Preferencje help
Widoczny [Schowaj] Abstrakt
Liczba wyników

Znaleziono wyników: 10

Liczba wyników na stronie
first rewind previous Strona / 1 next fast forward last
Wyniki wyszukiwania
Wyszukiwano:
w słowach kluczowych:  FE modelling
help Sortuj według:

help Ogranicz wyniki do:
first rewind previous Strona / 1 next fast forward last
EN
In the paper a fragment of research on development of modelling methods of asymmetrical multi-bolted flange connections is presented. The effect of the bolt modelling method in a single bolted joint on both the stiffness characteristics of elements joined in the multi-bolted flange connection and bold forces have been examined. An analysis of the multi-bolted flange connection is carried out for selected models created using the finite element method (FEM). Guidelines for the selection of the bolt modelling method in the case of both the stiffness analysis and the load analysis of multi-bolted flange connections have been pointed out.
PL
Przedstawiono modelowanie i obliczenia połączenia wielośrubowego charakteryzującego się niesymetrycznym rozmieszczeniem śrub. Zaprezentowano fragment badań dotyczących rozwoju metod modelowania tego typu połączeń. Zbadano wpływ sposobu modelowania pojedynczego złącza śrubowego na siły robocze w śrubach podczas zewnętrznego obciążenia połączenia wielośrubowego. Przedstawiono analizę obciążenia połączenia wielośrubowego na przykładzie wybranego modelu utworzonego w konwencji metody elementów skończonych (MES).
EN
The paper deals with modelling and calculations of a multi-bolted joint noted for irregular arrangement of bolts. A fraction of research work on development of the methods of modelling these type of joints is presented. The effect of the method selected to model a single bolted joint on actual forces in the bolts during external loading of the multi-bolted flanged joint is examined. Analysis of the load charged on multi-bolted flange joint for a selected model created by means of the finite element method (FEM) is performed.
EN
A theory of one-dimensional physical and mathematical modelling of the composite (steel-concrete) bridge/track structure/highspeed train system is developed including viscoelastic suspensions of rail-vehicles with two two-axle bogies each, non-linear Hertz contact stiffness and one-sided contact between wheel sets and rails, the viscoelastic and inertia features of the bridge, the viscoelastic track structure on and beyond the bridge, approach slabs, and random vertical track irregularities. Compared to the state-of-the-art, the physical model developed in the study accurately reproduces dynamic processes in the considered system. Division of the system into the natural subsystems, a method of formulation of the equations of motion partly in implicit form and the finite element method are applied. Vibrations in the vertical plane of symmetry are described by more than nine matrix equations of motion with constant coefficients. Couplings and non-linearity are hidden in the generalized load vectors. The equations of motion are integrated using the implicit Newmark average acceleration method with linear extrapolation of the interactions between the subsystems.
EN
A new series-of-types of single-span simply-supported railway composite (steel-concrete) bridges, with a symmetric platform, has been designed according to the Polish bridge standards. The designed bridges/viaducts are located on the main railways of the classification coefficient k = +2. A ballasted track structure adapted to high operating speeds has also been designed. The ultimate limit states and the limit states corresponding to the bridges undertaken are collected and discussed. The bridges have been designed in accordance with contemporary art engineering, with geometric and material optimization, avoiding overdesign. A new methodology of numerical modelling and simulation of dynamic processes in composite bridge/ballasted track structure/high speed train systems, developed in Part 2 and Part 3, has been applied and implemented in a problem-oriented computer programme. A new approach to predicting forced resonances in those systems is formulated and tested numerically. It has been proved that in the case of typical structural solutions of bridges and ballasted track structures, it is necessary to introduce certain limitations for operating speeds of trains.
EN
A review of various bulk metal forming processes that take into account influence of strain path changes on material flow is presented in this paper. Particular attention is put on computer aided design of innovative angular accumulative drawing (AAD) operation. Research in the area of development of metal forming processes taken advantage of strain path phenomena is conducted in many scientific laboratories as the strain patch change effect influences many crucial properties of the deformed material. As a result it provides a possibility of forming materials, which are e.g. difficult to form in a conventional manner. Advantages and limitations of the AAD process are summarized and presented in this work. Difficulties in development of the complex rheological model that takes in to account strain path changes in the deformed material are also presented and discussed.
EN
The article contains a literature review, experimental results, and a Finite Element Model (FEM) composition. Orthogonal turning tests were executed in the range of cutting speeds and feed rate, after every test chip was collected. Further investigation was done using FE model validation and experimentation, which uses results of the experimental zone in which the built-up edge did not form and the cutting itself is of even plastic deformation. The essence of this research is that the adequacy of the composed FE model to the real physical process should conform not only to the evaluation of cutting forces, but also to the evaluation of chip form, that is, segmentation frequency.
EN
