Wyniki wyszukiwania - BazTech

1

Research of dynamic processes in an anvil during a collision with a sample

Pyr'yev Yuriy, Penkul Andrzej, Cybula Leszek

Acta Mechanica et Automatica

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2023

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Vol. 17, no. 1

104--111

EN

The paper concerns modelling the dynamics of the contact system of the tested sample with an elastic half-space (anvil) during their collision. The original elements in the paper include the proposed general approach to solving the problem of contact dynamics. The presented approach consists in determining the force of impact on the sample during the collision and the joint solution of the problem for the tested sample and the problem for an elastic semi-space under the conditions of the assumptions of Hertz's theory. The resulting interaction forces allow the determination of displacements and stresses.

2

An algorithm for diagnosing injection systems of marine engines

Bejger A., Drzewieniecki J.

New Trends in Production Engineering

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2018

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Vol. 1, Iss. 1

227--233

EN

The article presents the developed methods for diagnosing and analysing signals from injection systems of marine engines. As a source signal, the authors use elastic waves of acoustic emission. The essential fact in the case here considered is that the high frequency of signal from working elements of the injection system comes from a close source directly related to the change of the working parameters of the element (system). Characteristically for elastic waves of acoustic emission, low frequencies (e.g. those from other sources, such as machines in the engine room) are in this case attenuated. Therefore, the proper selection of the method for the analysis allows us accurately diagnose the injection system of a working engine.

3

Material definition to design vehicle components, application to crashworthiness

Rusinek A., Zaera R.

Logistics and Transport

|

2018

|

Vol. 38, No. 2

63--67

EN

In this paper a short description is reported allowing to take into account some aspects to design structures used for automotive industries. It allows to define correctly the behaviour of a vehicle and mainly the passive structures to absorb energy during an accident or an impact. The main aspect related to the behaviour is the strain rate sensitivity coupled to the process of elastic wave propagation.

4

Wyznaczanie porowatości ogólnej i parametrów szkieletowych utworów węglanowych na podstawie pomiarów prędkości fal sprężystych i gęstości

Jarzyna J., Puskarczyk E., Ogórek E., Motyka J.

Biuletyn Państwowego Instytutu Geologicznego

|

2018

|

nr 473

13--25

PL

Badania wykonano w celu wykazania zależności między prędkościami fal sprężystych uzyskanymi w wyniku pomiarów laboratoryjnych a parametrami otrzymanymi w badaniach hydrogeologicznych (porowatością i gęstością objętościową). Pomiary przeprowadzono na 73 próbkach skalnych, pochodzących w większości z poziomów wodonośnych z rejonu Olkusza. Informacja o prędkościach fal sprężystych w połączeniu z parametrami zbiornikowymi (porowatością, współczynnikiem filtracji i gęstością) dostarczyła dodatkowych informacji o badanych skałach. Zestawienie prędkości fali podłużnej P oraz gęstości objętościowej z porowatością otwartą, obliczoną w badaniach hydrogeologicznych, dało informację o zakresie zmian prędkości oraz gęstości szkieletowej w badanych skałach, które następnie wprowadzono do wzorów na obliczenie porowatości ogólnej badanych próbek. Na podstawie prędkości fal sprężystych, zmierzonych na próbkach wyciętych z rdzeni w dwóch prostopadłych kierunkach, wykonano także analizę anizotropii, co pozwoliło zidentyfikować szczeliny w skale. Analiza wyników hydrogeologicznych i petrofizycznych pokazała, że łącząc ze sobą różnorodne parametry można uzyskać dodatkowe informacje o właściwościach zbiornikowych poziomów wodonośnych.

