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1

Study on damage mechanism of concrete under water jet combined with mechanical breaking

Liu Jialiang, Ling Jun, Cai Yuting, Ju Anjun, Long Wanpeng, Zhang Xuguang

Archives of Civil and Mechanical Engineering

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2023

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Vol. 23, no. 2

art. no. e139,2023

EN

Traditional mechanical breaking technology has the disadvantages of serious equipment wear, large vibration, large dust, and low breaking accuracy. Water jet assisted traditional mechanical breaking technology can improve the breaking efficiency of traditional mechanical breaking technology, reduce equipment wear and pollution. However, due to the problems of fluid-solid coupling and nonlinear failure, the fracture characteristics and damage mechanism of concrete arenot clear, which hinders the development of this technology. In this paper, the experimental system of water jet combined with mechanical breaking concrete is built, and the numerical model of combined breaking is established by smoothed particle hydrodynamics(SPH) method. The cracking characteristics and damage mechanism of water jet combined with mechanical breaking concrete are deeply explored. The results show that compared with the mechanical breaking method, this method reduces the breaking pressure by about 16%, saves the cost and improves the breaking efficiency. The water jet slit has a guiding effect, so that the cracks generated by mechanical breaking concrete are concentrated between the two slits, to avoid secondary damage to the original concrete structure. The mechanism of water jet combined with the mechanical breaking of concrete can be divided into three stages: crater formation stage, crack derivation stage, and stage of cracking.

2

Damage mechanism of conventional joints and proposal of a novel joint for hollow-core slab bridges

Cui Yujun, Xue Xingwei, Yao Hao, Hua Xudong, Huang Yuanming

Archives of Civil Engineering

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2022

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Vol. 68, nr 4

571--590

EN

The prefabricated hollow-core slab bridge is a common bridge. In prefabricated hollow-core slab bridges, joints play an important role in connecting prefabricated slabs and ensuring the integrity of the bridge. However, as the service time of the bridge increases, conventional joints have a large number of typical diseases that affect the safety and durability of bridges. In this study, a three-dimensional finite element model of the entire construction phase is established to investigate the development difference of shrinkage and creep between joints and hollow-core slabs. The effects of vehicle load and temperature gradient on joints were analysed, the failure mechanism of joints was explored, and a novel joint was proposed. The results of a nonlinear analysis showed that the novel joint can effectively improve the mechanical performance of joints and cracks can be effectively controlled. Moreover, the novel joint solves the problem in that the conventional novel joint cannot be vibrated effectively.

3

Performance degradation comparisons and failure mechanism of silver metal oxide contact materials in relays application by simulation

Wang ZhaoBin, Li WeiYan, Shang Shang, Wang Zhan, Han ChunYang

Eksploatacja i Niezawodność

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2020

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Vol. 22, no. 1

86--93

EN

To evaluate the electrical contact behaviors of silver metal oxide contact materials in relays application more accurately, and to guide the selection of contact materials, the test device and testing method for simulating electrical contact performance in relays application were analyzed in this paper. The electrical contact simulation test system was designed and developed, which can easily simulate contact materials. The contact resistance, static force and rebound energy degradation parameters of AgSnO2, AgCdO and AgNi contact materials under the same load conditions were obtained through experimental research, the contact resistance and arcing energy degradation parameters of AgSnO2 under different opening distances were acquired at the same time. The result indicated that accurate data are received by the electrical contact simulation testing method. Finally, based on the test data, the degradation performance of three selected test materials was tested, and the failure mechanism of AgSnO2 materials was analyzed.

