In-Situ Monitoring, Identification and Quantification of Strain Deformation in Composites Under Cyclic Flexural Loading Using Nylon/Ag Fiber Sensor

Abstract

Despite having vast structural applications, Composites are not exempt from limitations and are susceptible to deforming during operation. Therefore, it is essential to develop in-situ monitoring systems to avoid their catastrophic failure or high repairing cost. So, the objective of this study was to monitor the deformation behavior of composites subjected to cyclic flexural deformation in real-time using a Nylon/Ag fiber sensor. Nylon/Ag fiber sensor was integrated at different direction i.e. 0°, +45°, 90°,-45° gradually between each ply of the composite specimens which were then machined in star shape where each leg signified the direction of the sensor. These specimens were then tested under cyclic flexural deflection at the strain rate of 2mm/min for 10 cycles. Mechanical results of composite specimens and electrical response of each Nylon/Ag sensor fiber showed excellent repeatability however, each Nylon/Ag fiber sensor showed a specific resistance behavior because of their respective position. The increase or decrease in the resistance of the fiber sensor signified the presence of tensile or compressive strain respectively and the intensity of the signal quantified the amount of deformation. The results confirmed that the fiber sensor showed good potential as flexible sensor reinforcement in composites for in-situ monitoring, identification and quantification of the deformation.

Study of mechanical performance of polymer nanocomposites reinforced with exfoliated graphite of different mesh sizes using micro-indentation

“…Including nano-fillers into polymers create a significant increase in their properties (electrical, thermal, and mechanical) and, consequently, their multifunctionality. [17][18][19][20][21] This enhancement of the composites performances 5 counts mostly on the filler source, filler type, preparation and treatment technique, 2 the nano-fillers particles size and shape, definite surface area, surface growth the degree, the energy of the surface, and the mode of nanoparticles partition into a polymer matrix. 16 In this case, several carbon additives have been used to improve the neat polymer proprieties.…”

Fabrication and electromechanical performance of carbon nanotube based conductive membrane and its application in real-time multimode strain detection in composites

“…So, it is important to discover novel methods for monitoring the deformation of the structure in realtime, and structural health monitoring (SHM) is a renowned and extensively used system to study the behavior of the structure in real-time to guarantee their reliability and safety [8]- [12]. Currently used SHM techniques include fiber optic sensors, piezoelectric or piezoresistive sensors, strain gauges, and accelerometers to monitor the mechanical deformation, vibrations, or other parameters of the structure during the operation [13]- [23].…”

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

“…In-situ monitoring, though, has some disadvantages, such as manufacturing/embedding difficulties [24], or intrusiveness risks as the integrated device may degrade the mechanical properties of the monitored part [25]. Different types of devices have already been embedded into composite structures to perform insitu SHM, such as optical fibers ( [26,27]: monitoring of cracks), or piezoresistive elements including conductive fiber reinforcement ( [28]: delamination identification), conductivecoated fibers ( [29]: strain monitoring under cyclic flexural loading), nanofillers ( [30]: relation electrical resistance vs. mechanical loading [31]: uniaxial tension-tension fatigue monitoring), Z-pins ( [32]: delamination crack surveillance), and tuft threads ( [33]: tufted 'Omega' stiffener monitoring). Piezoelectric devices are also particularly investigated in the in-situ SHM literature, with the use of PolyVinylidene Fluoride (PVDF) [34] or Lead Zirconate Titanate (LZT or PZT) [17] as primary base materials.…”