EN

The purpose of the research was to find relationship between elastic waves velocities obtained from lab measurements and parameters from hydrogeological research. Measurements were conducted on 73 rock samples originating mostly from Jurassic limestone of the Olkusz area. Additional information about the rock samples was obtained when the elastic wave velocities were compared with reservoir parameters such as porosity, permeability and density. Plots of elastic waves velocities vs. porosity and bulk density vs. porosity gave information about the range of P wave velocities from the boundary velocity to the values when porosity is equal to zero. Matrix velocity and density values were introduced into the formulas used to calculate porosity. Anisotropy analysis was made on the basis of elastic wave velocities measured on cores cut in two perpendicular directions. This allowed for identification of fractures in rocks. Results showed that by comparing various petrophysical parameters it was possible to get better information about reservoir properties of aquifers.

5

Analiza płaskiej fali naprężenia metodą ruchomych, najmniejszych kwadratów

Dornowski Wojciech

Modern Engineering

|

2017

|

1

1--17

PL

W pracy rozwiązano zadanie początkowo-brzegowe propagacji płaskiej fali naprężenia w tarczy stalowej metodą ruchomych najmniejszych kwadratów. Stosowano różne siatki węzłów. W przypadku siatek z węzłami generowanymi losowo istotne znaczenie ma wybór węzłów sąsiedztwa aproksymacyjnego. Przyjęto kryterium topologiczne wynikające z triangulacji zbioru węzłów, która minimalizuje łączną długość krawędzi triangulacji. Stwierdzono, że triangulacyjny sposób wyboru otoczenia aproksymacyjnego i wygładzanie siatki nieregularnej metodą Laplace’a znacznie poprawia dokładność rozwiązania. Efekt odbicia fali naprężenia od brzegu swobodnego modelowano przez wprowadzenia węzłów fikcyjnych (poza obszarem tarczy). Otrzymane rezultaty porównano z wynikami obliczeń metodą różnicową stwierdzając ich zgodność jakościową i ilościową.

EN

A meshless method based on the moving least squares aproximation is applied to stress wave propagation analysis. Two kinds of node meshes, the randomly generated mesh and the regular mesh are used. The nearest neighbors problem are developed from a triangulation that satisfies mini-mum edges length conditions. It is found that this method of neighbors choice significantly improves the solution accuracy. The reflection of stress waves from the free edge is model edusing fictitious nodes(outside the plate). The comparison with the finite difference results also demonstrated the accuracy of the proposed approach.

6

Detection of damages in hybrid composite plates with the use of elastic waves generated by PZT active sensors

Barski M., Pająk P.

Journal of KONES

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2017

|

Vol. 24, No. 2

17--24

EN

The presented article is devoted to the problem of detection and localization of damages occurring in components of structures, which are made of hybrid composite materials. The subject of the work is a square plate consisting of a single layer made of aluminum alloy and several layers made of glass fibres (glass fabric) and epoxy resin. On the surface, which is made of composite, 12 piezoelectric elements are installed. These elements sequentially, one by one, generates a signal that is further recorded by the remaining piezoelectric elements. Picked up signal for the selected pair of activator – sensor is compared with the reference signal. The reference signal corresponds to the intact structure. This kind of approach is known as the pitch – catch configuration. In situations when the signal obtained for interrogated structure and reference one differs significantly, this may indicate that a damage exists between the activator and the sensor. Next, taking into account the information obtained from the other sensors, it is possible not only to detect but also to determine the approximate location of the flaw and to estimate its size. In order to visualize the obtained results, an especially dedicated software is developed according to the algorithms available in the literature – probability ellipse. Several computer simulations of wave propagation are performed using the finite element method. The proposed procedure is also tested experimentally. The presented approach makes it possible to detect both single and multiple damages.

7

Analytical and numerical identification of lamb waves modes for hybrid composites

Barski M., Pająk P.

