Lidé na fakultě
Ing. Jaromír Kylar

rozklikni NABÍDKU

Publikace

informace pocházejí z univerzitní databáze V3S

Autoři:
Ing. Jan Šleichrt, Ph.D.; Ing. Jan Falta; Ing. Jaromír Kylar; Ing. Vojtěch Kotek; Ing. Václav Rada; doc. Ing. Tomáš Fíla, Ph.D.
Publikováno:
2025, Measurement: Sensors, p. 1-7), ISSN 2665-9174
Anotace:
In this contribution, we introduce a control system and instrumentation of the in-house developed dynamic testing device with linear motors suitable for experiments ranging from quasi-static regime up to intermediate strain rates with impact velocities of up to 8 m/s. In the contribution, we demonstrate the temporal resolution of the whole system to perform dynamic experiments with closed-loop control of displacement, velocity, or force within a period of a few milliseconds. Frequency bandwidth and testing capabilities of standard membrane pancake load-cells as well as quartz-based piezoelectric load-cells for impact testing are analysed. The system is combined with high-resolution optical inspection, high-speed photography, or even X-ray imaging. The advantages of the device and instrumentation are demonstrated in a case study revealing its potential.
DOI:
10.1016/j.measen.2024.101674
Typ:
Článek v odborném recenzovaném periodiku

Autoři:
doc. Ing. Petr Zlámal, Ph.D.; Ing. et Ing. Radim Dvořák; Ing. Jan Falta; Ing. Petr Koudelka, Ph.D.; Ing. Ján Kopačka, Ph.D.; Ing. Jaromír Kylar; prof. Ing. Ondřej Jiroušek, Ph.D.
Publikováno:
2025, Measurement: Sensors, ISSN 2665-9174
Anotace:
Hopkinson pressure bar is a commonly used technique to test the response of a specimen to shock load under constant strain rate to determine its material parameters. In addition to that, we propose that the Hopkinson bar apparatus can be employed to test the response of the specimen in the sense of frequency analysis; that is, specimens made of a complex metamaterial could behave as a filter of specific frequencies. Here, several difficulties arise. The structure of the metamaterial affects only those waves that have a wave length comparable to the specific length in the metamaterial of the specimen. However, the bar geometry of the apparatus itself behaves as a low-pass filter, so the high frequencies are attenuated with distance traveled. Hence, here we have the situation that the longer the specimen is, we lose the ability to investigate high frequencies, and, at the same time, the shorter the specimen is, the higher the lowest affected frequency is. Our contribution is to find a compromise for the length of the sample and to design a high-frequency testing method for such an investigation of metamaterials.
DOI:
10.1016/j.measen.2024.101673
Typ:
Článek v odborném recenzovaném periodiku