Wyniki wyszukiwania - BazTech

1

Wpływ sposobu obciążenia na nośność i morfologię uszkodzeń połączeń ścian wykonanych z ABK

Galman Iwona

Materiały Budowlane

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2024

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nr 7

110--112

2

Numerical simulation on effect of coal pillar width on stability of retained roadway: A case study of Khe Cham Coal Mine, Vietnam

Le Quang Phuc, Le Tien Dung

Journal of Sustainable Mining

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2024

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Vol. 23, iss. 1

1--9

EN

When extracting coal seams in Vietnam underground mines, coal pillars are often left unmined for the protection of retained roadways in the longwall mining method. During longwall mining operations, coal pillars are often placed where high-stress concentrations occur in the abutment pressure zone of adjacent panels, especially when extracting seams under hard-to-cave main roof conditions. The instability of coal pillars under the loading of the main roof may cause the roadway to collapse, threatening the safe operation of a coal mine. This paper presents a detailed numerical investigation of the effect of coal pillar width on the stability of retained roadway under hard-to-cave main roof conditions, which has not been fully understood in previous studies. The results indicate that as the width of the coal pillar increases, the peak stress gradually moves from the virgin coal side to the pillar side, and an elastic zone will gradually be formed in the center of the pillar. A pillar width of less than 40 m coal pillars is easily destroyed under the great pressure caused by the hard main roof. A pillar width greater than 40 m creates a safe condition and has enough bearing capacity to maintain the stability of retained roadways. Based on these results, this paper proposes to use an improved longwall mining method where the coal pillars should be mined together with the adjacent panel to reduce coal loss in pillars.

3

Study on crack growth resulting from spacing and alignment of two circular holes : a phase field approach

Alfat Sayahdin

Computer Assisted Methods in Engineering and Science

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2024

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Vol. 31, no. 4

431--447

EN

This study investigates the effects of spacing and alignment between two circular holes on crack growth simulation. Key aspects analyzed include: (a) crack growth behavior, (b) von Mises stress distribution, and (c) energy profiles, all through variations in the spacing and alignment of the holes. The material is assumed to be homogeneous and isotropic, with the following non-dimensional properties: Young’s modulus E = 70, Poisson's ratio ν = 0.35, which correspond to the real values E = 70 GPa, ν = 0.35, and ɣ = 2800 J · m–2. Additionally, the body force is neglected (f(x; t) = 0). The numerical method used in this research is the adaptive finite element method, which is considered highly robust for solving the phase field model for crack growth. Notable findings include: (a) spacing between the two holes did not significantly alter the crack path, while alignment differences had a significant impact; (b) during the cracking process, the highest stress occurs at the crack tip and the lowest at the crack center; and (c) the time for cracking in materials with two holes varies with spacing and alignment, and elastic and surface energy curves help predict total damage.

4

Research on optimum design method of cushion thickness in composite foundation under rigid base

Xiao Yaoting, Wang Jing

Archives of Civil Engineering

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2023

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Vol. 69, nr 2

471--482

EN

At present, the cushion thickness of composite foundation under rigid base is mostly selected by the experience of the engineer, which is of great arbitrariness. In order to improve this problem, the optimum design method of cushion thickness is proposed by theoretical research. First, the stress diffusion line in the cushion is assumed to be a quadratic curve, and the critical diffusion thickness of the pile top stress is obtained. Then, by analyzing the relative deformation between soil and pile, pile top penetration into the critical cushion thickness is proposed. Finally, based on the relationship between stress ratio of pile to soil and cushion thickness, the calculation method of optimum cushion thickness is put forward. The application of engineering cases shows that the proposed method has better calculation results, which attests to the correctness of the method. The method can be used for the optimal design of cushion thickness of single-type-pile or multi-type-pile composite foundation.

