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1

Comparison of Methods for Calculating Fragmentation of Blast Muck Piles in Quarries

Nowak-Szpak Anna, Wesoły Michał, Bajcar Adam

Mining Science

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2024

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Vol. 31

145--162

EN

The size distribution and fragmentation level of the blasted rock mass are crucial factors in enhancing the efficiency of loading, transportation, crushing, and milling processes. This article provides a comparative analysis of grain size distribution curves derived from image analysis using various methods. The first method compares representative fragments of the muck pile through manual analysis, commercial software, and an Open-Source Algorithm. The second method evaluates the grain size distribution curves of the entire muck pile, utilizing both commercial software and an open-source algorithm.

2

Fracture fusion : revolutionizing the recognition of bone fractures with MetaMag efficiency approach

Rajeashwari S., Arunesh K.

Machine Graphics and Vision

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2024

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Vol. 33, No. 1

69--93

EN

Bone fractures are common in diabetic patients and can result in several musculoskeletal conditions. Both type 1 and type 2 diabetes substantially increase the risk and severity of bone fractures. Prompt treatment and management of diabetes and its complications are crucial to mitigate this serious complication. Detection and diagnosis in its early stage can reduce the challenging conditions in treatment. Traditional image processing techniques like digital-geometric analysis, entropy measures, and gray-level co-occurrence matrices have been used for automated bone fracture detection. However, these detection methods rely neither on healthy controls nor diabetic-affected patients. Only few studies focused on detecting fractures in diabetic patients. The rising prevalence of diabetic ankle fractures made the study emphasize the development of a fracture detection model based on the Meta Magnify(MetaMag) efficiency model. The proposed model involves the Lower Extremity Radiographs (LERA)dataset, which consists of image samples of normal and abnormal lower extremities of the body, such as the hip, ankle, knee, and foot. Pre-processing involves a one-hot encoding method that handles the missing data and represents categorical variables as numerical values. Further, the classification is performed using the MetaMag efficiency model, incorporated with MetaMag scaling and unified normalization. Further, the efficiency of the proposed model is analyzed by comparing it with conventional EfficientNet and another model. Finally, the proposed work’s performance is analyzed using evaluation measures such as accuracy, precision, recall and F1-score. The results indicate the improved efficiency of the model.

3

Mechanical behaviour and failure mechanism of resistance spot welded aluminium and copper joint used in the lightweight structures

Fakhri Marwah Sabah, Al-Mukhtar Ahmed, Mahmood Ibtihal A.

Diagnostyka

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2024

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Vol. 25, No. 2

art. no. 2024207

EN

Recently, dissimilar metals have found applications in the process of resistance spot welding (RSW), particularly within the electric vehicle industry. Notably, copper and aluminum have gained significant importance in these sectors due to their advantageous characteristics for the industry requirements. The mechanical behavior of these materials is essential to maintaining structural integrity. The study aims to estimate the mechanical behavior of dissimilar RSW joints and optimize welding parameters for Cu-Al joints. Hence, understanding the joining processes in the electric vehicle industry to design reliable components. Combining different types of materials, such as T2-grade commercially pure copper sheets and aluminum AA1050 with the same thickness of 1 mm has been welded. The determination of optimal welding conditions takes into account material thicknesses and types. Through tensile-shear testing, welding parameters that yield maximal joint strength were identified. Using Minitab 19 software, the Taguchi method helped achieve optimized welding parameters. The hardness, fracture characteristics, and weld strength have been investigated. Hardness measurements were conducted across the nugget thickness and surface, offering insights into potential failure modes. The welding process involves the transition to a liquid state for the aluminum components, resulting in the formation of intermetallic compounds. Consequently, crack initiation was observed within the aluminum segments, leading to a plug-out fracture mechanism. In contrast, copper exhibits superior strength and hardness compared to aluminum, where increased hardness correlates with heightened strength. The discrepancy in hardness, especially the lower values observed on the aluminum side, caused fractures to appear within the heat affected zone (HAZ). Subsequently, this fracture propagated until pull-out failure was realized. The study revealed that dissimilar joining of Cu and Al resulted in an ultimate tensile stress of 26 MPa, while similar joining of copper showcased a strength of 98 MPa. Additionally, the symmetric join in aluminum exhibited a strength of 93 MPa. The maximum tensile shear force is equal to 512 N at a maximum welding current of 14000 A. The pull-out failure mode occurs in the Cu-Al RSW joint. The maximum hardness was noted in the fusion zone (FZ). Relevant literature sources have supported and confirmed these outcomes.

