Study of the defect closure behaviour during forging in a step-wedge strikers

    Machines. Technologies. Materials., Vol. 16 (2022), Issue 4, pg(s) 127-129

    This work is devoted to the study of the internal defect closure during metal broaching in step-wedge strikers with wedge and depression by FEM in Deform program. A through cylindrical hole with a diameter of 3 mm was considered as an internal defect. At the same time, three variants of the defect vertical location were modeled – in the workpiece center, near the upper face of the wedge and near the lower face of the depression. In all three cases, the internal defect closure is uneven. The most intense defect closure is observed when it is located in the workpiece axial zone. Defects located near the strikers surface zones are not closed well enough. The stress-strain state analysis showed that the defect location affects the distribution nature of stresses and strains along the workpiece section.


    Fixed joints applied in car construction

    Trans Motauto World, Vol. 6 (2021), Issue 4, pg(s) 127-130

    The paper deals with the problem of joints of car parts of the car construction. The construction of the car must meet the emission standards, in order to meet them it is necessary to reduce the weight of the car while maintaining strength and durability. Therefore, different materials are used in the design of car construction, such as different types of steels, aluminum alloys, composites and plastics. This increases the demands on the car construction and on the type of sheet metal joining technology used. The paper deals mainly with glued and welded joints in the design of car construction. The suitability of individual types of joints is solved using the finite element method.


    Simulation of the main components of a nuclear reactor under load, made of ultrafinegrained steel AISI-321 in the normal and irradiated state

    Mathematical Modeling, Vol. 4 (2020), Issue 4, pg(s) 110-113

    The creation and calculation of computer models of various products under load with the properties of UFG materials in the normal and irradiated state was performed. To model the UFG properties of non-irradiated AISI-321 steel, hardening curves were constructed based on the Hall-Petch equation for the base state of the material at a grain size of 1500 nm and for two UFG states (with grain sizes of 700 and 200 nm). To simulate the properties of irradiated AISI-321 steel, plastometric tests were performed using uniaxial compression of cylindrical samples at constant values of the strain rate of 1 s-1 and the temperature of 20°C on the “Gleeble 3800” plastometric unit. Fast neutron fluence with the following values was selected as a variable parameter: 0.5∙1018 n/cm2, 1∙1018 n/cm2, 0.5∙1019 n/cm2, 1∙1019 n/cm2. The maximum operating pressure of 340 MPa was used as a static load. The simulation results showed that for both parts, the use of the material in the UFG state is the most appropriate solution.


    Finite element simulation on tensile creep behaviour of underground support liner

    Machines. Technologies. Materials., Vol. 13 (2019), Issue 10, pg(s) 417-420

    Polymer-based products are widely used as load-carrying components in different structural applications due to the ease of manufacture, installation, and long lifetime properties. In mining and tunnelling industry, fast-setting, thin polymer-based products are in demand as an underground support liner. Researchers have agreed that the time-dependent material properties of underground support liners have significance for short to long term applications. Although some creep tests were performed in literature, there is no available study on the numerical analysis/simulation of the creep behaviour of underground support liners. In this study, viscoelastic mathematical
    models developed for two different underground support liners were analyzed in ABAQUS finite element numerical modelling software with a developed subroutine. After the implementation, tensile creep test specimens were modelled to verify the new subroutine. There are two main purposes of the simulation of experiments; Firstly, to verify that the subroutine works in accordance with the actual behaviour of the material, secondly, to obtain realistic creep behaviour results for cases where experiments were not performed. As a result, a good  agreement was obtained between the mathematical model predictions and numerical results for different stress levels. The proposed subroutines may create a basement for future numerical studies.

  • Material model parameters identification of blast environment

    Security & Future, Vol. 2 (2018), Issue 3, pg(s) 142-145

    In terms of designing or building new protective and security structures or equipment as a physical component of force protection, experimental verification of analytical or numerical calculations and vice versa becomes necessary. While the experiment can be performed on individual components, complex assessment of more complex variants or performing a parametric study is becoming more and more relevant in modelling and simulation domain. For this reason, there is a clear necessity to find the right connection between numerical simulation and experiment.
    Fast, nonlinear processes require nonlinear material models to capture the rate of deformation and material behaviour under extreme loads such as the effect of explosions or the impact of a projectile, i.e. the effects, which the theories and practices of protection of the population and troops are trying to minimize. The important part of the accuracy of computational models is the correct identification of the parameters of material models used in the simulations.
    This paper deals with the simulation of explosion and its effects and identification and optimization of material parameters of the environment in which the explosion and the shockwave propagates, with a focus on the soil material model. The inverse identification method is based on a combination of the experimental measurement data and the computational methods implemented in the finite element solvers and optimization programs. The simulation proceed from experimental measurement curves of blast effects. For measured parameter in the air overpressure at specific measuring points was chosen, while ground-propagating shock wave was evaluated by measuring
    acceleration values. The numerical simulation took place in the LS-Dyna software environment interconnected with the Optislang optimization program.


    Machines. Technologies. Materials., Vol. 10 (2016), Issue 4, pg(s) 23-26

    In this paper elastic deflections of press frame when symmetric load is applied have been investigated and press stiffness calculated. The commercial FEM package ABAQUS was used to estimate elastic stress and elastic deformation of press frame in case of 6.3 MN hydraulic press. For validation of FE results both axial and radial displacements of the press frame were measured by means of universal displacement transducers. Obtained results are compared and discussed.


    Machines. Technologies. Materials., Vol. 8 (2014), Issue 3, pg(s) 51-53

    The aim of this work is to extract modal parameters of a light aircraft wing. Modal parameters like natural frequencies, and mode shapes characterise the dynamic response of a structure and can be used for determining of the wing divergence and flutter. The CAD (Computer-Aided Design) model plays a pivot role in the design and development phases of an aircraft. Creating drawings, preparing reports of assembly and part drawings, preparing bill of materials, the aircraft design becomes easier and faster with the use of CAD system.
    CAD model has to be imported in FEM (Finite Element Method) software, and so it can do FE model, which have to be solved. In this work a light aircraft wing is modelled by SolidWorks software. After that the CAD model is imported in ANSYS Workbench. The FE model is generated and solved by using ANSYS Workbench. The first six natural frequencies and mode shapes are shown for the proposed light aircraft wing.



    Industry 4.0, Vol. 2 (2017), Issue 3, pg(s) 123-126

    A Continuum (filled polymer) is inhomogeneous and anisotropic. The Continuum is used in an injection moulding simulation at first (generally unnewton type of fluid). Then the continuum is solid (after cooling) and it is possible to carry out ordinary dynamics structural analysis with it. The solid continuum has different mechanical properties for each of discrete element. A consequent dynamics properties (natural frequencies) will generally have different values when influence of injection moulding is taken into account for analyses.