5

Wpływ rodzaju szyny na wartość lokalnych pionowych naprężeń ściskających w środniku belki podsuwnicowej

Chybiński Marcin, Polus Łukasz, Kurzawa Zdzisław

Przegląd Budowlany

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2022

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R. 93, nr 11-12

35--41

PL

W pracy przeprowadzono numeryczne analizy rozkładu naprężeń w środniku belki podsuwnicowej. W celu oceny wpływu rodzaju szyny na wartość naprężeń wykonano analizy numeryczne dla różnych rodzajów szyn zamocowanych w sposób sztywny. Wartości lokalnych pionowych naprężeń ściskających wywołanych oddziaływaniem przekazywanym przez koło suwnicy otrzymane z analiz numerycznych zostały porównane z wielkościami obliczonymi wg normy PN-EN 1993-6.

EN

In this paper, numerical analyses of the stress distribution in the crane runway beam web were conducted. The analyses were carried out for different crane rail types rigidly fixed to the flange, to evaluate their impact on the stress value. The values of the vertical compressive stress generated by the wheel load obtained from the numerical analyses were compared with the ones calculated using the PN-EN 1993-6 standard.

6

Characteristics of stress distribution of a multi layered cylindrical pressure vessel

Somadder Somnath, Das Palash, Islam Md. Ashraful

Journal of Mechanical and Energy Engineering

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2022

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Vol. 6, No 2

1--6

EN

The operation of a multilayer pressure vessel subjected to thermomechanical loads is very significant. The cylindrical pressure vessel is widely used in industrial engineering: for example, to hold a variety of different types of liquid. On thick-walled cylinders, various loading circumstances such as internal overpressure, external overpressure, heat, bending, twisting, and combinations of these load characteristics are applied. Researchers have developed a number of strategies for enhancing the strength of cylinders, including the use of multilayer cylinders and increasing the thickness of the walls. This paper presents the results of an analytical and numerical analysis of a three-layer cylinder. The Abaqus FEA software is used to determine temperature, displacement, and stress distribution of a multilayer cylinder considering the effect of centripetal and centrifugal heat flow. From the numerical analysis, it is observed that centrifugal heat flux is more hazardous than centripetal heat flux for a multi-layered cylinder under thermo-mechanical loading.

7

Material dynamic behavior in cutting zone of Inconel 718 and its infuence on cutting process

Hao Zhaopeng, Cheng Gang, Li JiNing, Fan Yihang

Archives of Civil and Mechanical Engineering

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2022

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Vol. 22, no. 3

art. no. e146

EN

The nickel-based superalloy Inconel 718 is widely used in aerospace and other fields due to its excellent performance. However, the alloy elements are presented in the form of compounds with high hardness, such as TiC, NbC, MoC, TiN and so on, which lead to complex cutting deformation in machining Inconel 718. In this study, the cutting experiments and the fast tool-drop test were carried out to obtain the chip root. Combining the split Hopkins pressure bar (SHPB) test, a scanning electron microscope (SEM) was used to observe the metallographic micrographs of the specimens and analyzed the plastic dynamic behavior of the material in the cutting area. The soft and hardening mechanism in the dynamic deformation process was described. The stress distribution model of material in the cutting area was proposed and the influence of stress distribution on cutting deformation, side fow and tool wear during the cutting process were also given.

8

Trwałość strukturalnego kleju silikonowego w projektowaniu szklenia giętego na zimno

Kimberlain Jon, Carbary Lawrence D., Descamps Pierre, Hayez Valerie, Feng Jie

Świat Szkła

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2021

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R. 26, nr 6

44--48

9

Analysis of the associated stress distributions to the nonlinear forced vibrations of functionally graded multi-cracked beams

Chajdi Mohcine, Adri Ahmed, El Bikri Khalid, Benamar Rhali

Diagnostyka

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2021

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Vol. 22, No. 1

101--112

EN

Geometrically non-linear vibrations of functionally graded Euler-Bernoulli beams with multi-cracks, subjected to a harmonic distributed force, are examined in this paper using a theoretical model based on Hamilton's principle and spectral analysis. The homogenisation procedure is performed, based on the neutral surface approach, and reduces the FG beams analysis to that of an equivalent homogeneous multi-cracked beam. The so-called multidimensional Duffing equation obtained and solved using a simplified method (second formulation) previously applied to various non-linear structural vibration problems. The curvature distributions associated to the multi-cracked beam forced deflection shapes are obtained for each value of the excitation level and frequency. The parametric study performed in the case of a beam and the detailed numerical results are given in hand to demonstrate the effectiveness of the proposed procedure, and in the other hand conducted to analyse many effects such as the beam material property, the presence of crack, the vibration amplitudes and the applied harmonic force on the non-linear dynamic behaviour of FG beams.

