Application of Teager–Kaiser’s Instantaneous Frequency for Detection of Delamination in FRP Composite Materials

Abstract

Composite materials are widely used in many engineering applications and fields of technology. One of the main defects, which occur in fiber-reinforced composite materials, is delamination. It manifests itself in the separation of layers of material and the damaged structure once subjected to mechanical loads degrades further. Delamination results in lower stiffness and the decrease of structure’s carry load capability. Its early detection is one of the tasks of non-invasive structural health monitoring of layered composite materials. This publication discusses a new method for delamination detection in fiber-reinforced composite materials. The approach is based on analysis of energy signal, calculated with Teager–Kaiser energy operator, and comparison of change of the weighted instantaneous frequency for measurement points located in- and outside of delamination area. First, applicability of the developed method was tested using simple models of vibration signals, reflecting considered phenomena. Next, the authors’ weighted instantaneous frequency was applied for detection of deamination using signals obtained from FEM simulated response of the cantilever beam. Finally, the methods effectiveness were tested involving real experimental signals collected by the laser Doppler vibrometer (LVD) sensor measuring vibrations of the delaminated glass-epoxy specimens.

Frequency Estimation in DSOGI cells by means of the Teager Energy Operator

“…Then, by applying the continuous form of the TEO [10], given by This work has been supported by the Ministry of Science and Innovation through the project RTI2018-095138-B-C31:"Electrónica de potencia aplicada a la red eléctrica y a procesos industriales": PEGIA.…”

“…A novel approach is proposed here to estimate the grid frequency where only inner SOGI cell variables are used. To this extent, the Teager Energy Operator (TEO) [10] is used to evaluate the frequency of the signal across the SOGI cell and adjust the estimated grid frequency accordingly. The resulting SOGI-TEO cell is described in Section 2.…”

Application of the Combined Teager-Kaiser Envelope for bearing fault diagnosis

“…The properties of the operator have been discussed extensively in [26], [27] and [28]. The TKEO itself and the TKEO based measures have been already effectively applied to tasks including demodulation [29], [30] signal processing and diagnostics of gears and bearings [3], [31], [32], [33]. The energy operator also proved to be sensitive to impulses [34] which could be generated by faults.…”