Journal of KONES

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2017

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Vol. 24, No. 1

31--38

EN

The current work is devoted to the problem of analytical and numerical identification of fundamental elastic waves' modes, namely symmetric mode S0 and antisymmetric mode A0, in the case of hybrid composite. The investigated material consists of one layer made of aluminum alloy Pa38 and six layers made of glass fabric/epoxy resin. At the very beginning, the dispersion curves are determined with the use of stiffness matrix method. The calculated values of phase velocities are verified by numerical simulation. The semi – analytical finite element method is applied. Next, the numerical simulations of elastic waves propagation are performed. In the studied model, the plane state of strain is assumed. These simulations are carried out with the use of finite element method. The excitation signal is a sine wave modulated by Hanning window. The simulation is repeated for different excitation frequency. The group velocities of wave modes S0 and A0 are estimated and compared with the analytical results. The evaluation of the group velocities is based on the analysis of the appropriate components of displacement. The two different method are employed, namely: cross – correlation method and envelope extraction by Hilbert transform. Generally, the obtained results are in a good agreement. However, the method based on envelope extraction by Hilbert transform provides better correlation between analytical and numerical results. The significant discrepancy is observed in the case of symmetric mode S0 for relatively high values of frequency. It is caused by the dispersion phenomena. The analytical calculations are performed with the use of SCILAB 5.5.2 free software and the numerical simulations are carried out with the use of finite element system ANSYS 13.0.

8

Reflection and Refraction of Plane HarmonicWaves at an Interface Between Elastic Solid and Magneto-thermoelastic Diffusion Solid with Voids

Kumar R., Kansal T.

Computational Methods in Science and Technology

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2017

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Vol. 23, No. 1

43--56

EN

The problem of the reflection and refraction phenomenon due to longitudinal and transverse waves incident obliquely at a plane interface between uniform elastic solid half-space and magneto-thermoelastic diffusive solid half-space with voids has been studied. It is found that the amplitude ratios of various reflected and refracted waves are functions of the angle of incidence and frequency of the incident wave. The amplitude ratios and energy ratios have been computed numerically for a particular model. The variations of energy ratios with angle of incidence are shown graphically.

9

Analiza teoretyczno-symulacyjna transformatora piezoelektrycznego

Łabędzki P., Pawlikowski R., Radowicz A.

Mechanik

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2016

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R. 89, nr 12

1836--1839

PL

Przedstawiono analizę teoretyczno-symulacyjną transformatora piezoelektrycznego o dowolnej konfiguracji. Poszukiwano optymalnych parametrów geometrycznych ze względu na uzyskiwane wzmocnienie napięcia. Dokonano analizy pracy transformatora przy różnych postaciach drgań własnych dla dwóch różnych materiałów.

EN

Theoretical and simulation analysis for the description of a piezoelectric transformer with respect to unrestricted configuration is developed. The working conditions of the transformer dependent on various eigen vibrations for two different kinds of material are considered and the influence of the gauge optimal parameters on a voltage amplification have been studied.

10

An application of stiffness matrix method to determining of dispersion curves for arbitrary composite materials

Barski M., Pająk P.

Journal of KONES

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2016

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Vol. 23, No. 1

47--54

EN

Nowadays multi-layered composite material is very often applied in different kind of structures, like aircrafts, boats or vehicles. Parts of structures, which are made of these materials, are significantly lighter in comparison with traditional materials, like aluminum or steel alloys. On the other hand, the process of damage creation and evolution in the case of composites is much more complex. Moreover, the damages, which are characteristic for multi-layered materials (matrix cracking, fibre breakage, delaminations), are very difficult to detect at early stage of creation. Hence, there is a need to develop the advanced methods to detect them without destroying tested composite element. One of them is based on analysis of elastic wave propagation through the composite structure. Unfortunately, elastic waves possess strongly dispersive character. Thus, it is necessary to determine dispersion curves for investigated material before the tests in order to appropriate interpretation of received dynamic response of structure. In the case of arbitrary composite materials, it is rather challenging task. In the present article the relatively new, analytical method is applied, namely stiffness matrix method. The fundamental assumptions and the theoretical formulation of this method are discussed. Next numerical examples are presented, namely the dispersion curves are determined for the single orthotropic lamina and multi-layered 'quasi - isotropic' composite plate. The studied plates are made of glass fibres and epoxy resin. In the case of single lamina, the dispersion curves are determined in the parallel, perpendicular and arbitrary direction of waves propagation with respect to the fibre direction. In the case of multi-layered plates, the dispersion curves are computed for one arbitrary direction. Additionally, the phase and group velocities for fundamental modes and fixed excitation frequency are estimated in all directions of waves propagation.