10

An Influence of Geometrical Parameters of the Lock of the Blade-Disc Joint on Stress in the FEA and DIC Methods

Kozakiewicz Adam, Grzejszczak Olga

Advances in Science and Technology. Research Journal

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2021

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Vol. 15, no. 1

209--217

EN

In this paper, an assessment of strength properties of the existing blade-disc dovetail joint was presented, taking the parametric optimization of its geometry. A sensitivity of the analysis was carried out to determine the relationship between the selected geometric parameters and strength properties of the structure questioned. The results from experiments and computer simulations were compared. In addition, the fatigue life of the structure was analyzed for different materials and using the change of speed ranges and parameterization of geometry.

11

Front Stress Distribution Under the Impact of Cutting Height to Caving Height Ratio in Extra-thick Longwall Top Coal Caving Technology

Bui Manh Tung, Nguyen VanQuang, Nguyen Phi Hung, Vo Ngoc Dung, Do Hoang Hiep

Inżynieria Mineralna

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2020

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no. 2, vol. 1

123--129

EN

The extraction with higher cutting height for extra-thick seam is the new research orientation in longwall caving technology. Due to the increase of top coal thickness and of cutting height which leads to the change of cutting/caving height ratio, the rule of roof failure (including top coal caving) and the distribution of stress around the face alter correspondingly. This paper is based on the geological conditions of face 8102 of Tashan-DaTong mine, employing the numerical model by UDEC2D code, analysing the effect of cutting/ caving height ratio on the law of stress distribution ahead of the face. When the ratio of cutting/caving height decreases and the cutting height increases, the results of the research have shown that: (i)- peak stress redistributes further ahead of the face and its value manifestly drops; (ii)- the plastic deformation ahead of face significant increases and the zone of plastic strain also expands. It is therefore concluded that the variation of cutting/caving height ratio results in the redistribution of roof pressure, which contributes to the control of roof failure and face stability.

PL

Przy bardzo grubych pokładach, eksploatacja z dużą wysokością to nowy kierunek badań w technologii zawału stropu węgla. Ze względu na grubość warstwy stropu węglowego i zwiększoną wysokość urabiania prowadzi do zmiany stosunku urabiania do odzyskania, co również zmienia regułę zapalenia skał stropowych i zmienia stan rozkładu naprężeń wokół ściany. W artykule, przedstawiono wyniki analizy wpływu stosunku urabiania do uzyskania opierając się na prawie rozkładu obciążenia przed ścianą. Analiza ta została oparta na warunkach geologicznych kopalni 8102 TaSan-DaTong wykorzystując model numeryczny UDEC2D. Wyniki badań pokazują, że wraz ze spadkiem stosunku urabiania do odzyskania, oznacza to wzrost wysokości urabiania, położenie maksymalnego naprężenia jest daleko od ściany, maksymalna wartość naprężeń znacznie spada, zniszczenie plastyczne przed ścianą i stropem gwałtownie rośnie, zwiększa się strefa odkształcenia plastycznego. Dlatego zmiana stosunku urabiania do odzyskania może zmienić stan rozkładu ciśnienia stropowego, co jest korzystne dla procesu niszczenia stropu i kontrolowania stabilności ściany.

