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1

Vibration analysis of delaminated CNT-Reinforced CFRP composite plates

Imran Muhammad

Advances in Mechanical and Materials Engineering

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2026

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Vol. 43, nr 1

159--177

EN

Fiber-reinforced polymer composite materials have gained extensive application in aerospace, automotive, marine, and civil infrastructure owing to their exceptional specific strength, stiffness, and design flexibility. However, delamination - a critical interlaminar failure mode compromises structural integrity and dynamic performance. This comprehensive study investigates the vibration behavior of carbon fiber-reinforced polymer (CFRP) composite plates subjected to varying delamination extents, laminate stacking sequences, and boundary constraints through integrated analytical and finite element methodologies. The governing differential equations are derived using the Rayleigh-Ritz energy method based on classical laminated plate theory, and numerical simulations are performed using ANSYS finite element software. The investigation examines delamination sizes ranging from 0% to 56.25% of plate area, three distinct stacking configurations ([0/90/45/90], [0/45], [0/90]), and all sides clamped (CCCC), simply supported (SSSS), cantilever (CFFF), and free edges (FFFF) boundary conditions. Results demonstrate that natural frequencies decrease systematically with increasing delamination size, with maximum reduction of 5-8% occurring for the largest delamination extent (56.25%) across all boundary condition.. Furthermore, CNT integration enhances both natural frequencies (up to 29.8% increase at 2.5 wt% CNT loading) and damping characteristics (42.1% improvement). These findings support improved design and vibration control of advanced composite structures.

PL

Polimerowe materiały kompozytowe wzmacniane włóknami zyskały szerokie zastosowanie w przemyśle lotniczym, motoryzacyjnym, morskim i lądowym ze względu na swoją wyjątkową wytrzymałość właściwą, sztywność i elastyczność projektowania. Jednakże de laminacja, krytyczne międzywarstwowe uszkodzenie, zagraża integralności strukturalnej i właściwościom dynamicznym. W niniejszym artykule przedstawiono wyniki kompleksowych badań drgań płyt kompozytowych wykonanych z polimeru wzmacnianego włóknami węglowymi poddanych różnym stopniom delaminacji, sekwencjom układania laminatów oraz ograniczeniom brzegowym, wykorzystując zintegrowane metody analityczne i metodę elementów skończonych. Równania różniczkowe zachowania płyt kompozytowych wyprowadzono za pomocą metody energetycznej Rayleigha-Ritza opartej na klasycznej teorii płyt laminowanych, a symulacje numeryczne przeprowadzono za pomocą oprogramowania ANSYS do analiz metodą elementów skończonych. W badaniach analizowano rozmiary delaminacji w zakresie od 0% do 56,25% powierzchni płyty, trzy różne konfiguracje ułożenia warstw ([0/90/45/90], [0/45], [0/90]) oraz warunki brzegowe: zaciskanie wszystkich boków (CCCC), swobodne podparcie (SSSS), podparte i ze swobodnymi krawędziami (FFFF). Wyniki ujawniły, że częstotliwości własne systematycznie zmniejszają się wraz ze wzrostem rozmiaru delaminacji, przy czym maksymalna redukcja wynosi 5–8% dla największego zakresu delaminacji (56,25%) we wszystkich rozpatrywanych warunkach brzegowych. Ponadto integracja nanorurek węglowych poprawia zarówno częstotliwości własne (wzrost do 29,8% przy zawartości nanorurek 2,5% wag.), jak i charakterystyki tłumienia (poprawa o 42,1%). Uzyskane wyniki wspierają ulepszone projektowanie i kontrolę drgań zaawansowanych struktur kompozytowych.