11

Fale sprężyste : wybrane zagadnienia

Kuliński K.

Zeszyty Naukowe Politechniki Częstochowskiej. Budownictwo

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2015

|

Z. 21 (171)

161--167

PL

W artykule zaprezentowano i omówiono wybrane rodzaje występujących w przyrodzie fal, tj. fal słabej nieciągłości oraz fal silnej nieciągłości (tzw. fale uderzeniowe). Ponadto w pracy przedstawiono możliwe zastosowanie opisanych fal, jak również dokonano przeglądu literaturowego ze wskazaniem prac, w których wykorzystuje się metodę elementów skończonych do walidacji opisów matematycznych i wyników badań prezentowanych fal.

EN

In this paper there are presented and discussed two different naturally occurring wave types i.e. low discontinuity waves and strong discontinuity waves called impact waves. Moreover, in this paper there are presented possible applications of described waves and a small literature overview has been performed indicating the works, where finite element method is used to validate the mathematical problem descriptions and the experimental results of presented wave types.

12

Effects of liquid loadings on lamb waves in context of size dependent couple stress theory

Sharma V., Kumar S.

Journal of Theoretical and Applied Mechanics

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2015

|

Vol. 53 nr 4

925—934

EN

For understanding the effects of an internal microstructure, generalised microcontinuum theories with additional microstructural parameters are developed. One such a parameter, called the characteristic length of the material comparable with the internal cell size of the material is involved in the couple stress theory. The problem of propagation of Lamb waves in a plate with an internal microstructure and loaded with an inviscid liquid on both sides is studied using the couple stress theory. The dispersion equation of Lamb waves with the liquid loadings is derived. The impact of the liquid loadings is studied on the propagation of Lamb waves. The effect of the characteristic length is also studied on the phase velocity of Lamb waves in the plate for various modes in the presence of liquid loadings.

13

Modern acoustic techniques for testing concrete structures accessible from one side only

Schabowicz K.

Archives of Civil and Mechanical Engineering

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2015

|

Vol. 15, no. 4

1149--1159

EN

This paper presents nondestructive methodologies for investigating selected geometrical and material imperfections in unilaterally accessible concrete structures by means of modern acoustic techniques. The imperfections include: improper structure thickness, delamination, large air voids and zones of concrete macroheterogeneities. The presentation of the methodologies is preceded by a survey of the literature on the subject. The available knowledge, also contributed by the present author, has been collected and systematized as well as complemented with two new methodologies for determining the depth of cracks. The methodologies have been validated in situ on building structures whereby their practical usefulness has been confirmed.

14

Diagnostics of bolted lap joint using guided wave propagation

Kędra R., Rucka M.

Diagnostyka

|

2014

|

Vol. 15, No. 4

35--40

EN

The paper presents numerical and experimental analyses of elastic waves propagation in a bolted lap joint. In experimental investigations condition assessment of the joint was performed with the use of symmetric waves excited by a piezoactuator. Numerical calculations were conducted in commercial finite element method software Abaqus. The influence of number of bolts and the value of the initial stress on recorded signals was examined. The study showed the possibility of using elastic waves in the context of diagnostics of bolted joints.

PL

Praca przedstawia numeryczne i eksperymentalne analizy propagacji fal sprężystych w zakładkowym połączeniu śrubowym. W badaniach eksperymentalnych wykorzystano fale wzbudzane w płaszczyźnie połączenia za pomocą piezoaktuatora. Obliczenia numeryczne wykonano w środowisku komercyjnego programu metody elementów skończonych Abaqus. W badaniach analizowano wpływ liczby śrub i wartości momentu dokręcającego na zarejestrowane sygnały. Wykazano możliwość zastosowania fal sprężystych do diagnostyki połączeń.

