People
Ing. Jan Falta

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

Ing. Tomáš Doktor, Ph.D.; Ing. Jan Falta; Ing. Tomáš Fíla, Ph.D.

The unique feature of shear thickening fluid (STF), which shifts its phases from liquid state to solid state under dynamic loading, recently peaked attention in literature for shock absorbing systems or dashpots. Owing to phase shifting capability, employing STF as a vibration-damping system (VDS) can upgrade the performance of the structures under low probable dynamic actions (or accidental load). Therefore, a novel approach [i.e., STF-damped structural system] can tune the deficient structural system to a resilient one. Namely, an efficient, viable, and feasible rehabilitation solution for deficient structures can enhance the seismic performance of these structures by converting the kinetic energy of the shock into another energy form in the damper. To this end, the project proposes a novel approach, using STF to damp structural vibrations. Within the content of the project, STF working under a low strain rate and frequency is first synthesized. Then, the mechanical properties of the STF are obtained under dynamic load, which will be followed by a development of a damper filled with synthesized STF. Finally, real-time applications such as lab scale tests of STF dampers and computer simulations are targeted.

2024 - 2027

Program na podporu aplikovaného výzkumu a inovací SIGMA

Ing. Jan Falta; Ing. Nela Krčmářová; Ing. Jan Šleichrt, Ph.D.

Flash X-ray system and high speed X-ray imaging methods will be used to investigate the internal processes in the materials during dynamic loading. The developed experimental equipment will be employed for investigation in field of modern materials for ballistic and impact protection, personal protective equipment or aerospace/space applications, e.g., sandwiches, composite panels and metamaterials, and to characterize their fundamental mechanical processes like failure and fracture behavior, wave propagation and constituent materials interaction. Significant part of research will be aimed on experimental investigation of materials filled with dilatant fluid. In this field, the combination of X-ray flash system with instrumented dynamic experiments can reveal crucial aspects of their deformation behavior. The outputs of the project will provide an important insight into deformation behavior and will serve as an important basis for reliable numerical modeling of the related problems and for relevant optimization schemes during design process of state-of-the-art materials. The goal of the project is experimental investigation of state-of-the-art materials during impacts

2022 - 2026

JUNIOR STAR

Ing. Marcel Adorna; Ing. Tomáš Doktor, Ph.D.; Ing. Jan Falta; Ing. Tomáš Fíla, Ph.D.; Ing. Michaela Jurko; doc. Ing. Petr Zlámal, Ph.D.; Ing. Jan Šleichrt, Ph.D.

The goal of the project is to develop and experimentally validate a new structural panel for energy absorption applications with unique properties based on polymeric cellular core and nanocrystalline metal coating. The strain-rate sensitivity of the strut material (polymeric foam and auxetic) will be achieved by micro inertia of the coated framework showing a stretching- induced additional amount of energy dissipation. Design optimization of such a structure requires in-deep investigation of the deformation behavior for the given specific impact conditions. Advanced numerical modelling will be performed at all structural levels, from cell wall mechanics up to whole panel behaviour. For this, a combination of several experimental methods (micro-CT, static compression, drop tests, SHPB and gas gun experiments) will be used. The experimental results will be used to validate our FE models describing the deformation behaviour at small to high velocity impacts. The project is building upon our previous experiences with numerical/experimental optimization of metal foams and auxetics.

2019 - 2021

Standard projects

Ing. Tomáš Doktor, Ph.D.; Ing. Jan Falta; Ing. Michaela Jurko

Konference 17th Youth Symposium on Experimental Solid Mechanics (YSESM2019) navazuje na předchozí pravidelné setkávání mladých vědeckých pracovníků, doktorandů a studentů z oblasti především experimentální mechaniky. Organizace konference po pěti letech opět připadla české straně. Vzhledem k dlouhé tradici konference (17. ročník) a poměrně velkému počtu zúčastněných institucí ze zemí střední Evropy se pro ČVUT jedná o akci prestižní a významnou především s ohledem na utváření mezinarodních vazeb mezi začínajícími výzkumníky. Konference je spolupořádána Ústavem teoretické a aplikované mechaniky AV ČR a časově i místem konáni navazuje na High-Resolution 3D X-ray Imaging Workshop, na který budou mít registrovaní účastníci YSESM volný přístup. Program konference je koncipován tak, aby nebylo nutné organizovat paralelní sekce. Účastníci přednesou své krátké (10 min) ústní referáty, které budou po skončení příslušné sekce následovány diskuzí u posterů. Tento koncept se v minulých ročnících osvědčil a dopomohl vzniku či dalšímu rozvoji spolupráce mezi jednotlivými účastníky a jejich domovskými institucemi. Publikačním výstupem konference bude sborník jednostránkových abstraktů, který bude k dispozici před zahájením konference a především pak samostatné číslo Acta Polytechnica CTU Proceedings (indexované WoS) kde budou publikovány plné texty příspěvků. Všechny příspěvky projdou před publikováním standardním peer-review procesem, pro nemalou část účastníků prvním v jejich publikační činnosti. Tematické zaměření konference zahrnuje zejména - Pokročilé experimentální metody mechaniky kontinua a mechaniky tekutin - Nedestruktivní zkoušení - Lomová mechanika, poruchy materiálu - Biomechanika - Hybridní numericko-experimentální metody - Problematika technologických procesů - Aditivní výroba

2019 - 2019

Studentská vědecká konference ČVUT - SVK 44/19/F6

prof. Ing. Josef Jíra, CSc.

The subject of the proposed project is the analysis and realization of reactive force measurements during fast dynamic processes on split Hopkinson pressure bar and its modifications. Initial part of the project is the design and realization of components related to the recording reactive force of deformation pulse by load cells in cooperation with existing instrumentation using strain gauge sensors. The experimental part will include design, manufacture and subsequent adaptation of the load cells to the given measuring devices, further calibration to verify the applicability and accuracy of the solution. In the final phase of the project, the different methods of recording reaction forces will be compared with the existing and newly implemented sensors. The results of this project will serve to optimize the measurement of the properties of advanced materials in the field of dynamic loads usable in transport and other applications.

2018 - 2019

Studentská grantová soutěž ČVUT - SGS18/154/OHK2/2T/16