PL

W celu dokładniejszej oceny zachowania styków elektrycznych z kompozytów srebra i tlenku metalu stosowanych w przekaźnikach elektromagnetycznych oraz w celu ułatwienia wyboru materiałów stykowych, w niniejszej pracy przeanalizowano urządzenie testowe oraz metodę testowania, które pozwalają na symulację działania styku przekaźnika. Zaprojektowano i zbudowano system testowania styków elektrycznych, który umożliwia łatwą symulację zachowania materiałów stykowych. Parametry degradacji rezystancji zestykowej, siły statycznej oraz energii odbicia materiałów stykowych AgSnO2, AgCdO i AgNi uzyskano w badaniach eksperymentalnych prowadzonych w takich samych warunkach obciążenia. Jednocześnie badano także parametry degradacji rezystancji zestykowej energii łuku AgSnO2 przy różnych odległościach otwarcia styków. Wyniki pokazują, że proponowana metoda badania symulacyjnego styków elektrycznych pozwala na uzyskanie dokładnych danych. W oparciu o dane testowe, przebadano zachowanie degradacyjne trzech wybranych materiałów oraz przeanalizowano mechanizm uszkodzenia styków z kompozytu AgSnO2.

4

Degradation modeling method for rotary lip seal based on failure mechanism analysis and stochastic process

Liu Di, Wang Shaoping, Tomovic Mileta M.

Eksploatacja i Niezawodność

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2020

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Vol. 22, no. 3

381--390

EN

Rotary lip seal is widely used in aircraft and its performance affects the safety of the aircraft. Hence, it is necessary to estimate useful lifetime and reliability of the seal. Degradation of rotary lip seal is always with random effects, which cannot be considered by theoretical failure mechanism analysis. Hence, in order to consider the random effects of rotary lip seal degradation, stochastic processes are applied. Furthermore, considering the monotonic degradation of the seal, Gamma process and inverse Gaussian process are selected as the candidate processes. To combine the candidate processes, Bayesian model averaging is introduced. Based on the failure mechanism analysis and numerical simulation, the theoretical wear path is predicted and corresponding linearization method is proposed. The measured degradation data is converted and the seal wear process is transformed to a linear degradation process. The model parameters and model probabilities are evaluated by fully Bayesian inference method. The effectiveness of the proposed method is verified by comparing the predicting degradation and experimental observations. The proposed method can be used to evaluate reliability and useful lifetime of rotary lip seal. According to sensitivity analysis, an effective way to improve lifetime and reliability of the seal is to increase the wear depth threshold.

PL

Obrotowe uszczelnienia wargowe znajdują szerokie zastosowanie w samolotach, a ich sprawność wpływa na bezpieczeństwo statków powietrznych. Oznacza to, iż szacowanie żywotności i niezawodności tego rodzaju uszczelnień ma kluczowe znaczenie. Degradacja obrotowego uszczelnienia wargowego jest zawsze związana z efektami losowymi, których nie uwzględnia teoretyczna analiza mechanizmu uszkodzenia. Dlatego też do oceny efektów losowych degradacji obrotowego uszczelnienia wargowego wykorzystuje się procesy stochastyczne, takie jak proces Gamma czy odwrotny proces Gaussa. W przedstawionej pracy, wybrane procesy degradacji łączono za pomocą metody bayesowskiego uśredniania modeli. Na podstawie analizy mechanizmów uszkodzeń i symulacji numerycznej, konwertowano uzyskane w pomiarach dane degradacyjne, co pozwoliło na przekształcenie procesu degradacji obrotowego uszczelnienia wargowego w proces liniowy. Parametry modelu i prawdopodobieństwa oceniano za pomocą metody pełnego wnioskowania bayesowskiego na podstawie obserwacji degradacji. Skuteczność przedstawionej metody weryfikowano porównując przewidywane i obserwowane wartości degradacji. Proponowaną metodę można wykorzystywać do oceny niezawodności i żywotności obrotowego uszczelnienia wargowego. Przeprowadzona analiza czułości pokazuje, że skutecznym sposobem na poprawę żywotności i niezawodności omawianego typu uszczelnienia jest zwiększenie progu uszkodzenia w postaci maksymalnej głębokości zużycia.

