People
Ing. et Ing. Radim Dvořák

Ing. et Ing. Radim Dvořák; doc. Ing. Petr Zlámal, Ph.D.

Project is aimed at precise simulations for training of physics-informed machine learning schemes in optimization of materials with respect to deformation energy mitigation. Advanced finite element simulations methods with state-of-the-art techniques of dynamic testing are combined for investigation of intermediate and high strain rate impact response of materials with complex internal structure in relation to machine learning applications. The investigated materials are additively manufactured structures, including auxetic lattices, and inter-penetrating composites. Experimental methods involve flash and high-speed X-ray radiography togetherwith high speed visible-light and infrared cameras. The numerical methods using finite element methods with explicit time integration will enable physically accurate simulations of loading scenarios and in-house solver for unprecedented insight into wave propagation in materials during impact will be developed. Moreover, simulations of radiographical methods will allow tosimulate all aspects of experiments.

2025 - 2027

Standard projects

Ing. et Ing. Radim Dvořák; Ing. Jan Falta; prof. Ing. Ondřej Jiroušek, Ph.D.; Ing. Ján Kopačka, Ph.D.; Ing. Petr Koudelka, Ph.D.

The project is aiming to control the stress wave propagation in additively produced metal components composed of at least two different metals with spatially shaped and multiple interfaces produced by laser powder bed fusion. This enables to control of internal arrangement and shaping of the interface between the two materials. Dynamic loading with different strain rates using Hopkinson pressure bars will be used to describe the stress wave propagation and kinetic energy absorption. At the same time, theoretical and numerical modelling of wave reflection/transmission will be performed on various geometrically arranged interfaces. Innovative numerical tools for advanced multi-material optimization of nested spatial structures will be developed for wave process control. The results will answer the questions of whether it is possible to control the propagation of stress waves by means of multi-material 3D metal printing, and what geometrical and mechanical parameters have a fundamental influence on the attenuation and concentration of stress waves.

2024 - 2026

Standard projects

prof. Ing. Ondřej Jiroušek, Ph.D.

The proposed project deals with the development of innovative and robust numerical dynamics methods specialized for solving high-speed impact problems. In the first phases of the project, the objective will be to complete a finite element method (FEM) solver considering nonlinear material models and large deformations with an implemented method for domain (spatial) decomposition via Localized Lagrange Multiplier Method (LLM), which will allow robust parallelization of the computations. The benefits of parallelization lie in the potential to solve complex nonlinear problems of millions of degrees of freedom in acceptable time period. The LLM method will be applied for coupling domains of different dimensions (typically 1D and 3D), allowing the structure of modern materials to be directly modelled, rather than using homogenised constitutive models. In the area of time discretization, advanced methods for direct time integration will be developed. Namely, an asynchronous integration algorithm will be generalized to allow computations to be performed on individual domains with their own time step, and a procedure considering Helmholtz decomposition of the displacement field will be developed to separately compute longitudinal and shear waves that differ in phase velocity and hence in the critical time step that enters the computation. These procedures have a critical impact on the quality of the solution of dynamic impact problems using FEM and direct time integration, which is prone to dispersion. The synergy of parallel computation, mastered domain decomposition using LLM, and the use of innovative methods for direct time integration will enable direct and precise computation of materials of complex structures by large-scale numerical models, e.g., even with time-varying material parameters (piezoelectricity). In the advanced phases of the project, the primary focus will be on smooth particle hydrodynamics (SPH) method, material point method (MPM), particle finite e

2022 - 2024

Studentská grantová soutěž ČVUT - SGS22/196/OHK2/3T/16

Ing. Michal Bartošák, Ph.D.; Ing. et Ing. Radim Dvořák; Ing. Jiří Halamka; Ing. Ondřej Havlíček; Ing. Jiří Hlavnička; Ing. Radek Skácelík

The project is focused on research of modeling of metals degradation with the use of finite element method. Effects of multiaxial mechanical loading and temperature will be incorporated. Main objectives of the research project will be low-cycle fatigue and ductile damage behavior. Interaction between creep and fatigue and thermo-mechanical fatigue will be studied in the framework of the project. New experimental results will be obtained in the scope of this project, and they will be supplemented by experimental results obtained from other projects. The experimental results will be used for the identification of parameters and for the research of the material models.

Department of Mechanics, Biomechanics and Mechatronics

2021 - 2023

Studentská grantová soutěž ČVUT - SGS21/150/OHK2/3T/12