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1

Probabilistic finite element analysis of failures in concrete dams with large asperities in the rock-concrete interface

Ulfberg Adrian, Gonzalez-Libreros Jaime, Das Oisik, Bista Dipen, Westberg Wilde Marie, Johansson Fredrik, Sas Gabriel

Archives of Civil and Mechanical Engineering

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2023

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Vol. 23, no. 2

art. no. e109, 2023

EN

Common analytical assessment methods for concrete dams are unlikely to predict material fracture in the dam body because of the assumption of rigid body behavior and uniform- or linear stress distribution along a predetermined failure surface. Hence, probabilistic non-linear finite element analysis, calibrated from scale model tests, was implemented in this study to investigate the impact of concrete material parameters (modulus of elasticity, tensile strength, compressive strength, fracture energy) on the ultimate capacity of scaled model dams. The investigated dam section has two types of large asperities, located near the downstream and/or upstream end of the rock-concrete interface. These large-scale asperities significantly increased the interface roughness. Post-processing of the numerical simulations showed interlocking between the buttress and the downstream asperity leading to fracture of the buttress with the capacity being determined mainly by the tensile strength of the buttress material. The capacity of a model with an asperity near the upstream side, with lower inclination, was less dependent on the material parameters of the buttress as failure occurred by sliding along the interface, even with inferior material parameters. Results of this study show that material parameters of the concrete in a dam body can govern the load capacity of the dam granted that significant geometrical variations in the rock-concrete interface exists. The material parameters of the dam body and their impact on the capacity with respect to the failure mechanism that developed for some of the studied models are not commonly considered to be decisive for the load capacity. Also, no analytical assessment method for this type of failure exists. This implies that common assessment methods may misjudge the capacity and important parameters for certain failure types that may develop in dams.

2

Finite Element Modeling of Self-Compacting Concrete Beams Under Shear

Hosseinimehrab lham, Sadeghi Abbasali, Noroozinejad Farsangi Ehsan

Civil and Environmental Engineering Reports

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2021

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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.

3

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

Talebi S., Hedayati R., Sadighi M.

Archives of Civil and Mechanical Engineering

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2021

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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.

4

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

Liu Hongguang, Shin Yung C.

Archives of Civil and Mechanical Engineering

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2021

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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.

5

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

Guo Ning, Sun Zhidao, Wang Xiaojun, Yeung Eric Hiu Kwong, To Michael Kai Tsun, Li Xiaodong, Hu Yong

Biocybernetics and Biomedical Engineering

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2020

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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.

6

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

Cacko Robert, Chmielewski Tomasz, Hudycz Michał, Golański Dariusz

Archives of Civil and Mechanical Engineering

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2020

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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.

7

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

Kopernik Magdalena, Major Roman, Lis Grzegorz, Wilczek Piotr, Lis Maciej, Imbir Gabriela, Chrouda Abir, Mzyk Aldona, Ostrowski Roman, Sanak Marek

Acta of Bioengineering and Biomechanics

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2020

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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.

8

Interaction of the Kinetic Energy Penetrators and Steel and Composite Armours

Burian W., Magier M., Żochowski P.

Machine Dynamics Research

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2018

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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.

9

Numeryczna ocena nośności i sztywności króćców w doczołowych połączeniach rur prostokątnych

Głuszko A., Ślęczka L.

Czasopismo Inżynierii Lądowej, Środowiska i Architektury / Journal of Civil Engineering, Environment and Architecture

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2017

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z. 64, nr 3/I

387--396

PL

W pracy przedstawiono metodykę modelowania oraz rezultaty analiz numerycznych nośności i sztywności króćca teowego (T) oraz króćca podwójnie teowego (Π). Króciec teowy (T) jest elementem składowym styków doczołowych kształtowników o przekroju poprzecznym otwartym (IPE lub HEB), króciec podwójnie teowy (Π) jest zaś fragmentem styku doczołowego rur o przekroju prostokątnym. Zastosowanie metody składnikowej do określania nośności i sztywności połączeń doczołowych z rur prostokątnych wymaga numerycznego i/lub doświadczalnego zbadania zachowania króćców podwójnie teowych (Π) i stwierdzenia na ile odbiega ono od dobrze znanego zachowania króćców teowych (T). Rezultaty symulacji zachowania się obu typów króćców skonfrontowano ze sobą. Przeprowadzono analizę parametryczną z uwzględnieniem zmiany grubości blachy czołowej oraz szerokości rozstawu ścianek rury. Wynikiem analiz jest określenie nośności i sztywności oraz występujących form zniszczenia. Porównano je z rezultatami analitycznego określenia tych parametrów przy użyciu metody składnikowej (w ujęciu PN-EN 1993-1-8) i za pomocą innych dostępnych metod obliczeniowych. Przeprowadzone analizy wskazują na możliwość stosowania metody składnikowej w połączeniach doczołowych rur, lecz niezbędne jest jej odpowiednie dostosowanie do takiego podejścia.

