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Comparison of the damping properties of different strip steels at different frequencies.

Number: pap. 1411

Author(s) : TOFIQUE M. W., LOF A., MILLWARD C., et al.

Summary

The flapper valve is one of the most critical components of the reciprocating compressor. During the compressor’s service lifetime, the flapper valve has to open and close billions of times without failure or maintenance. Smooth and efficient operation of the compressors not only requires an optimized design of the valve but it also places high demands on its material. Material damping of the flapper valves in the reciprocating compressors positively influences the flapper valve operation by directly reducing the magnitude of the induced stress waves in the valve reeds. It has also been reported in several studies that material damping reduces the amplitude of fatigue stresses in components or specimens subjected to fatigue load conditions. The current study presents an investigation of the material damping properties of a range of hardened and tempered martensitic steels including the new flapper valve steel grade, Flap-X, developed by voestalpine Precision Strip AB. The tested materials included three flapper valve steel grades Flap-X, AISI 420 (SS716) and AISI 1095 (20C) along with two other thin strip materials: the S-Coat L+ tool steel and 13Cr 0.7C martensitic stainless steel grade known as UHB AEB-L. Material damping was measured using impulse excitation apparatus that measured the resonant frequencies and the loss rate of vibrations in the flexural mode in order to evaluate the material damping parameter (Q-1) at room temperature. Different frequencies were investigated in this study ranging from 50 Hz to approximately 10 kHz for all the tested materials. The measured material damping data for the tested materials showed that damping decreased with increasing frequency above 50 Hz up to around 2000 Hz and then stabilized until approximately 9000Hz. Material damping for the Flap-X grade was found to be higher than the SS 716 grade at all the measured frequencies and higher than all the tested grades at ~9000 Hz. The material damping of the 20 C grade was found to be the highest at 50 Hz while the UHB AEB-L grade displays the highest damping at 250 Hz and 2000 Hz. In addition, an attempt has been successfully made to fit the Rayleigh damping model to the obtained damping data. These results have significant implications for the impact fatigue stresses in the valves, their impact fatigue life and the noise levels they contribute to in the reciprocating compressors.

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Pages: 8

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Details

  • Original title: Comparison of the damping properties of different strip steels at different frequencies.
  • Record ID : 30024336
  • Languages: English
  • Source: 2018 Purdue Conferences. 24th International Compressor Engineering Conference at Purdue.
  • Publication date: 2018/07/09

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