Wyniki wyszukiwania - Biblioteka Nauki

1

Load carrying capacity numerical study of I-beam pillar structure with blast protective panel

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Mazurkiewicz L. , Kolodziejczyk D. , Damaziak K. , Malachowski J. , Klasztorny M. , Baranowski P.

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tom Vol. 61, nr 2

451--457

EN

The paper presents numerical analyses aimed at preliminary assessment of the protective panel effectiveness, which task is to protect the elements of building structures against explosion. For the criterion of assessing the effectiveness of the panel the load capacity of the column made of steel I-beam was chosen. Ultimate force was determined by using advanced computational procedure, which consisted of four stages: preload, blast simulation, dynamic response and static analysis of deformed structure. Blast load was simulated using Lagrangian- Eulerian domain coupling. Results indicated that the application of the protective panel significantly reduces the plastic deformation of the structure.

2

Numerical analysis of friction influence on the transverse welding phenomenon in the forward extrusion process

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Piwnik J. , Mogielnicki K. , Kuprianowicz J.

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2014

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tom Vol. 52 nr 2

547--555

EN

There is often a need to join billets being extruded in the forward extrusion processes in order to preserve the continuity of manufacturing of products. The primary problem connected with joining while extruding is to ensure the required state of stress, deformation and temperature assuring a good weld quality. The paper contains numerical analyses of the transverse joining processes of billets in the course of forward extruding. The impact of the friction between welded objects on the material flow in vicinity of the joints is analyzed. A numerical method for determination of the weld length at the longitudinal section, by assuming the homogeneity of the strain rate at both sides of the joined elements contact line, is proposed. Three cases of the forward extruding are analyzed. Two friction shear factors equal to m = 0.4 and m = 0.9 at the billets interface are modelled for each case and weld the lengths at the longitudinal sections are presented. In addition, distributions of the flowing material velocities and effective strains in the weld vicinity are added for all tested processes.

3

Analysis of a light caterpillar vehicle loaded with blast wave from detonated IED

100%

Barnat W. , Niezgoda T. , Panowicz R.

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tom Vol. 17, No. 4

27-34

EN

More and more impudent attacks on the military convoys in Afghanistan proved a huge danger of the improvised explosive devices - IED. Huger and more clever charges are a serious problem for vehicles protection. Additionally, hitherto defence standards and STANAG didn't predict such huge charges. Majority investigations were based on a 3 kg anti-tank mine. The article presents the results of numerical calculations for the elements of the combat vehicle supporting structure loaded with an impact generated by explosion of a huge explosive charge under the bottom of the vehicle with consideration of the wave reflected from the ground. Such an approach allows obtaining a good approximation of numerical simulations to real conditions of terroristic attacks. Additionally, the analysis of IED side influence on the vehicle shell was conducted. The explosive charge — IED — was simulated with the use of concentrated energy of properly selected (on the base of literature investigations) density and initial energy. During analyses of side explosive on the vehicle structure, the obstacle in the form of a building increasing the pressure impulse was taken into account. The paper presents the results of a numerical analysis in which Euler and Lagrange domains(describing a vehicle) were coupled. A perfect gas model was used to describe air parameters.. Additionally, the ground was described with a gas model. Every kind of material data were selected on the base of experimental investigations. A bilinear material model with a Cowper and Symonds strain rate model was used to describe a vehicle. Such an approach fully describes the phenomena occurring in the system.

4

Analysis of a protective composite panel with energy adsorbent in the form of foamed aluminium

100%

Barnat W. , Panowicz R. , Niezgoda T. , Gieleta R.

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tom Vol. 17, No. 4

35-44

EN

The article presents the results of the investigations into modelling a blast wave for huge charges of l kg TNT equivalent. Modelling of huge charges is a very interesting problem due to a scale effect. During numerical analyses a detonation phenomenon was ignored (for the reason of the analysis time). The paper considers the effects of the influence of a pressure wave coming from a huge TNT charge (modelled with energy) on a 6 mm thick steel plate as well as on a protective panel made of foamed aluminium with composite layer. A panel of foamed aluminium was used for the protection of the described plate. The particular elements of a panel, subjected to an experimental analysis, were jointed with the use of a glueing method. In the numerical model the particular component layers were jointed with contact. The ALE (Arbitrary-Lagrange-Euler) function was used for coupling between the Euler domain and the Lagrange domain. The method requires absolute location compatibility of the nodes from both jointed areas. In the results of the conducted investigations, the permanent deformation of the steel plate was obtained.. Additionally, the possibility of the steel plate deformation evaluation was considered on the basis of accessible literature. Due to a huge charge, the analysis was performed with the use of the finite element method with the eiperimental verification.