EN

The paper describes results of the finite element modeling of two types of stubs in bolted end-plate connections. The first one is the T-stub which is the part of open section joints and second one is the Π-stub which is the part of rectangular hollow section joints. The investigation is made to compare the behavior and find differences between those stubs and then to use Π-stub in application of the component method in end-plate joints for rectangular hollow sections. The impact of flange plate thickness and pitch of hollow section wall on resistance and initial stiffness is investigated. The results are compared to the predictions of the component method of EN 1993-1-8 and to the another analytical method. It is shown that the component method can be used to determine the structural properties of rectangular hollow section connections after appropriate adjustment.

10

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

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

Computer Methods in Materials Science

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2017

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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.

11

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

Louis M. J., Malayalamurthi R.

Biocybernetics and Biomedical Engineering

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2017

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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.

12

Inflation simulation of tractor radial tire

Pelc J.

Technical Sciences / University of Warmia and Mazury in Olsztyn

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2016

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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.

13

Modelowanie jako narzędzie do zrozumienia i udoskonalenia techniki iskrowego spiekania plazmowego

Laptev A.

Obróbka Plastyczna Metali

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2016

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T. 27, nr 3

223--240

PL

Iskrowe spiekanie plazmowe (SPS) jest nowoczesną metodą prasowania na gorąco bazującą na szybkim nagrzewaniu oporowym. Aktualnie SPS znajduje się w fazie przejściowej pomiędzy pracami badawczo-rozwojowymi a produkcją masową części z proszków metalicznych i ceramicznych. Kluczowym elementem tej metody jest zrozumienie i kontrolowanie rozkładu temperatury wewnątrz narzędzi, w szczególności w wyprasce. Zagadnienie to jest szczególnie ważne przy spiekaniu części wielkogabarytowych, części o złożonej geometrii oraz przy spiekaniu materiałów gradientowych i ogniotrwałych. Wiedza w zakresie pola termicznego pozwala na opracowanie konstrukcji matryc oraz przebiegu procesu spiekania, umożliwiając jednorodny, zdefiniowany rozkład temperatury zależny od aplikacji. W rezultacie, jednorodna lub gradientowa struktura i właściwości mogą zostać osiągnięte. Temperatura nie może być mierzona bezpośrednio wewnątrz wypraski. Dlatego zastosowano metodę elementów skończonych (MES) do numerycznego modelowania rozkładu temperatury. W niniejszym artykule przedstawiono szczegółowo teoretyczne podstawy modelowania. Podkreślono wzajemne oddziaływanie pola elektrycznego, cieplnego i mechanicznego podczas SPS. Przedyskutowano metodologię rozwiązania tego złożonego problemu multifizycznego oraz jego ewentualnego wdrożenia poprzez komercyjne kody MES. Przedstawiono przykład modelowania. Sformułowano perspektywę dla dalszego modelowania. Szczególnie, pole magnetyczne musi być poza tym rozważane podczas modelowania SPS z nagrzewaniem hybrydowym np. z dodatkowym zewnętrznym nagrzewaniem indukcyjnym (nowa hybrydowa koncepcja nagrzewania).

EN

Spark Plasma Sintering (SPS) is a new hot pressing technique based on the rapid resistive heating. Currently, SPS is in a transition from the R&D phase to the mass production of metallic and ceramic powder parts. The critical point of this technique is understanding and control of temperature field inside the tool and especially in the powder preform. This issue is particularly important at sintering of large-sized parts, parts with a complex geometry and at sintering of functionally graded and refractory materials. The knowledge of temperature field allows the elaboration of die design and sintering cycle profile enabling homogeneous or predefined temperature distribution depending on application. As a result, homogeneous or functionally graded structure and properties can be achieved. The temperature cannot be directly measured inside the powder preform. Therefore, the Finite Element Method (FEM) is used for numerical modeling of the temperature field. In the present paper the theoretical background of modeling is presented in detail. The interaction of electrical, thermal and mechanical fields during SPS is highlighted. The solution methodology for this complex problem of Multiphysics and its possible implementation by commercial FEM codes are discussed. An example on sintering modeling of tungsten-based powder composite is presented. The outlook for further modeling is formulated. Particularly, magnetic field has to be besides considered during the modeling SPS with the hybrid heating i.e. with an additional external inductive heating (new hybrid heating concept).

