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Wyszukujesz frazę "finite elements method" wg kryterium: Temat


Tytuł:
Numerical analysis of temperature influence on deformation and effort of bimetallic element
Autorzy:
Panowicz, R.
Kucewicz, M.
Tematy:
finite elements method
bimetallic elements
thermoelasticity
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Wydawca:
Instytut Techniczny Wojsk Lotniczych
Powiązania:
https://bibliotekanauki.pl/articles/241699.pdf  Link otwiera się w nowym oknie
Opis:
Bimetallic elements consist of at least two, connected together, material layers. The materials have different coefficients of thermal expansion. An active layer of bimetallic elements has a greater thermal expansion coefficient, whereas a passive layer has a lower one. Therefore, deformation of bimetallic elements occurs due to a change in temperature. The simplest case of bimetallic elements is a strip, which bends in the shape of an arc. As a consequence of elements deformation, stresses appear in them. An important problem is optimization of each layer of the element to achieve certain characteristics of the system. The elements should work in an elastic domain in the entire operating range. The aim of the paper is to present both numerical and analytical results for three different bimetallic elements. The following pairs of materials are considered: invar – incoloy, steel – brass and aluminium – molybdenum subjected to uniform heating. An influence of temperature and active layer dimensions of the sample on deformation and stresses of each layer was developed. It was found that the stress value is close to zero, on the boundary of each layer, for characteristic deflections of the considered bimetallic elements. The results of numerical analyses were compared with a theoretical solution presented by Timoshenko. Numerical analyses were performed using the Finite Element Method implemented in the commercial software LS-Dyna.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analysis and monitoring of electrical grounding grid encapsulated with concrete: case study using simulation in finite element method
Autorzy:
Pereira, T. M.
Lima, R.
Gomes, V. M.
Calixto, W. P.
Alves, A. J.
Tematy:
grounding systems
finite elements method
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Wydawca:
EEEIC International Barbara Leonowicz Szabłowska
Powiązania:
https://bibliotekanauki.pl/articles/136184.pdf  Link otwiera się w nowym oknie
Opis:
This work study the influence of concrete, plaster, clay and others buried structures in grounding systems. Comparison of soil characteristics between dry and rainy seasons on different grounding systems. The study includes comparison of six different grounding system on dry season and wet season. Simulations in finite element method was performed for tree layer stratified soil and the electrostatic equipotential surfaces were mapped into the region of interest.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical analysis of a shell with a main shaped charge warhead stroke into a bar armour with square section
Autorzy:
Niezgoda, T.
Panowicz, R.
Sybilski, K.
Barnat, W.
Tematy:
mechanics
finite elements method
bar armor
RPG
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Wydawca:
Instytut Techniczny Wojsk Lotniczych
Powiązania:
https://bibliotekanauki.pl/articles/247419.pdf  Link otwiera się w nowym oknie
Opis:
Recent operations of Polish troops within the framework of peacemaking missions' uncovered weak points of the equipment used there. It turned out that one of the most significant threats is a shell equipped with a main shaped charge warhead used by partisan detachments. These can break even 900mm of shell-proof steel so it is very difflcult to protect anything from the shells. One of the ways of protection from high explosive anti-tank (HEAT) warheads is using bar armours. This paper focuses on analysis of a shell with PG-7G main shaped charge warhead stroke into a bar armor with a square section. This work presents a short description of the analyzed object. Moreover, there is a principle of operation of a shell with the speciflcation of the most trouble elements from the point ofview of high velocity partial stream creation. In addition, the paper indicates steps of a numerical model construction together with geometry simplifications and initial-marginal conditions. On the basis of the results the researchers evaluated the extent of destruction of shell key elements. Furthermore, the work indicates drawings with deformed parts and presents stresses maps of these elements. The summary states to what extent PG-7G shell stroke into the armor made of bars with a square section influences reduction of operation efficacy of this type of firearm. Calculations were conducted in LS-Dyna system, which is used for oscillation analyses with a finite elements method. In order to solve the motion equation the researchers used an ordinary integration method used for i.e. analyses of highly non-linear oscillation phenomena.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Introduction to numerical analysis of directed fragmentation warheads
Autorzy:
Panowicz, R.
Nowak, J.
Konarzewski, M.
Niezgoda, T.