5

Numerical investigation of the influence of a rigid obstacle on the multiple reflected pressure impulse

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Barnat W. , Panowicz R. , Niezgoda T.

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tom Vol. 17, No. 4

45-54

EN

The article presents the case of multiple reflection ofa blast wave from a rigid obstacle. The pressure impulse was generated in the Euler domain according to Taylor-Sedov theory. Additionally, there the results of numerical and analytical investigations on the behaviour of the reflected pressure impulse from the flat stiff obstacle were discussed. The analytical considerations are pursuant to the accessible literature. This case is identical with the explosion under a flat bottom of the tank-type vehicle or BWP. All the considered obstacles which are influence by the pressure impulse are similar to the construction of the vehicles used by Polish Army. As it was mentioned above, the numerical investigations were supported by analytical modelsfrom the scientific literature. In the previous papers, the authors conducted the numerical and experimental investigations on the flat blast wave. Those papers concentrated on the selection of the Euler domain parameters and parameters describing an explosive charge for numerical analyses. Additionally, the parameters of the boundary elements of the Euler domain were selected in order to unable the uncontrolled influence of gases. The innovation presented in the paper is the description of the issue of the numerical problem of multiple pressure impulse reflection from a rigid obstacle. The presented papers aim at increasing the safety of the military vehicles crews during the stabilisation missions in Iraq and Afghanistan.

6

Investigation of a panel with an elastomer layer plus carbon fibres loaded with a blast wave

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Barnat W. , Niezgoda T. , Gieleta R. , Panowicz R.

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tom Vol. 17, No. 4

19-26

EN

Terrorist attacks are directed against the most important elements of the infrastructure and human life. Crews of the combat vehicles as well as transmission installation of oil, gas and electric energy are, first of all, exposed to such operations. Such a situation caused striving to increase the safety against the activity of short-time loads coming from explosions [l, 2]. The object of the presented investigations was a numerical-experimental analysis of an elastomer layer of the protective panel combined with an experimental verification. Developed elastomer structures constitute perspective materials and will be applied to solve the problems connected with the increase of combat vehicle safety as well as trouble constructions of pipelines and gas pipelines especially in the dangerous places such as passages over rivers. A plate with an elastomer layer (with carbon fibres) loaded with a 100 g TNT charge was subjected to the analysis. The numerical analysis was verified experimentally. The results of the conducted analyses will be applied in further works on the selection of the kinds and parameters of the energy absorbing layers. They will be also used for further validating and optimizing investigations, which will aim at absorbing or dispersion of a maximum great value of energy influencing the energy absorbing panel. Such panels can be used for constructing armoured vehicles and protective elements of stationary strategic constructions. The constructions which can be exposed to damages resulted from a different kind of dynamic forces such as impacts or influences of the pressure wave comingfrom detonation of an explosive material should have the structure enabling absorption of as great as possible part of energy which influences them. Energy absorbing elements are constructed in the form of sandwich structures coats with a specially selected core material. One of the interesting types of materials which can be used for this purpose is elastomer. These materials enable significant increasing of the protective degree due to their capacities of absorbing energy of a blast wave. Applying of these materials results in decreasing of vibrations frequency of a system loaded with a pressure impulse.

7

Modelling the growth of rolling contact fatigue cracks in rails

100%

Bogdanski S. , Brown M. W.

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tom Z. 68, t. 1

53--58

EN

A 2D FE analysis along with the fatigue tests results was used to predict growth rate and direction of a surface breaking rolling contact fatigue (RCF) crack in a rail head. The FE analysis was used to determine the LEFM crack tip stress intensity histories including the effects of residual stress, crack face friction and fluid entrapment. The new FE results for the longer cracks (a/b=2) as well as those of previous FE analyses are examined again with a view to identifying the enhancement of the SIF ranges by the fluid entrapment mechanism. The values determined are superposed on the other 2D solutions. Full solutions of the rolling contact history in the presence of fluid are both time consuming and laborious to perform. In the paper, an approximate method employing superposition is presented, which allows relatively rapid estimates of fatigue crack behaviour to be made.

8

Parallel computations of multiphase electromagnetic systems

100%

Kołota J. , Smykowski J. , Stępień S. , Szymański G.

