Preliminary analysis of fuel tank impact

Following the accident involving the Air France Concorde in 2000 the effects of fluid structure interactions resulting from the impact of a fluid filled tank has become a cause for concern. The work reported here relates to the design of a series of experiments loosely based upon the Concorde incident which aimed to assess whether the probable failure mode in the Concorde accident could occur in land based vessels. Preliminary numerical analyses were undertaken for two of the nine cases that were investigated experimentally in which an empty tank was impacted by a projectile with a velocity of 14m/s and 21.9m/s Initial numerical results for the acceleration at two points on the tank surface and the deformation at the impact zone showed good agreement with test data. Future work is discussed including further numerical modelling incorporating fluid structure interactions for the analysis of the cases when the tank is partially full or completely full

Numerical simulation of the dynamic response in pulse-loaded fibre-metal-laminated plates

This article presents a three-dimensional constitutive model to replicate the dynamic response of blastloaded fibre–metal laminates made of 2024-0 aluminium alloy and woven composite (glass fibre–reinforced polypropylene). Simulation of the dynamic response is challenging when extreme localised loads are of concern and requires reliable material constitutive models as well as accurate modelling techniques. It is well known that back layers in a fibre–metal laminate provide structural support for front layers; thus, proper modelling of constituent failure and degradation is essential to understanding structural damage and failure. The improved developed model to analyse damage initiation, progression and failure of the composite is implemented in finite element code ABAQUS, and a good correlation is observed with experimental results for displacements of the back and front faces as presented by other researchers. The model was also able to predict accurately the tearing impulses. Finally, the concepts of the ‘efficiency of the charge’ and ‘effectiveness of the target’ are proposed in the context of localised blast loading on a structure. Dimensionless parameters are introduced to quantify these parameters

Experimental verification of an Oseen flow slender body theory

Consider uniform flow past four slender bodies with elliptical cross-section of constant ellipticity along the length of 0, 0.125, 0.25 and 0.375, respectively, for each body. Here, ellipticity is defined as the ratio of the semiminor axis of the ellipse to the semimajor axis. The bodies have a pointed nose which gradually increases in cross-section with a radius of curvature 419mm to a mid-section which then remains constant up to a blunt end section with semimajor axis diameter 160 mm, the total length of all bodies being 800 mm. The bodies are side-mounted within a low-speed wind tunnel with an operational wind speed of the order 30ms−1. The side force (or lift) is measured within an angle of attack range of −3◦ to 3◦ such that the body is rotated about the major axis of the ellipse cross-section. The lift slope is determined for each body, and how it varies with ellipticity. It is found that this variance follows a straight line which steadily increases with increasing ellipticity. It is shown that this result is predicted by a recently developed Oseen flow slender body theory, and cannot be predicted by either inviscid flow slender body theory or viscous crossflow theories based upon the Allen and Perkins method

Lagrangian and ALE Formulations For Soil Structure Coupling with Explosive Detonation

Simulation of Soil-Structure Interaction becomes more and more the focus of computational engineering in civil and mechanical engineering, where FEM (Finite element Methods) for soil and structural mechanics and Finite Volume for CFD (Computational Fluid Dynamics) are dominant. New advanced formulations have been developed for FSI (Fluid Structure Interaction) applications using ALE (Arbitrary Lagrangian Eulerian), mesh free and SPH (Smooth Particle Hydrodynamic) methods. In defence industry, engineers have been developing protection systems for many years to reduce the vulnerability of light armoured vehicles (LAV) against mine blast using classical Lagrangian FEM methods. To improve simulations and assist in the development of these protections, experimental tests and new numerical techniques are performed. Initial conditions such as the loading prescribed by a mine on a structure should be simulated adequately in order to conduct these numerical calculations. The effects of blast on structures often depend on how the initial conditions are estimated and applied. This article uses two methods to simulate a mine blast, namely the classical Lagrangian as well as the ALE formulations. The comparison was carried out for a simple and also a more complex target. Particle methods as SPH method can also be used for soil structure interaction

Deployment of a Neo-Hookean membrane: experimental and numerical analysis

The aim of this research is to assess the response of a thin membrane subjected to high-pressure gas loading for inflation. This procedure is applied during the design process of the membrane structure to allow the product to resist high-pressure loading and to further characterize the hyper-elastic material. The simulation in this work considers the standard procedures used in the LS-DYNA software, which applies such assumptions as a uniform airbag pressure and temperature in addition to a more recently developed procedure that takes into account the fluid-structure interaction between the inflation gas source and the hyper-elastic membrane; this approach is referred to as the Arbitrary Lagrangian Eulerian (ALE) formulation. Until recently, to simulate the inflation of the hyperelastic membrane, a uniform pressure based on a thermodynamic model or experimental test has been applied to the structure as the boundary conditions. To conserve CPU time, this work combines both methods; the fluid structure coupling method is used at an earlier stage in which the fluid is modeled using full hydrodynamic equations, and at the later stage, the uniform pressure procedure is applied, and the fluid mesh and analysis are removed from the computation. Both simulations were compared to test data, indicating satisfactory correlation with the more recently developed procedure, the ALE theory, which showed the greatest accuracy both in terms of graphical and schematic comparison, particularly in the early stages of the inflation process. As a result, the new simulation procedure model can be applied to research on the effects of design changes in the new membrane

