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EN
Development of a reliable numerical model capturing major physical mechanisms controlling explosive welding and considering properties of all process components i.e. base plate and flyer plate is the goal of the paper. To properly replicate materials behavior under these severe conditions a meshfree approach, namely Smooth Particle Hydrodynamics (SPH), was used to discretize the computational domain. The model is based on the Mie-Gruneisen shock equation of state applied to the Ti/Cu system as a case study. Examples of results in the form of velocity, equivalent stress, equivalent strain, and pressure fields are presented within the paper.
EN
The paper presents the results of experimental-numerical tests of firing at aluminum composite materials. The test materials were manufactured by pressure infiltration of porous ceramic preforms made of α-Al2O3 particles in the amount of 30% and 40% by volume. The EN AW-7075 alloy was chosen as the material matrix, and the steel 7.62×39 mm (M 43) FMJ (Full Metal Jacket) intermediate ammunition was selected for firing. In the result of the experiment, the samples were perforated with a clear difference in the muzzle diameter. The projectile with fragments caused damage to up to three reference plates placed behind the samples (witness plates) in composites with 40% of particles by volume. The mechanics of crack propagation during ballistic impacts of the projectile was characterized based on microstructure studies. Then, using numerical analysis of impact load, the examination of composite materials puncture in the ABAQUS environment was carried out. The Finite Element Method (FEM) was employed for the discretization of geometric models using Hex elements. The Johnson-Cook constitutive model describing the relationship between stress and strain in metal-ceramic composites was applied for the analyses. Numerical models were then subjected to numerical verification using smoothed particle hydrodynamics (SPH). Based on the obtained results, it was found that the hybrid FEM/SPH method correlates significantly with the experimental results.
EN
This article presents a sequential model of the heating-remelting-cooling of steel samples based on the finite element method (FEM) and the smoothed particle hydrodynamics (SPH). The numerical implementation of the developed solution was completed as part of the original DEFFEM 3D package, being developed for over ten years, and is a dedicated tool to aid physical simulations performed with modern Gleeble thermo-mechanical simulators. Using the developed DEFFEM 3D software to aid physical simulations allows the number of costly tests to be minimized, and additional process information to be obtained, e.g. achieved local cooling rates at any point in the sample tested volume, or characteristics of temperature changes. The study was complemented by examples of simulation and experimental test results, indicating that the adopted model assumptions were correct. The developed solution is the basis for the development of DEFFEM 3D software aimed at developing a comprehensive numerical model allows the simulation of deformation of steel in semi solid state.
EN
The break-up of liquid ligaments and formation of droplets are elementary phenomena in multiphase flows which are of high importance in industrial and medical applications. From the numerical point of view, they require proper interface and surface tension treatment. In the present work, we apply Smoothed Particle Hydrodynamics, a meshless approach, to simulate the break-up of a liquid cylinder inside the gaseous phase, i.e. the Rayleigh-Plateau instability. Results obtained in 3D show that even a relatively coarse resolution allows one to predict correctly the size of droplets formed in the process. The detailed analysis of the break-up time in 2D setup implies that a certain level of spatial discretisation needs to be reached to determine this moment precisely.
EN
In this paper, the applications of mesh-free SPH (Smoothed Particle Hydrodynamics) continuum method to the simulation and analysis of trimming process is presented. In dealing with shearing simulations for example of blanking, piercing or slitting, existing literatures apply finite element method (FEM) to analysis of this processes. Presented in this work approach and its application to trimming of aluminum autobody sheet allows for a complex analysis of physical phenomena occurring during the process without significant deterioration in the quality of the finite element mesh during large deformation. This allows for accurate representation of the loss of cohesion of the material under the influence of cutting tools. An analysis of state of stress, strain and fracture mechanisms of the material is presented. In experimental studies, an advanced vision-based technology based on digital image correlation (DIC) for monitoring the cutting process is used.
PL
W artykule przedstawiono sposób modelowania procesu wykrawania elementów pojazdów samochodowych z wykorzystaniem metody cząstek hydrodynamicznych (SPH). Symulację komputerową opracowano z wykorzystaniem Solvera LS-DYNA oraz aplikacji LS-PrePost. Otrzymano mapy intensywności naprężeń i odkształceń dla dowolnej chwili czasowej z uwzględnieniem nieliniowości występujących w procesie. Przedstawiono wybrane wyniki analizy numerycznej, które mogą być wykorzystane do projektowania procesu i jego optymalizacji.
