Delamination detection in composites using wave modulation spectroscopy with a novel active nonlinear acousto-ultrasonic piezoelectric sensor

Abstract

A novel structural health monitoring (SHM) methodology, based on nonlinear wave modulation spectroscopy, is presented for the detection of delamination cracks in composites. The basic element is a novel active nonlinear acoustoultrasonic piezoelectric sensor enabling low-cost and wide-frequency operational bandwidth. The active sensor configuration involves two piezoceramic wafer actuators, each one excited with a low-and high-frequency signal respectively, and a piezoceramic sensor, all permanently bonded on the tested structure. Experiments are conducted on two sets of composite strips containing delamination cracks of different sizes. Measured results illustrate first the efficiency of the nonlinear ultrasonics methodology to detect delamination cracks, as well as, the potential and benefits of the new active sensor. The sensitivity of the active sensor response to the crack size and the applied high-frequency carrier signals at the actuators, vary at various frequency and voltage levels indicating the appropriate testing setup. Additionally repeatability of proposed SHM methodology is studied.

2D finite element modeling of the non-collinear mixing method for detection and characterization of closed cracks

“…If the two excitation sources are independent, then the modulation is due only to the nonlinear behavior of the sample. NWMS has successfully been applied to detect closed cracks in steel [18,19], aluminum [20,21] or delaminations in composite material [22,23]. However, classical material nonlinearity can also lead to wave modulation, which makes distinguishing closed cracks difficult.…”

Noncontact fatigue crack visualization using nonlinear ultrasonic modulation

“…A fatigue crack in an aluminum plate was detected using a piezoelectric (PZT) stack actuator for generation of a low frequency (LF) input and a surface-mounted PZT for creation of a high frequency (HF) input [11]. The usage of two surface mounted PZTs for generation of both LF and HF high-voltage inputs was investigated to detect boltloosening in an aluminum lap joint and delamination in composites [12][13]. Yoder and Adams fixed the frequency of the LF input and swept the HF input to find an optimal combination of the HF and LF frequencies that can amplify the modulation level [14].…”

Nonlinear vibroacoustic wave modulations for structural damage detection: an overview

“…More recently, the technique has been applied to detect barely visible impact damage in laminated composites 51,52,61,65,66 composite sandwich panels with a Nomex honeycomb core 55,88 and polyurethane foam core, 57 chiral panels, 53,89 cracks in wind turbine blades, 62 and composite airframe components. 82 …”