Fluid structure interaction of submerged metallic and composite plates subjected to low velocity impact loading

An instrumented low velocity impact rig has been used to acquire experimental data for impacts in air and underwater for both metallic and composite plates when subjected to a low velocity drop-weight impact with a 2kg steel impactor. Initial impact studies were conducted in air and then repeated for submersed conditions underwater. Experimental results are compared for all tests with numerical solutions and are found to be in good agreement. For underwater impact, the numerical model incorporates the use of a Eulerian formulation for the water with a coupled fluid-structure interaction algorithm. The effect of the water surrounding the target plates was found to reduce the peak accelerations and also reduce the overall impact duration when compared to the same impacts in air. X-Ray imagery of the composite plates also showed visibly reduced damage for the submersed test specimens. This research provides data on the impact response of metallic and composite materials, and validates numerical methodologies for use in future work on fluid-structure interactions which show strong potential for relevant industrial applications

Witches in media

Tema je ovoga rada prikazati kako su vještice i podaci o njihovim progonima utjecali na književnost i medije u Hrvatskoj. Pojam vještica, vrlo je raširen pojam u raznim umjetnostima te je neiscrpan je izvor nadahnuća. Kako bi pojam bio što jasniji trebalo bi ga staviti u kontekst, stoga treba reći nešto o prapočecima vještica. Vještice su poznate pod raznim imenima, od samih početaka ljudske civilizacije. Prethodnice kasnijeg poimanja vještica, seže u daleku prošlost, a veže se uz čarobnjaštvo. Vještice su poznati likovi usmenih pripovijedaka i bajki kao na primjer Snjeguljica i sedam patuljaka, Ivica i Marica, Trnoružica. Bajke nadahnuće crpe iz usmene književnosti. Hrvatska usmena književnost određena je i obilježena je različitim tradicijama, a specifično hrvatskom. Čini ju jezik pripovjedača ili pjevača. Postoje različiti žanrovi usmenoknjiževnih vrsta: pripovijetke koje se dijele na bajke, predaje, novele legende i druge prozne oblike

Application of the penalty coupling method for the analysis of blood vessels

Due to the significant health and economic impact of blood vessel diseases on modern society, its analysis is becoming of increasing importance for the medical sciences. The complexity of the vascular system, its dynamics and material characteristics all make it an ideal candidate for analysis through fluid structure interaction (FSI) simulations. FSI is a relatively new approach in numerical analysis and enables the multi-physical analysis of problems, yielding a higher accuracy of results than could be possible when using a single physics code to analyse the same category of problems. This paper introduces the concepts behind the Arbitrary Lagrangian Eulerian (ALE) formulation using the penalty coupling method. It moves on to present a validation case and compares it to available simulation results from the literature using a different FSI method. Results were found to correspond well to the comparison case as well as basic theory

Multiphysics Modelling of Powder Coating of U-Profiles: Towards Simulation-based Optimization of Key-Performance Attributes by Variation of Powder-Parameters

Multiphysics simulation software has been developed to predict the key performance attributes of industrial powder coating applications based on applied process-parameter settings. The software is a Eulerian-Lagrangian finite-volume Multiphysics solver based on OpenFOAM, capable of modelling mass transfer effects between powder-coating pistols and electrically grounded metallic substrates. It considers various factors such as fluid dynamics of process airflow, coating-particle dynamics, particle-substrate interactions, and particle charging mechanisms within the corona. The software is fully compatible with Massive Simultaneous Cloud Computing technology, allowing hundreds of simulated coating scenarios to be computed simultaneously. Experimental validation efforts have been conducted, indicating a high degree of practical relevance of the technology. The current simulation study aims to demonstrate the potential of the simulation software for adjusting coating lines and optimizing powder coating of U-profiles. Specifically, the study focuses on optimizing the key-performance-attributes of the powder coating application with respect to varying material parameters of the applied powder, namely mean particle diameter, standard deviation of Gaussian particle size distribution, and powder particle density. The software predicts and visualizes coating patterns, coating efficiencies, and the batch-based standard deviation of coating thickness on a U-shaped metallic substrate, resulting in concrete and optimized powder settings. The presented results and the applied software are highly relevant for powder material suppliers

A Qualitative Comparison of ANSYS and OpenFOAM results for Carbon dioxide Plume Transport

This research presents Computational Fluid Dynamics (CFD) simulations in ANSYS® illustrating emissions of to the air. The CFD simulations is employed to study plume transport in urban environment, i.e., Breivika port in the city of Tromsø. The case study presents a two-phase model considering specific wind strength and direction in the city of Tromsø. Geographical coordinates, temperature, and wind data were obtained from the open sources, such as Google Maps, and Norwegian Meteorological Institute. The results from the simulations indicates a potential outcome with respect to various weather conditions. It was revealed for vessels less than 30 meter chimney height, the higher the wind strength, the lower the plume dispersion, causing the plume to stay closer to the terrain. This brings in a concentrated amount of pollutants closer to the public areas. The terrain in the model is recognizable for the Tromsø port’s location. From the CFD results, it is illustrated that onshore wind with high wind strength could affect the environment. The results simulated in OpenFOAM are qualitatively showing the same as visible in ANSYS®