2

Torsional mode shapes of FGM shafts with various cross section

Kumor Mateusz

Technical Transactions

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2025

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Vol. 122, iss. 1

art. no. e2025003

EN

In this study, the torsional mode shapes of circular and non-circular functionally graded material shafts, focusing on triangular, rectangular, circular cross-sections are investigated. The shafts are composed of an aluminum-titanium (AlTi) alloy and various functionally graded materials, utilizing different mixing rules to create a gradient surface. The modal analysis is conducted using ANSYS Mechanical leading finite element analysis software to assess and visualize the vibrational characteristics of these shafts under torsional loading. Then, the same shafts made of isotropic material (pure Al) is prepared, and compared with respect to results. The objective is to understand the influence of FGMs compared to homogeneous and isotropic materials on the torsional behavior of shafts with non-circular geometries. By comparing the torsional mode shapes and frequencies, one can identify the distinct vibrational properties introduced by the gradient material composition. This comparison is highlight the potential advantages of FGM shafts in applications requiring tailored mechanical properties that traditional homogeneous materials cannot provide. The study also explores how the different cross-sectional shapes affect the torsional response, which is crucial for designing components subjected to twisting loads in aerospace, automotive, and construction industries. The results from ANSYS Mechanical are analyzed to extract the mode shapes and frequencies of torsional modes, providing a comprehensive understanding of how FG materials behave relative to isotropic counterparts under similar conditions. The study aims to show how the natural frequency and torsional mode shapes differ for a functionally graded material compared to isotropic material, may be useful for researchers working with applications where vibration behavior is crucial.

3

Zastosowanie metodyki eksperymentalnej analizy modalnej w badaniu stalowej konstrukcji kratownicowej

Żółtowski Mariusz, Ogrodnik Paweł, Baryłka Adam

Inżynieria i Budownictwo

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2025

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R. 81, nr 5

632--636

PL

Konstrukcje stalowe są poddawane dużym obciążeniom dynamicznym, co znajduje wyraźne odzwierciedlenie w generowanych procesach drganiowych. Drgania te mogą wpływać na stan użytkowalności konstrukcji poprzez obniżenie komfortu osób w niej pracujących, jak również mogą osiągać poziom zagrażający bezpieczeństwu konstrukcji. Wpływ drgań na konstrukcję objawia się głównie dodatkowymi naprężeniami w danym przekroju, które sumują się z naprężeniami wynikającymi z obciążeń statycznych. Obciążenia dynamiczne mogą powodować szkodliwe skutki w budynkach o różnych typach konstrukcji, a nawet prowadzić do ich zniszczenia. Uznając konieczność doskonalenia metod oceny jakości konstrukcji budowlanych na potrzeby szacowania ich stanu oraz współczynników bezpieczeństwa dla konstrukcji stalowych, autorzy niniejszej pracy podjęli próbę zbadania procesu niszczenia wybranego obiektu metodą eksperymentalnej analizy modalnej.

EN

Steel structures are subject to large dynamic loads clearly reflected by generated vibration processes. The vibrations may affect state of serviceability of structures by lowering comfort of persons working there as well as possible reaching the level hazardous to safety of the structures. The effect of vibrations to structure is mainly manifested by additional stresses in a given cross-section, which are summed up with those resulting from static loads. The dynamic loads may cause damaging effects in buildings of various structural types or even lead to their destruction. Judging the necessity of improving the quality assessment methods of building structures for purposes of estimation of their state as well as safety factors for steel structures, the authors of this work undertook an attempt to investigate destruction process of selected object by using the method of experimental modal analysis.

4

Integrating numerical simulation and experimental data for enhanced structural health monitoring of bridges

Singh Om Narayan, Dey Kaushik

Informatyka, Automatyka, Pomiary w Gospodarce i Ochronie Środowiska

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2025

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T. 15, nr 1

22--26

EN

The research described in this paper aims to enhance the structural health monitoring (SHM) of highway bridges by integrating numerical simulations with experimental data. A simply supported highway bridge is studied under traffic loads, and both numerical and experimental approaches were employed. The numerical model of the bridge was developed using ANSYS, while high-resolution experimental data were collected from velocity transducers placed at key points on the bridge. The experimental data were compared with the results from the numerical model for validation. The results showed that the natural frequencies obtained from both the experimental and numerical analyses were closely aligned, demonstrating the reliability of the model. The validated model was further used to predict long-term structural behaviours under different operational conditions, contributing to better maintenance planning and the sustainability of infrastructure. The study concludes that combining numerical simulations with experimental data improves the accuracy of SHM, enabling early detection of potential structural issues and extending the lifespan of bridges. Key findings emphasize the significant role of vehicle speed in influencing the dynamic response of the bridge, as well as the importance of considering material properties and vehicle loads in predicting structural health.