4

Inspections of aircraft composite components

Zeltiņa Sintija, Kleinhofs Mārtiņš, Chatys Rafał

Composites Theory and Practice

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2024

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R. 24, nr 3

200--204

EN

Inspections and intervals between inspections are often controlled by various parameters in the aviation industry. One of them is the method related to the p-set function, which determines the probability of crack formation and its impact on the service life of a component. It especially concerns polymer matrix composite components. Consequently, a deeper look into the basic principles and analysis of economics is needed, which will develop the theory and broaden the perspective from different angles.

5

Rysy, pęknięcia w betonowych nawierzchniach drogowych (część 1)

Litwinowicz Andrzej, Rechnio Mariusz

Budownictwo, Technologie, Architektura

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2024

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nr 2

38--42

6

Rysy, pęknięcia w betonowych nawierzchniach drogowych (część 2)

Litwinowicz Andrzej, Rechnio Mariusz

Budownictwo, Technologie, Architektura

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2024

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nr 3

52--56

7

Structural integrity of AA7075-T651 UWFSW joints

Kosturek Robert, Ślęzak Tomasz, Torzewski Janusz

Advances in Materials Science

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2024

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Vol. 24, nr 4(82)

98--110

EN

This investigation is focused on the comparison of selected low-cycle fatigue properties of AA7075-T651 friction stir welded and underwater friction stir welded joints together with the evaluation of their lifetime prediction by the Manson-Coffin-Basquin formula. Additionally, the analysis of the fractured surface was involved to describe the character of joints decohesion. The analysis of the obtained hysteresis loops revealed that FSW joint exhibits cyclic hardening, with a stable maximum stress and a decreasing minimum stress, leading to an increased contribution of compressive stresses and a lower mean stress during stabilized fatigue. In comparison, the UWFSW joint also shows cyclic hardening but with a greater contribution of tensile stresses, a higher mean stress, and a reduced participation of plastic deformation. The Manson-Coffin-Basquin equation effectively predicts the fatigue life of AA7075-T651 alloy joints, with UWFSW joints showing significantly lower standard deviation (0.0035 vs. 0.0135) and narrower dispersion bands (1.61 vs. 1.93) compared to conventional FSW joints.

8

Fatigue behaviour of medium carbon steel assessed by the barkhausen noise method

Makowska Katarzyna, Szymczak Tadeusz, Kowalewski Zbigniew L.

Acta Mechanica et Automatica

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2024

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Vol. 18, no. 1

40--47

EN

In this paper, an attempt to estimate the stage of the fatigue process using the Barkhausen noise method is studied. First, microstructural and static tensile tests were carried out and, subsequently, fatigue tests up to failure were conducted. After determination of the material behaviour in the assumed static and dynamic conditions, the interrupted fatigue tests were performed. Each specimen was stressed up to a different number of cycles corresponding to 10%, 30%, 50%, 70% and 90% of fatigue lifetime for the loading conditions considered. In the next step of the experimental programme, the specimens were subjected to the Barkhausen magnetic noise measurements. Various magnetic parameters coming from the rms Barkhausen noise envelopes were determined. The linear relationship betweenthe full-width at half-maximum (FWHM) of the Barkhausen noise envelope and the number of loading cycles to fracture was found. Specimens loaded up to a certain number of cycles were also subjected to a tensile test to assess an influence of fatigue on the fracture features.

