Conference Papers (KME)
Permanent URI for this collection
Browse
Recent Submissions
Item Dynamic Electroactive Metamaterials with Flexoelectric and Piezoelectric Microstructures(National Technical University of Athens, 2025) Rohan, Eduard; Hosseinkhani, Ali; Cimrman, RobertWe consider periodic microstructures composed of flexoelectric, or piezoelectric materials and involving electrodes which enable for control of the response due to the electromechanical transmission and tunable external electric circuits. The asymptotic homogenization is employed to derive models describing the effective properties of such metamaterials. Piezoelectric or dielectric materials with a weak flexoelectric property, constituting the skeleton ofgeneral periodic porous structures enable to generate the strain gradients. Using the asymptotic homogenization, it is shown that effective behaviour of such materials is piezoelectric, whereby the homogenized piezoelectric coefficients are computed using the characteristic responses of the flexoelectric microstructure.
Item Tension-compression Tests of 3D-printed PETG(Technical University of Liberec, 2025) Vaňková, Tereza; Krystek, JanThe present study focuses on the tension-compression tests of 3D-printed PETG. The anti-buckling device is designed and manufactured to perform the test. The printed specimens are exposed to tensile and subsequently compressive loading at five different temperatures. The obtained data are then processed and compared with the results of the monotonic tension and compression tests. The influence of loading and temperature on the mechanical properties of the material is analysed.Item Methodology and Determination of Parameters for Modeling Brittle Adhesive(University of West Bohemia in Pilsen, 2024) Horák, Lukáš; Krystek, JanIn the numerical simulation of adhesive joints, a significant challenge lies in obtaining reliable experimental data due to the wide variety of adhesives available, each with distinct material properties and different material models. This study focused on testing the methodology for obtaining mechanical parameters using bulk adhesive specimens. The experiments were conducted on a brittle adhesive, specifically Araldit AV 138+HY 998, which was selected as a representative material for structural adhesives. The study also evaluated fracture parameters, including the strain energy release rate, an essential parameter for predicting the fracture behavior of adhesive joints. By focusing on a specific adhesive material, this study aimed to obtain its mechanical parameters and use them in numerical simulations.Item Acoustic properties of porous metamaterials featured by acoustic streaming - homogenization based modelling(2024) Rohan, Eduard; Moravcová, FannyWe consider secondary effects induced by acoustic waves in viscous barotropic fluids saturating pores in elastic, or rigid scaffolds with elastically suspended particles. The asymptotic homogenization method is applied to derive models of the acoustic wave propagation and of the related acoustic streaming (AS) as the secondary effect. This phenomenon originating due to the nonlinearity (divergence of the Reynolds stress) in the Navier Stokes equation is retained using the perturbation analysis. This yields the first and the second order sub-problem enabling to linearize the model governing fluid dynamics. The local AS in the microstructure produces forces acting on the suspended particles, transforming the pore geometry, hence, modulating the acoustic properties. As the consequence, the permeability involved in both the subproblems is modified due to the slowly oscillating particles. The sensitivity analysis can be employed to introduce the homogenized coefficients of the model depending on the particle motion.
Item Geometric multiscale blood flow modelling with patient-specific applications(University of West Bohemia in Pilsen, 2025) Augustiňák, Tomáš; Vimmr, Jan; Jonášová, AlenaThis contribution concerns several applications of geometric multiscale modelling of blood flow in compliant arteries of the human body. A multiscale model is formed from zero- and one-dimensional submodels by connecting them in a suitable way. All of the presented results were computed using a finite volume program developed by the author. Said software was verified against results published in literature and further applied to several cases. The first application describes an estimated influence of vascular aging manifesting itself in decreased arterial compliance. Further application shows a patient-specific model whose parameters were estimated to fit measured quantities. Last but not least, a comparison of a traditional constitutive relation of the vascular wall to a novel one based on a neo-Hookean material subject to large deformations is presented.Item Acoustic metamaterials with flexoelectric or piezoelectric microstructures incorporating electric circuits(University of West Bohemia in Pilsen, 2025) Rohan, E.; Cimrman, R.; Adámek, Vítězslav; Jonášová, Alena; Plánička, StanislavItem The finite element analysis of pelvic ring osteosynthesis(University of West Bohemia in Pilsen, 2025) Lobovský, L.; Karbanová, A.; Mařík, L.; Mandys, T.; Salášek, M.; Křen, J.; Adámek, Vítězslav; Jonášová, Alena; Plánička, StanislavItem On the modelling of patient-specific exercise stress tests based on tunable multiscale blood flow models(University of West Bohemia in Pilsen, 2025) Jonášová, A.; Vimmr, J.; Plánička; Adámek, Vítězslav; Jonášová, Alena; Plánička, StanislavItem Efficient simulations of multibody systems with clearances using reduced interface modelling(University of West Bohemia in Pilsen, 2025) Hrabačka, M.; González, F.; Hajžman, M.; Rodríguez, A. J.; Bulín, R.; Adámek, Vítězslav; Jonášová, Alena; Plánička, StanislavItem Deformation gradient evaluation in a particle-based approach for soft material simulation(University of West Bohemia in Pilsen, 2025) Hansen, H.; Heczko, J.; Hajžman, M.; Adámek, Vítězslav; Jonášová, Alena; Plánička, StanislavItem Periodical solution of nonlinear vibrating systems with n-DOF(University of West Bohemia in Pilsen, 