PL

Badania opisane w niniejszym artykule mają na celu poprawę monitorowania stanu konstrukcji (structural health monitoring – SHM) mostów na autostradach poprzez integrację symulacji numerycznych z danymi eksperymentalnymi. Prosto podparty most na autostradzie jest badany pod obciążeniem ruchem drogowym i zastosowano zarówno podejście numeryczne, jak i eksperymentalne. Model numeryczny mostu został opracowany przy użyciu programu ANSYS, podczas gdy dane eksperymentalne o wysokiej rozdzielczości zostały zebrane z przetworników prędkości umieszczonych w kluczowych punktach mostu. Dane eksperymentalne zostały porównane z wynikami modelu numerycznego w celu walidacji. Wyniki pokazały, że częstotliwości drgań własnych uzyskane zarówno z analiz eksperymentalnych, jak i numerycznych były ściśle dopasowane, co świadczy o niezawodności modelu. Zweryfikowany model został następnie wykorzystany do przewidywania długoterminowych zachowań strukturalnych w różnych warunkach operacyjnych, przyczyniając się do lepszego planowania konserwacji i zrównoważonego rozwoju infrastruktury. W badaniu stwierdzono, że połączenie symulacji numerycznych z danymi eksperymentalnymi poprawia dokładność SHM, umożliwiając wczesne wykrywanie potencjalnych problemów strukturalnych i wydłużając żywotność mostów. Kluczowe wyniki badań podkreślają istotną rolę prędkości pojazdu we wpływie na dynamiczną reakcję mostu, a także znaczenie uwzględnienia właściwości materiału i obciążeń pojazdu w przewidywaniu stanu konstrukcji.

5

Wpływ wymuszenia drgań podstawy na zachowanie się konstrukcji – eksperyment numeryczny i fizyczny

Małysa Adrian, Kosmalski Kacper, Nowak Julia, Łabecka Magdalena, Weber Hanna

Builder

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2025

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R.29, nr 12

58--66

PL

W pracy przedstawiono wyniki badań eksperymentalnych mających na celu wyznaczenie wpływu częstotliwości wymuszenia drgań podstawy na zachowanie się stworzonych modeli wspornikowych oraz prostych przestrzennych modeli prętowych w celu oszacowania obszaru rezonansu. W testach wykorzystano samodzielnie zaprojektowany i stworzony stolik wibracyjny. Uzyskane wyniki zestawiono z wartościami częstotliwości drgań własnych modeli, określonych w sposób teoretyczny, z zastosowaniem wzorów analitycznych, oraz numeryczny przy wykorzystaniu analizy modalnej. Dla stworzonych modeli określono wartości częstotliwości wymuszenia, dla których w trakcie drgań konstrukcja przybierała odpowiednie formy deformacji i obserwowano negatywne efekty związane z wystąpieniem zjawiska rezonansu. Całość pracy opatrzono stosownymi wnioskami dotyczącymi wpływu zastosowanych rozwiązań konstrukcyjnych na częstotliwości drgań własnych.

EN

The paper presents the results of experimental research aimed at determining the impact of excitation frequency of base and its effect on behaviour of created cantilever models and simple spatial bar models for the purpose of estimating the area of resonance. The tests used self-designed and made vibration table. The obtained results were compared with the natural vibration frequencies determined theoretically, using the analytical equations and numerical using modal analysis. For the created models, the values of excitation frequencies were determined in which during vibrations the structure assumed the relevant forms of deformations, and the negative effects caused by the resonance was observed. The entire work was accompanied by relevant conclusions concerning the impact of the applied design solutions on the natural vibration frequencies.

6

Research on vibration characteristics of motorized spindle at high speed based on power flow

Bao Yudong, Zhou Zhentao, Wu Linkai, Dai Ye

Journal of Theoretical and Applied Mechanics

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2024

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Vol. 62 nr 1

61--73

EN

To show dynamic properties of a motorized spindle at high speed, C01 type motorized spindle bearing-rotor system is used as a study object, and the dynamic model of the bearing-rotor system is established. The method to analyze vibration characteristics of motorized spindles by power flow is proposed, and it is found that the vibration energy is not necessarily considerable at the position where the vibration displacement response is significant. Finally, the system vibration energy distribution under different bearing stiffness is analyzed. The power flow method can analyze the dynamic characteristics of the bearing-rotor system in terms of energy distribution.

7

Model analysis of worm gear pair system using finite element analysis

Barshikar Raghavendra Rajendra, Baviskar Prasad R., Patil Milind M., Dube Anil S., Dhore Vishal J.