5

Microstructural Damage Characteristic of a Layer-to-Layer Three-Dimensional Angle-Interlock Woven Composite Under Quasi-Static Tensile Loading

Ma Qian, Wang Ke, Wang Shu-Dong, Chen Hong-Wu, Jin Li-Min, Liu Hua, Qin Xiao

Autex Research Journal

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2020

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Vol. 20, no. 2

121--127

EN

Three-dimensional angle-interlock woven composites (3DAWCs) are widely used for their excellent mechanical properties. The most significant feature is the existence of the undulated warp yarns along the thickness direction, which makes it interesting to study the mechanical properties in the warp direction. The quasi-static tensile behavior of a layer-to-layer 3DAWC along the undulated warp direction was studied by experimental and finite element analysis (FEA) methods. Based on the experimental results, the typical failure mode involving fibers, resin, and their interfaces was found. According to the FEA results, the stress concentration effect, key structural regions, and microstructural (yarn and resin) damage mechanism were obtained, which provided effective guidance for structural optimization design of the 3DAWC with stronger tensile resistance performance. In addition, the three-step progressive failure process of the 3DAWC under quasi-static tensile load was also described at the “yarn–resin” microstructural level.

6

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.

7

Parametric studies of failure mechanisms in thermal barrier coatings during thermal cycling using FEM

Srivathsa B., Das D. K.

International Journal of Applied Mechanics and Engineering

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2015

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Vol. 20, no. 4

899--915

EN

Thermal barrier coatings (TBCs) are widely used on different hot components of gas turbine engines such as blades and vanes. Although, several mechanisms for the failure of the TBCs have been suggested, it is largely accepted that the durability of these coatings is primarily determined by the residual stresses that are developed during the thermal cycling. In the present study, the residual stress build-up in an electron beam physical vapour deposition (EB-PVD) based TBCs on a coupon during thermal cycling has been studied by varying three parameters such as the cooling rate, TBC thickness and substrate thickness. A two-dimensional thermomechanical generalized plane strain finite element simulations have been performed for thousand cycles. It was observed that these variations change the stress profile significantly and the stress severity factor increases non-linearly. Overall, the predictions of the model agree with reported experimental results and help in predicting the failure mechanisms.

8

Governing Differential Equations for the Mechanics of Undamageable Materials

Voyiadjis G. Z., Kattan P. I.

Engineering Transactions

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2014

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Vol. 62, iss. 3

241–-267

EN

In this work the mathematical foundations of the mechanics of elastic undamageable materials are presented. In particular the governing differential equations are derived for both the scalar and tensorial cases. In the isotropic case it is found that the resulting scalar differential equations are simple and easy to solve. However, in the anisotropic case the tensorial differential equations are complicated and unsolvable at this time. The current work presents the solution in the form of explicit nonlinear stress-strain relations for the simple one-dimensional case. However, the general solution of the three-dimensional case remains unattainable at the present time. Only the governing tensorial differential equations are derived for this latter case. It is to be noted that the term “undamageable” is reflected in the context of the material stiffness and not the property of indestructibility due to various loading conditions. Thus, the undamageable material reflects that no microcracks or microvoids occur as well as no plastic yielding in the material. To illustrate this concept, a last section is added on applications.

9

Modeling of dry-stacked masonry panel confined by reinforced concrete frame

Lin K., Totoev Y. Z., Liu H. J., Page A. W.

Archives of Civil and Mechanical Engineering

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2014

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Vol. 14, no. 3

497--509

EN

In order to increase the energy dissipation of wall/frame elements subjected to in plane shear loading a conceptually new system for masonry infilled RC frame has been proposed and proved as effective. The interaction between frame and infilled panel is considered as the major cause of the nonlinear behavior of structure. In this paper, the experimental results are briefly summarized and a micro finite element model is developed to simulate the monotonic response of the masonry infilled structure. A novel type of element called “initial gap element” is presented to simulate the gap between the frame and panel to allow the continual simulation of the response for the full load cycle. All the material parameters are experimentally evaluated. The initial testing included free vibration and cyclic tests on a bare RC frame followed by cyclic test on the RC frame infilled with a dry-stacked concrete brick panel. These results are used to verify the accuracy of the model. It is shown that the model is able to simulate the failure mechanisms exhibited by experiment including the crushing and cracking of the concrete frame and the diagonal compressive stress contribution of the masonry panel. The load–displacement response predicted by the model was also in good agreement with that obtained from the tests. Furthermore, the model was used for ultimate analysis, which discovered four typical stages of structural response of the dry-stack infilled RC frame and found the friction between bricks in the dry-stacked panel contributes significantly (about 50%) to the assembly.