9

Influence of mechanical factors on the performance and aging process of oil pump jack

Aliyev Alesker M., Aliyeva Sevda Y.

Nafta-Gaz

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2023

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R. 79, nr 12

776--785

EN

The paper discusses the influence of mechanical factors on the performance and aging process of rocking machines, specifically focusing on oilfield equipment such as the downhole rod pump jack. The authors emphasize the importance of analyzing the condition and aging process of oilfield equipment to ensure reliability, safety, and efficiency in oil production processes. The mechanical factors discussed in the paper include vibrations, loads, wear, and corrosion. Vibrations can be caused by improper balance, bearing failures, or other factors, and they have a negative impact on equipment performance and can lead to breakdowns. High mechanical loads associated with raising and lowering sucker rods can cause wear and damage to the pump jack. Operating in harsh environments with sand, abrasive particles, or chemicals can also cause wear on surfaces and equipment parts. Corrosion of metal components can occur due to moisture, chemical attack, or improper storage and maintenance, leading to deterioration and breakage of equipment. The consequences of these mechanical factors on the aging of an oil pump jack include accelerated aging, decreased performance, and an increased risk of accidents. Continuous exposure to vibration, stress, wear, and corrosion accelerates the aging process, resulting in deterioration and reduced equipment life. Damage and breakdowns caused by mechanical factors lead to decreased efficiency, negatively impacting oil production processes. Moreover, insufficient maintenance and failure to address mechanical influences increase the risk of accidents, downtime, and damage to other parts of the manufacturing process. To assess the health and aging status of an oil pump jack, various analysis and diagnostic methods are used, including visual inspection, strength testing, monitoring of parameters, and non-destructive testing. Visual inspection helps identify visible damage, wear, and defects. Strength testing evaluates the reliability of pump jack parts and identifies potential issues. Monitoring parameters like vibrations, temperature, and pressure allows for detecting deviations from normal operation and preventing breakdowns. Non-destructive testing methods such as ultrasonic testing, magnetic particle testing, and radiography help identify hidden defects and damage. The authors recommend several strategies to maintain the reliability and efficiency of an oil pump jack. These strategies include implementing a preventive maintenance program with regular inspection, testing, and parts replacement based on manufacturer’s recommendations and equipment condition analysis. Determining optimal service and part replacement intervals based on historical data, monitoring results, and manufacturer’s recommendations is crucial. Additionally, utilizing more durable materials, anti-corrosion coatings, improved designs, and technologies can increase equipment resistance to mechanical stress and improve performance. The paper also describes the device and components of a pump jack, such as the installation base, platform, balancer, electric motor, crank, connecting rod, and control station. It emphasizes the importance of considering various characteristics when selecting and evaluating the effectiveness of a pump jack, including working load, maximum plunger stroke, reducer dimensions, output torque, and swing frequency. The kinematics of the pump jack drive system are discussed, highlighting the need for reconfiguration to adapt to changing operating conditions and optimize oil production performance. Overall, the paper emphasizes the importance of analyzing mechanical factors, managing the aging process, and implementing maintenance strategies to ensure the reliable and efficient operation of oilfield equipment, specifically the pump jack used in oil production processes.

