Wyniki wyszukiwania - Biblioteka Nauki

1

Modeling of the stress-deformed state and cracking inreinforced concrete structures using ANSYS Mechanical

100%

Dorofeev V. S. , Karpyuk V. M. , Neutov O. S. , Neutov S. F.

Technical Sciences / University of Warmia and Mazury in Olsztyn

|

2014

|

tom nr 17(2)

105--121

EN

The article presents the results of reinforced concrete beams modeling under short-term loading with the use of the ANSYS Mechanical software. The obtained parameters were compared with the experimental ones. The comparison showed a satisfactory concordance of the parameters. In case of the discrepancies, the authors suggest that they are due to the idealization of material properties and structural model of the finite method. The paper is divided into the following chapters: Introduction, Literature Review, Research Significance, Element Types, Real Constants, Material Properties Modeling, Geometric Modeling, Loads and Boundary Conditions, Cracking and Failure and Conclusions. Each of the five conclusions in the last chapter offers a summary of the presented experimental research.

2

Simulation of ballistic impact on polymer matrix composite panels

100%

Long D.

Journal of Theoretical and Applied Mechanics

|

2015

|

tom Vol. 53 nr 2

263--272

EN

Composite panels, for example fuselage skins or wing skins of military aircraft, may be subjected to a variety of ballistic impacts. It is meaningful to understand the mechanical response, damage evolution and residual velocity of a projectile for panels under ballistic impact. In this paper, the numerical simulation method of ballistic impact on a laminated composite panel is considered. A rate-dependent material model based on the continuum damage mechanics concept is developed for polymer matrix composite materials. A full three-dimensional finite element model implemented with the material model is built up using material subroutine. The ballistic impact behavior is simulated employing an explicit dynamic finite element analysis technique. The effects of projectile size and velocity, layup of the composite panel, and failure criteria used on the ballistic impact response are investigated.

3

Recent and future developments in finite element metal forming simulation

100%

Andrietti S. , Chenot J. L. , Bernacki M. , Bouchard P. O. , Fourment L. , Hachem M. , Perchat E.

Computer Methods in Materials Science

|

2015

|

tom Vol. 15, No.2

265--293

EN

After more than 40 years of development, finite element metal forming simulation has reached a high level of maturity. After a short mechanical and thermal introduction, the main scientific and technical developments are briefly described. We consider numerical issues, such as adaptive remeshing or parallel computing; coupling phenomena for a more realistic simulation, such as thermal and metallurgical coupling, with a special emphasis on modeling of microstructure evolution; the use of optimization for forming processes or for parameters identification. Finally the main potential future research fields for the next 10 years are outlined: process stability and stochastic approaches, more effective massively parallel computing and extension of the application to generate the whole “virtual factory”.

PL

Po ponad 40 latach rozwoju metoda elementów skończonych (MES) osiągnęła wysoki poziom doskonałości. W artykule przedstawiono krótki wstęp do rozwiązywania tą metodą zadań mechanicznych i cieplnych, a następnie opisano główne naukowe i techniczne aspekty rozwoju MES. Rozważono problemy numeryczne, takie jak adaptacyjna przebudowa siatki (adaptive remeshing), rozwiązywanie zadań sprzężonych, takich jak sprzężenie cieplno-mechaniczne, dla otrzymania bardziej realistycznych symulacji. Duży nacisk położono też na modelowanie rozwoju mikrostruktury, zastosowanie metod optymalizacji procesów kształtowania metali oraz na identyfikację parametrów modeli. W końcowej części artykułu omówiono główne potencjalne kierunki badań przewidywanych na najbliższe 10 lat, obejmujących stabilizację rozwiązania, uwzględnienie aspektów stochastyczne oraz bardziej efektywne obliczenia rozproszone. Podsumowaniem jest propozycja rozszerzenia zastosowań MES i stworzenie „wirtualnej fabryki".

4

Passive vibration damping in a truss telecommunication tower

88%

Pelc J. , Kolator B.