2025) Dupal, J.; Adámek, Vítězslav; Jonášová, Alena; Plánička, StanislavItem Vortex-induced dynamic interaction between two coupled systems using reduced models(University of West Bohemia in Pilsen, 2025) Byrtus, M.; Dyk, Š.; Adámek, Vítězslav; Jonášová, Alena; Plánička, StanislavItem Prediction of steady-state flow in a 3D domain using a convolutional neural network(University of West Bohemia in Pilsen, 2025) Bublík, O.; Heidler, V.; Vimmr, J.; Adámek, Vítězslav; Jonášová, Alena; Plánička, StanislavItem Geometric multiscale blood flow modelling with patient-specific applications(University of West Bohemia in Pilsen, 2025) Augustiňák, T.; Vimmr, J.; Jonášoví, A.; Adámek, Vítězslav; Jonášová, Alena; Plánička, StanislavItem Towards an agreement between the numerical simulations and the experimental data obtained in a transonic linear turbine blade cascade for flutter testing(MATEC Web of Conferences, 2025) Tsymbalyuk, Volodymyr; Eret, Petr; Sláma, Václav; Hron, David; Peterka, Tomáš; Macálka, Aleš; Ira, JiříThe paper reports on the progress in the agreement between the results of numerical simulations and the experimental data obtained in a transonic linear turbine blade cascade for flutter testing. The outcomes show that previously omitted details in CFD geometry have a detrimental impact on the results, and their implementation reduces the difference between the two approaches tested. In detail, small gaps between the wind tunnel wall and the blades are introduced in the numerical model according to the experimental setup. Experimentally evaluated and computed aerostatic and aerodynamic forces and moments are compared. The findings show reasonable agreement and suggest promising advances in numerical data validation.Item Transitions to chaos of kinematically excited bistable magnetic pendulum(Institute of Thermomechanics of the CAS, v.v.i Prague, 2024) Byrtus, Miroslav; Smolík, LubošThe paper investigates the dynamic behaviour of a bistable system which is represented by a magnetic pendulum fixed to a moving plate. Bistable systems are often employed in energy harvesting or vibration attenuation issues because of their broad-band high-amplitude response. Here, the transitions to chaotic response are investigated both numerically and experimentally.Item Effective piezoelecric behaviour due to flexoelectric microstructure - homogenization based modelling(University of West Bohemia, 2024) Rohan, EduardThe flexoelectricity is a property of all dielectric materials, occurring in both centrosymmetric and asymmetric crystals when strain gradient is generated. Conversely, also a "hyperstress" is generated due to gradient of electric field, contributing to the material stiffness. Both these direct and reverse effects appear at small scales, rather then at the ``macrolevel''. The aim of the present study is to explore behaviour of weakly flexoelectric periodically heterogeneous materials. For this, the asymptotic homogenization method is employed. We consider piezoelectric or dielectric materials with a weak flexoelectric property, constituting the skeleton of general periodic porous structures which enable to generate the strain gradients. Using the asymptotic homogenization, it is shown that effective behaviour of such materials is piezoelectric, whereby the homogenized piezoelectric coefficients are computed using the characteristic responses of the flexoelectric microstructure. Analytic result is derived for a 1D periodic rods designing a porous structure.Item Exploration of workspace of active tensegrity structures using actuation planning process(The Korean Society of Mechanical Engineers, 2024) Hrabačka, Martin; Bulín, Radek; Hajžman, Michal; Rendl, Jan; Polach, PavelThis paper focuses on creating a methodology for workspace exploration of tensegrity manipulators consisting of stiff struts in compression and compliant cables in tension. The actuation of the structure is done via changing rest lengths of cables. The work includes an introduction to tensegrity structures, an explanation of the methodology for workspace exploration, and an illustration of the procedure on the example structure.Item Trajectory planning and control of manipulators based on tensegrity structures with manipulability and modal properties optimization(University of West Bohemia, 2024) Halamka, Vojtěch; Hrabačka, Martin; Zavřel, Jan; Beneš, Petr; Hajžman, Michal; Šika, ZbyněkThis paper presents a control methodology for robots based on tensegrity structures with redundant actuators. This methodology is divided into two tasks: trajectory planning and shape control. The basis of the trajectory planning is the workspace exploration using the Dynamic Relaxation method, followed by the interpolation and key manipulator properties optimization of the rod angles and the cable forces with respect to the desired end-effector trajectory. The Computed Torque Control method extended with Singular Value Decomposition is used for the shape control. The methodology is demonstrated on a virtual prototype of planar manipulator. The values of the tracking errors of the end-effector trajectory confirm its functionality.Item Numerical simulations of pantograph and catenary interaction considering imperfect joints(The Korean Society of Mechanical Engineers, 2024) Hajžman, Michal; Bulín, Radek; Hrabačka, Martin; Smolík, Luboš; Byrtus, MiroslavCatenary systems, utilized in the railway industry for transmitting electrical energy to a vehicle, consist of support poles and wires. Resolving dynamic issues related to the interaction between a pantograph and catenary systems poses another challenge. Key aspects involve a moving load on the contact wire due to the pantograph and nonlinearities arising because droppers can transmit force only under tension.The introduction of imperfect joints in the pantograph of an electric rail vehicle introduces a significant challenge in accurately modelling its behaviour. Imperfect joints can result in non-ideal connections, leading to deviations from the expected motion and performance. To address this issue, a comprehensive approach utilizing a multibody dynamics methodology was employed.
