging system in real time. Fatigue damage processes has been observed and analyzed. Furthermore, heat condition effect has been to analyze. Design/methodology/approach: Fatigue behaviour in the very high cycle regime of 1010 cycles were investigated with a cast iron (GS51) under ultrasonic fatigue test system in ambient air at room temperaturę with a stress ratio R=-1. The influence of frequency was examined by comparing similar data generated on conventional servo hydraulic test systems. An infrared camera was also used to record specimen temperatures at various load levels caused by internal damping due to cycling at a very high frequency. Findings: The S-N curves obtained show that fatigue failure occurred beyond 10 9 cycles, fatigue limit does not exist for the cast iron and there is no evidence of frequency effect on the test results. A detailed study on fatigue specimens subjected to ultrasonic frequency shows that the temperature evolution of the cast iron specimen is very evident, the temperature increased just at the beginning of the test, the temperature increased depending on the maximum stress amplitude. Research limitations/implications: Ultrasonic fatigue test methodology had been applied extensively in exploring fatigue lives at very high cycle regime. However, it is a predominant problem that the thermal Energy dissipation results in increasing of temperature of specimen at very high frequency fatigue experiment. In order to investigate the heat dissipation of ultrasonic fatigue specimen and understand the influence of temperaturę evolution on the fatigue properties, it is necessary to obtain the temperature response of vibratory specimen. Originality/value: Early stage of damage of the cast iron which lead to crack initiation and micro crack growth are characterized by local microstructure temperature evolution, so as to understand the relationship between heat dissipation and fatigue state of material.

14

Damage diagnostics of turbine blades.

Madej J.

Archive of Mechanical Engineering

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2003

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Vol. L, nr 1

69-87

EN

The paper presents the most frequently encountered types and mechanisms of damage of turbines' flow elements. The methods used nowadays for diagnosis of the damage are presented. A new possibility of localisation of damaged areas of turbine blades based upon the analysis of isotherm layout is proposed.

PL

W artykule opisano najczęściej spotykane rodzaje i mechnizmy uszkodzeń elementów przepływowych turbin. Na tle aktualnie stosowanych metod diagnozowania uszkodzeń zaproponowano nową możliwość lokalizowania defektów łopatek turbinowych drogą analizy rozkładu izoterm. Niniejsze opracowanie stanowi kontynuację wcześniejszych prac autora na temat wpływu uszkodzeń na rozkład temperatur w materiałach konstrukcyjnych i dotyczy wykorzystania poczynionych spostrzeżeń do diagnozowania części maszyn.