15

Analiza falowa tarczy w płaskim stanie naprężenia metodą ruchomych, najmniejszych kwadratów

Dornowski W.

Biuletyn Wojskowej Akademii Technicznej

|

2014

|

Vol. 63, nr 3

189-206

PL

W pracy rozwiązano zadanie początkowo-brzegowe propagacji płaskiej fali naprężenia w tarczy stalowej metodą ruchomych najmniejszych kwadratów. Stosowano różne siatki węzłów. W przypadku siatek z węzłami generowanymi losowo istotne znaczenie ma wybór węzłów sąsiedztwa aproksymacyjnego. Przyjęto kryterium topologiczne wynikające z triangulacji zbioru węzłów, która minimalizuje łączną długość krawędzi triangulacji. Stwierdzono, że triangulacyjny sposób wyboru otoczenia aproksymacyjnego i wygładzanie siatki nieregularnej metodą Laplace’a znacznie poprawia dokładność rozwiązania. Efekt odbicia fali naprężenia od brzegu swobodnego modelowano przez wprowadzenie węzłów fikcyjnych (poza obszarem tarczy). Otrzymane rezultaty porównano z wynikami obliczeń metodą różnicową, stwierdzając ich zgodność jakościową i ilościową.

EN

A meshless method based on the moving least squares approximation is applied to stress wave propagation analysis. Two kinds of node meshes, the randomly generated mesh and the regular mesh are used. The nearest neighbours’ problem is developed from a triangulation that satisfies minimum edges length conditions. It is found that this method of neighbours’ choice significantly improves the solution accuracy. The reflection of stress waves from the free edge is modelled using fictitious nodes (outside the plate). The comparison with the finite difference results also demonstrated the accuracy of the proposed approach.

16

Reflection at free surface in micropolar thermoelastic solid with two temperatures

Sharma K.

International Journal of Applied Mechanics and Engineering

|

2013

|

Vol. 18, no. 1

217--234

EN

The present investigation is concerned with the effect of two temperatures on reflection coefficients in a micropolar thermoelastic solid half space. With two relaxation times, reflection of plane waves impinging obliquely at a plane interface of the micropolar generalized thermoelastic solid half space with two temperatures is investigated. The incident wave is assumed to be striking at the plane surface after propagating through the micropolar generalized thermoelastic solid with two temperatures. Amplitude ratios of the various reflected waves are obtained in closed form and it is found that these are functions of angle of incidence, frequency and are affected by the elastic properties of the media. The effect of two temperatures is shown on these amplitude ratios for a specific model.

17

Wave-quasi-particle dualism in the transmission-reflection problem for elastic waves

Maugin G. A., Rousseau M.

Journal of Theoretical and Applied Mechanics

|

2012

|

Vol. 50 nr 3

797-805

EN

Following along the line of recent works in which the notion of quasi-particles associated with surface acoustic waves of different types was introduced via canonical conservation laws, here the emphasis is placed on the possible exploitation of this dualism in the classical problem of the transmission and reflection of waves by a discontinuity between two media (in perfect contact or with possible delamination) and the more general case of a mono-layer or multi-layer sandwiched slab.

PL

Idąc w ślad za ostatnimi publikacjami, w których użyto pojęcia tzw. quasi-cząstek wprowadzonego poprzez zastosowanie kanonicznych praw zachowania w odniesieniu do powierzchniowych fal akustycznych różnego rodzaju, w prezentowanej pracy położono nacisk na możliwe wykorzystanie dualizmu falowo-quasi-korpuskularnego w klasycznym zagadnieniu przesyłania i odbicia fal na nieciągłości pomiędzy dwoma ośrodkami (doskonale połączonych lub zdelaminowanych) i w ogólniejszym przypadku jednolub wielowarstwowej płycie typu sandwich.