Technical Sciences / University of Warmia and Mazury in Olsztyn

|

2014

|

tom nr 17(3)

249--258

EN

A dynamic model of a truss telecommunication tower was developed. A viscoelastic absorber was proposed for reducing structural vibrations caused by wind. Small linear system vibrations were assumed. A finite element three-dimensional model was used to determine the damper viscoelastic parameters which guarantee the highest damping effectiveness. Simulation results indicate that a damper can reduce the amplitude of tower vibrations by half and produce a similar reduction in forces acting upon the most loaded members of the structure.

5

Inflation simulation of tractor radial tire

88%

Pelc J.

Technical Sciences / University of Warmia and Mazury in Olsztyn

|

2016

|

tom nr 19(1)

83--92

EN

The possibility of prediction of some parameters of large-size pneumatic tire was presented. Author’s computer program based on the finite element method with the use of axisymmetric tire model was utilized. Material constants required for the tire analysis were determined experimentally. The procedure for obtaining a simplified axisymmetric tire tread was described. The method used for simulation of tire inflation process allows obtaining the shape of an inflated tire, forces in cords and elastic energy density distribution. A test tire overall dimensions obtained in this way are close to measured values.

6

Modelling the effect of phase transformations on cooling rate during quenching in nuclear forgings using effective heat capacity

88%

Howson M. P. , Wynne B. P. , Davies P. S. , Talamantes-Silva J.

Computer Methods in Materials Science

|

2017

|

tom Vol. 17, No. 3

137--144

EN

A modelling methodology based on experimental heat capacity measurements has been used to predict the effects of latent heat formation on cooling rates in a thick sectioned nuclear forging during quenching. Differential scanning calorimetry was used to measure specific heat capacity as a function of temperature (100 - 1000°C) and cooling rate (5 - 70°C/min) that also incorporates the heat energy release during transformations, which is termed the effective specific heat. A user defined routine then incorporated this data into a finite element model of a full scale heat treatment trial forging that had section thicknesses of 200 and 330mm approximately. Excellent agreement with thermocouple data, taken from key test locations, was obtained, particularly at 0.25 and 0.5 thickness. However, some deviations from thermocouple data were seen that has been attributed to the model assumptions, particularly the method used to represent boundary conditions.

PL

Metodologię modelowania z wykorzystaniem efektywnej pojemności cieplnej wykorzystano do przewidywania wpływu ciepli przemiany na prędkość chłodzenia w masywnych częściach hartowanej odkuwki dla przemysłu jądrowego. Różnicowa kalorymetria tria skaningowa została zastosowana do pomiaru ciepła właściwe go w funkcji temperatury (100 - 1000°C) i prędkości chłodzeni; (5 and 70°C/min) z uwzględnieniem ciepła uwalnianego w czasie przemiany. Wyznaczone w taki sposób ciepło właściwe nazywane jest efektywnym. Uzyskane dane zaimplementowano poprze procedurę użytkownika do programu metody elementów skończonych modelującego w pełnej skali obróbkę cieplną odkuwki posiadającej masywne części z przekrojem poprzecznym o grubości 200.5 i 331 mm. Uzyskano bardzo dobrą zgodność wyników z modelu i pomiaru za pomocą termopar umieszczonych w punktach testowych, w szczególności dla 0.25 i 0.5 grubości. Za przyczynę zaobserwowanych pewnych odchyłek wyników obliczeń od pomiarów uznano przyjęte założenia modelu, w szczególności metodę opisu warunków brzegowych.

7

New Methods for Modeling Laterolog Resistivity Corrections

88%

Jarzyna J. A. , Cichy A. , Drahos D. , Galsa A. , Bała M. J. , Ossowski A.

Acta Geophysica

|

2016

|

tom Vol. 64, no. 2

417--442

EN

The paper presents methods for laterolog response modeling. In Coulomb’s charges method, Laplace’s equation is solved for the electric field distribution in rock medium with internal boundaries between different resistivity layers. There, the boundary problem is reduced to Fredholm integral equation of the second kind. The second method uses a finite element array to model apparent resistivity from laterolog. The task is treated as DC problem and the Laplace equation is solved numerically. The presented methods were applied to borehole data covering a typical stratigraphic section of the Fore-Sudetic Monocline in southwestern Poland. Apparent resistivity was calculated using the Coulomb’s charges method and alternatively modeled using a finite element method which gave similar results. Then, a series of linear corrections for borehole, shoulder bed, and filtration effects for apparent resistivity obtained by the Coulomb’s charges method demonstrated the feasibility of calculating true resistivity of virgin and invaded zones. The proposed methods provide a flexible solution in modeling which can be adapted to other logs.