International Journal of Applied Mechanics and Engineering

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2024

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Vol. 29, no. 2

1--15

EN

Spur gear, helical gear, worm gear, and bevel gear are all important components in industrial applications such as vehicles, pushes, conveyors, elevators, bowl mill, rolling mills, ribbon blender, machine tools, aeroplanes, and windmills. When various types of defects, such as wear, tooth breakage, corrosion, and scratches on bearings, appear in gearboxes, normal machine function may be abruptly terminated. As a result, output and dependability suffer. As a result, several quality tracking and evaluation approaches have been adopted by companies. Finite element analysis (FEA) is one of the approaches. This research paper presents the FEA of a ribbon blender worm gear pair by using Ansys 18.0 to identify the weak gear of the worm gear pair, natural frequency, and deformation. Proe-5 utilized for creation of three-dimensional geometry of threaded worm and toothed worm wheels, as well as other related elements such as shafts and bearings. Steel is used for the worm, shaft, and bearing, whereas bronze is used for the worm wheel. Ansys 18.0 is implemented to carry out worm gear pair model analysis. The results demonstrate that the worm wheel had the most deformation when compared to the worm, and that the natural frequency is greater than the operational frequency of the worm gear pair. The findings of the research study, worm wheel deteriorate early than worm, model analysis plays a significant role in vibration monitoring of worm gear pair, and this work is valuable for further fault analysis of ribbon blender worm gearbox utilising vibration response.

8

Analyzing frequency response analysis experimentally for bone healing detection: examining the potential of vibrational evaluations

Kadhim Abbas Jawad, Aubad Mohammed Jawad, Al-Juboori Ameen M.

Diagnostyka

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2024

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Vol. 25, No. 3

art. no. 2024315

EN

Assessment of bone healing is essential for efficient orthopedic treatment. This work investigates the feasibility of assessing frequency response experimentally for bone healing detection, with a particular emphasis on the use of vibrational assessments. Detailed experimental studies were carried out to determine the ability of frequency response analysis to assess bone healing. Mechanical excitation was delivered to cracked bone samples at various frequencies, and the vibrational responses of the displacement and accelerations were measured. The experimental setting includes testing five samples, to cover a wide range of possibilities. The obtained vibrational, such phase, magnitude, and coherence, were examined to find common patterns and changes linked with the healing process. The results showed that frequency response analysis has the potential to identify bone healing, as unique vibrational responses were seen in healed samples under cyclic load for different turns (0, 1000, 2000, 3000, and 4000). The findings demonstrate the sensitivity of vibrational evaluations in capturing the mechanical properties and healing condition of bone tissue. Furthermore, the presence of cracks impacts both structural integrity and natural frequency. Natural frequency decreases as the number of cycles increases. The highest frequency reduction occurred at the first mode shape and maximum cycle number, indicating considerable fracture behaviour changes. Natural frequency can be used to assess bone health; higher stiffness and frequency are associated with smaller crack size.

9

Structural Health Monitoring for Dębica Railway Steel Arch Bridge in Poland

Nguyen Duc Cong, Salamak Marek, Katunin Andrzej, Poprawa Grzegorz

Civil and Environmental Engineering Reports

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2024

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Vol. 34, no. 2

216--223

EN

The study presents the vibration-based SHM system for the Dębica railway bridge located in Poland. The railway bridge owner was concerned about the excessive and self-excited vibrations of the hangers, the vibration measurement of 8 hangers per span in a total of two spans being monitored. The dynamic responses in both the transverse and longitudinal directions for each hanger under different load events over a nine-month period were recorded and introduced in this paper. The tension force and stress on each hanger are estimated through the natural frequency of the experimental vibration analysis. The proposed approaches could be used to develop a smart alarm system integrated into a vibration-based data-driven SHM system for heavy railway bridges.

