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1

An individual core structure of a sandwich beam due to the “broken line” theory of the shear effect–three-point bending

Magnucki Krzysztof, Magnucka-Blandzi Ewa

Acta Mechanica et Automatica

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2025

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Vol. 19, no. 1

1--6

EN

The work concerns a sandwich beam with an individual core structure giving a shear effect exactly in accordance to the "broken line" theory. According to the general theoretical scheme of a planar cross section deformation, longitudinal displacements, strains and stresses are analytically formulated. Moreover, the unknown deformation function of the core, with consideration of the classical shear stress formula, is analytically derived. Based on the condition regarding the linear deformation function of the core, according to the “broken line” theory, the differential equation is obtained. The solution of this equation is the sought individual core structure. Then, the bending problem of a clamped sandwich beam under three-point bending is studied.

2

Conception of suspension system with variable stiffness for mobile robots

Duda Sławomir, Gembalczyk Grzegorz, Kowalik Zygmunt, Machoczek Tomasz

Vibrations in Physical Systems

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2024

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Vol. 35, nr 1

art. no. 2024118

EN

The paper presents the results of work on an innovative form of the suspension node. It is a concept of semi-active suspension that allows for control the stiffness system during operation of the device. This type of suspension can be used in robotic intralogistics systems, where mobile platforms must have a suspension that ensures adequate vibration damping, keeps the platform in a horizontal position, and at the same time provides adequate pressure to the ground of the drive wheels. A particularly interesting object with the potential possibility of using such a suspension are vehicles with omnidirectional wheels. The proposed design form is the first prototype version, which should primarily be used to validate computational models. The idea of the developed suspension element refers to the double torsion shafts.

3

Cold forming of steel - selected processes, issues, and CAx

Horajski Piotr

Systemy Wspomagania w Inżynierii Produkcji

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2024

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Vol. 13, iss. 1

41--54

EN

This paper presents an analysis of the key challenges and irregularities associated with metal plastic deformation processes, with particular emphasis on phenomena such as springback, wrinkling, folding, cracking, microcracking, and burr formation. These undesirable effects can negatively impact the quality of final products and their mechanical properties, as well as the durability of tools used in processes such as bending, stamping, spinning, and cutting. The paper discusses the mechanisms leading to the formation of these defects, highlighting the role of process conditions, such as stress, processing speed, and tool geometry, which can cause technological issues. It also emphasizes the significance of tool wear, particularly in cutting processes, where abrasive, adhesive, and fatigue wear can lead to burr formation and deterioration in the quality of cut components. The study further explores methods to minimize these defects through process parameter optimization and proper tool design. Special attention is given to the use of numerical tools, such as the finite element method (FEM), which enables precise modeling of stress and strain distributions and the prediction of potential defect locations. Advanced simulations allow for improved prediction of issues like cracking, wrinkling, and springback, which ultimately enhances the quality of deformation processes and final products. The paper also highlights the need for further research in plastic deformation and the development of numerical models, particularly in the context of accounting for microstructural changes and residual stresses in materials.