8

Flexural behavior of precast concrete-filled steel tubes connected with high-performance concrete joints

88%

Abadel A. A. , Baktheer A. , Emara M. , Ghallah M. , Hamoda A.

|

2024

|

tom Vol. 42, No. 3

72--85

EN

Precast concrete-filled steel tube (CFST) columns with connection joints are widely used in building structures, yet research on their flexural behavior when connected with various high-performance concrete (HPC) types is limited. This study presents experimental investigations on precast circular CFST columns subjected to flexural loading until failure. These CFST columns, encased in galvanized steel sheets (GSSs), are connected using HPC joints. Two types of HPC joints were tested: an engineered cementitious composite (ECC) and an ultra-high fiber reinforced concrete (UHFRC). Additionally, the study was conducted varying the development length of the reinforcement/concrete filler joint to 150, 200, and 300 mm. Results indicated that increasing the development length of the reinforcement and the connecting concrete joint enhances both the cracking resistance and load-bearing capacity of slender precast CFST columns with an intermediate joint. Moreover, the combination of GSSs with ECC and UHFRC connections enhances the load-bearing capacity, demonstrating performance comparable to that of a typical precast normal concrete control column without an intermediate connection. The experimental results revealed that ECC and UHFRC connections increased the performance by 11 and 17%, respectively, compared to the control column. Additionally, doubling the development length of the ECC joint improved the cracking force, ultimate force, elastic stiffness, and energy absorption by 20, 15, 133, and 64%, respectively, while UHFRC connections showed improvements of 10, 10, 82, and 94%, respectively.

9

Simulation analysis for optimal design of pneumatic bellow actuators for soft-robotic glove

75%

Guo N. , Sun Z. , Wang X. , Yeung E. H. K. , To M. K. T. , Li X. , Hu Y.

Biocybernetics and Biomedical Engineering

|

2020

|

tom Vol. 40, no. 4

1359--1368

EN

Soft actuators that have a bellows structure are favorable candidates for robots designed to interact with humans. However, a weak point in the actuator can occur as a result of deformation from the driving pressure. In this study, a simulation analysis of a soft bellows actuator composed of ethylene-vinyl acetate copolymer molding was conducted. The mechanical characteristics along different latitudes of the bellows in the soft actuator were evaluated using finite element modeling and analysis. Functional performance was studied during both compression and inflation using two driving methods (constant pumping rate-driven and constant displacement-driven). To validate the simulation, experimental tests were performed on a version of the soft bellows actuator that was constructed according to the same specifications as the model version; simulation and experimental displacements in relation to air pressure were compared. The results showed points near the trough were more likely to experience the largest stress during inflation and may suffer critical structural damage. During compression, points near the crest were more easily damaged. Stress variation showed good symmetry at points of interest on either side of the trough, during both inflation and compression. These findings provide a basis for precise control of and design improvements to soft bellows actuators for human-friendly usage.

10

Stress response of patellofemoral joint subjected to femoral retroversion with various patellar kinematics and flexions – An FEA study

75%

Louis M. J. , Malayalamurthi R.