PL

: W artykule omówiono wpływ czynników mechanicznych na wydajność i proces starzenia się kiwonów, koncentrując się na urządzeniach do eksploatacji złóż ropy naftowej. Autorzy podkreślają znaczenie analizy stanu i procesu starzenia się sprzętu naftowego dla zapewnienia niezawodności, bezpieczeństwa i wydajności procesów produkcji ropy naftowej. Czynniki mechaniczne omówione w artykule obejmują drgania, obciążenia, zużycie i korozję. Drgania mogą być wywołane przez nieodpowiednie zbalansowanie, usterki łożysk lub inne czynniki i mają negatywny wpływ na wydajność sprzętu oraz mogą prowadzić do awarii. Wysokie obciążenia mechaniczne powiązane z podnoszeniem i opuszczaniem żerdzi pompowych mogą powodować zużycie i uszkodzenie kiwona. Praca w trudnych środowiskach z piaskiem, cząstkami ścierającymi lub chemikaliami może także skutkować zużyciem powierzchni i części sprzętu. Korozja komponentów metalowych może wystąpić w związku z wilgocią, agresywnością chemiczną lub nieodpowiednim przechowywaniem i konserwacją i doprowadzić do degradacji i uszkodzeń sprzętu. Konsekwencje tych czynników mechanicznych względem starzenia się kiwona obejmują przyspieszone starzenie, zmniejszoną wydajność i zwiększone ryzyko wypadków. Stałe narażenie na drgania, naprężenie, zużycie i korozję przyspiesza proces starzenia, powodując degradację i zmniejszenie żywotności sprzętu. Uszkodzenia i awarie wywołane przez czynniki mechaniczne prowadzą do zmniejszenia wydajności, wpływając negatywnie na procesy produkcji ropy naftowej. Ponadto niewystarczająca konserwacja i brak uwzględnienia wpływów mechanicznych zwiększają ryzyko wypadków, przestoju i uszkodzenia innych elementów procesu produkcyjnego. Aby ocenić stan i status starzenia się kiwona, stosuje się różne analizy i metody diagnostyczne, w tym inspekcję wizualną, próby wytrzymałościowe, monitorowanie parametrów i próby nieniszczące. Inspekcja wizualna pomaga zidentyfikować widoczne uszkodzenia, zużycie i defekty. Próby wytrzymałościowe oceniają niezawodność części kiwona i identyfikują potencjalne problemy. Monitorowanie parametrów takich jak drgania, temperatura i ciśnienie pozwala wykryć odchylenia od normalnej pracy i zapobiec awariom. Metody prób nieniszczących, takie jak badania ultradźwiękowe, badania magnetyczno-proszkowe i radiografia, pomagają odnaleźć ukryte defekty i uszkodzenia. Autorzy rekomendują kilka strategii dla zachowania niezawodności i wydajności kiwona. Strategie te obejmują wdrożenie zapobiegawczego programu konserwacji z regularnymi przeglądami, testami i wymianą części na podstawie rekomendacji producenta i analizy stanu sprzętu. Kluczowe jest ustalenie optymalnych przedziałów serwisowania i wymiany części, opierając się na danych historycznych, wynikach monitoringu i rekomendacjach producenta. Dodatkowo stosowanie wytrzymalszych materiałów, powłok antykorozyjnych, ulepszonych konstrukcji i technologii może zwiększyć wytrzymałość sprzętu na naprężenia mechaniczne i poprawić wydajność. W artykule opisano także urządzenia i komponenty kiwona, takie jak podstawa instalacyjna, platforma, wahacz, silnik elektryczny, korba, żerdź łącząca i stanowisko sterowania. Podkreślono znaczenie uwzględnienia różnych cech podczas wyboru i oceny wydajności kiwona, w tym obciążenia roboczego, maksymalnego suwu tłoka, wymiarów reduktora, wyjściowego momentu obrotowego i częstotliwości ruchu wahadłowego. Omówiona została kinematyka systemu napędowego kiwona, z podkreśleniem potrzeby rekonfiguracji w celu przystosowania się do zmiennych warunków pracy i optymalizacji wydajności produkcji ropy naftowej. Ogólnie rzecz biorąc, w artykule podkreślono znaczenie analizy czynników mechanicznych, zarządzania procesem starzenia i wdrażania strategii konserwacji dla zapewnienia niezawodnej i wydajnej pracy sprzętu na złożach ropy naftowej, a konkretnie kiwona stosowanego w procesach produkcji ropy naftowej.