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tom R. 83, nr 11

29-31

EN

In this paper an effective approach for parallel computations of multiphase electromagnetic systems is presented. This method is used to accelerate solving of multiphase models using socket interface algorithm. Discussed algorithm has been examined in example of 3D FE three-phase transformer.

PL

W niniejszym artykule przedstawiona została efektywna metoda na zrównoleglenie obliczeń dla wielofazowych układów elektromagnetycznych. Omówione zagadnienie zrównoleglenia obliczeń jest do stosowane w celu przyspieszenia uzyskania rozwiązań dla modeli wielofazowych stosując interfejs gniazd. Omawiany algorytm został sprawdzony na przykładzie obliczeń dla trójwymiarowego modelu transformatora trójfazowego.

9

The assessment of the influence of selected passive safety systems on the level of dynamic loads of soldiers during collision

88%

Hryciów Z.

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2013

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tom Vol. 20, No. 3

161--168

EN

The work describes chosen problem connected with using of armoured personnel carriers (APC) in the frame of military operations. The soldiers inside the APC are exposed to dynamic loads and shock which are, among other things, an effect of collision with other vehicle or terrain obstacles. In military vehicles, which design is based on a rigid frame or integral body, there is no technical solution to mitigate the effects of a crash. The only applicable means of protection against the effects of collisions are lap belts and helmet designed to protect the head. Preliminary research shows that this kind of equipment is not sufficient. In the work an assessment of the influence of chosen solutions of safety belts and helmets on dynamic loads of carrier’s crew during collision with a rigid obstacle are presented. In simulation researches the HYBRID III dummies models have been used and calculations were carried out in LS-DYNA system. The work shows the numeric test results. Behaviour of the dummies during the impact on both the driver and crew member were presented. To assess a risk of injury standard indicators of crash test were used, including: maximum value of the head acceleration and the maximum values of the forces and moments in the neck. The distributions of these parameters were presented. The assessment of applied passive safety systems was made from the point of view of treat to soldiers inside a carrier.

10

Analysis of dynamic loads of the armoured personnel carrier crew during frontal crash

88%

Hryciów Z.

Journal of KONES

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2012

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tom Vol. 19, No. 4

223-230

EN

The work describes chosen problem connected with using of armoured personnel carriers (APC) in the frame of stabilisation and peacekeeping mission. The new type of tasks appears: ramming obstacles such as fences, entry gates, light engineering obstacles and also pushing other vehicles aside the road in order to obtain trafficability. The main threat in such situation is a risk of serious injury of soldiers inside vehicle. The lack of a crumple zone increases a value of acceleration acting on the crew. In the work models of driver and crew member seats used in the APC were showed. To the tests a Hybrid III 50th male dummy model in a seated position were used, which is a good representation of the average population of men. To the modelling LS-DYNA software was applied. The work shows the numeric test results. Behaviour of the dummies during the impact on both the driver and crew member were presented. To assess a risk of injury standard indicators of crash test were used, including: maximum value of the head acceleration, the criterion HIC and the maximum values of the forces and moments in the neck. The distributions of these parameters were presented. Results of simulation indicated that velocity and location of dummies has large influence on levels of dynamic loads. To further research is proposed to take into consideration models of dummy with additional equipment of soldiers (e.g. a helmet, a weapon, a bullet-proof jacket).

11

Study on computational methods applied to modelling of pulse shaper in split-Hopkinson bar

88%

Baranowski P. , Janiszewski J. , Malachowski J.

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tom Vol. 66, nr 6

429--452

EN

The paper presents a possibility of numerical modelling of a copper shaper utilized in an SHPB device with additional attention paid to the proper bar-shaper interaction simulation. The pulse shaper was modelled with the use of three methods available in the commercial code, i.e., applying typical finite Lagrangian elements, meshless smoothed particle hydrodynamics (SPH) method and multi- material arbitrary Lagrangian–Eulerian (MM-ALE) formulation. Additionally, the authors performed a mesh (particles) sensitivity study and the assessment of its influence on the obtained incident pulse characteristics. Consequently, the results obtained from all numerical analyses were compared and validated with the experimental ones with a particular attention given to the shape of the incident pulse and copper shaper deformation. The paper describes also the investigation of a relationship between the contact (coupling) force and the impulse shape.

12

Stability analysis of cylindrical composite shells in MSC/Nastran

88%

Kreja I.