Biocybernetics and Biomedical Engineering

|

2017

|

tom Vol. 37, no. 2

316--325

EN

The purpose of this study is to observe the stress response of the patellofemoral joint associated with three patellar kinematics: shift, spin and tilt under femoral retroversion conditions. By assigning various flexions and different loads, the stresses were quantified in the bones, tendons, cartilages and cartilage–bone interface. Four different loads of 600, 657, 706 and 753 N were applied on 12 models representing each of the various kinematics of shifts, spins and tilts of the patella with femoral flexions of 30º, 60º, 90º and 120º which gave results for 48 analyses. The 'Q' angle of the femur bone was maintained at 14º with femoral retroversion of 21º. Based on the patellar kinematics, three different cases were modeled as (a) 5 mm shift 10º spin 4º tilt, (b) 10 mm shift 13º spin 8º tilt, and (c) 15 mm shift 16º spin 12º tilt. Medial shift, spin and tilt with femoral retroversion were limited in this study. The femoral displacement for 30º flexion at 600 N was found to be same in all the (a), (b), and (c) cases. Similarly, respective same displacements were achieved in all three cases when subjected to 60º flex at 657 N, 90º flex at 706 N and 120º flex at 753 N. From the simulated results it is inferred that femoral retroversion with case (b) kinematics susceptibly dominated by the cartilages causes patellofemoral joint pain, arthritis and instability due to the larger contact areas between the patella and femur bone at flexions 60º and 90º.

11

Interaction of the Kinetic Energy Penetrators and Steel and Composite Armours

75%

Burian W. , Magier M. , Żochowski P.

Machine Dynamics Research

|

2018

|

tom Vol. 42, No. 2

81--91

EN

The article presents numerical simulations of APFSDS projectile impact on thick, semi-inﬁnite, oblique steel armours. The aim of the study was to analyse the defeat mechanisms provided by different types of armours against segmented kinetic projectiles. Additionally, the penetration capability of the projectile made of heavy tungsten alloy was evaluated by numerical simulations. The outcomes of the simulations were compared to the experimental observations in order to validate the numerical model. Then, the veriﬁed model was used in the analysis of the protection capability of different types of armours containing layers made of RHA steel, alumina ceramics and rubber. In this way, the most effective variant of the tank armour was chosen.

12

Finite Element analysis for Edge-to-Edge Technique to Treat Post-Mitral Valve Repair Systolic Anterior Motion

75%

Zhong Q. , Zeng W. , Huang X. , Zhao X.

Acta of Bioengineering and Biomechanics

|

2014

|

tom Vol. 16, no. 4

3--12

EN

Systolic anterior motion of the mitral valve is an uncommon complication of mitral valve repair, which requires immediate supplementary surgical action. Edge-to-edge suture is considered as an effective technique to treat post-mitral valve repair systolic anterior motion by clinical researches. However, the fundamentals and quantitative analysis are vacant to validate the effectiveness of the additional edge-to-edge surgery to repair systolic anterior motion. In the present work, finite element models were developed to simulate a specific clinical surgery for patients with posterior leaflet prolapse, so as to analyze the edge-to-edge technique quantificationally. The simulated surgery procedure concluded several actions such as quadrangular resection, mitral annuloplasty and edge-to-edge suture. And the simulated results were compared with echocardiography and measurement data of the patients under the mitral valve surgery, which shows good agreement. The leaflets model with additional edge-to-edge suture has a shorter mismatch length than that of the model merely under quadrangular resection and mitral annuloplasty actions at systole, which assures a better coaptation status. The stress on the leaflets after edge-to-edge suture is lessened as well.

13

The effects of friction on the performance of a concrete block mine seal with pressurized grout bags

63%

Perry K. A.

Archives of Mining Sciences

|

2014

|

tom Vol. 59, no. 3

793--805

EN

Mine seals are necessary in nearly every underground coal mine to isolate mined-out areas from the ventilation network. Many seals are already in place in active mines and more need to be constructed to keep up with the development of underground coal reserves. The accidents involving seal failures at Sago and Darby prompted MSHA to create and implement new regulations regarding the strength of the seals. These regulations require the design and construction of seals that are larger and stronger than ever before. Structural seals capable of withstanding the new required design loads are now designed by an engineer and no longer approved through explosion testing. Prior to the seal failure accidents, a solid-block wall with pressurized grout bags at the wall/ribs and wall/roof interfaces was a popular design which met the 137.9 kPa (20 psi) requirement. After implementation of the new 344.7 kPa (50 psi) or 827.4 kPa (120 psi) design regulations depending on whether the atmosphere is kept inert in by the seal, a re-design of the seal was necessary. This paper discusses the quantification of the coefficients of friction which are then implemented into finite element modeling.