PL

Niniejsza praca przedstawia analizę kluczowych wyzwań i nieprawidłowości związanych z procesami deformacji plastycznej metali, ze szczególnym uwzględnieniem takich zjawisk jak powrót sprężysty, marszczenie, fałdowanie, pękanie, mikropęknięcia oraz powstawanie gratu. Te niepożądane efekty mogą negatywnie wpływać na jakość finalnych produktów oraz ich właściwości mechaniczne, a także na trwałość narzędzi wykorzystywanych w procesach, takich jak gięcie, tłoczenie, wyoblanie czy cięcie. W pracy omówiono mechanizmy prowadzące do powstawania tych wad, zwracając uwagę na rolę warunków realizacji procesu i zjawisk fizycznych, takich jak naprężenia, prędkość obróbki oraz geometrię narzędzi, które mogą prowadzić do problemów technologicznych. Podkreślono również znaczenie zużycia narzędzi, w szczególności w kontekście procesów cięcia, gdzie zużycie cierne, adhezyjne oraz zmęczeniowe może prowadzić do powstawania gratu oraz pogorszenia jakości ciętych elementów. Analizowano także metody minimalizowania wspomnianych wad poprzez optymalizację parametrów procesowych i odpowiednie projektowanie narzędzi. Szczególną uwagę poświęcono wykorzystaniu narzędzi numerycznych, takich jak metoda elementów skończonych (MES), która pozwala na precyzyjne modelowanie rozkładów naprężeń, odkształceń oraz przewidywanie miejsc potencjalnych wad. Dzięki zaawansowanym symulacjom możliwe jest lepsze przewidywanie zjawisk takich jak pękanie, fałdowanie czy powrót sprężysty, co pozwala na poprawę jakości procesów deformacyjnych i produktów końcowych. Wskazano również na potrzebę dalszych badań w zakresie obróbki plastycznej oraz rozwoju modeli numerycznych, szczególnie w kontekście uwzględniania zmian mikrostrukturalnych i naprężeń resztkowych w materiałach.

4

Numerical investigation of the asymptotic behavior of tape springs

Coppedè Michele, Paroni Roberto, Picchi Scardaoni Marco

Journal of Theoretical and Applied Mechanics

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2024

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Vol. 62 nr 3

535--545

EN

Here, we investigate the behavior of the energy of a tape spring as its thickness becomes smaller and smaller. We consider the case of pure bending, i.e., we impose opposite rotations at both ends of the device. First, tape springs are introduced and their peculiar mechanical behavior is explained, and the details of the numerical model are carefully introduced. Then, a parametric study of the device is conducted for increasing end rotations and decreasing values of the thickness. Thus, we obtain parametric diagrams of reaction moments, energy per unit thickness, and energy densities. Finally, energy estimates are obtained.

5

Bending of a homogeneous beam with a monosymmetric cross section – shear effect

Magnucki Krzysztof, Magnucka-Blandzi Ewa, Witkowski Dawid, Stefańska Natalia

Engineering Transactions

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2024

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Vol. 72, iss. 3

285--307

EN

This paper is devoted to the study of a homogeneous clamped beam with a monosymmetric cross section under uniformly distributed load or three-point bending. A nonlinear shear deformation theory of a plane beam cross section based on the classical shear stress formula known as the Zhuravsky shear stress is developed. The values of shear coefficients and maximum deflections of exemplary beams are analytically determined. Moreover, numerical FEM computations for these beams are carried out. The results of the research from both methods are shown in figures, specified in tables, and compared. The percentage relative differences between the analytical and numerical results prove that the proposed original shear deformation theory accurately describes the shear deformation problem of a beam’s planar crosssection.

6

Fatigue fracture cross-sections after cyclic tests with a combination of cyclic bending and torsion of samples made of aluminum alloy 6060

Łagoda Tadeusz, Małecka Joanna, Małys Slawomir, Derda Szymon, Kuś Juliusz, Krysiński Paweł

Eksploatacja i Niezawodność

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2024

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Vol. 26, no. 1

art. no. 176203

EN

The paper presents the results of fatigue tests of the 6060 aluminum alloy. The test material was taken from the profiles used for the production of side windows and external doors of the passenger trains by the RAWAG company. The tests were carried out for cyclic loads with pure bending, pure torsion, and two combinations of bending and torsion. Fatigue tests were performed at zero mean values. Using scanning electron microscopy, a fractographic analysis was made, which is a supplementary basic for considerations about the mechanism of initiation and development of fatigue cracks. Based on the appearance of individual zones and the characteristics of cracks, a picture of the behavior of the material under specific conditions was obtained. Finally, the plastic property of fatigue cracks was indicated.