EN
The paper presents the modeling of the blanking process of the car elements using Smoothed Particle Hydrodynamics (SPH). Numerical analysis was performed in LS-DYNA solver and LS-PrePost application regarding process nonlinearities. Obtained maps of stresses, strains, displacement at any moment of time can be used to design of the process and it’s optimization.
7
Content available remote Smoothed particle hydrodynamics simulations using graphics processing units
EN
Smoothed Particle Hydrodynamics (SPH) is a fully Lagrangian, particle-based technique for fluid-flow modeling. As a gridless method, it appears to be a natural approach to simulate multi-phase flow with complex geometries. Since SPH involves a large set of short-range particle-particle interactions, numerical implementations present a high degree of spatial data locality and a significant number of independent computations. Therefore, the numerical code can be easily written in a massively parallel manner. The main purpose of this study is to discuss the issues related to the implementation of the SPH method for computation using Graphics Processing Units (GPU). The study is supported by two-dimensional validation cases: the lid-driven cavity and oscillation of a droplet. The obtained results show a good accuracy of the method, as well as, high numerical efficiency of its GPU implementation.
EN
A theoretical base of SPH method, including the governing equations, discussion of importance of the smoothing function length, contact formulation, boundary treatment and finally utilization in hydrocode simulations are presented. An application of SPH to a real case of large penetrations (crater creating) into the soil caused by falling mass in Dynamic Replacement Method is discussed. An influence of particles spacing on method accuracy is presented. An example calculated by LS-DYNA software is discussed. Chronological development of Smooth Particle Hydrodynamics is presented. Theoretical basics of SPH method stability and consistency in SPH formulation, artificial viscosity and boundary treatment are discussed. Time integration techniques with stability conditions, SPH+FEM coupling, constitutive equation and equation of state (EOS) are presented as well.
PL
W artykule przedstawiono metodę symulowania topnienia obiektów zbudowanych z lodu, implementowaną przy wykorzystaniu możliwości obliczeniowych nowoczesnych procesorów graficznych (GPU). Proces topnienia zrealizowano jako rezultat wymiany ciepła pomiędzy obiektami lodowymi i płynami (woda i powietrze), modelowanymi jako zbiory ruchomych cząstek o określonych parametrach fizycznych. Do obliczenia ruchu cząstek wykorzystano wariant algorytmu SPH. Zaprezentowano nowy cząstkowy model powietrza, który pozwala m.in. na uwzględnienie w symulacji lokalnych zmian temperatury powietrza w czasie. Otrzymywane wyniki symulacji są bardziej realistyczne z punktu widzenia poprawności fizycznej i końcowego efektu wizualnego, aniżeli rezultaty otrzymywane przy użyciu metod poprzednich.
EN
The paper presents a fast GPU-based approach to simulation of melting ice objects at interactive frame rates. Our main contribution is a new particlebased model of air which allows one to take into account in simulation the effects of local changes in the air temperature. The process of melting is realized as heat transfer between ice and fluids (water and air), which are represented by means of sets of movable particles (Fig. 2). To convert the triangle-mesh representation of solids into particles, we use a GPU-based voxelization method [4]. Each particle carries some physical local properties of fluid, and their evolution over time is described by the Navier-Stokes equation for incompressible fluids. In order to solve the equation, we utilize a modified version of Smoothed Particle Hydrodynamics (SPH) method [6]. Then, triangle meshes of solids are extracted from the particle representation using marching cubes algorithm, and visualized via ray tracing. Thanks to the new model of air, the results of ice melting supplied by our method (Fig. 3) are more realistic from the standpoint of physical correctness as well as visual appearance than those obtained with the previous approaches.
10
Content available remote Numeryczne modelowanie zjawiska wybuchu
PL
W artykule przedstawiono metodykę numerycznego modelowania zjawiska wybuchu przy użyciu metody elementów skończonych (MES) oraz bezsiatkowej metody SPH (Smoothed Particle Hydrodynamic). Zaprezentowano i porównano wyniki symulacji otrzymane wymienionymi metodami. Wartości ciśnienia fali uderzeniowej wyznaczone numerycznie zostały porównane z istniejącymi w literaturze zależnościami empirycznymi. Możliwości metod numerycznych w analizie zjawiska wybuchu przedstawiono na przykładzie analizy oddziaływania fali uderzeniowej na przykładową konstrukcję.
EN
This article presents methodology of numerical modeling of explosion phenomenon by using the finite element method (FEM) and meshless SPH (Smoothed Particle Hydrodynamic) method. Obtained simulations results are presented and compared. Computed numerically shock wave pressure values were compared with existing empirical solutions. Testing the influence of blast wave on the exemplary structure is presented as an example of capabilities of numerical methods in modeling of the explosion phenomenon.