10

Free Vibration Analysis of Prestressed Timoshenko Beams Using the Modal Analysis Method

Nguyen Sy Nam, Nguyen Xuan Cuong, Nguyen Trung Hieu

Advances in Science and Technology. Research Journal

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2024

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Vol. 18, no. 8

125--141

EN

Natural frequency and mode shape are important features in the dynamic analysis of beam structures. They are used in the analysis, design, and verification of beam structures. In dynamic problems, these characteristics influence the dynamic response of the beam. This study presents the equations for the free vibration analysis of prestressed Timoshenko beams and derives the characteristic equations to determine the natural frequencies and general mode functions using the modal analysis method. For each different boundary condition of the beam, the corresponding characteristic equations and eigenforms are then obtained. Using numerical methods, the change in natural frequencies is investigated and compared with the natural frequencies of ordinary Timoshenko beams and Euler-Bernoulli beams. As the beams undergo pre-compression, the gap in natural frequencies between the prestressed Timoshenko beam and the unstressed beam widens with increasing prestress. The natural frequency of the pre-tensioned beam is higher than that of the beam without pre-tension. This difference is most noticeable at the first order of the frequency, where it is most significant, but it decreases quickly as the frequency order rises.

11

A parametric study of higher-mode natural frequencies of composite stiffened cylindrical shell with cut-out

Chaudhuri Puja Basu, Sahoo Sarmila, Mitra Anirban

Engineering Transactions

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2023

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Vol. 71, iss. 1

81--109

EN

A finite element-based dynamic study of cut-out borne composite cylindrical shells reinforced with stiffeners is conducted. Isoparametric shell element with eight nodes and beam element with three nodes are used to study the mode-frequency behavior of shells with varied edge conditions. Anti-symmetric angle-ply laminates of two, four and ten layers with varying lamination angles are considered. Ten-layer laminates are investigated further as they exhibit better performance in fundamental frequency than two and four-layer laminates. The reduced integration method is adopted to find the shell element’s stiffness and mass matrices and the subspace iteration method is used for the eigenvalue solution of free vibration formulation. Natural frequencies for the first five modes are considered. The effects of fiber orientation angle (θ), degree of orthotropy (E11/E22), and width/thickness ratio (b/h) on the natural frequency are determined through numerical studies. It is revealed that vibration behavior strongly depends on both the number and arrangement of boundary constraints.

12

Effects of non-classical boundary conditions on the free vibration response of a cantilever Euler-Bernoulli beams

Afras Abderrachid, El Ghoulbzouri Abdelouafi

Diagnostyka

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2023

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Vol. 24, No. 1

art. no. 2023107

EN

In this article, the problem of the free vibration behavior of a cantilever Euler-Bernoulli beam with various non-classical boundary conditions, such as rotational, translational spring, and attached mass is investigated. For describing the differential equation of the system. An analytical procedure is proposed firstly, and a numerical method based on the differential transform method DTM is developed in order to validate the obtained results. A parametric study for various degenerate cases is presented with the aim to analyze the influence of rotational stiffness, vertical stiffness, and mass ratio on the free vibration response of the beam, particularly on its modal characteristics. The results show that the non-classical boundary conditions significantly affect the natural frequency and mode shapes of the studied beam system in comparison to the case of a classical boundary conditions such as Simply supported, clamped-clamped, etc. The comparison between the obtained results based on the proposed analytical solution and numerical scheme, and those available in the literature shows an excellent agreement.

13

Effect of icing as a non-structural mass on the variation of natural frequency of a lightweight lattice structure

Kowalski Wiesław, Richter Mateusz, Tokarczyk Katarzyna

Archives of Civil Engineering

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2023

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Vol. 69, nr 4

37--53

EN

This paper analyzes the effect of additional masses for lattice structures on the nature of changes in the natural frequencies of the structure. An attempt to mathematically describe this nature and the scale of the effect with a known thickness of the icing layer was also made. The discussion concerns a structure with a sacred purpose - the Gate of the Third Millennium, located in the Lednickie Fields, in the Kiszkowo Municipality, Gniezno Poviat. The icing of structural bars (frost, rime) is treated as a source of additional masses, although the origin of non-structural mass is of secondary importance for the analysis in question. The analysis was carried out by Finite Element Method (FEM) modeling of the structure, assuming a single-parameter variation of its mass (that is, the additional mass of all elements of the test object varies proportionally to a single parameter, which is the outer surface of the element on which the ice layer is deposited). By solving the vibration eigenproblem for successive models, representing different intensities of icing of the object, the values of successive frequencies and descriptions of the corresponding eigenmodes were determined. The results obtained allow us to formulate a postulate that the possibility of a change in the mass of the analyzed object resulting from icing or other causes should be taken into account in strength analyses, wherein the dynamic properties of the structure play an important role, such as in assessing the susceptibility of the structure to dynamic loads.