Tematy:
finite elements method
dynamic
directed fragmentation warheads
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Wydawca:
Instytut Techniczny Wojsk Lotniczych
Powiązania:
https://bibliotekanauki.pl/articles/243275.pdf  Link otwiera się w nowym oknie
Opis:
The aim of the paper is to presents one of the possible approaches to the numerical analysis of the behaviour of directed fragmentation war heads. These kinds of warheads consists of: metallic or composite cover, explosive material and a driven and fragmentation liner. The explosives are initiated by a booster causes driving the liner in a few milliseconds up to about 900 m/s. The liner fragments into many parts during this intensive and dynamic load. The fragments move in a cone which dimensions depend on the warheads shape and mechanical parameters of others warheads parts. All of the warheads elements are selected to meet the assumed parameters. The fragments velocity, their mass or geometric dimensions and cone angle are the most important parameters of the warheads fragments. Such a warhead, in the initial phase of the liner driving can be numerically modelled in the field of the continuum damage mechanics. Such a description is presented in other papers. This approach in a further phase of driving cause the increases of inaccuracies. Therefore, this paper proposes the use of ALE and FSI approach to describe the behaviour of the fragmentation warheads. A three-dimensional numerical model of the directed fragmentation warheads was made in the MSC Patran, and the dynamic phenomena analysis used a nonlinear finite element method implemented in the LS-Dyna program.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An analysis on the effect of crosscuts within shaft protective pillars on deformations of the surrounding rock mass deformations
Autorzy:
Warchala, Ewa
Szostak-Chrzanowski, Anna
Tematy:
finite elements method
stress
protective pillar
deformation
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Wydawca:
Politechnika Wrocławska. Wydział Geoinżynierii, Górnictwa i Geologii. Instytut Górnictwa
Powiązania:
https://bibliotekanauki.pl/articles/1402313.pdf  Link otwiera się w nowym oknie
Opis:
The development of crosscuts within mining shafts’ protective pillars causes a change of state of stress in the surrounding rock mass. It also causes deformations of the rock mass and the surface. It is essential to conduct prediction analysis of the deformations and stresses in order to secure a proper functioning of a shaft located within the protective pillar. It is recommended that the analysis should be based on the integration of the finite element method (FEM) and geodetic monitoring results. FEM makes it possible to determine the rock mass stresses and displacements in the shaft protective pillars and in the surrounding rock mass. It makes is possible to determine the safety and proper functioning of the shaft. The results of the FEM analysis of the impact of crosscuts and mining activities on rock mass deformations inside and on the surface of the protective shaft pillar are presented. The influence of mining extractions was investigated. The mining panels were located around the safety pillar in three regions NW, SE and SW and the crosscut were located within the safety pillar. The presented methodology will allow for the determination of the deformations and strains in case of farther development of crosscuts within the protective shaft pilar and by planned mining activities around the pillar.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analysis of the detonation initiation point position influence on the cylindrical fragmentation warhead effectiveness
Autorzy:
Panowicz, R.
Konarzewski, M.
Trypolin, M.
Tematy:
finite elements method
dynamics
directed fragmentation warheads
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Wydawca:
Instytut Techniczny Wojsk Lotniczych
Powiązania:
https://bibliotekanauki.pl/articles/243709.pdf  Link otwiera się w nowym oknie
Opis:
The article presents results of the numerical analyses of the fragmentation warhead, which is one of the key elements of the missile used to combat anti-tank missiles. The fragmentation warhead is composed of such elements as outer casing, inner casing, explosive material and fragmentation liner. The fragmentation liner is built from steel spheres or cylinders embedded in epoxy resin. As a result of the explosive material detonation the pressure wave is generated, which affects the liner, causes its fragmentation, and drives each splinter. In order to perform numerical analyses the model of the cylindrical fragmentation warhead with a diameter of 80 millimetres and a length of 100 mm was prepared. The fragmentation liner consists of steel spheres with a diameter of 5 mm. It was assumed in simulation that the detonating material is the plastic explosive C4. The influence of the position of the explosive charge detonation initiation point of the fragmentation warhead on its effectiveness was studied. Effectiveness was evaluated by measuring the maximum speed obtained by the fragments and their spatial distribution. A three-dimensional model of the studied system has been prepared using the MSC Patran software and the numerical analyses were performed using the finite element method with explicit scheme of the time integration implemented in the LS-Dyna solver. To model gas domain Arbitrary Lagrangian-Eulerian (ALE) method was used and interaction between gas and solid body was modelled with FSI coupling.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Evaluation of impact of the deflector shape on effectiveness of weakening the blast wave originating from a mine or IED
Autorzy:
Panowicz, R.
Nowak, J.
Konarzewski, M.