10

Destruction of high pressure vessels in pipeline structures

Rahimova Mahluqa S., Abbasov Sakit H., Ahmadov Alihikmat A.

Nafta-Gaz

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2023

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R. 79, nr 5

360--364

EN

The article indicates that engineering design criteria do not provide measures to prevent failures; this is evidenced by the occurrence of many accidents. Fracture prevention criteria should be derived from the principles of fracture mechanics, what should be developed further. However, the current concepts of fracture mechanics, when properly applied, provide an opportunity to ensure the reliability of the structure or organise the supervision of expensive structures to ensure their safe operation. These methods of preventing damage can be divided into two large groups: 1) checking for the formation of cracks and 2) monitoring their development. Both methods are based on similar principles; it would be easier to explain them with examples. To ensure the safe operation of the pressure vessel used in the reactor, the maximum allowable initial crack size should be known. The size of this crack should not expand to a critical point during the entire operation of the reactor. Knowing how the process of crack propagation proceeds and how the structure behaves during failure, it is possible to calculate the critical size of the defect and, based on this, calculate the maximum allowable size of the crack at the beginning of operation. Proper inspection of the new vessel will eliminate the possibility of shells that are larger than the original size. Checking for the presence of cracks, and determining their rate of growth during operation, presents significant difficulties. Therefore, checks should be avoided during operation. If the fracture and crack growth calculations, as well as the initial checks, are carried out correctly, then checks made during operation are an optional extra. However, in practice, such checks should still be performed. For vessels used in reactors, remote observation of crack growth using ultrasonic waves is a particularly useful method. If a crack is found, measures must be taken to either repair or replace the partially destroyed element.

PL

W artykule wskazano, że kryteria na etapie tworzenia projektu technicznego często nie uwzględniają środków zapobiegających awariom, o czym świadczą liczne wypadki przy pracy. Kryteria zapobiegania powstawaniu pęknięć powinny być wyprowadzane z zasad mechaniki powstawania pęknięć, co wymaga dalszego rozwoju. Jednak obecne koncepcje mechaniki powstawania pęknięć, przy ich właściwym stosowaniu, dają możliwość zapewnienia niezawodności konstrukcji lub zorganizowania nadzoru nad kosztownymi konstrukcjami, aby zapewnić ich bezpieczną eksploatację. Te metody zapobiegania uszkodzeniom można podzielić na dwie duże grupy: 1) kontrola pod kątem powstawania pęknięć, 2) monitorowanie ich wzrostu. Obie metody opierają się na podobnych zasadach i lepiej wyjaśnić je na przykładach. W celu zapewnienia bezpiecznej eksploatacji zbiornika ciśnieniowego używanego w reaktorze należy znać maksymalną dopuszczalną początkową wielkość pęknięcia. Wielkość takiego pęknięcia nie powinna wzrosnąć do wartości krytycznej przez cały czas pracy reaktora. Wiedząc, jak przebiega proces propagacji pęknięć i jak zachowuje się konstrukcja podczas uszkodzenia, można obliczyć krytyczną wielkość uszkodzenia i na tej podstawie obliczyć maksymalną dopuszczalną wielkość pęknięcia na początku eksploatacji. Prawidłowa kontrola nowego zbiornika wyeliminuje możliwość wystąpienia pęknięć większych niż o pierwotnym rozmiarze. Kontrole pod kątem obecności pęknięć i określenie tempa ich wzrostu podczas pracy wiążą się z dużymi trudnościami. Dlatego należy unikać wykonywania kontroli podczas pracy. Jeżeli obliczenia dotyczące pęknięć i ich wzrostu, jak również kontrole wstępne, zostały przeprowadzone prawidłowo, to kontrole podczas eksploatacji byłyby opcjonalnym dodatkiem. Jednak w praktyce takie kontrole i tak są przeprowadzane. W przypadku zbiorników używanych w reaktorach szczególnie przydatną metodą jest zdalna obserwacja wzrostu pęknięć za pomocą fal ultradźwiękowych. W przypadku stwierdzenia pęknięcia należy podjąć działania w celu naprawy lub wymiany częściowo zniszczonego elementu.

