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1
EN
In this paper, the authors present studies leading to the evaluation of the elastic resistance of the steel part of a continuous shear connection named MCL dowel. The MCL dowel is now the most commonly used shape of continuous connector, chosen among many others for its combination of good fatigue, elastic, and ultimate resistances. A method for the calculation of stress in the steel dowel is described in the paper. It is based on mathematical derivations followed by FE analysis. It is assumed that the steel connector is stressed as a result of a global stress state at the dowel root (being a part of the entire beam) and of a local effects of longitudinal shearing between the steel and concrete parts. Results of the mathematical derivations are confirmed experimentally. Full-scale tests of beam elements were performed with measures of strain in many points of selected connectors. A comparison of strains derived from the proposed design methodology and measured during the experimental tests is shown and discussed. The results herein presented are fundamental research which were one of backgrounds for fatigue limit states of composite dowels for purposes of implementation of composite dowels to the second version of Eurocode 1994-2.
EN
Durability calculations of bearings take in account the distribution of forces on rollers. Calculation of these forces in flexibly supported rings is the aim of the paper. We use simplified finite element (FE) models of bearings, which are integrated into the external geometry. This approach can consider the stiffness of the surrounding structure as well as the clearance of the bearing rings, the misalignment of bearings, shaft deflections, and the forces of crowning rollers. The presented results show an influence of the initial radial interference of the outer ring with housing on the distribution of forces in bearing rollers. As the radial stiffness of the housing is close to the stiffness of the outer ring interference, this causes considerable deformation of the housing. The presented approach is also able to calculate the distribution of contact pressures over any rolling element.
EN
The article presents the research carried out on the experimental construction of a crane, where a hoist with an AC motor without a motor control system was used as an excitation signal for the girder. The purpose of the described research is to determine the relationship between the values of the dynamic surplus factor when lifting the load with the loose rope in the initial phase of lifting and the distance of the hoist from the supporting structure. The data was obtained based on the force tests in a steel wire rope and subsequent determination of the values of stresses and deflections accompanying the selected test cases for different positions of the vibration inductor using the FE method.
4
EN
Calculation of pullout capacity of anchoring concrete cylindrical block by finite element method is carried out. 3D model of the block assumes its free rotation. Alternative solutions with one and two pulling forces attached at different heights of the block are considered. Dependency of the ultimate pulling force on the points of its application, the block’s embedment depth as well as contact friction are investigated. Results of FE analysis and simple engineering estimations are compared. The maximum pullout resistance results from FE analysis when the rotation of the block is prevented.
PL
W pracy przedstawiono prototypową maszynę elektryczną z zagnieżdżonymi magnesami trwałymi oraz barierami magnetycznymi, dedykowaną do napędu pojazdu elektrycznego. W artykule zamieszczono wybrane wyniki badań symulacyjnych prototypu, otrzymane przy użyciu programu Ansys Maxwell, a także rezultaty badań eksperymentalnych przeprowadzone na modelu fizycznym. Zaprezentowane zostały poszczególne etapy prac projektowych i konstrukcyjnych opracowanej maszyny. Celem pracy było wykonanie i zbadanie prototypu maszyny elektrycznej z magnesami trwałymi dedykowanej do napędu pojazdu elektrycznego o wysokim stosunku indukcyjności w osi q do indukcyjności w osi d, niskiej wartości momentu zaczepowego i pulsacji. Na podstawie przeprowadzonych badań symulacyjnych różnych topologii, dokonano wyboru struktury wirnika o pożądanych parametrach magnetycznych. Model eksperymentalny zbudowano na bazie stojana i obudowy seryjnego silnika asynchronicznego M3AA 132 MC 8 o mocy 6,3 kW.
EN
The paper presents an electric machine prototype with embedded permanent magnets and magnetic barriers for electric vehicle drive. Selected experimental results compared with simulation results carried out by using Ansys Maxwell have also been presented. Individual stages of design and construction of the proposed machine have been reported. The aim of the work was to build and to test the prototype of electric machine with permanent magnet dedicated to the electric vehicle drive. The machine should have a high ratio of inductances in the q-axis to the d-axis, low values of cogging torque and low torque ripples. On the basis of simulation study, carried out for different topologies, the selection of the rotor structure with the favorite magnetic parameters has been done. A prototype machine was built based on the stator and housing from 6.3 kW induction motor M3AA 132 MC 8 series.
EN
Fracture behavior of two types of steel (1.4762 and 1.7147) is compared based on their numerically obtained J-integral values. The J-integral are chosen to quantify the crack driving force using the finite element (FE) stress analysis applied to single-edge notched bend (SENB) and compact tensile (CT) type fracture specimens. The resulting J-values are plotted for growing crack length (∆a – crack length extension) at different a/W ratios (a/W – relative crack length; 0.25, 0.5, 0.75). Slightly higher resulting values of the J-integral for 1.4762 than 1.7147 can be noticed. Also, higher a/W ratios correspond to lower J-integral values of the materials and vice versa. J-integral values obtained by using the FE model of the CT specimen give somewhat conservative results when compared with those obtained by the FE model of the SENB specimen.
EN
One of the methods to increase the load carrying capacity of the reinforced concrete (RC) structure is its strengthening by using carbon fiber (CFRP) strips. There are two methods of strengthening using CFRP strips - passive method and active method. In the passive method a strip is applied to the concrete surface without initial strains, unlike in the active method a strip is initially pretensioned before its application. In the case of a steel-concrete composite beam, strips may be used to strengthen the concrete slab located in the tension zone (in the parts of beams with negative bending moments). The finite element model has been developed and validated by experimental tests to evaluate the strengthening efficiency of the composite girder with pretensioned CFRP strips applied to concrete slab in its tension zone.