EN
The mouth of the Vistula River, which is a river outlet located in tideless area, is analyzed. The Vistula River mouth is a man-made, artificial channel which was built in the 19th century in order to prevent the formation of ice jams in the natural river delta. Since the artificial river outlet was constructed, no severe ice-related flood risk situations have ever occurred. However, periodic ice-related phenomena still have an impact on the river operation. In the paper, ice processes in the natural river delta are presented first to refer to the historical jams observed in the Vistula delta. Next, the calibrated mathematical model was applied to perform a series of simulations in the Vistula River mouth for winter storm condition to determine the effects of ice on the water level in the Vistula River and ice jam potential of the river outlet.
EN
The article presents the application of the SPH method for the modeling of cutting composite bundles using a guillotine. For many years, the SPH method has been applied in the modeling of dynamic phenomena in which rapid strain and large deformations occur. The discrete model has been performed by combining the FEM and the SPH. The SPH method has only been applied for to the fragment in which the material separation during cutting appears. To verify the numerical results, experiments have been performed using a special test stand for the confirmation of the correctness of the developed model and the numerical simulations.
EN
The paper considers the failure study of concrete structures loaded by the pressure wave due to detonation of an explosive material. In the paper two numerical methods are used and their efficiency and accuracy are compared. There are the Smoothed Particle Hydrodynamics (SPH) and the Finite Element Method (FEM). The numerical examples take into account the dynamic behaviour of concrete slab or a structure composed of two concrete slabs subjected to the blast impact coming from one side. The influence of reinforcement in the slab (1, 2 or 3 layers) is also presented and compared with a pure concrete one. The influence of mesh density for FEM and the influence of important parameters in SPH like a smoothing length or a particle distance on the quality of the results are discussed in the paper.
PL
Praca ta skupia się na przedstawieniu wyników badań dynamicznej odpowiedzi struktury gumowej na przykładzie koła pojazdu terenowego w warunkach oddziaływania fali podmuchowej. W analizowanym przykładzie wzięto pod uwagę układ zawieszenia wraz z uproszczonym podwoziem rozpatrywanego pojazdu. Mając na uwadze, że w pierwszej kolejności fala ciśnienia pochodząca od detonacji ładunku wybuchowego oddziałuje na oponę, autorzy postanowili odwzorować ten element w sposób jak najbardziej zbliżony do rzeczywistości. W związku z tym model MES podzielono na sześć odrębnych części oraz zaimplementowano do niego układ kordów, których konfiguracja oraz położenie zostały zweryfikowane przy użyciu mikroskopu oraz urządzenia rentgenowskiego. Tak utworzony układ koło-zawieszenie został poddany obciążeniu falą ciśnienia powstałą z eksplozji ładunku wybuchowego. Analizy numeryczne wykonane zostały przy użyciu kodu obliczeniowego LS-Dyna oraz dwóch dostępnych metod numerycznych umożliwiających realizację opisu procesu detonacji, tj. sprzężenia Lagrange-Euler (ALE) oraz metody Smoothed Particle Hydrodynamics (SPH). W drugiej części badań zbadano odpowiedź struktury gumowej (opony) na zadane dynamiczne obciążenie w postaci fali ciśnienia ze szczególnym zwróceniem uwagi na prędkość odkształceń oraz proces zniszczenia materiału. Dodatkowo porównano wyniki dla dwóch rodzajów ładunku wybuchowego: C4 oraz TNT.
EN
This paper focuses on a rubber structure behaviour assessment under dynamic loading on the example of a terrain suspension system subjected to pressure wave. Due to the fact that pressure wave interacts with the tire, in the first place, it was important to develop a discrete model of it as much similar to the real one as possible. Thus, numerical model of the tire was divided into six different parts with steel cords inside. The non-linear dynamic analyses were performed using the LSDYNA code. In order to simulate the blast wave propagation, the Smoothed Particle Hydrodynamics method and Arbitrary Lagrangian-Eulerian formulation with Jones Wilkins Lee equation defining the explosive material were used. In the second part of investigations, the rubber behaviour under dynamic loading with the strain rate effect and failure process taking into consideration was assessed and compared for TNT and C4 charge.
EN
For solving a partial different equation by a numerical method, a possible alternative may be either to use a mesh method or a meshless method. A flexible computational procedure for solving 1D linear elastic beam problems is presented that currently uses two forms of approximation function (moving least squares and kernel approximation functions) and two types of formulations, namely the weak form and collocation technique, respectively, to reproduce Element Free Galerkin (EFG) and Smooth Particle Hydrodynamics (SPH) meshless methods. The numerical implementation for beam problems of these two formulations is discussed and numerical tests are presented to illustrate the difference between the formulations.