11

Numerical analysis of propagation of femur crack due to osteoporotic changes

Kuryło Piotr, Zaborowska K., Czarnecki P., Pruszyński P.

Journal of Achievements in Materials and Manufacturing Engineering

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2023

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Vol. 121, nr 2

320--326

EN

The aim of the research was to analyse the possibilities of a model description of the type of bone fracture, the state of stress and strain, the method of fix and load, and the physical properties of bone tissue in relation to the method of loading the hip joint in individual phases of physical activity. Design/methodology/approach Analysis of the phenomenon of bone fracture with the use of the finite element method (FEM), which allows to observe the phenomenon of bone fracture affected by osteoporosis, taking into consideration bone disease foci. Modelling of femoral fracture propagation at different periosteal densities was performed. Findings Differences in the method of fracture of the femoral neck are presented, showing different boundaries of bone discontinuity depending on the point of fracture initiation and the force required for its propagation. Research limitations/implications Reproduction of the diseased bone may be limited by the accuracy of its digital model and the physically limited density of the FEM mesh. Using model tests allows us to understand the phenomenon of osteoporotic bone fracture and predict the effects of fracture, which will allow for faster implementation of an effective treatment method. Practical implications The use of the FEM method for analysis allows obtaining knowledge about the formation of bone discontinuities after fracture. It also allows for predicting the place of its occurrence and selecting the appropriate treatment method. Originality/value There was a significant difference in the shape of the femoral neck fracture depending on the place of its initiation. The effectiveness of the FEM analysis in predicting the location, shape and type of fracture is presented.

12

Walcowanie poprzeczno-klinowe odkuwki osi kolejowej

Bulzak Tomasz, Winiarski Grzegorz, Wójcik Łukasz

Hutnik, Wiadomości Hutnicze

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2023

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Vol. 90, nr 2

16--20

PL

Artykuł przedstawia wyniki modelowania numerycznego procesu walcowania poprzeczno-klinowego odkuwek osi kolejowych. Na wstępie przedstawiono główny problem, jakim jest pękanie materiału w procesie walcowania poprzeczno-klinowego. Przedstawiono propozycję ograniczenia zjawiska pękania materiału, polegającą na zmianie konstrukcji narzędzi kształtujących. Zaprojektowano trzy warianty narzędzi, których przydatność w procesie walcowania poprzeczno-klinowego osi kolejowych została zweryfikowana na drodze symulacji numerycznych. Symulacje numeryczne przeprowadzono metodą elementów skończonych w oprogramowaniu Simufact Forming. Uzyskane wyniki nie potwierdziły przyjętych założeń. Zastosowanie narzędzi z dwoma kątami kształtującymi wpłynęło na wzrost wartości kryterium pękania, co tym samym zwiększa ryzyko pękania materiału podczas walcowania osi kolejowych.

EN

This paper presents the results of numerical modelling of the cross-wedge rolling process of railway axle forgings. The main problem of material cracking in the cross-wedge rolling process is first presented. A proposal to reduce the phenomenon of material cracking by changing the design of forming tools is presented. Three tool variants were designed, the suitability of which in the process of cross-wedge rolling of railway axles was verified by means of numerical simulations. Numerical simulations were carried out using the finite element method in the Simufact Forming software. The results obtained did not confirm the assumptions made. The use of tools with two forming angles increased the value of the fracture criterion, thereby increasing the risk of material fracture during rolling of railway axles

13

Study on Tensile Properties and Microstructures of Different Sites in Al-Si Alloy Casting Component

