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  • Author: Jerzy Malachowski x
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Open access

Małachowski Jerzy and Niezgoda Tadeusz

Abstract

This research has been inspired by security concerns due to the recent increase in the terrorist threat to gas and crude oil transportation around the world, especially in regions that are of significant value for the energy supplies. Computational mechanics methods will be used in this research to apply shock wave analysis for possible damage assessment of the affected pipelines. These methods may be also used for pipelines at power plants, which are usually placed high on the homeland security priority list. This study is primarily focused on the behaviour of some type of pipeline elements existing in gas pipeline system which can be subjected to the shock wave produced by the detonation of highly explosive (HE) materials. In this kind of studies the numerical coupling procedure describing interaction between gas and solid domain was implemented. Outcomes of this research are very important in preventing damage progression of pipelines under the blast loading.

Open access

Jerzy Małachowski, Marian Klasztorny, Łukasz Mazurkiewicz, Damian Kołodziejczyk and Tadeusz Niezgoda

Abstract

Issues related to critical infrastructure safety is highly demanding in aspect of newly projected systems. In this paper a problem of modeling and simulation of the supporting structure behavior of critical facility (without or with proposed protective cover) loaded with a shock wave is presented. Authors assume that two different phenomena will be responsible for minimization of shock wave effects: flow around cylindrical panel and energy absorption by panel structure. In this paper research focuses on the description and analysis of the process of explosion near the supporting elements and the blast interaction with the structure.

Open access

Paweł Baranowski, Jerzy Małachowski, Łukasz Mazurkiewicz and Krzysztof Damaziak

Abstract

Split Hopkinson pressure bar (SHPB) is one of the most important and recognisable apparatus used for characterizing the dynamic behaviour of various materials. Incident pulse generated one the incident bar usually have a rectangular shape, which is proper for some materials but for others is not. Therefore, several methods of shaping the incident pulse are used for obtaining constant strain rate conditions during tests. Very often pulse shapers made of copper or similar material are implemented due to its softness properties. In this paper such material was investigated using the FE model of SHPB. Its mechanical behaviour was characterised with and without copper disc between the striker and incident bar. Numerical simulations were carried out using explicit LS-DYNA code. Two different methods were used for modelling the copper sample: typical finite Lagrangian elements and meshless Smoothed Particle Hydrodynamics (SPH) method. As a result of two techniques used axial stress-strain characteristics were compared for three different striker’s velocity with an influence of the copper pulse shaper taking into account. Finally, FE and SPH method was compared with taking into consideration: the efficiency, computer memory and power requirements, complexity of methods and time of simulation

Open access

Jerzy Malachowski, Volodymyr Hutsaylyuk, Petr Yukhumets, Roman Dmitryenko, Grigorii Beliaiev and Ihor Prudkii

Abstract

Mechanical properties of the pipeline samples that had been cut in annular and axial directions were investigated. The methodology of modeling and calculation of the real stress-strain state was described. The stable state during in the deformation process was defined. The results of the experimental researches were used as a test variant during examination of pipe strength.

Open access

Pawel Baranowski, Roman Gieleta, Jerzy Malachowski, Krzysztof Damaziak and Lukasz Mazurkiewicz

Abstract

Materials and their development process are highly dependent on proper experimental testing under wide range of loading within which high-strain rate conditions play a very significant role. For such dynamic loading Split Hopkinson Pressure Bar (SHPB) is widely used for investigating the dynamic behavior of various materials. The presented paper is focused on the SHPB impulse measurement process using experimental and numerical methods. One of the main problems occurring during tests are oscillations recorded by the strain gauges which adversely affect results. Thus, it is desired to obtain the peak shape in the incident bar of SHPB as “smooth” as possible without any distortions. Such impulse characteristics can be achieved using several shaping techniques, e.g. by placing a special shaper between two bars, which in fact was performed by the authors experimentally and subsequently was validated using computational methods.

Open access

Łukasz Mazurkiewicz, Jerzy Małachowski, Krzysztof Damaziak, Paweł Baranowski and Paweł Gotowicki

Abstract

The main objective of the study is to develop experimentally validated FE model and perform numerical analysis of layered composites made by hand lay-up techniques during tension and bending test. The research object is glass - polyester laminate made of four unidirectional layers. In order to validate the numerical models experimental test were performed. Due to the very different stiffness modulus in tension and bending loading the material properties obtained from standard test are not suitable to apply in numerical model. Significantly different behaviour compared to experimental test was obtained for tree point bending where the numerical model becomes too stiff. Simple coupons, relatively easy to manufacture presented in the paper have very low quality. The differences in actual and theoretical bending stiffness (obtained from tension stiffness) exceed 70%. In order to represent the actual structure the layers of the composite were divided by resin layers and also additional resin layer at the top and bottom of the model were defined. Single stage optimization process was used to adjust the material layout. After layer set-up modification very significant improvement can be seen for flexural behaviour

Open access

Pawel Baranowski, Krzysztof Damaziak, Jerzy Malachowski, Lukasz Mazurkiewicz, Henryk Polakowski, Tadeusz Piatkowski and Mariusz Kastek

Abstract

This article presents the validation process of a brake FE model by means of temperature measured on a special stand using infrared technology. Unlike many other publications, the authors try to show the interaction between measurement technology and numerical modeling rather than only nice, perfectly correlated graphs. Some difficulties in choosing and using validation parameters are also pointed out and discussed. Finally, results of FE analyses are compared with measured data, followed by explanation of applied numerical technology and estimation of validation process effectiveness.