Simultaneous Application of Fibrous Piezoresistive Sensors for Compression and Traction Detection in Glass Laminate Composites

Abstract

This article describes further development of a novel Non Destructive Evaluation (NDE) approach described in one of our previous papers. Here these sensors have been used for the first time as a Piecewise Continuous System (PCS), which means that they are not only capable of following the deformation pattern but can also detect distinctive fracture events. In order to characterize the simultaneous compression and traction response of these sensors, multilayer glass laminate composite samples were prepared for 3-point bending tests. The laminate sample consisted of five layers of plain woven glass fabrics placed one over another. The sensors were placed at two strategic locations during the lay-up process so as to follow traction and compression separately. The reinforcements were then impregnated in epoxy resin and later subjected to 3-point bending tests. An appropriate data treatment and recording device has also been developed and used for simultaneous data acquisition from the two sensors. The results obtained, under standard testing conditions have shown that our textile fibrous sensors can not only be used for simultaneous detection of compression and traction in composite parts for on-line structural health monitoring but their sensitivity and carefully chosen location inside the composite ensures that each fracture event is indicated in real time by the output signal of the sensor.

New Textile Sensors for In Situ Structural Health Monitoring of Textile Reinforced Thermoplastic Composites Based on the Conductive Poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) Polymer Complex

“…Higher difference in electrical resistance values could not be observed at higher elongations, which confirms the coating uniformity achieved of treated yarns. Non-uniform coatings [ 66 ] tend to crack where there is a thin deposited layer. This causes a marked increase in electrical resistance whenever a conductive track breaks up.…”

Structural health monitoring of GFRP laminates using graphene-based smart strain gauges

“…The contour of the normalized resistance plot (DR/R) intimately follows that of the stress-strain plot. This feature has already been reported by the authors for similar sensors developed from nanocomposites [9,10,[50][51][52][53][54]. The ability of the sensors to map the deformation of composites with high fidelity makes them ideally suited for the purpose of structural health monitoring (SHM) as against traditional strain gauges.…”

“…Because of non-homogeneous nature of these materials, their failure mechanisms are different from those of metals and other conventional materials. For SHM of FRPs, conventional methods though applicable do not take full advantage of the unique opportunity accorded by composites, i.e., inclusion of extraneous sensors during manufacturing without significant changes to their original properties [9][10][11]. Thus, an embedded sensor once integrated provides information about the damage events for in situ structural health monitoring.…”

Screen-printed nanocomposite sensors for online in situ structural health monitoring

“…3 The fabrication of composite piezoresistive sensors and their integration during composite fabrication is one of the most suitable and cost-effective technique for continuous online structural health monitoring of aircraft structures whereby the change in resistance could be correlated to the strain. [4][5][6][7][8][9][10][11][12][13][14][15] The fabrication techniques are compatible with composite manufacturing processes and the sensitivities of these sensors could be tailored to achieve desired monitoring results. 4,5 In nanocomposites, a certain minimum concentration of conductive nanofillers is maintained to obtain the electrical conductivity.…”

“…[4][5][6][7][8][9][10][11][12][13][14][15] The fabrication techniques are compatible with composite manufacturing processes and the sensitivities of these sensors could be tailored to achieve desired monitoring results. 4,5 In nanocomposites, a certain minimum concentration of conductive nanofillers is maintained to obtain the electrical conductivity. It goes without saying that below this threshold, conductivity can't be achieved as conductive particles don't form "percolation networks."…”