16
Content available Numerical Aspects of Penetration Simulation
EN
Several numerical methods were studied as means of solution to a penetration problem. The Element Free Galerkin (EFG), Smooth Particle Hydrodynamics (SPH), Finite Element Analysis (FEA) methods were considered. The above mentioned algorithms implemented in the LS-DYNA code were applied. Additionally, the mesh density was taken into consideration. The reference case assumed an average node to node distance of 1 mm. The finer and coarser mesh densities were analysed. The full 3D models of the projectile and target were developed with a strain rate and temperature dependent material constitutive relations. An impact of 12.7x108 mm B32 armour piercing projectile on a 80 mm thick block of 7017 aluminium alloy was modelled. The results obtained by a computer simulation were validated and then verified by experimental data. The study of the erosion criteria involves defining the most efficient and reliable way of removing the failed and extremely deformed parts of the projectile and targets. Generally, EFG method applied to solve the perforation/penetration problems can be characterized as a very stable, reliable and effective method.
PL
Poniższa praca przedstawia opis koncepcji numerycznej symulacji procesu zużycia okładzin ciernych. Dodatkowo przedstawione zostaną poszczególne etapy budowy modelu numerycznego stanowiska badawczego okładzin ciernych. Analizę procesu hamowania przeprowadzono przy użyciu kodu numerycznego wykorzystującego jawny schemat całkowania z uwzględnieniem numerycznej zamiany sił tarcia na ciepło. Wstępnie przeprowadzone zostały symulacje zjawisk zużycia w skali mikroskopowej wykorzystującej metodę SPH.
EN
In this paper the concept of numerical wear process simulation of brake friction linings is presented. Moreover, the development process of the special test rig's numerical model is described. Performed computations of brake process were done based on the dynamic code with explicit solution scheme with heat generation. In order to represent the brake linings abrasive wear with numerical methods the Smooth Particle Hydrodynamics approach was finally adopted.
EN
In this paper a numerical model of a terrain vehicle suspension system development process is presented. In the performed studies the suspension system with and without a simplified motor-car body was taken into consideration. Geometry of the tire, wheel and system elements were achieved using reverse engineering technology. Moreover, with the assistance of a microscope and an X-ray device it was possible to achieve the exact tire cords pattern, which in the next stages was implemented into the FE model. Subsequently, numerical simulations of both cases were performed simulating the TNT explosion under a wheel. The non-linear dynamic analyses were performed using the LS-DYNA code. To solve both presented cases the explicit central difference scheme with modified time integration of the equation of motion was implemented. Computations of blast wave propagation were carried out with the Smooth Particle Hydrodynamics (SPH) method with Jones Wilkins Lee (JWL) equation of state defining the explosive material. Obtained results have shown different suspension system elements damage and tire destruction characteristic, which come from blast wave reflection of the motor-car body surface.
EN
The main aim of this paper is to present the effective example of coupled experimental and numerical tests. Moreover, a development process of a numerical model of a terrain vehicle suspension system is presented. Experimental tests were carried out on the machine Instron 8802 with an assistance of the high-speed camera Phantom v12. Obtained stress-strain curves were applied into the FE model to estimate material constants for Mooney-Rivlin constitutive rubber model and for numerical failure criterion. Geometry of the tire and other suspension elements were achieved using reverse engineering technology. Due to the fact that a tire is such a complex structure to be represented with numerical methods, it was important to develop a discrete model of tire as much similar to the real one as possible. Consequently, an exact tire cords pattern was implemented into the FE model of the tire, which was obtained by the assistance of a microscope and X-ray device. In the next step, numerical analyses were performed simulating the TNT explosion under the suspension system with a simplified motor-car body. Nonlinear dynamic simulations were carried out using the explicit LS-Dyna code, with central difference scheme with modified the time integration of the equation of motion. In order to simulate the blast wave propagation the Smoothed Particle Hydrodynamics (SPH) method and Arbitrary Lagrangian-Eulerian formulation with Jones Wilkins Lee (JWL) equation defining the explosive material were used. Finally, results from both approaches were compared.
EN
The study is concerned about an application of the smoothed particle hydrodynamics (SPH) method in elastodynamics. A brief description of the SPH model for elastic materials and related stabilising terms are presented. The performance of the implemented SPH code is tested for elementary problems of linear elasticity as well as for a complex problem involving large deformations.
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