Evaluation of the sensitivity and fatigue performance of embedded piezopolymer sensor systems in sandwich composite laminates

Abstract

Evaluation of the sensitivity and fatigue performance of embedded piezopolymer sensor systems in sandwich composite laminates AbstractIt has been claimed that embedding piezoceramic devices as structural diagnostic systems in advanced composite structures may introduce mechanical impedance mismatches that favor the formation of intralaminar defects. This and other factors, such as cost and their high strain sensitivity, have motivated the use of thin-film piezopolymer sensors. In this paper, we examine the performance of sandwich composite panels fitted with embedded piezopolymer sensors. Our experiments examine both how such thin-film sensors perform within a structure and how the inclusion of sensor films affects structural performance. Strain-controlled tests on sandwich panels subjected to three-point bending under wide-ranging static and dynamic strains lead us to conclude that embedding thin piezopolymer films has no marked reduction on the tensile strength for a wide range of strain loading paths and magnitudes, and that the resilience of the embedded sensor is itself satisfactory, even up to the point of structural failure. Comparing baseline data obtained from standard surface-mounted sensors and foil gauges, we note that whereas it is possible to match experimental and theoretical strain sensitivities, key propertiesespecially the pronounced orthotropic electromechanical factor of such films-must be duly considered before an effective calibration can take place.

On the manufacturing, integration, and wiring techniques of in situ piezoelectric devices for the manufacturing and structural health monitoring of polymer–matrix composites: A literature review

“…PVDFs and piezo films, in general, can be used for this purpose. PVDF films were embedded inside and on the surface of the lower skin of sandwich composite panels to perform strain measurement during static and dynamic three-point bending tests (Chrysochoidis and Gutie´rrez, 2015). In situ PVDFs were shown not to be intrusive (no marked reduction in tensile specimens' strength) and were able to give information during the cyclic tests as their sensitivity (mstrain/Volt) was increasing until final failure of the specimens.…”

“…All the studies used commercially available PVDF (films or powders) as raw material for the sensors. Films can be industrially poled (Caneva et al, 2008;Chrysochoidis and Gutie´rrez, 2015;De Rosa and Sarasini, 2010;Guzman et al, 2013;Mills, 2013;Park et al, 2005), wired (riveted lead wires; Guzman et al, 2013;Mills, 2013) or metallized (Bellan et al, 2005) beforehand.…”

“…Bellan et al (2005) used a laser ablation process to create an interdigitated pattern on a gold film to obtain interdigitated electrodes (IDE) on the surface of their P(VDF-TrFE) films. Silver-ink screen-printed electrodes (Caneva et al, 2008;Chrysochoidis and Gutie´rrez, 2015;De Rosa and Sarasini, 2010) can also be used to connect the PVDF films to thin wires with the use of adhesive copper strips (Chrysochoidis and Gutie´rrez, 2015) or conductive silver epoxy resin (De Rosa and Sarasini, 2010). Another option is the use of chemical vapor deposition (CVD) to deposit copper layers on both sides of the piezo film (Park et al, 2005).…”

Capacitance measurements on integrated conductors for detection of matrix cracks in GFRP

“…As in concrete, capacitative imaging with coplanar non-contact electrodes can also be used for moisture or damage detection and localisation in different FRP composites as CFRP, honeycomb structures and GFRP [25,26]. Recently, piezoelectric sensors embedded in FRP have also been used as capacitance sensors [27,28] instead of just as acoustic emission [29,30] or voltage sensors [31][32][33][34] as established by many research groups (review in [35]). It was shown that capacitance measurements on embedded piezoelectric transducers are in good agreement with loading and unloading trends in different tensile tests on GFRP [28].…”

Integration of piezoelectric transducers (PZT and PVDF) within polymer-matrix composites for structural health monitoring applications: new success and challenges

“…Research have already been conducted in this area [16][17][18][19][20][21]23,34,35,39,[41][42][43][44][45][46][47][48], but this article stands out of them for several reasons. First, the authors used the embedded piezoelectric transducer as a capacitance sensor and not otherwise, such as an AE sensor [16,17,[19][20][21]23,34,39,43] or an electric charge sensor [41,42,44,45] to perform in-situ and real-time SHM. Finally, the use of a multi-instrumentation comprising various NDT techniques, and the combination of their signals with the transducer capacitance signature to perform SHM have never been realized until now according to the authors.…”