10

Rodzaje i przyczyny uszkodzeń szkła. Cz. 3

Giaquinto D., Dall F. J.

Świat Szkła

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2013

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R. 18, nr 3

41--42

11

Własności niezawodnościowe wargowych pierścieni uszczelniających

Zdziennicki Z., Maciejczyk A.

Problemy Eksploatacji

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2011

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nr 1

213-220

PL

Artykuł opisuje własności niezawodnościowe wargowych pierścieni uszczelniających -jednego z najbardziej popularnych i najszerzej stosowanych uszczelnień wirujących wałków. W artykule przedstawiono mechanizm uszkodzenia tych uszczelnień, jak i konsekwencje ich uszkodzeń. Opierając się na danych dostępnych w literaturze fachowej, zostały wyznaczone dwie podstawowe funkcyjne charakterystyki niezawodnościowe tych uszczelnień: funkcja prawdopodobieństwa uszkodzeń i funkcja niezawodności. Zmienna losowa opisująca uszkodzenia wargowych pierścieni uszczelniających ma rozkład Gaussa, stąd funkcja prawdopodobieństwa uszkodzeń dla tych pierścieni jest charakterystyczną funkcją gaussowską typu "dzwon". Funkcję niezawodności rozważanych uszczelnień podano w postaci analitycznej, stosując do tego tzw. funkcję błędu. W oparciu o uzyskane funkcyjne charakterystyki niezawodnościowe wyznaczono wartości liczbowe kwantyli rozważanego uszczelnienia - zarówno dla pojedynczego pierścienia, jak i dla jego układów składających się z kilku sztuk. Uzyskane wielkości funkcyjne przedstawiono w postaci wykresów.

EN

The paper describes reliability of lip-type seals, the most popular and most often used seals for rotating shafts. In the paper, a mechanism of seal failure was explained as well as its impact on others elements of mechanical systems. On basis of data from technical literature, these seals have two basic reliability functions, probability density function and reliability function. The random variable, which describes failures of lip seals, has a Gauss distribution. So the probability density function is a "bell" curve. The reliability function of the seals was given in an analytical form with an error function. The resulting functions were presented in their graphical forms as well. On the strength these functions, the probability density function, and the reliability function, the numerical values of the seal quantiles were calculated. It was done for a single lip seal as well as some systems of lip seals. The paper is ended with conclusions.

12

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.

13

Torsional fatigue behaviour and damage mechanisms in the very high cycle regime

Bayraktar E., Xue H., Ayari F., Bathias C.

Archives of Materials Science and Engineering

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2010

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Vol. 43, nr 2

77-86

EN

Purpose: of this paper: Many engineering components operate under combined torsion and axial cyclic loading conditions, which can result in fatigue fracture after a very long life regime of fatigue. This fatigue regime were carried out beyond 109 loading cycles called very high cycle fatigue (VHCF) to understand the fatigue properties and damage mechanisms of materials. Design/methodology/approach: Torsional fatigue tests were conducted using a 20 kHz frequency ultrasonic fatigue testing device. The results obtained were compared to those of the conventional torsional fatigue test machine operated at 35 Hz to observe any discrepancy in results due to frequency effects between two experiments. Findings: All the fatigue tests were done up to 1010 cycles at room temperature. Damage mechanisms in torsional fatigues such as crack initiation and propagation in different modes were studied by imaging the samples in a Scanning Electron Microscope (SEM). The results of the two kinds of material show that the stress vs. number of cycle curves (S-N curves) display a considerable decrease in fatigue strength beyond 107 cycles. Research limitations/implications: Each test, the strain of specimen in the gage length must be calibrated with a strain gage bonded to the gage section. This is a critical point of this study. The results are very sensitive to the calibration system. Control of the displacement and the output of the power supply are made continuously by computer and recorded the magnitude of the strain in the specimen.