18

Novelty detection based on elastic wave signals measured by different techniques

Nazarko P., Ziemiański L.

Computer Assisted Methods in Engineering and Science

|

2012

|

Vol. 19, no. 4

317-330

EN

The paper discusses the results of laboratory experiments i n which three independent measurement techniques were compared: a digital oscilloscope, phased array acquisition system, a laser vibrometer 3D. These techniques take advantage of elastic wave signals actuated and sensed by a surface-mounted piezoelectric transducers as well as non-contact measurements. In these e xperiments two samples of aluminum strips were investigated while the damage was modeled by drilling a hole. The structure responses recorded were then subjected to a procedure of signal processing, and features’ extraction was done by PrincipalComponents Analysis. A pattern database defined was used to train artificial neural networks for the purpose of damage detection.

19

Reflection and refraction of plane waves at the interface of an elastic solid half-space and a thermoelastic diffusive solid half-space

Kumar R., Kansal T.

Archives of Mechanics

|

2012

|

Vol. 64, nr 3

293-293

EN

The problem of reflection and refraction phenomenon due to longitudinal and transverse waves incident obliquely at a plane interface between uniform elastic solid half-space and thermoelastic diffusive solid half-space has been studied. It is found that the amplitude ratios of various reflected and refracted waves are functions of angle of incidence, frequency of incident wave and are influenced by the elastic properties of media. The expressions of amplitude ratios and energy ratios are obtained in closed form. The amplitude ratios and energy ratios have been computed numerically for a particular model. The variations of energy ratios with angle of incidence are shown graphically. The conservation of energy across the interface is verified. Some particular cases are also discussed.

20

Goal-oriented mesh adaptivity for fluid-structure interaction with application to heart-valve settings

Wick T.

Archive of Mechanical Engineering

|

2012

|

Vol. LIX, nr 1

73-99

EN

We apply a fluid-structure interaction method to simulate prototypical dynamics of the aortic heart-valve. Our method of choice is based on a monolithic coupling scheme for fluid-structure interactions in which the fluid equations are rewritten in the 'arbitrary Lagrangian Eulerian' (ALE) framework. To prevent the backflow of structure waves because of their hyperbolic nature, a damped structure equation is solved on an artificial layer that is used to prolongate the computational domain. The increased computational cost in the presence of the artificial layer is resolved by using local mesh adaption. In particular, heuristic mesh refinement techniques are compared to rigorous goal-oriented mesh adaption with the dual weighted residual (DWR) method. A version of this method is developed for stationary settings. For the nonstationary test cases the indicators are obtained by a heuristic error estimator, which has a good performance for the measurement of wall stresses. The results for prototypical problems demonstrate that heart-valve dynamics can be treated with our proposed concepts and that the DWR method performs best with respect to a certain target functional.

PL

W artykule przedstawiono analizę zagadnienia oddziaływania płyn-struktura (FSI) w komputerowej symulacji pracy zastawki serca. Przedstawiono monolityczne sformułowanie tego zagadnienia, w którym równania dla struktury i płynu rozwiązywane są w pełnym sprzężeniu, przy czym do opisu ruchu płynu stosowane jest podejście typu Arbitrary Lagrangian-Euelerian (ALE). Zaproponowano metodę eliminacji zjawiska niefizycznego odbicia fal odkształceń struktury, polegającą na wprowadzeniu sztucznej dyssypacji energii tych fal w części brzegu obszaru położonej za zastawkami. W celu zwiększenia efektywności obliczeniowej wprowadzono lokalną adaptację siatki. W szczególności, porównano heurystyczne techniki adaptacji siatki z techniką opartą na wykorzystaniu ważonego residuum sprzężonego (Dual Weighted Residual, DWR). Przedstawiono wyniki obliczeń testowych demonstrujące poprawność zaproponowanego podejścia oraz skuteczność metody adaptacyjnej DWR.