Archives of Civil and Mechanical Engineering

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2005

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tom Vol. 5, no 3

31-41

EN

In the paper, the capabilities of the MSC/NASTRAN system in the field of stability analysis of com-posite laminated shells are critically tested. Two selected benchmark examples of laminated cylindrical panels under axial compression are examined. The MSC/NASTRAN results obtained either in buckling analysis or in nonlinear incremental calculations are compared with the solutions available in the litera-ture.

PL

Zanalizowano przydatność systemu MSC/NASTRAN for Windows w zakresie analizy stateczności kompozytowych powłok cylindrycznych. Przedstawiono krótki przegląd literatury dotyczącej numerycznej analizy powłok warstwowych. Omówiono zasadnicze równania opisujące problem stateczności konstrukcji w zakresie uogólnionego zagadnienia własnego stateczności początkowej oraz na drodze wyznaczenia pełnej ścieżki równowagi układu z zastosowaniem podejścia przyrostowego. Zaprezentowano podstawowe informacje o systemie MSC/NASTRAN for Windows ze szczególnym uwzględnieniem elementu powłokowego QUAD4. Obliczenia przeprowadzono dla dwóch wybranych przykładów paneli cylindrycznych poddanych równomiernemu ściskaniu w kierunku tworzącej, dokonując analizy zarówno stateczności początkowej, jak i problemu geometrycznie nieliniowego w procesie przyrosto-wym. Podstawowa różnica między analizowanymi przykładami polegała na przyjęciu innych warunków podparcia na prostych krawędziach: w przypadku pierwszego badanego panelu przyjęto swobodne podparcie prostych brzegów, podczas gdy w drugiej rozpatrywanej po-włoce proste krawędzie były swobodne. Dla obu rozważanych wariantów przyjęto, że zakrzywione krawędzie są utwierdzone, z tym że jedna z nich ma możliwość sztywnej translacji na kierunku tworzącej. Otrzymane wyniki zestawiono z rozwiązaniami dostępnymi w literaturze oraz z rozwiązaniami uzyskanymi za pomocą własnego programu SHL04. Przeprowadzone badania porównawcze w pełni potwierdziły bogate możliwości systemu MSC/NASTRAN for Windows. Zaobserwowano ponadto, że zmiana warunków podparcia na wzdłużnych krawędziach paneli ma decydujący wpływ na zmianę jej podatności na imperfekcje. Jak wykazano w drugim przykładzie, numeryczne niedokładności modelu MSC/Nastran w przypadku konstrukcji wrażliwej na imperfekcje mogą prowadzić do przeskoku rozwiązania na ścieżkę pobifurkacyjną.

13

A child seat numerical model validation in the static and dynamic work conditions

75%

Baranowski P. , Damaziak K. , Malachowski J. , Mazurkiewicz L. , Muszyński A.

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tom Vol. 15, no. 2

361--375

EN

Over last decade, road safety attracts increased attention of EU authorities. EU makers believe that new regulations forcing producers to fulfill extremely difficult safety requirement will help to diminish annual road fatalities. One of the latest of such ideas is standardization of side impact resistance of child seats. Since engineers cannot do anything else but to follow the regulations, number of projects aimed toward improvement of child seats side impact resistance has started. The problem is not easy and thus high-end engineering tools have to be used in the design process. One of such tools – a necessity, if one wants to truly understand structure behavior under dynamic working conditions – is numerical analysis of structures. The very basis of effective usage of this technique is reliable model of an analysis subject. This paper presents detailed information on numerical FE model of child seat and its validation based on test results. Effect of modeling techniques and dynamic material behavior on the obtained results is also discussed. Difficulties that arose during real life test are pointed and its influence on FE modeling is showed up.

14

Identification of layers distribution in the composite coupon using finite element method and three point bending test

75%

Mazurkiewicz Ł. , Małachowski J. , Damaziak K. , Baranowski P. , Gotowicki P.

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2013

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tom Vol. 7, no. 3

160--165

EN

The main objective of the study is to develop experimentally validated FE model and perform numerical analysis of layered composites made by hand lay-up techniques during tension and bending test. The research object is glass - polyester laminate made of four unidirectional layers. In order to validate the numerical models experimental test were performed. Due to the very different stiffness modulus in tension and bending loading the material properties obtained from standard test are not suitable to apply in numerical model. Significantly different behaviour compared to experimental test was obtained for tree point bending where the numerical model becomes too stiff. Simple coupons, relatively easy to manufacture presented in the paper have very low quality. The differences in actual and theoretical bending stiffness (obtained from tension stiffness) exceed 70%. In order to represent the actual structure the layers of the composite were divided by resin layers and also additional resin layer at the top and bottom of the model were defined. Single stage optimization process was used to adjust the material layout. After layer set-up modification very significant improvement can be seen for flexural behaviour.