12

Rozkład naprężeń w stalowym złączu doczołowym z jednostronnymi nakładkami rombowymi określony metodą elementów skończonych

Wichtowski Bernard, Konecki Krzysztof

Inżynieria i Budownictwo

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2020

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R. 76, nr 12

594--599

PL

W większości mostów blachownicowych wybudowanych do roku 1953 złącza doczołowe pasów „wzmacniano” jedno- lub dwustronnymi nakładkami. Określona nieograniczona wytrzymałość zmęczeniowa takich złączy wyniosła Zrj = 79 MPa. Dla tych złączy przedstawiono analizę rozkładu naprężeń metodą MES. Uzyskano zaskakujące wyniki, które pozwalają wyjaśniać powstawanie pęknięć zmęczeniowych. Wzmocnienie okazało się fikcją.

EN

In the majority of the plate girder bridges, built before 1953, the butt joints of the chords were "strengthened" with one or two-sided cover plates. The determined unlimited fatigue strength of such joints was Zrj = 79 MPa. For such joints, the analysis of the stress distribution using the FEM method is presented in this article. Thanks to the surprising results it was possible to explain the formation of fatigue cracks. The intended "strengthening" turned out to be a fiction.

13

Fatigue life prediction of a radial cylindrical roller bearing subjected to a combined load using FEM

Chudzik Agnieszka, Warda Bogdan

Eksploatacja i Niezawodność

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2020

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Vol. 22, no. 2

212--220

EN

The article presents the results of studies on the impact of a combined load of a radial cylindrical roller bearing for its predicted fatigue life. The distributions of maximum equivalent subsurface stresses and their depths, necessary during calculations of fatigue life, were determined using the finite element method, using the basic package of the ANSYS program. The calculations took into account the geometrical parameters of the bearing, including radial clearance and the shape of the rolling elements generators. The calculation results showed that the axial load of the radial cylindrical roller bearing and the tilt of the rollers associated with its operation reduces fatigue life. The obtained results were compared with the results of calculations according to the SKF catalogue method, obtaining satisfactory compliance.

PL

W artykule zaprezentowano wyniki badań wpływu złożonego obciążenia promieniowego łożyska walcowego na jego prognozowaną trwałość zmęczeniową. Rozkłady maksymalnych zastępczych naprężeń podpowierzchniowych oraz głębokości ich występowania, niezbędne podczas obliczeń trwałości zmęczeniowej, określono za pomocą metody elementów skończonych, z wykorzystaniem pakietu podstawowego programu ANSYS. W obliczeniach uwzględniono geometryczne parametry łożyska, w tym luz promieniowy i kształt tworzących elementów tocznych. Wyniki obliczeń wykazały, że obciążenie osiowe promieniowego łożyska walcowego i przechylenie wałeczków towarzyszące jego działaniu powoduje zmniejszenie trwałości zmęczeniowej. Otrzymane wyniki porównano z wynikami obliczeń według katalogowej metody firmy SKF, otrzymując zadowalającą zgodność.

14

A multimode approach to geometrically non-linear forced vibration of beams carrying point masses

Fakhreddine Hatim, Adri Ahmed, Chajdi Mohcine, Rifai Said, Benamar Rhali

Diagnostyka

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2020

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Vol. 21, No. 4

23--33

EN

The present work deals with the geometrically non-linear forced vibrations of beams carrying a concentric mass under different end conditions. Considering the axial strain energy and expanding the transverse displacement in the form of a finite series of spatial functions, the application of Hamilton's principle reduces the vibration problem to a non-linear algebraic system solved by an approximate method developed previously. In order to validate the approach, comparisons are made of the present solutions with those previously obtained by the finite element method. Focus is made here on the analysis of the non-linear stress distribution in the beam with an attached mass. The non-linear forced deflection shapes and their corresponding curvatures are presented for different magnitudes of the attached mass, different excitation levels and different vibration amplitudes.