7

Functionally graded porous material and its application in sandwich beams for bending and vibration behaviors

Ton That Hoang Lan

Computer Methods in Materials Science

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2024

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Vol. 24, No. 1

15--24

EN

The article describes a functionally graded porous material in an application for sandwich beams. The bending and vibration behaviors of this structure are studied using the finite element method based on a simple beam model. The influences of some parameters, e.g., the porosity factor or the exponent graded, are also studied in this article. Finally, the numerical results are presented with some discussion.

8

An analytical model for the tool center point placement in Robotic Roller Forming

Stewens Thomas, Liu Yi, Wang Ling, Min Junying

Computer Methods in Materials Science

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2024

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Vol. 24, No. 2

39--48

EN

Robotic Roller Forming (RRF) is a novel process using an articulated robotic manipulator that can bend Ultra-High Strength materials into thin-walled profiles. For high strength or difficult-to-form sheet materials, a laser can be employed to synchronously heat and soften the local material during RRF. The aim of RRF is to establish itself as a highly flexible process for rapid prototyping as well as for small batch production. However, in finished parts formed with different materials, a new defect that shapes the profile like that of a hook was observed. To overcome this defect and to improve the adaptability of the process, a new analytical model is suggested for the automatic calculation of the tool center point based on the given process parameters. The model was compared to the previous state, where the hook defect was noticeably reduced. Additionally, the control of the bend radius was studied, and the resulting bend radius diverged from the target radius by 0.04 mm (2.45%). Further, when examining the reproducibility, the same bend angles could be achieved as in previous experiments using the constant laser power density. Finally, the development of the bend allowance was studied in various experiments. The analytical model for RRF is a promising method for calculating tool placement and controlling the bend radius in a freeform environment.

9

On the deformation of elastic rods in a symmetric micromorphic theory

De Cicco S.

Archives of Mechanics

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2024

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Vol. 76, nr 4

311--333

EN

We investigate the deformation of an elastic isotropic rod in the framework of a simplified micromorphic theory introduced by Forest and Sievert. In contrast with the classical micromorphic model, which includes 18 elastic constants, this theory is characterized by constitutive equations which involve 6 constants and a material length scale parameter to describe microstructure-dependent size effects. First, we formulate the equilibrium problem of a rod subjected to a resultant force and resultant moment acting on its plane ends. Then, we generalize the method of construction of the solution avoiding a priori assumptions proposed by Iesan in classical elasticity. The method leads to the decomposition of the general problem into the basic problems of extension, bending, torsion and flexure. The analytical solutions are obtained in a closed form and reduced to their classical elasticity counterparts when the microstructure effects are suppressed. The results are useful to obtain explicit solutions when the shape of the cross section is assigned and are preliminary to the solution of the problem of cylinders loaded on a lateral surface such as the Almansi–Michel problem.

10

Design of flexural strengthening based on fib Bulletin 90

Kotynia Renata, Kaszubska Monika

Archives of Civil Engineering

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2024

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Vol. 70, nr 2

291--308

EN

This paper presents the analysis of intermediate and end debonding failure in slab strengthened using carbon tapes (Carbon Fiber Reinforced Polymer). The calculations are based on the more accurate method in the latest fib Bulletin 90. Consideration of additional effects based on three conditions: basic bond, bond friction and member curvature in the intermediate crack debonding analysis give the ratios ΔFf Ed / ΔFf Rd from 0.01 to 0.11, depending on the cross-section. For comparison in the simplified analysis of the ratio, MEd / MRd is equal 0.76. It is clearly visible the methods requiring more computational effort give lower values of element effort and allows the design to be more economical. As the strengthening fulfills the ultimate limit state, it does not meet the serviceability limit state.