15

Computer Aided Design of Wires Extrusion from Biocompatible Mg-Ca Magnesium Alloy

75%

Milenin A. , Gzyl M. , Rec T. , Płonka B.

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2014

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tom Vol. 59, iss. 2

551--556

EN

Mathematical model of small-diameter wires extrusion from biocompatible MgCa08 (Mg - 0.8% Ca) magnesium alloy was developed in the current paper in order to determine window of allowable technological parameters. Compression and tensile tests were carried out within temperature range 250-400°C and with different strain rates to determine the fracture conditions for the studied alloy. Finite element (FE) analysis was used to predict the billet temperature evolution and material damage during processing. The extrusion model takes into account two independent fracture mechanisms: a) surface cracking due to exceeding of the incipient melting temperature and b) utilization of material formability. FE simulations with different initial billet temperatures and pressing speeds were performed in order to determine the extrusion limit diagram (ELD) for MgCa08 magnesium alloy. The developed ELD was used to select the parameters for the direct extrusion of wires with diameter of 1 mm. Then, the extrusion of twelve wires was conducted at 400°C with pressing speed 0.25 mm/s. It was reported that the obtained wires were free from defects, which confirmed the good agreement between numerical and experimental results.

PL

W pracy zaproponowano model matematyczny procesu wyciskania prętów o małych średnicach z biokompatybilnego stopu magnezu MgCa08 (Mg - 0.8% Ca). Na podstawie opracowanego modelu możliwy jest dobór parametrów technologicznych rozpatrywanego procesu. Model procesu wyciskania zawiera model do prognozowania utraty spójności materiału, który został opracowany w oparciu o próby spęczania oraz jednoosiowego rozciągania w zakresie temperatur 250-400°C dla różnych prędkości odkształcenia. W oparciu o metodę elementów skończonych (MES) przeprowadzona została analiza numeryczna rozkładu temperatury oraz wskaźnika wykorzystania odkształcalności materiału w procesie wyciskania. Zaproponowany model zawiera dwa możliwe mechanizmy utraty spójności: a) wynikający z lokalnego przekroczenia temperatury topnienia, b) wynikający z wyczerpania zapasu plastyczności. W oparciu o przeprowadzoną analizę MES procesu wyciskania dla różnych temperatur oraz prędkości wyciskania opracowano diagram ELM (extrusion limit diagram) dla stopu MgCa08. Na podstawie opracowanego diagramu ELM dobrano parametry procesu wyciskania prętów o średnicy 1 mm. Weryfikację modelu procesu wyciskania dla stopu MgCa08 wykonano w warunkach laboratoryjnych, gdzie przeprowadzono dwunasto żyłowy proces wyciskania prętów w temperaturze 400°C i prędkości 0.25 mm/s. Otrzymane pręty były| wolne od wad. co potwierdziło dobrą zgodność pomiędzy wynikami numerycznymi i eksperymentalnymi.

16

Façade scaffolding behaviour under wind action

63%

Lipecki T. , Jamińska-Gadomska P. , Bęc J. , Błazik-Borowa E.

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2020

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tom Vol. 20, no. 1

375--389

EN

The main objective of the study was to estimate the mean horizontal wind action on a façade scaffolding on the basis of full-scale data. Measurements of climatic parameters were carried out for a number of façade scaffoldings (120 structures) located in Poland over a 30-month period. The measurement points were located on 2–3 deck levels of each structure and at 2–4 points placed in each level. The measurements were carried out 3–4 times during each day for 5 consecutive days. At each point, two components of wind speed were measured: first with the vane probe directed perpendicular to the façade and then parallel to the façade. Each measurement lasted 60 s, and the data were recorded every 1 s. On the basis of wind speeds, a procedure was suggested that enabled estimation of the static wind action on façade scaffoldings. The responses of structures to this action were computed via FEM simulations. The results were compared with those based on the approaches recommended by the wind and scaffolding codes. Initial analyses, illustrated by three scaffoldings without a protective cover, indicated large discrepancies between the approaches and the possibility of wind action, which is not considered in the codes.

17

Dynamic testing of copper material : numerical approach

63%

Baranowski P. , Małachowski J. , Mazurkiewicz Ł. , Damaziak K.