PL

Tamy uszczelniające niezbędne są prawie w każdej kopalni podziemnej do oddzielenia obszarów wybranych od sieci wentylacyjnej. W kopalniach aktywnych znajdują się już liczne tamy a coraz większa ich ilość zostanie zbudowana w miarę udostępniania kolejnych złóż węgla. Wypadki spowodowane przez awarie tamy w kopalni Sago i Darby stanowiły bodziec dla urzędu górniczego MSHA do stworzenia i wdrożenia nowych regulacji odnośnie wytrzymałości tam. Przepisy te wymagają projektowania i budowania tam większych i bardziej wytrzymałych niż kiedykolwiek w przeszłości. Tamy strukturalne zdolne do przenoszenia na nowo określanych obciążeń obliczeniowych muszą być obecnie projektowane przez inżynierów a procedura ich odbioru nie obejmuje badań w warunkach wybuchu. Przed wypadkami spowodowanymi przez awarie tam, popularnym rozwiązaniem były ściany z jednolitych bloków ze sprasowanymi workami zaprawy umieszczanymi na styku pomiędzy ścianą, żebrami oraz stropem. Rozwiązanie to było szeroko stosowane i zapewniało spełnianie kryterium przenoszenia obciążeń na poziomie 137.9 kPa (20 psi). Po wdrożeniu nowych wymogów określających obciążenia obliczeniowe: 344.7 kPa (50 psi) lub 827.4 (120 psi) w zależności od tego, czy atmosfera w rejonie zamkniętym tamą uszczelniająca ma pozostawać obojętna czy też nie, niezbędne okazało się przeprojektowanie tamy. W pracy tej zbadano w ujęciu ilościowym współczynniki tarcia, a wyniki badania zaimplementowano z wykorzystaniem metody elementów skończonych.

14

New approach of friction AlN ceramics metallization with the initial FEM verification

63%

Cacko R. , Chmielewski T. , Hudycz M. , Golański D.

Archives of Civil and Mechanical Engineering

|

2020

|

tom Vol. 20, no. 3

385--395

EN

Although, the friction method is well known for metals surface modification, the novelty of the article is based on the new idea of ceramics surface treatment with metal. The paper describes AlN ceramic metallization process by titanium coating deposition, obtained in friction surfacing method, which has been developed by the authors. The friction energy is directly transformed into heat and delivered in a specified amount precisely to the joint being formed between the metallic layer and the ceramics substrate material. The stress and temperature fields (as factors promoting the formation of diffusion joints) induced in the joint during the metallization process were qualitatively determined with the finite element method analysis and these results were verified experimentally. Finally, obtained structures of the metallic coatings were investigated and the results are discussed in the paper. As a novelty it was found, that the conditions of frictional metallization can favour the formation of a coating-substrate bond based on diffusion phenomena and atomic bonds of the coating components with the components of the substrate, despite the fact that it happens for metal–ceramics pairs. This type of connection is usually associated with long-term heating/annealing in chamber furnaces, because for diffusion in a solid state the most effective factor is time and temperature. It was shown that other components of the chemical potential gradient, such as temperature gradient, gradient and stress level, load periodicity and configuration of pairs of elements with high chemical affinity may play an important role in friction metallization. As a result, the relatively short time of operation (friction) is compensated.

15

The interaction of laser radiation with tissue in the aspect of generating the process of decellularization in the preparation of animal origin autologous tissue

63%

Kopernik M. , Major R. , Lis G. , Wilczek P. , Lis M. , Imbir G. , Chrouda A. , Mzyk A. , Ostrowski R. , Sanak M.