PL

Wzmacnianie elementów żelbetowych na zginanie przy użyciu taśm i mat kompozytowych jest powszechnie stosowaną metodą zwiększania nośności. Potrzeba zwiększenia nośności może wynikać ze zmiany funkcji użytkowej obiektu, jak również z powstania dodatkowego obciążenia skupionego lub liniowego na stropie. Taki przykład jest podstawą niniejszego artykułu, w którym zaprezentowano projektowanie wzmocnienia płyty na zginanie przy użyciu taśm węglowych (Carbon Fiber Reinforced Polymer – CFRP), według wytycznych fib Bulletin 90 w wersji dokładnej. Analizie poddano płytę żelbetową wzmocnioną 3 taśmami na 1 metr szerokości płyty. Dodatkowe obciążenie wynikało z zaprojektowania nowej ściany. W pierwszym kroku obliczenia zostały wykonane w odniesieniu do możliwości odspojenia taśmy w części środkowej. Ze względu na symetrię analizowano tylko połowę płyty, rozpoczynając położenie kolejnych przekrojów od środka belki. Metoda dokładna opiera się na analizie naprężeń przyczepności taśm CFRP do betonu na odcinkach między rysami. Warunek nośności jest spełniony, jeśli siła rozciągająca w taśmach CFRP ΔFfEd jest niższa niż siła przyczepności taśm do betonu ΔFfRd na każdym odcinku pomiędzy rysami: ΔFfEd ≤ ΔFfRd. Siła występująca w taśmach CFRP w miejscach, gdzie założono położenie kolejnych rys została ustalona iteracyjnie na podstawie równowagi przekrojów. W przedstawionym przykładzie warunek ten został spełniony w każdym analizowanym przekroju. Następnie wykonano obliczenia odnoszące się do możliwości odspojenia taśmy w miejscu zakotwienia.

11

The Process of Bending Pipes for Components of Aircraft Frames and Trusses

Bałon Paweł, Rejman Edward, Kiełbasa Bartłomiej, Smusz Robert, Szeliga Grzegorz

Advances in Science and Technology. Research Journal

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2024

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Vol. 18, no. 3

333--342

EN

Demand for bent pipe profiles in various industrial sectors is increasing due to considerations necessitating lightweight construction, safety, as well as space and cost savings. Lightweight construction is becoming increasingly important for economic and ecological reasons. This can be seen in the automotive and aerospace industries, as well as in civil engineering, where curved structures are often required. In order to reduce the weight of the aircraft, the aviation industry often uses spatial truss structures with bent elements. The challenge is to meet all of the stringent requirements regarding design, safety, structure, size, cost, etc., without compromising a structure's stiffness. Profiles with complicated cross-sections and so-called tailored tubes are increasingly used in the production of automotive and aircraft structures (General Aviation). Pipe and profile bending technologies are constantly being improved upon to meet the growing expectations of customers and ensure greater process efficiency. Currently, efforts are being made to increase the level of automation in this area by combining the functionality of modern bending machines with the capabilities of industrial robots. CNC bending machines currently dominate the industrial pipe bending process. A technologically advanced bending machine allows for the production of increasingly complex shapes and profiles.

12

The effect of blankholder pressure on the amount of springback in the U-draw bending process

Fejkiel Romuald

Advances in Mechanical and Materials Engineering

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2024

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Vol. 41, nr 1

195--204

EN

Springback in sheet metal forming processes is a phenomenon that makes it difficult to obtain products with the desired geometry. This paper presents the results of research on the effect of the blankholder pressure on the elastic deformations of sheets during the forming of strip specimens (50 mm wide and 400 mm long) into U-shaped components. A special die was developed for the forming of sheet metals under variable blankholder pressure conditions in the range between 1 and 3 MPa. Three grades of sheets with significantly different properties were used as the research material: 6063 aluminium alloy, S235JR structural steel and X46Cr13 stainless steel. The research was conducted under dry friction conditions. The elastic deformations of the sheet metal in the U-draw bending process were of a different character in the punch radius and die radius areas. In the area of the punch edge, the springback coefficient decreased with increasing blankholder pressure. This relationship was observed for all the tested materials. In the area of the die edge, a decrease in the value of the bending angle was generally observed in relation to the bending angle in the loaded state.