PL

W pracy dokonano analizy wpływu dodatkowych mas dla konstrukcji typu kratownicowego na charakter zmian częstotliwości drgań własnych tej konstrukcji. Przeprowadzono też próbę matematycznego opisu tego charakteru oraz skali wpływu przy znanej grubości warstwy oblodzenia. Rozważania dotyczą budowli o przeznaczeniu sakralnym - Bramy Trzeciego Tysiąclecia, zlokalizowanej na Polach Lednickich w gminie Kiszkowo w powiecie gnieźnieńskim. Jako źródło dodatkowych mas traktowane jest oblodzenie prętów konstrukcyjnych (szron, szadź), jakkolwiek pochodzenie masy niekonstrukcyjnej ma dla przedmiotowej analizy znaczenie drugorzędne. Analizy dokonano w drodze modelowania Metodą Elementów Skończonych (MES) konstrukcji, przyjmując założenie o jednoparametrycznej zmienności jej masy (to znaczy, że dodatkowa masa wszystkich elementów badanego obiektu zmienia się proporcjonalnie do jednego parametru, którym jest powierzchnia zewnętrzna elementu, na której odkłada się warstwa lodu). Rozwiązując zagadnienie własne drgań dla kolejnych modeli, reprezentujących różne intensywności oblodzenia obiektu, wyznaczono wartości kolejnych częstotliwości i opisy odpowiadających im postaci drgań własnych. I tak, przyrost grubości warstwy lodu na powierzchniach, od 0 do 1 cm spowodował redukcję wszystkich wyznaczonych (dziesięciu podstawowych) częstotliwości drgań własnych o co najmniej 11%. Grubość oblodzenia 2 cm wpływa na redukcję częstotliwości, jak wyżej, o ok. 22% zaś 4 cm warstwa oblodzenia oznacza redukcję przedmiotowych częstotliwości powyżej 39%. Są to istotne wartości, z punktu widzenia zastosowań technicznych. Uzyskane wyniki pozwalają na sformułowanie postulatu, aby w analizach wytrzymałościowych, w których istotną rolę odgrywają właściwości dynamiczne konstrukcji, np. w ocenie podatności konstrukcji na obciążenia dynamiczne, uwzględniana była możliwość zmiany masy analizowanego obiektu wynikająca z oblodzenia lub z innych przyczyn.

14

Assessment of the impact of the number of girders on the dynamic behaviour of Geiger dome

Obara Paulina, Solovei Maryna

Archives of Civil Engineering

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2023

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Vol. 69, nr 3

597--611

EN

In this paper, the dynamic behaviour of the tensegrity domes is explored. The consideration includes all cable structures called Geiger domes, i.e., two cases of configurations (with a closed and open upper section) and two variants of the nature of a dome (regular and modified) are taken into account. Particularly, the impact of the number of girders on the natural frequencies is analysed. A geometrically quasi-linear model is used, implemented in an original program written in the Mathematica environment. The results confirm that the number of girders affects the number of infinitesimal mechanisms. However, the dynamic behaviour does not depend on the number of mechanisms. The most important is the nature of a dome and the type of load-bearing girder. Especially, the behaviour of Geiger domes with a closed upper section is specific. In this case, not only the frequencies corresponding to the infinitesimal mechanisms depend on the prestress. There are additional frequencies that depend on prestress. The number of them, and the sensitivity on the initial prestress changes, depends on the number of girders. Generally, for the same number of girders, the natural frequencies of regular domes are higher than for the modified ones.

PL

W artykule zbadano zachowanie dynamiczne kopuł Geigera. W sposób szczególny przeanalizowano wpływ liczby dźwigarów nośnych na częstotliwość drgań własnych. Analizie poddano dwa typy dźwigarów nośnych tj. z zamkniętą (typ A) oraz otwartą (typ B) górną częścią dźwigara. Dodatkowo wzięto pod uwagę dwa typy geometrii kopuły (zwykłą i zmodyfikowaną). Przedstawione rozważania odpowiadają na następne pytania tj. czy jest możliwa kontrola liczby mechanizmów poprzez zmianę liczby dźwigarów nośnych? Jaki typ kopuły (zwykła czy zmodyfikowana) jest łatwiejszy do kontroli? Czy zachowanie kopuł z taką samą liczbą mechanizmów infinitezymalnych jest podobne? Czy liczba częstotliwości drgań własnych, zależnych od wstępnego sprężenia, jest równa liczbie nieskończenie małych mechanizmów? Analiza potwierdziła, że liczba dźwigarów nośnych ma wpływ na liczbę nieskończenie małych mechanizmów. Jednak zachowanie dynamiczne kopuł zależy głównie od geometrii kopuły oraz od typu dźwigara nośnego, a nie od liczby mechanizmów.

