Studies on the loose part evaluation technique

Enhancement of Impact Mass Estimation Algorithm for a Plate Type Structure

“…Accordingly, the impact mass can be obtained by using the 'FR versus mass' diagram previously obtained by an experiment. 4) It is noteworthy that both the center frequency and FR methods assess the impact mass by utilizing the frequency spectra of the impact response signal. Thus these techniques are only reliable when the multi path effect of the propagating response signal is negligible and the signal has a high signalto-noise ratio (SNR).…”

“…[1][2][3][4] Presently, many a new source localization method has been developed and successfully applied in the industry. [5][6][7] However, the mass estimation problem has not been as successful as the localization one.…”

Mass Estimation of Impacting Objects Against a Structure Using an Artificial Neural Network Without Consideration of Background Noise

“…Using a whole set of raw APSDs will increase the complexity of the ANN model and lead to deterioration of its estimation performance. For this reason, a portion of the information in the APSD such as the FR value [8] or four-band representative values [9] have been used for the mass estimation of an impact object. For finding a considerable feature vector representing the difference between APSD curves, this study proposes a process combining two methods: a smoothing technique and the discrete cosine transform.…”

“…The high frequency band is the range wherein features of the used sensor are dominant and the APSD pattern is rarely changed by external excitation. The FR method has a wide uncertainty range of approximately 0.7 decade for the estimated mass [8]. In addition, the user should select how to determine the maximum and minimum frequency limits for dividing the whole frequency range into low and high ranges.…”

“…Furthermore, it is assumed that the two colliding solid objects (two solid spheres or one solid sphere and one plate) are rigid, which is usually not true in the real world. Another approach is the frequency ratio (FR) method [8]. FR is defined as follows:…”