PL

Sprężynowanie jest zjawiskiem, które utrudnia otrzymanie wyrobów o pożądanej geometrii w procesach kształtowania blach. W pracy przedstawiono wyniki badań wpływu nacisku dociskacza na odkształcenia sprężyste blach podczas ich kształtowania pasów blachy o szerokości 50 mm i długości 400 mm w wyroby w kształcie litery U. Opracowano specjalny tłocznik pozwalający na kształtowanie wyrobów w warunkach zmiennego nacisku dociskacza w zakresie 1-3 MPa. Jako materiał badawczy wykorzystano trzy gatunki blach o znacznie różniących się właściwościach: stop aluminium EN AW-6063, stal konstrukcyjna S235JR oraz stal nierdzewna X46Cr13. Badania przeprowadzono w warunkach tarcia suchego. Odkształcenia sprężyste blachy w procesie gięcia w kształcie litery U miały inny charakter w obszarach promienia stempla i promienia matrycy. W obszarze krawędzi stempla współczynnik sprężynowania zmniejszał się ze wzrostem nacisku dociskacza. Tę zależność zaobserwowano dla wszystkich badanych materiałów o różnych właściwościach mechanicznych. W strefie krawędzi matrycy generalnie zaobserwowano zmniejszenie kąta gięcia w stosunku do kąta gięcia w stanie obciążonym.

13

A study of factors affecting wear and destruction of teeth in gear mechanisms

Mustafayev Amir G., Nasirov Chingiz R

Nafta-Gaz

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2023

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R. 79, nr 9

604--610

EN

Transmission gears are very widely used in the modern construction of the machine. Even though electrical transmissions are used, mainly mechanical transmissions are widely used in the machine building industry as they are independent and better than other transmissions. Distributing power between the transmission mechanisms and working units of various machines, by changing the angle of momentum by adjusting the speed of the parts, it is possible to change the type of movement, turn the mechanism on and off, and change the direction of the transmission mechanisms. One of the most widespread types of transmission technology is gear transmission. Tens of thousands of kilowatt-hours of gears can be transmitted. The advantages of gear transmission in comparison with others are their ability to maintain their reliability and long-term functioning of the teeth, high value of the working coefficient (0.90–0.99), simple construction, lack of special service, simplicity of the transmission number and compactness of dimensions. The missing aspects of these transmissions are high precision in their preparation and installation, and low noise level. The main criterion for the working ability of the closed gear transmissions is the contact endurance of the active surface of the tooth. For this reason, the main dimensions of the transmission are determined by the contact tension and by teeth bending.

PL

Przekładnie zębate znajdują szerokie zastosowanie w nowoczesnych maszynach. Chociaż stosuje się także przekładnie elektryczne, to w przemyśle maszynowym stosowane są głównie przekładnie mechaniczne, ponieważ są one niezależne i lepsze od innych rodzajów przekładni. Przekładnie zębate umożliwiają rozprowadzenie mocy między mechanizmami przekładni a różnymi jednostkami roboczymi poszczególnych maszyn, poprzez zmianę kąta pędu i regulację prędkości części. Dzięki temu można zmieniać rodzaj ruchu, włączać i wyłączać mechanizmy oraz zmieniać kierunek mechanizmów przekładni. Jednym z najbardziej powszechnych rodzajów przekładni są przekładnie zębate. Mogą one przenosić dziesiątki tysięcy kilowatogodzin mocy. Przewaga przekładni zębatych nad innymi mechanizmami tego typu tkwi w ich niezawodności, trwałości zębów, wysokiej wartości współczynnika pracy (0,90–0,99), prostej konstrukcji, braku wymogu specjalnego serwisowania, prostocie liczby przełożeń i niewielkich wymiarach. To, czego im brakuje, to zachowanie wysokiej precyzji wykonania i montażu oraz niski poziom hałasu. Głównym kryterium decydującym o sprawności zamkniętych przekładni zębatych jest wytrzymałość styku aktywnej powierzchni zęba. Z tego powodu główne wymiary przekładni zależą od naprężenia stykowego i zginania zębów.

