Browsing by Subject "damping coefficient"

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Access status: Open Access ,
Facility for investigating the vibration of the plate with magnetorheological fluid
(2012) Snamina, Jacek
This study briefly outlines the structure of the test facility for investigating the behaviour of a sandwich plate filled with magnetorheological (MR) fluid. The plate has two outer layers made of aluminium and the space between them is filled with MR fluid. The test facility is engineered within the framework of the research project focused on vibration reduction in beams and plates using MR fluids. The paper outlines the design of the test facility and the measurement equipment. Measurement data are summarised, including the free and forced vibration of the plate.
Access status: Open Access ,
Influence of cooling rate on the structure and damping properties of the AlSi6Cu4 alloy
(AGH University Press, 2025) Piwowarski, Grzegorz; Ogrodnik, Mateusz
The investigated alloy was cast as a shaft into seven casting molds. Casting molds made of different materials were char acterized by different abilities to conduct heat from the sample. This property significantly influenced the cooling rate of the sample casting from the AlSi6Cu4 alloy. The highest cooling rate was achieved in a steel mold at 25°C and the lowest in a mold made of insulating mass. Different cooling rates significantly influenced the structure of the alloy. Different grain sizes were obtained and the morphology of the microstructure components changed. At the highest cooling rate of 16.63 K·s?1, a grain with an average size of 0.58 mm was obtained. However, in the mold with the lowest cooling rate of 0.36 K·s?1, the average grain size was 3.76 mm. Changes in the structure of the alloy also influenced its damping prop erties. The tested values f the vibration damping coefficient ? indicated that the AlSi6Cu4 alloy cooling with the highest cooling rate has the highest value of damping coefficient. This is influenced by the grain size and shape of the silicon pre cipitates. The refinement structure and fragmented components effectively disperse the vibration wave in the structure of the casting alloy.
Access status: Open Access ,
The influence of cooling rate on the damping characteristics of the ZnAl4Cu1 alloy
(AGH University Press, 2022) Piwowarski, Grzegorz; Gracz, Beata
The paper presents the results of damping coefficient tests on the ZnAl4Cu1 alloy (ZL5). The damping coefficient has been calculated on the basis of specimen measurements obtained with the use of the signal echo method. The method consists in passing an ultrasonic wave through the tested material. The ultrasonic wave from a transmitting and receiving head passes through a specimen, bounces off its bottom surface and comes back to the measuring head in the form of a signal echo. The difference in the signal intensity between the first and the second echo in relation to the distance travelled by the ultrasound wave is avalue of the material's damping characteristics. The specimens were cast into three molds made of different materials, i.e. green sand, plaster and metal. The thermophysical properties of these materials are different, affecting the rate of heat absorption from the cast. Three series of specimens have been obtained which have different cooling rates. The specimens were then subjected to ultrasound and microscopic tests to assess the alloy structure. The internal alloy structure affects its damping properties to a great extent.