15

Obliczeniowa weryfikacja segmentowego modelu zależności między współczynnikami KHβ oraz KFβ dla kół walcowych o zębach prostych

Kamycki Wiktor, Noga Stanisław, Batsch Michał

Zeszyty Naukowe Politechniki Rzeszowskiej. Mechanika

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2019

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z. 91 [299], nr 1-2

27--39

PL

W pracy omówiono zagadnienia dotyczące wyznaczania współczynników nierównomiernego rozkładu obciążenia w przekładniach zębatych. Zaproponowano metodę wyznaczania korelacji pomiędzy współczynnikami KHβ i KFβ odnoszącymi się odpowiednio do nierównomiernego rozkładu naprężeń stykowych oraz naprężeń u podstawy zęba od zginania w kole zębatym. Zaproponowane rozwiązanie pozwala analizować w zębie odkształcenia i naprężenia w dwuwymiarowej skali, uwzględniając wysokość i szerokość zęba. Otrzymane z zaproponowanego modelu wyniki porównano z rezultatami obliczeń, otrzymanymi zgodnie z zaleceniami według normy ISO, dotyczącymi wyznaczania nierównomierności rozkładu obciążenia. Następnie ustalono obszary zgodności wygenerowanych rozwiązań.

EN

This paper deals with the problem of determining the face load factors for spur gears. The authors propose a method used for determination of the correlation between the KHβ and KFβ factors, related respectively to load distribution due to contact and load distribution due to bending of the gear tooth. The proposed method allows to analyze deformation and stress in two dimensions, taking into account height and width of the gear tooth. The obtained results were compared with the ISO guidelines regarding the face load factors determination and then the regions of compatibility between the methods were analyzed.

16

Wpływ rozkładu naprężeń szczątkowych na badania wytrzymałościowe

Neugebauer Jürgen, Kasumovic Irma, Blazevic Ivo

Świat Szkła

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2019

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R. 24, nr 6

34--37

17

Effect of radial internal clearance on the fatigue life of the radial cylindrical roller bearing

Chudzik Agnieszka, Warda Bogdan

Eksploatacja i Niezawodność

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2019

|

Vol. 21, no. 2

211--219

EN

The paper presents result of the research on influence of internal radial clearance in radial cylindrical roller bearing on its fatigue durability. By solving the Boussinesq problem for the elastic half-space and finite elements method, stress distributions were determined, necessary to estimate predicted fatigue life of the bearing. The calculations took into account geometrical parameters of the bearing: its radial clearance and shape of rolling parts. Predicted radical clearance was computed by using the Lundberg and Palmgren model. ANSYS program allowed to introduce the analysis of von Mises stress distribution in any plane of cooperating components. The outcome revealed, radial cylindrical roller bearing will have highest endurance with slight radial clearance.

PL

W pracy przedstawiono wyniki badań wpływu wewnętrznego luzu promieniowego w promieniowym łożysku walcowym na jego prognozowaną trwałość zmęczeniową. Wykorzystując zagadnienie Boussinesqa dla półprzestrzeni sprężystej i metodę elementów skończonych, określono rozkłady naprężeń podpowierzchniowych niezbędne do oszacowania prognozowanej trwałości zmęczeniowej łożyska. W obliczeniach uwzględniono geometryczne parametry łożyska: jego luz promieniowy i kształt części tocznych. Do określenia wartości luzu promieniowego wykorzystano model Lundberga i Palmgrena. Zastosowanie programu ANSYS pozwoliło na przeprowadzenie analizy rozkładu naprężeń von Misesa w dowolnej płaszczyźnie współpracujących ze sobą elementów tocznych łożyska. Analiza obliczeń wykazała, że promieniowe łożysko walcowe będzie miało najwyższą wytrzymałość z niewielkim luzem promieniowym.