14

Wykorzystanie zdolności pochłaniania energii do wyznaczania wytrzymałości resztkowych fibrokompozytów

Głodkowska Wiesława, Laskowska-Bury Joanna, Lehmann Marek

Materiały Budowlane

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2023

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nr 3

1--4

PL

W artykule omówiono sposób wyznaczania wytrzymałości resztkowych z wykorzystaniem zdolności pochłaniania energii przez fibrokompozyt. Badania przeprowadzono przez zginanie płyt o przekroju kwadratowym podpartych przegubowo na obwodzie. Określone w ten sposób wytrzymałości resztkowe cechują się znacznie mniejszym współczynnikiem zmienności niż wyznaczone wg PN-EN 14651:2007. Opisane badanie jest alternatywą dla 3-punktowego zginania belek i pozwala na wyznaczenie tej cechy z większą wiarygodnością.

EN

The article discusses the method of determining residual strength using the energy absorption capacity of fibrecomposite. The research was carried out by bending square cross-section plates simply supported at the perimeter. The residual strengths determined in this way are characterized by a much lower coefficient of variation than those determined using the normative method according to PN-EN 14651:2007. The described test is an alternative to 3-point bending of beams and allows to determine this feature with greater reliability.

15

Wykorzystanie technologii druku 3D do wzmocnienia zginanych zimnogiętych profili typu C

Major Maciej, Kalinowski Jarosław, Kosiń Mariusz

Materiały Budowlane

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2023

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nr 10

21--25

PL

Artykuł przedstawia wykorzystanie technologii druku 3D do wzmocnienia stalowych profili zimnogiętych typu C. Przedmiotem analizy były zimnogięte belki stalowe usztywnione w połowie rozpiętości elementami wykonanymi w technologii druku 3D. Zaprezentowano wyniki doświadczalno-numeryczne trójpunktowego zginania. Obliczenia numeryczne przeprowadzono, uwzględniając nieliniowość materiału z uwzględnieniem dużych przemieszczeń. Analiza potwierdziła zwiększenie sztywności modeli poddanych trójpunktowemu zginaniu z wykorzystaniem usztywnienia wykonanego w technologii druku 3D z użyciem filamentu ABS.

EN

The article presents the use of 3D printing technology to strengthen cold-formed C-type steel profiles. The subject of the analysis were cold-formed steel beams stiffened in the middle of the span with elements made in 3D printing technology. The paper presents experimental and numerical results of three-point bending. Numerical calculations were carried out in the nonlinear range of the material and taking into account large displacements. The analysis confirmed the increase in stiffness of the models subjected to three-point bending with the use of a stiffener made in the incremental printing technology with the use of ABS filament.

16

Badania doświadczalne zginanych kształtowników giętych na zimno

Górski Marcin, Budziński Rafał, Sieńkowska-Szpetnar Katarzyna

Inżynieria i Budownictwo

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2023

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R. 79, nr 1-2

30--34

PL

W artykule przedstawiono zakres oraz wyniki badań doświadczalnych elementów dwugałęziowych z ceowych lub zetowych kształtowników giętych na zimno o rozpiętości 3 m w schemacie czteropunktowego zginania. Porównano nośności otrzymane z badań doświadczalnych dla przekrojów bazowych i przekrojów z dodatkowymi usztywnieniami na środniku oraz opisano uzyskane formy zniszczenia.

EN

The article presents the course and results of experimental tests conducted on built-up members consisting of two cold-formed channel or zeta sections with a span of 3m in four point bending scheme. The bending resistance obtained from experimental tests for basic sections and sections with additional stiffeners on the web are compared and the observed forms of failure are described.