14

Mechanizm uszkodzenia betonu w obiektach oczyszczalni ścieków przemysłowych

Słomka-Słupik B., Zybura A.

Materiały Budowlane

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2009

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nr 12

14-15

15

Experimental and numerical study of damage initiation mechanism in elastomeric composites

Silva Botelho T. D., Bayraktar E.

Journal of Achievements in Materials and Manufacturing Engineering

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2009

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Vol. 36, nr 1

65-70

EN

Purpose: Experimental and Finite Element Analysis (FEA) of the damage initiation mechanisms in elastomeric composites were carried out under static loading at room temperature. Double Cantilever Beam (DCB) specimens from natural rubber (NR) vulcanised and reinforced with other materials such as carbon black, silica, fibres and textiles or metals (rubber composites). Design/methodology/approach: Very huge experimental results were compared with that of the Finite Element Analysis (FEA). Damage mechanism has been described with a threshold criterion to identify damage. The damage was evaluated just at the beginning of the tearing by assuming large strain. A typical type of specimen geometry of Double Cantilever Beam (DCB) specimens was considered under static tensile tests conducted on the notched specimens with variable depths. 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 Moonley-Rivlin law and a Griffith criterion are chosen. The finite elements analysis was performed with ABAQUS code (V.6.4.4). Practical implications: A damage criterion was suggested in the case of simple tension conditions by assuming large strain levels. an effective finite elements model has been developed to evaluate notch size effects on the load-displacement elastic response of 3D-DCB type specimen. Originality/value: This study proposes a threshold criterion for the damage just at the beginning of the tearing for Double Cantilever Beam (DCB) specimens from 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 applications.

16

Analiza mechanizmów uszkodzeń pierścieni ślizgowych uszczelnień czołowych pomp wirowych

Rewolińska A.

Tribologia

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2007

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nr 3-4

155-164

PL

Uszczelnienia czołowe stanowią istotny węzeł konstrukcyjny pomp wirowych decydujący o ich niezawodności. Podstawowym elementem uszczelnienia jest para ślizgowa pierścieni, w której zachodzi proces dławienia uszczelnianego czynnika. Pierścienie te stanowią jedyny element uszczelnienia, który ma prawo ulec naturalnemu zużyciu. Jednak, jak wynika z danych literaturowych, około 85% uszczelnień czołowych po demontażu posiada pierścień ślizgowy zużyty w niedopuszczalny sposób. Rozpoznanie tych procesów niszczących prowadzących do przedwczesnej utraty zdatności uszczelnień czołowych umożliwia wprowadzenie zmian w zakresie konstrukcji, technologii oraz eksploatacji tych uszczelnień. W pracy przeprowadzono analizę mechanizmów uszkodzeń pierścieni ślizgowych uszczelnień czołowych stosowanych w pompach wirowych linii rozlewniczych piwa.

EN

Mechanical seals significantly influence the reliability of centrifugal pumps, in which these seals are assembled. The basic elements of mechanical seals are face rings (thrust and washer). The rings are the only elements of seals which can go wear and tear. Unfortunately, in many cases - about 85% - face rings of mechanical seals, after disassembly, are worn in unacceptable way. It is very important to know the destructive process leading to premature loss of suitability of mechanical seals. The aim of the article is analysis of the failure mechanisms of the mechanical seals in centrifugal pumps in beer filling lines.

17

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

|

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.

18

Damage initiation mechanism in rubber sheet composites during the static loading

Luong R., Isac N., Bayraktar E.

Archives of Materials Science and Engineering

|

2007

|

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.

19

Damage diagnostics of turbine blades.

Madej J.

Archive of Mechanical Engineering

|

2003

|

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.