Composites represent approximately 50% of the weight of structural parts in new aircraft as Airbus 350 or Boeing 787. Damages could occur on these parts and their monitoring is required for the safety of users. A Structural Health Monitoring system composed by a Lamb’s waves generator and a sensor is a privileged candidate to detect such damages. The flexibility of composite manufacturing allows the integration of such a system. The topic of this study is to optimize the integration of a Structural Health Monitoring system in aircraft structural parts. The present article focuses on the optimization of the integration method of a piezoelectric Lead Zirconate Titanate transducer into laminated composite (Carbon/Epoxy), cured in autoclave according to aircraft manufacturing requirements. The health state of the integrated transducer with three connecting methods is evaluated using X-ray scanning. Punctual stress is responsible for the crack of the transducer occurred during composite curing. The connecting method with aluminum sheet and silver joint is selected because it minimizes local stresses and keeps the transducer integrity. The cohesion between the integrated transducer and the host material is observed by optical microscopy, it shows the presence of void zones located in the PZT edges. A Laser Doppler Vibrometer scanning shows the ability of the integrated piezoelectric transducer to generate Lamb waves.

In the context of an embedded structural health monitoring (SHM) system, two methods of transducer integration into the core of a laminate carbon fiber-reinforced polymer (CFRP) are tested: cut-out and between two plies. This study focuses on the effect of integration methods on Lamb wave generation. For this purpose, plates with an embedded lead zirconate titanate (PZT) transducer are cured in an autoclave. The embedded PZT insulation, integrity, and ability to generate Lamb waves are checked with electromechanical impedance, X-rays, and laser Doppler vibrometry (LDV) measurements. Lamb wave dispersion curves are computed by LDV using two-dimensional fast Fourier transform (Bi-FFT) to study the quasi-antisymmetric mode (qA0) excitability in generation with the embedded PZT in the frequency range of 30 to 200 kHz. The embedded PZT is able to generate Lamb waves, which validate the integration procedure. The first minimum frequency of the embedded PZT shifts to lower frequencies and its amplitude is reduced compared to a surface-mounted PZT.