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tom Vol. 7, no. 4

195--202

EN

Split Hopkinson pressure bar (SHPB) is one of the most important and recognisable apparatus used for characterizing the dynamic behaviour of various materials. Incident pulse generated one the incident bar usually have a rectangular shape, which is proper for some materials but for others is not. Therefore, several methods of shaping the incident pulse are used for obtaining constant strain rate conditions during tests. Very often pulse shapers made of copper or similar material are implemented due to its softness properties. In this paper such material was investigated using the FE model of SHPB. Its mechanical behaviour was characterised with and without copper disc between the striker and incident bar. Numerical simulations were carried out using explicit LS-DYNA code. Two different methods were used for modelling the copper sample: typical finite Lagrangian elements and meshless Smoothed Particle Hydrodynamics (SPH) method. As a result of two techniques used axial stress-strain characteristics were compared for three different striker’s velocity with an influence of the copper pulse shaper taking into account. Finally, FE and SPH method was compared with taking into consideration: the efficiency, computer memory and power requirements, complexity of methods and time of simulation.

18

Bone Remodelling Model Incorporating Both Shape and Internal Structure Changes by Three Different Reconstruction Mechanisms. A Lumbar Spine Case

63%

Wymysłowski P. , Zagrajek T.

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2016

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tom Vol. LXIII, nr 4

549--563

EN

The paper presents a method of analysis of bone remodelling in the vicinity of implants. The authors aimed at building a model and numerical procedures which may be used as a tool in the prosthesis design process. The model proposed by the authors is based on the theory of adaptive elasticity and the lazy zone concept. It takes into consideration not only changes of the internal structure of the tissue (described by apparent density) but also surface remodelling and changes caused by the effects revealing some features of “creep”. Finite element analysis of a lumbar spinal segment with an artificial intervertebral disc was performed by means of the Ansys system with custom APDL code. The algorithms were in two variants: the so-called site-independent and site-specific. Resultant density distribution and modified shape of the vertebra are compared for both of them. It is shown that this two approaches predict the bone remodelling in different ways. A comparison with available clinical outcomes is also presented and similarities to the numerical results are pointed out.

PL

Artykuł prezentuje metodę analizy przebudowy kości w otoczeniu implantów. Celem pracy było opracowanie modelu i procedur numerycznych mogących służyć jako narzędzie wspomagające projektowanie protez. Zaproponowany przez autorów model opiera się na teorii adaptacyjnej sprężystości i koncepcji strefy martwej. Uwzględnia on nie tylko zmiany struktury wewnętrznej tkanki (opisanej przez gęstość pozorną), ale także przebudowę powierzchniową i zmiany związane z efektami wykazującymi pewne cechy “pełzania”. Przeprowadzona została analiza metodą elementów skończonych segmentu ruchowego kręgosłupa ze sztucznym krążkiem międzykręgowym z wykorzystaniem systemu Ansys i własnego kodu APDL. Algorytmy zbudowano w dwóch wariantach: tzw. niezależnym i zależnym od miejsca. Porównano uzyskane rozkłady gęstości i zmiany kształtu pokazując, że obydwa warianty przebudowę kości przewidują w różny sposób. Zaprezentowano również porównanie wyników numerycznych z badaniami klinicznymi wskazując na ich podobieństwa.

19

A generalized FE formulation for buckling analysis of solid or built-up columns with nonprismatic section

63%

Li G.-Q. , Li J.-J.

International Journal of Applied Mechanics and Engineering

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2003

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tom Vol. 8, no 4

651-663

EN

In this paper, a generalized FE formulation for buckling analysis of nonprismatic columns with various cross-sections is established by using the Chebyshev polynomial approach to the governing differential equation. The proposed formulation includes the effects of shear deformation and is therefore applicable to solid or built-up columns. The change of the sectional properties along the length direction, such as the area and inertia moment, need not be fitted with approximate expressions and can be defined exactly and freely with user-defined functions in programming. Buckling of the three structures, respectively for a tapered mast column with a circular hollow section, a web-tapered I-sectional column and a tapered lattice column, is studied numerically and compared with the results of previous studies. The effects of shear deformation on the buckling loads of those tapered columns are specified.

20

Lifetime prediction on gas turbine components with thermal barrier coatings, using micromechanics

63%

Sjostrom S. , Burman J. , Jinnestrand M.

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tom Vol. 7, no 1

205-220

EN

Lifetime prediction of thermal barrier coatings on gas turbine hot components is described. Existing modelling strategies are discussed. A more fundamental strategy, based on micromechanical analyses of the coating system is finally presented.