Advances in Civil Engineering / 2010 / Article / Tab 1

Research Article

Integration of Networks of Sensors and Electronics for Structural Health Monitoring of Composite Materials

Table 1

List of some significant experimental contributions on the evaluation of the effects of integrated devices on the structural integrity of composite materials.

AuthorsDevices integratedMaterial studiedMain findings and conclusions

Warkentin, and Cawley 1991 [1]Circuits on silicon chipsGraphite/epoxy compositesNo change of in-plane mechanical properties. 15% reduction of the material strength.
Kim et al. 1992 [2]Simulated thermocouples with 0.381 mm wire diameter.
Simulated strain gauge Kapton film size: 10.16 mm 5.08 mm 0.127 mm
Quasi isotropic Fiberite T300/976 or Fiberite APC-2 graphite compositesNegligible effects on the strength in uniaxial compression and 3-point bending.
Holl, and Boyd
1993 [3]
Fiber Optic sensors (FO) with 100–200 mm diameterUnidirectional and quasi isotropic graphite laminatesFailure does not initiate near the fiber-optic sensor. No sensitivity to the embedded sensor is seen in quasi-isotropic cases The transverse strength is reduced.
Sirkis, and Singh 1994 [4]Fiber Optic sensors (FO)Graphite composite laminatesOptical microscopy and Moiré interferometry show no perturbation in the strain state of the material with embedded FO. The material lay-up and its thickness influence the results.
Singh, and Vizzini 1994 [5]Simulated actuator (glass slice)AS4/3501-6 graphite/epoxy laminatesInterlacing results in 42% reduction of the max. interlaminar tensile stress and a 22% reduction of the max. interlaminar shear stress
Shukla, and Vizzini 1996 [6]Simulated sensors/actuators. Device size: 25.4 mm 76.2 mm 1 mmUnidirectional AS4/3501-6 graphite-epoxy laminatesThe 72% material strength reduction under uniaxial loads improves with interlacing techniques.
Mall, and Coleman 1998 [7]Active PZT sensors. Device size: 50 : 8 mm 25 : 4 mm 0 : 254 mmQuasi-isotropic AS4/3501-6 graphite/epoxy laminates4% reduction of strength and Young’s modulus. No degradation of the fatigue life. The embedded PZTs maintain a steady output indefinitely if mechanically cycled within their operational strain limits
Paget, and Levin 1999 [8]Active thin (0.13 mm) PZT sensorsQuasi-isotropic graphite/epoxy laminatesNo effects on the strength and the failure modes
Hansen, and
Vizzini 2000 [9]
Simulated devices (glass slices) size: 76 mm by 25 mm by 1 mmUnidirectional AS4/3501-6 graphite/epoxy compositesStatic tension and tension-tension fatigue of interlaced materials with devices: 33% reduction of strength; endurance is improved; damage initiation delayed with respect to the use of cut-out methods.
Mall, and Hsu
2000 [10]
Zirconate-titanate, PZT actuators integrated with cut-out methods. Device size: 50.8 mm 25.4 mm 0.254 mmAS4/3501-6 graphite/epoxy laminatesFatigue of active PZT. Specimens cycled at different max stress levels while exciting the embedded actuator from 10 V to 100 V or 10 V to 100 V. 10 Hz and R = 0.1. Embedded PZT performed better in the out-of-phase than in-phase conditions.
Mall 2002 [11]Active PZT sensors integrate with or without cut-out method. Device size: 50.8 mm 25.4 mm 0.254 mmQuasi-isotropic AS4/3501-6 graphite/epoxy laminatesTensile strength and Young’s modulus are not affected by the integration of actuator/sensor using the two embedding techniques. No degradation in the fatigue life/strength. The PZT actuator/sensor functions mechanically fatigued or loaded to the maximum stress level equal to its operational design limit.
Lin., and Chang 2002 [12]Sensor network: thin flexible dielectric film, SMART layer (printed circuit material with piezoelectric on it). Layer thickness: 0.050 to 0.25 mmComposites made with RTM methodsThe SMART layer does not affect noticeably the strength of the host composite structure, nor promote delamination in 3 point bending tests.
Shivakumar, and Emmanwori 2004 and 2005 [13, 14]Samples with 0, 30, 45, 60, FO sensors oriented with respect the fibers direction.Unidirectional AS4/3501-6 carbon/epoxy laminatesThe material properties are unaffected by the integration of the fiber-optic sensor. 10% reduction of the tensile strength and 40% decrease of the compressive strength are reported.
et al. 2005 [15]
Active flexible piezoceramic sensors and actuators patches. Patches dimensions: 135 mm 55 mm 0.33 mm.Plain weave carbon/epoxy material(1) Cutout holes, (2) molded-in holes, and (3) embedding techniques. Manufacturing, durability, dynamic, and structural performance of embedded materials are optimal if materials with devices are made with method (3)

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