PL
Jednym ze sposobów zwiększenia nośności konstrukcji betonowej jest jej wzmocnienie przez zastosowanie taśm z włókien węglowych (CFRP). Wzmacnianie polega na mocowaniu lub doklejaniu ich do powierzchni konstrukcji. Stosuje się dwa sposoby mocowania taśm: tzw. sposób bierny lub czynny, czyli bez lub z wcześniejszym napięciem taśmy przed jej aplikacją na wzmacnianej konstrukcji. W przypadku stalowo-betonowych konstrukcji zespolonych taśmy mogą mieć zastosowanie do wzmacniania płyty betonowej w strefie działania momentów powodujących jej rozciąganie. Jednym ze sposobów znalezienia najbardziej skutecznego sposobu wzmocnienia przed jej zastosowaniem jest wykorzystanie symulacji numerycznych. Wymaga to opracowania poprawnego modelu obliczeniowego, który musi być zweryfikowany badaniami empirycznymi. Autorzy artykułu opracowali taki model numeryczny i zastosowali go do oceny skuteczności wzmocnienia omawianego typu dźwigara zespolonego taśmami CFRP wstępnie naprężonymi.
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.
EN
In the paper a chosen model of the light armoured vehicle was tested in terms of blast loading. More precisely, the blast propagation and interaction with the tire behaviour and suspension system elements of the light-armoured vehicle (LAV) was simulated. The chosen military vehicle meets the requirements of levels 2A and 2B of STANAG 4569 standard. Based on the obtained results, two modifications were proposed for the strength and resistance improvement of the wheel. The first consisted of inserting the rubber runflat ring inside the tire, whereas in the second the honeycomb-like composite wheel was implemented. Non-linear dynamic simulations were carried out using the explicit LS-Dyna code, with multi-material Arbitrary Lagrangian-Eulerian formulation for simulation the blast process.
10
Content available remote A child seat numerical model validation in the static and dynamic work conditions
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.
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.
EN
The object of the paper is to investigate the strenght of a separated subsystem of a wagon for transport of trucks semitrailers. The wagon designed in the Department of Mechanics and Applied Computer Science, Military University of Technology, allows easy and independent loading, transport and unloading without any special equipment or additional platform infrastructure. It is possible to utilize it for transport of various vehicles types such as tractors, cars, semitrailers, containers, heavy equipment. The tests presented in the paper concern a wagon separated construction element – a side lock. It is a key subsystem of the platform allowing transfer of its loads generated in the transport position (a wagon ready to go) to the form of longitudinal forces operating in the sides of the structure. The locks are simultaneously the most strained parts of the wagon. There were carried out the numerical analyses and experimental studies of a single lock were carried out. Owing to the application of Aramis non-contact optical system of strains measurement, the lock deformations as well as the areas of the minimum and maximum main deformations were defined.
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.
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.
PL
Wagon specjalny może być zastosowany do transportu kolejowego naczep i pojazdów. Konstrukcja taka może być użyta do transportu pojazdów o masie 36 ton i wysokości 4m z zachowaniem skrajni GB1. Niska platforma podwozia umożliwia szybki i wygodny załadunek i rozładunek pojazdów (bez urządzeń dźwigowych). Omówiono metodykę badań numerycznych, modele MES używane w testach, analizach weryfikacyjnych oraz w badaniach symulacyjnych wagonu. Otrzymane wyniki mogą być wykorzystane w pracach badawczo-rozwojowych w zakresie projektowania i modernizacji takich konstrukcji w aspekcie przedłużenia ich resursu.
EN
The special wagon can be used for railway transporting of semitrailers and vehicles. Such structure can be used for transporting high vehicles, up to 4m height and with weight up to 36 tons, on low gauges, such as GB1 gauge. A prototype model of a wagon with a low rotating floor for combined transport was designed at the Department of Mechanics and Applied Computer Science, Military University of Technology in Warsaw. The designed wagon allows easy and fast independent loading and then, transportation and independent unloading of semitrailers of truck type vehicles without investing in development of spare infrastructure, such as a platform. The construction may be also utilized for transport of various types of vehicles, such as tractors, trucks, trailers, containers, heavy equipment. The paper presents constructional modifications which were carried out in respect to the original model of the construction. The numerical investigation methodology and various FE models used in tests, verification and simulation studies of the wagon with the low rotatable platform and the obtained results can be used in development work in the area of special wagon design and modernization in the aspect of the service live extension.
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.
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.
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.
19
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.
20
Content available remote Static Characteristics of a Novel Low Cost Brushless DC Permanent Magnet Motor
EN
The paper presents the design attributes and static characteristics of a new 6/4 topology of a low cost brushless DC permanent magnet (BLDCPM) motor. To analyse the motor performance, steady state characteristics are obtained by using quasi-static finite element analysis (FEA). Computational results are presented in figures and tables. The analysis of the motor characteristics will be used as a reliable tool for design optimisation of this novel low cost BLDCPM motor.
PL
W artykule przedstawiono projekt nowego silnika bezszczotkowego DC z magnesami trwałymi w topologii 6/4. Do analizy właściwości silnika wykorzystano quasi-static metodę element skończonego.
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