15

Evaluation of sand p–y curves by predicting both monopile lateral response and OWT natural frequency

Amel Douifi, Djillali Amar Bouzid, Subhamoy Bhattacharya, Nasreddine Amoura

Studia Geotechnica et Mechanica

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2022

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Vol. 44, nr 1

66--81

EN

Extending the use of the p–y curves included in the regulation codes API and DNV to design large-diameter monopiles supporting offshore wind turbines (OWTs) was unsuccessful as it resulted in an inaccurate estimation of the monopile behavior. This had prompted many investigators to propose formulations to enhance the performances of Winkler model. In this paper, two case studies are considered. A case consisting of an OWT at Horns Rev (Denmark) supported by a monopile in a sandy soil was studied first. Taking the FEA using ABAQUS as reference, results of WILDOWER 1.0 (a Winkler computer code) using the recently proposed p–y curves giving design parameters were plotted and evaluated. In order to see the ability of proposed p–y curves to predict the monopile head movements, and consequently the first natural frequency (1st NF), a second case study consisting of a monopile supporting an OWT at North Hoyle (UK) was selected. The monopile head stiffness in terms of lateral, rocking, and cross-coupling stiffness coefficients, necessary for the 1st NF, were computed using both ABAQUS and WILDPOWER 1.0. Comparisons with the measured 1st NF showed that with the exception of one p–y model, none of other proposed Winkler methods is able to predict accurately this parameter.

16

Study the internal cracks effect on vibration of laminated composite square plates

Hassan M.S., Rashid Z.H., Sarhan R.A.

Archives of Materials Science and Engineering

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2022

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Vol. 116, nr 1

28--33

EN

Purpose: The study of cracks behaviour in a composite plate is of significant importance in the dynamics of the Mechanical parts in order to avoid design failures due to resonance or high amplitude vibrations. Design/methodology/approach: In this paper, a square glass-epoxy composite plate is adopted. The plate has four layers with symmetric and asymmetric lamination. Assuming the cracks are profound as defects. The results were obtained by using a numerical solution of mechanical APDL from ANSYS. Findings: It has been found for different boundary conditions that the rank of natural frequencies is decreased by increasing the crack ratio due to the reduction of the plate’s stiffness, whereas the crack direction has no mentioned effect for a small angle of rotation. Research limitations/implications: The accuracy of results is verified by comparing a single case of the current work with other previous investigations. value: Evaluate the influence of the crack length ratio, angle of the crack rotation, boundary conditions and lamination angles on the natural frequencies of the square composite plate with glass-epoxy materials.

17

Design and analysis of cementless hip-joint system using functionally graded material

Asiri Saeed

Archive of Mechanical Engineering

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2022

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LXIX, nr 1

129--146

EN

Functionally Graded Materials (FGM) are extensively employed for hip plant component material due to their certain properties in a specific design to achieve the requirements of the hip-joint system. Nevertheless, if there are similar properties, it doesn’t necessarily indicate that the knee plant is efficiently and effectively working. Therefore, it is important to develop an ideal design of functionally graded material femoral components that can be used for a long period. A new ideal design of femoral prosthesis can be introduced using functionally graded fiber polymer (FGFP) which will reduce the stress shielding and the corresponding stresses present over the interface. Herein, modal analysis of the complete hip plant part is carried out, which is the main factor and to date, very few research studies have been found on it. Moreover, this enhances the life of hip replacement, and the modal, harmonic, and fatigue analysis determines the pre-loading failure phenomena due to the vibrational response of the hip. This study deals with the cementless hip plant applying the finite element analysis (FEA) model in which geometry is studied, and the femoral bone model is based in a 3D scan.

18

Natural frequency and critical velocities of heated inclined pinned PP-R pipe conveying fluid

Mohmmed J. H., Tawfik M. A., Atiyah Q. A.