Tao Jianquan, Xiang Lin, Chen Xidong, Sun Jipeng, Wang Yanbin, Du Chuanhang, Peng Feifei, Gao Shiqing, Chen Qiang

Archives of Metallurgy and Materials

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2023

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Vol. 68, iss. 2

585--589

EN

The tensile properties and microstructures of ZL114A alloy component with a complex shape are investigated at room temperature and 200°C, using the tensile tests, scanning electron microscopy and electron backscattering diffraction. Both thin wall and thick structure exhibit excellent properties, of which max ultimate tensile strength and elongation at break reach 314 MPa and 2.5% at room temperature, respectively. The ultimate tensile strengths of thin wall are 40 MPa and 25 MPa greater than those of thick structure at room temperature and 200°C, respectively. Moreover, the eutectic Si phases of thin wall exhibit a predominantly spherical morphology while of the morphology of thick structure are rod-like, resulting in the different mechanical properties between thin wall and thick structure. The fracture morphologies of thin wall and thick structure are studied to explain the difference in performance between thin wall and thick structure.

14

Multi Wedge Cross Rolling of Axle Forgings

Bulzak Tomasz

Archives of Metallurgy and Materials

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2023

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Vol. 68, iss. 2

697--701

EN

This paper presents the results of research into the cross wedge rolling (CWR) process of axle forgings. The presented results concern the parallel rolling process with two wedges. The use of two parallel wedges is aimed at shortening the tool length (increasing productivity) and reducing the values of wedge opening angles and increasing the forming angles, so that the condition 0.04 ≤ tgαtgβ ≤ 0.08 is maintained to guarantee the highest quality forgings. The article analyses the influence of the design of the double wedge tool on the geometric correctness of the forgings obtained, the value of the failure criterion and the force parameters of the process. The results obtained show that the use of multi wedge tools improves rolling conditions by increasing productivity and reducing the tendency of the material to crack with appropriately selected tool parameters.

15

Investigation of electromagnetic punching process with adjustable collision velocity for ultra‑thin titanium sheet

Huang Yifan, Wu Zelin, Dong Pengxin, Liu Runze, Chen Yao, Han Xiaotao

Archives of Civil and Mechanical Engineering

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2023

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Vol. 23, no. 4

art. e263, 1--17

EN

Electromagnetic punching (EMP) is a new type of high-speed punching technology. In the existing EMP method, the blank has no initial loading velocity, so the punching force can only be increased by boosting the discharge energy, which greatly reduces the energy utilization and limits its application in high-strength thin sheet punching. To this end, this paper proposes and validates an EMP method with adjustable initial collision velocity based on the inner-field uniform pressure actuator (UPA) for manufacturing punched parts of TA1 pure titanium foil sheet. The results show that with the increase of collision velocity, the punchable aperture range expands, the dimensional accuracy and section quality of punched parts are significantly improved, and a punchable window is established. In addition, based on the dynamic material constitutive and fracture model, the electromagnetic-structural field simulation model of EMP is established. The analysis shows that the formation of the fracture section is the result of the combined effect of tensile stress and shear stress, and the increase of the collision velocity improves the section quality. Finally, a 100 μm thick titanium sheet with a hole diameter of 2–16 mm and a maximum dimension accuracy of less than 10 μm was successfully punched.

16

Does water lubrication affect friction differently for rocks and soils? Evidence and open questions

Cafaro F., Hamad A., Monterisi L.

Studia Geotechnica et Mechanica

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2022

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Vol. 44, nr 3

211--223

EN

The present paper focuses on the shear strength exhibited by rocks and soils when sliding along dry and wet surfaces, with this mechanism of failure being strongly related to the water lubrication phenomenon. It is well known that the frictional behaviour of geomaterials requires multiscale investigation. Under this perspective, experimental evidence of both friction at the grain scale (i.e. interparticle friction) and friction along sliding surfaces of rock and granular soil samples (i.e. surface friction) are analysed by using data from the literature. The review is addressed at linking different scales, stating the differences between rocks and soils in terms of frictional response to sliding and trying to point out still open problems for the research.