18

Thermal damage of CFRP laminate in fiber laser cutting process and its impact on the mechanical behavior and strain distribution

Li Maojun, Gan Guocui, Zhang Yi, Yang Xujing

Archives of Civil and Mechanical Engineering

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2019

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Vol. 19, no. 4

1511--1522

EN

Fiber laser cutting is a promising alternative to the conventional methods in machining CFRP with high efficiency, while the influence of machined quality on strain distribution and mechanical behavior of CFRP laminates is yet not fully understand. The aim of this paper is to study the effect of laser cutting parameters on thermal defects and related mechanical performance. DIC technique was successfully employed to assess full-field strain distribution under tensile loading. The relationship between strain distribution and failure evolution/mode was also investigated. Results showed that various thermal defects including matrix recession, resin decomposition, fiber burrs and delamination were observed on entry and exit surfaces, while microcracks, cavities and striations were prevalent on machined surface. Tensile strength of CFRP laminate with open hole was highly related to applied laser processing parameters. DIC technique indicated that the crack propagation and failure mode were in good agreement with the high level of strains developed around the hole. Matrix-fiber interface cracking, fiber breakage and splitting were the main failure modes at test cessation.

19

An Optimization Study for Bridge Design of a Porthole Extrusion Die

Ayer Önder, Özmen Burcu Gizem, Karakaya İsmail

Advances in Science and Technology. Research Journal

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2019

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Vol. 13, no. 4

270--275

EN

In this study, a porthole die extrusion simulation was carried out for a box profile by using HyperXtrude Inspire Extrude Metal 2019 which is a FEM based software. Aluminum AA6063 material was the billet material, tempera¬ture of the billet was 450 °C and ram speed was selected as 5 mm/sec. The die design was obtained according to the shape of the bridges of the porthole die. Finally, the design optimization was achieved by analyzing FEM results. It was obtained that the dies which have curved bridges offer optimum process conditions.

20

Numeryczna analiza zachowania się tylnego trójkąta ramy rowerowej z amortyzatorem poddanego obciążeniu statycznemu

Kuczek Ł., Mroczkowski M., Muzykiewicz W., Dąbrowski J., Marczak P.

Rudy i Metale Nieżelazne Recykling

|

2018

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R. 63, nr 7

5--11

PL

Współcześnie wiele analiz nowych urządzeń i ich elementów wykonywana jest za pomocą symulacji komputerowych. Tego typu analiza pozwala na przeprowadzenie szybkich testów, umożliwiających określenie niebezpiecznych obszarów pod względem ich wytrzymałości. W artykule przedstawiono wyniki analizy numerycznej, dotyczące zachowania się ramy rowerowej (tylnego trójkąta) z wbudowanym amortyzatorem pod wpływem przyłożonej siły pionowej do miejsca mocowania tylnego koła roweru. Wyniki pokazały, że w zakresie sprężystym materiału ze zwiększeniem wartości siły rosło liniowo zarówno maksymalne przemieszczenie, odkształcenie, jak i naprężenie. Główna lokalizacja odkształcenia wystąpiła w samym elemencie amortyzującym, natomiast największe naprężenia były zlokalizowane głównie w elemencie mocującym, w rejonie łączenia z elementem elastycznym amortyzatora. Stwierdzono również istotność odpowiedniego doboru krawędzi mocowania, ostre krawędzie doprowadziły do lokalnego zwiększenia wartości odkształceń i naprężeń. Przeprowadzone badania pozwoliły na określenie maksymalnego obciążenia ramy rowerowej, którego wartość dla badanej konstrukcji odpowiadała masie rowerzysty równej ok. 160 kg.

EN

Nowadays many analyzes of new devices and their elements are performed by computer simulations. This type of analysis allows for quick tests to identify dangerous areas in terms of their strength. The paper presents the results of numerical analysis concerning the behavior of the bicycle frame (rear triangle) with the built-in shock absorber under the influence of the applied vertical force in the position of the rear bicycle wheel. The results showed that in the elastic range of the material with increased force value, both the maximum displacement, deformation and stress increased linearly. The main location of the deformation occurred in the shock absorber element itself, while the greatest stresses were located mainly in the fixing element in the area of the connections with the shock absorber elastic element. The relevance of appropriate mounting edge selection was also highlighted, sharp edges led to local increase of deformation and stress values. The study allowed to determine the maximum load of the bicycle frame, the value of which corresponds to the mass of the cyclist of about 160 kg.