Lidé na fakultě
Ing. Jaromír Kylar

2025, Institute of Theoretical and Applied Mechanics of the Czech Academy of Sciences, 31, p. 1-228), ISSN 1805-8248

Wave propagation in 3D printed metals is an area of research that focuses on the behavior of mechanical waves in metallic materials produced by additive technologies, specifically 3D printing. This process is increasingly being used to produce complex geometric structures that can exhibit different properties compared to traditionally manufactured materials. In this context, the focus is on how the structure of the printing material, the microscopic arrangement of particles, porosity, and anisotropy affect the wave behavior. The aim of the research is to understand how different printing parameters (e.g., layer orientation, material composition) affect wave propagation and how this knowledge can be applied for e.g., defect detection, sound insulation, or structures with optimized mechanical properties. This work focuses on the instrumentation of 3D printed samples with actuators and measurement labels, the creation of an experimental setup and the measurement of initial high frequency mechanical wave propagation experiments.

Článek v odborném recenzovaném periodiku cizojazyčně

2025, Measurement: Sensors, p. 1-7), ISSN 2665-9174

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.

Článek v odborném recenzovaném periodiku

2025, Measurement: Sensors, ISSN 2665-9174

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.

Článek v odborném recenzovaném periodiku