17

Investigation of probabilistic aspects reliability of isotropic bodies with internal defects

Kvit Roman

Journal of Applied Mathematics and Computational Mechanics

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2022

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Vol. 21, nr 3

73--84

EN

A study of the stress state and reliability of an isotropic body with the same material crack resistance and evenly distributed internal defects-cracks under the conditions of homogeneous axisymmetric loading is carried out. Defects are characterized by two independent random variables – a radius and orientation angle. The probability density distribution of the defect radius is chosen in the form of an exponential law. The probability density distribution of the defect orientation angle is chosen in the form of a law that corresponds to the material isotropy. The influence of the loading level, type of stress state and body size (number of defects) on the most probable value, the mean value and the dispersion of failure loading (strength) are investigated.

18

Application of the design of experiments and statistical hypothesis to reduce defects in the flange of the steel plate process

Sadłowska Hanna, Wójcik Piotr

Computer Methods in Materials Science

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2022

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Vol. 22, No. 3

149--156

EN

The paper presents a discussion on the occurrence of defects in the circumferential flange of steel plate. The numerous flange face defects have been analysed. The types of defects have been selected and categorized using an experimental planning procedure involving 600 samples for 24 different process variants, considering variables such as material, hole diameter, tool size and tool position. The analysis of experimental results enabled to determine of the optimal values of process parameters to minimize the occurrence of defects. Furthermore, the influence of individual parameters on the quality of the flange surface has been carried out to obtain the process parameters’ impact using statistical hypotheses. As a result, it was possible to develop rules which will be helpful in the design process, especially important when changing the material to be processed.

19

Study of rock fracture under blast loading

Baranowski Paweł, Kucewicz Michał, Pytlik Mateusz, Małachowski Jerzy

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2022

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Vol. 70, nr 5

art. no. e141723

EN

A study of dolomite rock material failure using a simple small-scale blast setup is presented. Laboratory tests were conducted using disc specimens drilled with a borehole in the center. A detonation cord and a blasting cap were fitted inside the borehole to induce cracking and fracturing of the specimens. The specimens were inserted between two steel plates, which were compressed against the specimen using bolt screws. Prior to testing, the most suitable screw torque for constraining the vertical displacement of the specimen surfaces without compressing the specimen was selected based on numerical simulations. Then, the experimental tests with the blasting cap were simulated using the Johnson–Holmquist II (JH-2) material model, and the properties of the blasting cap were determined and verified in two special tests with a lead specimen. Possessing the validated model, the influence of specimen thickness on the cracking patterns was finally analyzed. This paper presents a relatively easy method for studying rock material behavior under blast loading and for validating the numerical and constitutive models used for rock simulations.

20

Research on Forming Parameters Optimization of Incremental Sheet Forming Process for Commercially Pure Titanium Grade 2 Sheets

Szpunar Marcin, Trzepieciński Tomasz, Ostrowski Robert, Zwolak Marek

Archives of Metallurgy and Materials

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2022

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Vol. 67, iss. 4

1411--1418

EN

This study aims to determine optimal forming parameters for Incremental Sheet Forming process Commercially Pure titanium Grade 2 sheets in terms of formability improvement, force reduction, and efficiency of forming. Based on the central composite design, data were collected during 20 runs and then variation analysis was performed. The experiments were performed on a 3 axis CNC milling machine equipped with a Kistler dynamometer plate. Subsequently, regression models have been developed to describe process responses by input factors. As crucial parameters, the relative velocity and step size of the tool that affect the forming force and the height of the fracture have been determined. Finally, the application of optimization algorithm has emerged optimal input factors in terms of selected multi-criteria goal. The results of this study suggest that there is a process window that allows the formation of 45° wall angle drawpieces of commercially pure titanium Grade 2.