Strength and fatigue life evaluation of composite laminate with embedded sensors

Abstract

Prognosis regarding durability of composite structures using various Structural Health Monitoring (SHM) techniques is an important and challenging topic of research. Ultrasonic SHM systems with embedded transducers have potential application here due to their instant monitoring capability, compact packaging potential toward unobtrusiveness and noninvasiveness as compared to non-contact ultrasonic and eddy current techniques which require disassembly of the structure. However, embedded sensors pose a risk to the structure by acting as a flaw thereby reducing life. The present paper focuses on the determination of strength and fatigue life of the composite laminate with embedded film sensors like CNT nanocomposite, PVDF thin films and piezoceramic films. First, the techniques of embedding these sensors in composite laminates is described followed by the determination of static strength and fatigue life at coupon level testing in Universal Testing Machine (UTM). Failure mechanisms of the composite laminate with embedded sensors are studied for static and dynamic loading cases. The coupons are monitored for loading and failure using the embedded sensors. A comparison of the performance of these three types of embedded sensors is made to study their suitability in various applications. These three types of embedded sensors cover a wide variety of applications, and prove to be viable in embedded sensor based SHM of composite structures.

A Review of Acoustic Impedance Matching Techniques for Piezoelectric Sensors and Transducers

“…As thin films ranging from few micrometers to nanometers, they have seen growing use in applications such as force microscopy [ 15 ], nano-positioning [ 16 ], micromechanical systems (MEMS) [ 17 , 18 , 19 ] and nanoelectromechanical systems (NEMS) [ 20 , 21 ], energy harvesters [ 22 , 23 ], etc. Some well-known applications of thin films are MEMS microphone [ 24 ], headphone [ 24 ], loudspeaker [ 24 , 25 , 26 ], acoustic emission sensor [ 27 , 28 ], vibration sensor [ 10 , 14 ], inertial sensor [ 19 ], tactile sensors [ 29 , 30 , 31 ], power harvesting [ 32 , 33 ], ultrasound transducers [ 34 , 35 , 36 , 37 , 38 ], and guided wave sensors [ 39 , 40 , 41 ]. Thin films are preferably made of nontoxic piezopolymers or piezocomposites.…”

Polymer and ceramic nanocomposites for aerospace applications

“…These sensors and piezoelectric transducers prove costly to monitor large aircraft structures. The cost-effective piezoresistive nanocomposite sensors serve as an alternative to such conventional sensors (Rathod et al 2014;Sundararaman et al 2015). Piezoresistive nanocomposites contain conductive nanofillers like CNT and CB that imparts conductivity.…”

“…To facilitate the processing, piezoelectric PMNCs have been developed (Jain et al 2014;Rathod et al 2014). Nanocomposites also possess structural and electrical properties that can be tailored by controlling its composition to make them suitable for transducer applications.…”