Acta of Bioengineering and Biomechanics

|

2020

|

tom Vol. 22, no. 1

67--77

EN

Purpose: The aim of the work was to create an appropriate substrate for organ transplantation using bioactive tissue-based scaffold populated by cells of the graft recipient. The purpose of the modeling was to investigate the mechanical effects of wave loading of aortic and pulmonary tissue material. Methods: The biological properties of tissues of aortic and pulmonary valves were modified by the process of decellularization. The host cells were removed by various physical methods with focus on minimal degradation of the extracellular matrix. Thus, the decellularization process was controlled by histological methods. The tissue decellularization process was simulated by finite element modelling. Results: The mechanical results represented by a displacement at the center of the sample were coherent and the heterogeneity of the distribution of the caves on the surface of the samples was confirmed, both by experiment and in the simulation by the alternate occurrence of local minima and maxima. The latter results from the uneven removal of cells from the effect of the wave causing decellularization were also predicted by the numerical model. Laser radiation had a destructive effect on the components of the extracellular matrix (e.g., collagen and elastic fibers), mainly depending on the fluence and number of pulses in a single exposure. Conclusions: The differences between the valve tissue materials were shown, and the impact of the process of decellularization on the properties of the tissues was analyzed. It should be emphasized that due to low absorption and high scattering, laser radiation can deeply penetrate the tissue, which allows for effective decellularization process in the entire volume of irradiated tissue.

16

Finite Element Modeling of Self-Compacting Concrete Beams Under Shear

63%

Hosseinimehrab l. , Sadeghi A. , Noroozinejad Farsangi E.

Civil and Environmental Engineering Reports

|

2021

|

tom Vol. 31, no. 4

1--16

EN

Development of self-compacting concrete (SCC) is a very desirable achievement in the reinforced concrete (RC) structures for overcoming issues associated with many problems such as congestions of steel reinforcement. This non-vibrating concrete is not affected by the skill of workers, and the shape and amount of reinforcing bar arrangement of a structure. Due to the high fluidity and resisting power of reinforcing of SCC, it can be pumped longer distances. In this study, the finite element (FE) modeling of three SCC beams in shear while taking into account, the flexural tensile strength of concrete is computed and the results are compared with the available experimental tested reinforced SCC beams. The stirrups are located at 75 mm apart from the end of beams up to the loading point. The electrical strain gauges (ESGs) have been embedded on the stirrups and their strain readings are taken for every step of load increment. For modeling longitudinal steel reinforcing bars and concrete, the 3-D elements with 2-node and 8-node, are used respectively. The comparison of results obtained by two methods is indicated that a good satisfactory agreement is achieved.

17

A crystal plasticity finite element-based approach to model the constitutive behavior of multi-phase steels

63%

Liu H. , Shin Y. C.

Archives of Civil and Mechanical Engineering

|

2021

|

tom Vol. 21, no. 2

707--720

EN

Steels are the most commonly used multi-phase materials in the industry, and their mechanical behaviors depend on the microstructure, composition, and phase fractions. Generally, the material behaviors need to be measured by experiments like a tensile test or split Hopkinson bar test, which is very time-consuming and expensive. Once the heat treatment and phase fractions are changed, it needs to be tested again, and, to avoid this, a better method is required to obtain the material behavior quickly and easily. In this study, a novel multi-scale approach is described to predict the material behaviors of multi-phase steels based on the phase fractions. A crystal plasticity finite element method is used to obtain the material behavior of each phase at a micro-scale with elevated strain rates, which is validated with experimental data or theoretical models at static or quasi-static conditions. Then a homogenization procedure with the rule of mixture method, which is based on the phase fractions measured from the microstructure characterization, is used to get the macro-scale constitutive behavior, and it is then implemented into the commercial software Abaqus/Standard to simulate the process of tensile test and compared with the experimental data. Good agreements are obtained between simulation and experimental results.

18

Thermo-mechanical model of a TIG welding process for the aircraft industry

63%

Hojny M.

Archives of Metallurgy and Materials

|

2013

|

tom Vol. 58, iss. 4

1125--1130

EN

TIG welding is the most important process, which is used in the aircraft industry. A number of components of airplane are made using this method. Thermo-mechanical models are needed to understand better phenomena involved in this process. In the presented work thermo-mechanical simulations were performed and the possibilities of welding distortion in the investigated process were evaluated. Comparison of the results of numerical simulation with the experimental data confirmed good predictive capabilities of the model and quite good description of the phenomena involved in this process.

PL

Spawanie metodą TIG jest jedną z ważniejszych metod używanych w przemyśle lotniczym. Wiele komponentów samolotu powstaje dzięki tej metodzie. Model termo-mechaniczny wspomnianego procesu jest konieczny do dokładnej analizy zjawisk powstających podczas procesu. W prezentowanej pracy opracowano model termo-mechaniczny w kontekście analizy deformacji spawanych elementów. Porównanie otrzymanych wyników na drodze symulacji z wynikami eksperymentalnymi wykazało poprawne odwzorowanie zjawisk zachodzących podczas procesu spawania.