Journal of Achievements in Materials and Manufacturing Engineering

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2021

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Vol. 107, nr 1

15--27

EN

Purpose: The flow velocity and pressure of fluid flowing through a pipeline can cause the vibration of pipes, and consequently result in the modification in natural frequency via fluid-structure interaction. The value of the natural frequency of a component when approaches the excitation force to a certain degree, a severe resonance failure may occur. Hence, avoiding the resonance failure of a pipe subjected to complex conditions is an essential issue that requires to be solved urgently in the engineering field. This work treats the transverse vibration for flexible inclined heated pipe, made of polypropylene randomcopolymer (PP-R), conveying fluid assuming pinned connections at the ends. The pipe was placed at different support angles and subjected to variant temperatures. Design/methodology/approach: The inclined pipe is modelled as Euler-Bernoulli beam taking into account its self-weight, temperature variation, inclination angle, aspect ratio, and internal fluid velocity. The integral transforms method, which includes the finite Fourier sine and the Laplace transforms, was used to develop an analytic solution to the modified equation of motion and the analytical expressions for dual natural frequencies of the pipefluid interaction system were computed. Findings: The proposed solution technique via finite Fourier sine and Laplace transforms offers a more convenient alternative to calculate the dynamic characteristic of pipes conveying fluid. The obtained results showed that the dynamical behaviour of pipe–fluid system is strongly affected by fluid flow velocity, degree of inclination, temperature variation, and aspect ratio of the pipe in transverse modes. Research limitations/implications: This work focuses on fundamental (first) mode in the most discussions. Practical implications: It was revealed that the thermal effects in the pipe are a very important factor and more significant in comparison with the internal fluid velocity and the inclination angle has a larger impact on vibration characteristics at a higher aspect ratio. The findings can be useful for the design of engineering components. Originality/value: Determining the combining effect of inclination angle, aspect ratio, and thermal loading on vibration characteristic of the pipes conveying fluid by using an improved analytic solution to the modified equation of motion via mixed of finite Fourier sine and Laplace transforms.

19

Natural frequencies of FG plates with two new distribution of porosity

Merdaci Slimane, Mostefa Adda Hadj, Khayal Osama M. E. S.

International Journal of Applied Mechanics and Engineering

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2021

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Vol. 26, no. 2

128--142

EN

The functionally graded plates (FGP) with two new porosity distributions are examined in this paper. In this work the plate is modeled using the higher-order shear deformation plate principle. The shear correction variables are neglected. To evaluate the equations of motion, the Hamilton method will be used herein. Therefore, the free vibration analysis of FG plate is developed in this work. For porous smart plates with simply-supported sides, natural frequencies are obtained and verified with the established findings in the literature. The impact of the porosity coefficient on the normal frequencies of the plate for various thickness ratios, geometric ratios, and material properties was investigated in a thorough numerical analysis.

20

A Study on Dynamic Behavior of Natural Draft Cooling Tower Considering the Effect of Soil-Structure Interaction

Chitrahalli Lingaraju Mahesh Kumar, Kotagi Girisha Shwetha, Bhaktanakatte Channabasappa Shanthappa, Karigowda Manjunatha

Civil and Environmental Engineering Reports

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2021

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Vol. 31, no. 4

17--32

EN

In this present era, the technology in advanced construction has developed to a very large extent. Some parts of the constructions are still in the improving stage which includes cooling tower construction. Hyperbolic cooling towers are large, thin shell reinforced concrete structures which contribute to power generation efficiency, reliability, and to environmental protection. Cooling towers use evaporation of water to eject heat from processes such as cooling the circulating water used in oil refineries and in power plants. Nowadays in many thermal power plants, we can see the cooling tower. So, preserving this industrial structure is an effort to save the cooling tower from dangerous earthquakes. The present-day cooling towers are exceptional structures in view of their sheer size and complexities. Present paper deals with the study of dynamic response that is modal analysis, seismic analysis of the two different cooling towers varying the H/t ratio and thicknesses with fixity at the base boundary condition, and the soil is modelled as raft for the effect of soil-structure interaction using the direct approach. In this paper, hyperbolic cooling towers are modelled using ANSYS software, which is a finite element software. Results show that the soil-structure interaction effect significantly modifies the earthquake behavior of hyperbolic cooling towers.