Energy dissipation caused by fatigue crack in beam-like cracked structures

In this study, free vibration of cracked beam in the first vibration mode was considered taking into account both the structural damping and the damping due to the presence of crack. Increased flexibility due to the presence of crack was modeled by a massless spring and the increased damping was modeled by a massless damper at crack location. Using continuous wavelet transform and based on exponential decay of the power of the wavelet transform, the damping coefficient and damping ratio of the beam was calculated. Applying the mechanical energy balance method, the time response of the cracked beam was calculated, and compared with the time response of experimentally tested beams; an optimization method was used to estimate the damping coefficient of crack and the share of the presence of crack in total energy dissipation was calculated. Results showed that the damping coefficient of crack increases by increase in crack depth as well as crack dimensionless location. Also, the share of crack in total energy dissipation depends on crack depth, crack location, and structural damping.