17

Theoretical probabilistic nonlinear analysis of post-tensioned bridge cross-sections with the application of random fields

Owerko Piotr

Architecture Civil Engineering Environment

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2023

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Vol. 16, no. 2

127--136

EN

The paper presents a proprietary procedure for the analysis of normal stress distributions in post-tensioned cross-sections. It has a significant advantage over conventional commonly used approaches based solely on the envelope analysis as it provides stress levels in all components of the cross-section. The procedure was used in a series of probabilistic analyses with the adoption of random fields. These fields represented uncertainties in strain-stress relationship in concrete. The analysis covered several types of cross-sections and several types of random fields. Key observations from the conducted simulations are as follows: (I) the widest ranges of the probable maximum stresses (i.e. the lowest indexes of reliability) were obtained for sections with relatively low heights of the compressive zone. (II) The highest probabilistic sensitivity to the type of random field used was found in tall sections with a relatively large compressive zone. (III) The greatest sensitivity to batch uncertainties was evident in all cross-sections when using squared exponential random fields. (IV) The greatest relative sensitivity to the batch uncertainties in the form of the random field compliant with the guidelines of the Joint Comity of Structural Safety (JCSS) was evident in the analyses of the tallest cross-section corresponding to the incrementally launched bridges.

18

Numerical failure analysis of laminated beams using a refined finite element model

Layachi Maroua, Khechai Abdelhak, Ghrieb Abderrahmane, Layachi Safa

Advances in Materials Science

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2023

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Vol. 23, nr 1(75)

32--57

EN

In the present investigation, laminated composite beams subjected to a bending static loading are studied in order to determine their failure mechanisms and the first ply failure (FPF) load. The FPF analysis is performed using a refined rectangular plate element. The present element is formulated based on the classical lamination theory (CLT) to calculate the in-plane stresses. To achieve this goal, several failure criterions, including Tsai-Wu, Tsai-Hill, Hashin, and Maximum Stress criteria, are used to predict failure mechanisms. These criterions are implemented within the finite element code to predict the different failure damages and responses of laminated beams from the initial loading to the final failure. The numerical results obtained using the present element compare favorably with those given by the analytic approaches. It is observed that the numerical results are very close to the analytical results, which demonstrates the accuracy of the present element. Finally, several parameters, such as fiber orientations, stacking sequences, and boundary conditions, are considered to determine and understand their effects on the strength of these laminated beams.

19

Effective shaping of a stepped sandwich beam with clamped ends

Magnucki Krzysztof, Kustosz Joanna, Goliwąs Damian

Acta Mechanica et Automatica

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2023

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Vol. 17, no. 2

200--204

EN

The aim of this work is to propose a sandwich beam with stepped layer thickness in three parts along its length. The total depth, width of the cross-section and its mass are constant. The beam is under a uniformly distributed load. The system of two equilibrium equa-tions was formulated for each part based on the literature. This system was analytically solved for the successive parts of the beam and the functions of the shear effect and deflection were determined in them. The effective stepped layer thicknesses was determined on the basis of the adopted criterion for minimizing the maximum deflection of the beam. The example calculations were made for two elected beams. The effective shapes of these beams are shown in the figures. Moreover, FEM numerical calculations of the deflections of these beams are performed.

20

An innovative approach to fabrication with photo-cured resins by shell-printed-core-casting

Szymczyk Emil, Rećko Maciej, Dzierżek Kazimierz, Sapiołko Karol

Acta Mechanica et Automatica

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2023

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Vol. 17, no. 4

485--489

EN

Modified LCD-based method was used to print three-dimensional (3D) elements. This innovative method combines printing the external shell and filling, thus obtaining mould by casting resin. In order to compare the properties of prints obtained with this method with the ones fabricated in a standard procedure, we conducted bending tests of vertically/horizontally printed and shell-printed cast specimens. The shell-cast samples showed higher flexural strength and larger values of apparent Young’s modulus. The presented results also concern the kinetics of curing samples obtained with different fabrication routes.