19

Dynamic crushing behavior of closed-cell aluminum foams based on different space-filling unit cells

63%

Talebi S. , Hedayati R. , Sadighi M.

Archives of Civil and Mechanical Engineering

|

2021

|

tom Vol. 21, no. 3

231--245

EN

Closed-cell metal foams are cellular solids that show unique properties such as high strength to weight ratio, high energy absorption capacity, and low thermal conductivity. Due to being computation and cost effective, modeling the behavior of closed-cell foams using regular unit cells has attracted a lot of attention in this regard. Recent developments in additive manufacturing techniques which have made the production of rationally designed porous structures feasible has also contributed to recent increasing interest in studying the mechanical behavior of regular lattice structures. In this study, five different topologies namely Kelvin, Weaire–Phelan, rhombicuboctahedron, octahedral, and truncated cube are considered for constructing lattice structures. The effects of foam density and impact velocity on the stress–strain curves, first peak stress, and energy absorption capacity are investigated. The results showed that unit cell topology has a very significant effect on the stiffness, first peak stress, failure mode, and energy absorption capacity. Among all the unit cell types, the Kelvin unit cell demonstrated the most similar behavior to experimental test results. The Weaire–Phelan unit cell, while showing promising results in low and medium densities, demonstrated unstable behavior at high impact velocity. The lattice structures with high fractions of vertical walls (truncated cube and rhombicuboctahedron) showed higher stiffness and first peak stress values as compared to lattice structures with high ratio of oblique walls (Weaire–Phelan and Kelvin). However, as for the energy absorption capacity, other factors were important. The lattice structures with high cell wall surface area had higher energy absorption capacities as compared to lattice structures with low surface area. The results of this study are not only beneficial in determining the proper unit cell type in numerical modeling of dynamic behavior of closed-cell foams, but they are also advantageous in studying the dynamic behavior of additively manufactured lattice structures with different topologies.

20

Modelowanie MES i numeryczna optymalizacja systemu podparcia układu soczewek magnetycznych

63%

Szybiński B.

Zeszyty Naukowe. Transport / Politechnika Śląska

|

2014

|

tom z. 82

261--270

PL

W pracy zaproponowano ramowy układ do mocowania zestawu czterech soczewek magnetycznych zaprojektowanych dla ogólnoeuropejskiego projektu High Intensity Neutrino Oscillation EURONu Project [1]. Następnie konstrukcja została przeanalizowana numerycznie za pomocą MES i przeprowadzono optymalizację wybranych parametrów geometrycznych ramy. Po raz pierwszy w proponowanym rozwiązaniu technicznym przeznaczonym do eksperymentalnego badania problemu oscylacji neutrin zastosowano układ współpracujących czterech soczewek magnetycznych. Są one przeznaczone do skupienia wiązki cząstek elementarnych – pionów i kaonów – będących produktem uderzenia rozpędzonej wiązki protonów w grafitowy cel. Każda z soczewek jest złożoną powłoką obrotowo-symetryczną, obciążoną złożonym, zmiennym układem sił magnetycznych, termicznych oraz ciężarem własnym. Zaproponowany w pracy system mocowania soczewek spełnia wymagania montażowe, zapewnia dostateczną sztywność, a częstość drgań własnych dostatecznie różni się od częstości zewnętrznych impulsów obciążenia.

EN

In the paper the supporting frame for four horns design for the High Intensity Neutrino Project EURONu [1] is proposed and numerically investigated. The whole set is designed for the experimental investigations of the neutrino oscillations. In the proposed design the system of four horns in one assembly is introduced. These magnetic horns serve for focusing of elementary particles – pions and kaons, which are the products of the interaction of the accelerated protons with the graphite target inserted into the horn. Each horn has the form of a complex shell, which is subjected to the complex system of loadings, like magnetic, thermal and the own weight. The proposed system of supports fulfills the assembly conditions, provides the reasonable stiffness and exhibits the natural frequencies distant enough from the excitation frequency.