14

New Methods for Modeling Laterolog Resistivity Corrections

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

Acta Geophysica

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2016

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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.

15

Simulation of ballistic impact on polymer matrix composite panels

Long D.

Journal of Theoretical and Applied Mechanics

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2015

|

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.

16

Recent and future developments in finite element metal forming simulation

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

Computer Methods in Materials Science

|

2015

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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".

17

Finite Element Analysis Of Large Deformation Of Articular Cartilage In Upper Ankle Joint Of Occupant In Military Vehicles During Explosion

Klekiel T., Będziński R.

Archives of Metallurgy and Materials

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2015

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Vol. 60, iss. 3

2115-2121

EN

The paper presents the analysis of the load of lower limbs of occupants in the armoured military vehicle, which has been destroyed by detonation of the Improvised Explosive Device (IED) charge under the vehicle. A simplified model of the human lower limb focused on upper ankle joint was developed in order to determine the reaction forces in joints and load in particular segments during the blast load. The model of upper ankle joint, include a tibia and an ankle bone with corresponding articular cartilage, has been developed. An analysis of the stress distribution under the influence of forces applied at different angles to the biomechanical axis of a limb has been performed. We analyzed the case of the lower limb of a sitting man leaning his feet on the floor. It has been shown that during a foot pronation induced by a knee outward deviation, the axial load on the foot causes significantly greater tension in the tibia. At the same time it has been shown that within the medial malleolus, tensile stresses occur on the surface of the bone which may lead to fracture of the medial malleolus. It is a common case of injuries caused by loads on foot of passengers in armored vehicles during a mine or IED load under the vehicle. It was shown that the outward deviation of the knee increases the risk of the foot injury within the ankle joint.

PL

W artykule przedstawiono analizę MES obciążenia kończyn dolnych osób w opancerzonym pojeździe wojskowym, który został zniszczony przez zaimprowizowaną detonację ładunku wybuchowego (IED) pod pojazdem. W uproszczonym modelu dolnej kończyny ludzkiej skoncentrowano się na górnej części stawu skokowego. Model opracowany został w celu określenia siły reakcji w stawach i obciążenia w poszczególnych segmentach podczas obciążenia wybuchowego. Model górnego stawu skokowego, obejmuje kość piszczelową oraz kości stawu skokowego z odpowiadającymi chrząstkami stawowymi. Przeprowadzono analizę rozkładu naprężeń pod wpływem sił wywieranych pod różnymi kątami w stosunku do osi biomechanicznej kończyny. Przeanalizowano przypadek kończyny dolnej siedzącego mężczyzny z nogą opartą na podłodze. Wykazano, że podczas skręcenia stopy indukowanego przez odwiedzenie kolana na zewnątrz, siła osiowa na stopie powoduje znacznie większe naprężenie rozciągające w kości piszczelowej. Jednocześnie wykazano, że w kostce przyśrodkowej, naprężenia rozciągające występują na powierzchni kości, co może prowadzić do wystąpienia złamania kostki przyśrodkowej. Jest to częsty przypadek obrażeń spowodowanych obciążeniami stóp pasażerów pojazdów pancernych podczas eksplozji miny lub wybuchu ładunku (IED) pod pojazdem. Wykazano, że odchylenie kolana zwiększa ryzyko obrażeń stopy w stawie skokowym.

18

Modelowanie MES i numeryczna optymalizacja systemu podparcia układu soczewek magnetycznych

Szybiński B.

Zeszyty Naukowe. Transport / Politechnika Śląska

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2014

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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.

19

Passive vibration damping in a truss telecommunication tower

Pelc J., Kolator B.

Technical Sciences / University of Warmia and Mazury in Olsztyn

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2014

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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.

20

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

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

Technical Sciences / University of Warmia and Mazury in Olsztyn

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2014

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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.