Tematy:
finite elements method
simulation
military vehicles
deflector
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Wydawca:
Instytut Techniczny Wojsk Lotniczych
Powiązania:
https://bibliotekanauki.pl/articles/244439.pdf  Link otwiera się w nowym oknie
Opis:
The situations which our forces faced during various stabilization military missions showed that light armored vehicles are not secure enough in the case of the mine or improvised explosive devices explosion. Nowadays, the primary way of protection against this type of threat is application of a V-shape bottom in the vehicle. Such a configuration of the bottom allows dissipation of explosion energy whereby the impulse, which is transmitted to the construction – the vehicle bottom or frame, has a much lower value than in the case where the bottom is flat. In the literature it is possible to find the results of model tests on an experimental laboratory test stand. These studies show that the value of the impulse which is transmitted to the structure depends on the shape of the deflector, actually on its angle. Assuming the above condition, there were performed numerical analyses of the values of the impulse transmitted to the construction for deflectors with different angles and for a variety of loads masses. The aim of the numerical analyses was to find the optimal angle of the deflector for the considered situation. In this model, the optimal value of the angle is that in which the considered value of the impulse transmitted to the construction reaches the minimum value. For this purpose, there was made a finite element model of deflector corresponding to the conditions of the experiment. The shell elements were used in this model. The model was loaded with a pressure impulse derived from the detonation of an explosive. The blast wave interaction with the structure was modeled using the fluid structure interaction. The numerical analyses were based on the finite element method with the explicit time integration method implemented in the LS-DYNA program.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Selected Methods of Obtaining Adequate Forms of Deformation of Supercritical Thin-Walled Flat Plates
Autorzy:
Kopecki, Tomasz
Tematy:
finite elements method
nonlinear analysis
advanced deformation
isogrid
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Wydawca:
Stowarzyszenie Inżynierów i Techników Mechaników Polskich
Powiązania:
https://bibliotekanauki.pl/articles/2024021.pdf  Link otwiera się w nowym oknie
Opis:
The study includes considerations on the numerical methods of obtaining the correct forms of deformation of thin-walled plates subjected to pure shear, operating under conditions of critical loads. Selected methods were presented and subjected to comparative tests, allowing for the obtaining of a state of large deformations of a perfectly flat system, loaded in its plane. These methods are based on application various forms of initial imperfections into the system, either geometrically or physically. A new solution was proposed in this area, differing in its essence from most commonly used solutions.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of destructor case type on behaviour of fragments in military vehicles active protection system
Autorzy:
Nowak, J.
Panowicz, R.
Konarzewski, M.
Tematy:
finite elements method
simulation
military vehicles
directed fragmentation warheads
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Wydawca:
Instytut Techniczny Wojsk Lotniczych
Powiązania:
https://bibliotekanauki.pl/articles/243721.pdf  Link otwiera się w nowym oknie
Opis:
Military vehicles active protection systems against cumulative missiles are designed to destroy the attacking missile before it hits the vehicle armour. The article presents the results of numerical studies of one of the elements of active protection system, which is the fragmentation destructor. A typical directed fragmentation warhead consists of a few parts: metallic or composite case, explosive material and fragmentation elements in the form of spheres, cylinders. The authors of this study evaluated the influence of the destructor case type – in particular material – on the effectiveness of the destructor. The effectiveness was evaluated on the basis of the maximum speed of balls. Evaluation was performed for the selected balls from each layer. Numerical calculations were performed for two materials of the case: steel and aluminum. It was assumed in simulation that the detonating material is the plastic explosive C4. The numerical analyses were based on the finite element method with the explicit time integration method implemented in the Ls-Dyna program. The interaction of solid and gaseous medium has been modelled using ALE coupling. Mechanical properties of the case were described using a simplified Johnson-Cook type material. The detonation process was described using programmed burn model approximations, and the behaviour of detonation products was described with the JWL (John, Wilkins, Lee) equation.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Adhesive bonded hot dip zinc coated sheet and titanium sheet joint strength - numerical analysis
Autorzy:
Rudawska, A.
Dębski, H.
Tematy:
adhesive joint
finite elements method (FEM)
adhesive joints strength
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Wydawca:
Instytut Techniczny Wojsk Lotniczych
Powiązania:
https://bibliotekanauki.pl/articles/248038.pdf  Link otwiera się w nowym oknie
Opis:
This paper describes a numerical analysis of adhesively bonded hot dip zinc coated sheet and titanium sheet and its comparison with the results of experimental tests. The study aims at presenting a comparative analysis of numerical calculation results with the results of strength test of the joints in question. Numerical simulations are an invaluable extension of experimental tests and, moreover, prove particularly useful at joint designing and analysis stages. The calculations were conducted with ABAQUS Standard software and allowed for the destructive force value obtained in experimental tests. Strength tests were conducted on single-lap adhesive joints for given structural materials; the samples were shear-loaded. The comparison of the results of experimental tests and numerical analysis led us to observe certain inconsistencies in the destructive force values, consequently providing information on the accuracy of a numerical model when compared with the actual model. Geometric model of the analysed single-lap adhesive joint, numerical model of the analysed single-lap adhesive joint, adhesive layer failure criterion description, visualisation of the analysed single-lap joint failure process, visualisation of adhesive joint failure stages of adhesive layer are presented.
Dostawca treści:
Biblioteka Nauki
Artykuł

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