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Crack identification through dynamic frequency shifts in steel wide flange beams
Free vibration analysis of frequency shifts in vibration signatures of simply supported steel wide flange beams having transverse flange cut(s) is the objective of this research work. Fibration measurements of defective wide flange beams are used to relative measured frequencies to crack depth and location. Frequency response data were collected and evaluated using accelerometers placed on wide flange beams for varying beam sizes, spans, crack locations, and crack sizes. Our results confirm earlier research in terms of limited global frequency shifts even after 50 % reduction in the flange cross-sectional area. However, higher order local frequency shifts are found to be sensitive to a small single crack. From the measured frequencies, the crack depth and location can be found with satisfactory accuray. The main thrust of the proposed nondestructive dynamic characterization method is that initially, peak frequencies are calculated using beam bending, stretching, and torsional vibrational frequency equations and good correlations are noted with the experimental data for undamaged wide flange sections. Later, a portion of the flange is treated as a plate of varying boundary conditions under free vibration to study the frequency shifts due to a crack in the flange. Efforts are underway to correlate the frequencies of damaged sections representing a crack as a massless spring of infinitesimal length which requires only spring stiffness to define the damage.
Crack identification through dynamic frequency shifts in steel wide flange beams
Free vibration analysis of frequency shifts in vibration signatures of simply supported steel wide flange beams having transverse flange cut(s) is the objective of this research work. Fibration measurements of defective wide flange beams are used to relative measured frequencies to crack depth and location. Frequency response data were collected and evaluated using accelerometers placed on wide flange beams for varying beam sizes, spans, crack locations, and crack sizes. Our results confirm earlier research in terms of limited global frequency shifts even after 50 % reduction in the flange cross-sectional area. However, higher order local frequency shifts are found to be sensitive to a small single crack. From the measured frequencies, the crack depth and location can be found with satisfactory accuray. The main thrust of the proposed nondestructive dynamic characterization method is that initially, peak frequencies are calculated using beam bending, stretching, and torsional vibrational frequency equations and good correlations are noted with the experimental data for undamaged wide flange sections. Later, a portion of the flange is treated as a plate of varying boundary conditions under free vibration to study the frequency shifts due to a crack in the flange. Efforts are underway to correlate the frequencies of damaged sections representing a crack as a massless spring of infinitesimal length which requires only spring stiffness to define the damage.
Crack identification through dynamic frequency shifts in steel wide flange beams
Rißerkennung durch dynamische Frequenzverschiebungen in Breitflanschstahlträgern
GangaRao, H.V.S. (author) / Shoukry, S.N. (author) / Petro, S.H. (author)
1994
9 Seiten, 6 Bilder, 1 Tabelle, 16 Quellen
Conference paper
English
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