Magnetorheological elastomers (MREs) are the materials with rheological properties which can be rapidly and reversibly changed in a continuous way by the applied magnetic field. They are the solid analogues of magnetorheological fluids (MRFs) consisting of magnetically permeable particles (such as iron) added to a viscoelastic polymeric material prior to crosslinking. In the paper different approaches to numerical modelling of the magnetorheological elastomers (MREs) structures are presented. The methods of the MRE micro- and macrostructural FE simulations are taken into consideration. The first approach is connected with the microstructural behaviour of the iron particles situated in the pure elastomer and subjected to the mechanical or magnetic load. The second approach is related to global material properties consideration and macrostructural behaviour modelling. The paper shows that there are many ways of such new materials structure behaviour modelling. All the FE analyses always need to be verified with the experiments as well as for macro- and micro scale material reactions, properties and phenomena describing.
EN
The possible options as materials for protective layers are aluminium foams which become also very popular due to their lightweight and excellent plastic energy absorbing properties. Such characteristics have been appreciated by the automotive industry with continued research to further understandfoam properties. Compressed foaming materials exhibit extensive plastic response, while the initial elastic region is limited in tension by a tensile brittle-failure stress. Aluminium foams have become an attractive material as blast protective layers due to their desirable compressive properties. With different material engineering techniques (as, for example double-layer foam cladding) they can be customized to achieve the most desirable properties. Energy absorption capacity of foams under blast load was analytically confirmed based on a rigid-perfectly plastic-locking foam model. Initial research indicates that energy absorbed by the cladding is much larger than that under quasi-static conditions due to shock wave effect. The methods of numerical modellingfor open and closed cell aluminium foams arepresented in the paper. The numerical models of foam ideal microstructures created with shell and together shell and beam finite elements are shown. The models were developed on the basis of Kelvin tetrakaidecahedrons - structures consisting of six sąuares and eight hexagons. In the case of open cell foams the circle wholes were removed from polyhedron surfaces. Then the numerical analysis o f a created models compressive test was carried out with the usage of MSC.Marc computer code. The nonlinear procedur es were applied. The results were analyzed in the scope of the assessing the behaviour of the open cell aluminium foam unit cell under the compressive load.
EN
Experiments have been described in which copper components have been subjected to combined cyclic thermal and constant mechanical loading. Two thermal cycles were employed leading to predominantly cyclic plasticity damage and balanced creep - cyclic plasticity damage loading cycles. The combined loading led to component ratchetting and ultimately to failure. Continuum damage-based finite element techniques have been developed for combined cyclic plasticity, creep and ratchetting in components subjected to thermo-mechanical loading. Cycle jumping techniques have been employed within the finite element formulation to minimise computer CPU times. The finite element methods have been used to predict the behaviour of the copper components tested experimentally and the results compared. Steady-state ratchet rates were found to be well predicted by the models. Modes of failure and component lifetimes were also found to be reasonably well predicted. The experimental results demonstrate the importance of isotropic cyclic hardening on the initial component ratchetting rates.
PL
W pracy przedstawiono doświadczenia, w których miedziane elementy poddawano złożonym obciążeniom zawierającym cykle termiczne i obciążenia stałe. Zastosowano dwa cykle termiczne prowadzące do uszkodzenia z przewagą cyklicznej plastyczności i zrównoważonego pełzania oraz cykle obciążeń wywołujących uszkodzenie typowe dla cyklicznej plastyczności. Obciążenia złożone wywoływały ratcheting badanych elementów, a w efekcie końcowym zniszczenie. Techniki metody elementów skończonych kontynualnej mechaniki uszkodzeń zostały rozwinięte dla cyklicznej plastyczności w złożonym stanie naprężenia, pełzania oraz ratchetingu w elementach poddawanych obciążeniom termo-mechanicznym. W sformułowaniu metody elementów skończonych, aby zminimalizować czasy centralnego procesora (CPU) komputera, zastosowano techniki skoków cyklicznych. Metody elementów skończonych zastosowano w przewidywaniu zachowania się elementów miedzianych wcześniej badanych doświadczalnie, a otrzymane wyniki porównano. Zaproponowane modele w sposób satysfakcjonujący pozwalają przewidywać prędkości stanu ustalonego ratchetingu. Także przewidywania dotyczące sposobów zniszczenia oraz żywotności badanych elementów są zadowalające. Wyniki doświadczalne pokazują istotny wpływ izotropowego wzmocnienia cyklicznego na początkowe składowe prędkości ratchetingu.
10
Content available remote Modelling of masonry wall buildings
EN
The aim of this work is to describe the response under lateral loading of a masonry building prototype analysed by means of FE linear and nonlinear modelling, comparing the theoretical results with experimental data. A technique for simulating crack development in masonry walls was employed and shear assessments of cross walls were finally carried out, comparing the stress-paths, evaluated in some elements, with the shear criterion of brickwork masonry.
PL
Celem niniejszej pracy jest opis reakcji prototypu budynku murowanego pod obciążeniem bocznym, analizowany przy pomocy modelowania liniowego i nieliniowego FE, porównujący wyniki teoretyczne z danymi eksperymentalnymi. Zastosowano technikę symulacji powstawania rysy w ścianie murowanej oraz przeprowadzono ocenę efektu ścinającego w ścianach poprzecznych, porównując linie naprężeń w niektórych elementach z kryterium ścinania w murowanej ścianie ceglanej.
first rewind previous Strona / 1 next fast forward last
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.