Preventing Fatal Fractures in Carbon‐Fiber–Glass‐Fiber‐Reinforced Plastic Composites by Monitoring Change in Electrical Resistance

Suzuki

Mizutani

et al. 2010

JMMP

This study deals with the durability tests of a new copper plated electrode process for self-sensing or self-healing Carbon Fiber Reinforced Plastic (CFRP) composites. The self-sensing or self-healing CFRP composites adopt carbon fibers as sensors or actuators. The electrical contacts at the electrodes have a significant effect on the self-sensing or self-healing ability. This research proposes a new electric copper plated process for fabricating reliable electrodes. Using single-ply specimens, electrical contact resistances after cyclic loading are measured. The cyclic loading test is performed to investigate the long term durability of these new electrodes. The new copper plated electrode was found to have high durability after cyclic loading and is appropriate for the practical self-sensing or self-healing CFRP composites.

Section: Resultsmentioning

confidence: 99%

Durability Estimates of Copper Plated Electrodes for Self-sensing CFRP Composites

Suzuki

Mizutani

et al. 2010

JMMP

“…Other researchers have also reported this positive piezoresistivity (positive gage factor) (3) - (7) : The electrical resistance in the fiber direction rises with the increase of applies tensile strain in the fiber direction.…”

Section: Introductionmentioning

confidence: 99%

Electrical Resistance Change of Unidirectional CFRP Due to Applied Load

Yoshida

2004

JSME Int. J., Ser. A

121

Carbon Fiber Reinforced Plastic (CFRP) is composed of electric conductive carbon fibers and electric insulator resin. Self-monitoring system has been reported utilizing electric resistance change of unidirectional CFRP due to fiber breakages and to applied strain. Piezoresistivity is electric resistance change with applied strain. Many researchers have already reported the piezoresistivity of unidirectional CFRP. There is, however, large discrepancy in the measured piezoresistivity even in the fiber direction during tensile loading: both positive piezoresistivity (electric resistance increase) and negative piezoresistivity (electric resistance decrease) are reported during tensile tests. Electric resistance change at electrodes due to poor electric contacts are reported to be a main cause of this large discrepancy. In the present study, therefore, basic properties of piezoresistivity were measured with specimens made from single-ply and multi-ply laminates using a four-prove method. Many cases of electric resistance changes in the fiber direction transverse direction were measured during tensile loading. Effect of shear loading was also investigated using a shear test. To investigate the effect of poor electric contact at the electrodes, electrodes were made without polishing specimen surface and a tensile test was performed with measuring piezoresistivity. After the test, the specimen surface was polished, and a tensile test was performed again using the identical specimen. As a result, positive piezoresistivity was obtained for both single-ply and multi-ply specimens and negative piezoresistivity is confirmed that it was caused by the poor electric contact at electrodes.

“…The prepreg production number was PYROFIL #380. As a thick CFRP laminate test piece, a simple sixteen-ply quasi-isotropic laminate with stacking sequence [(0/90/45/-45) 2 ]s was used. The CFRP laminates were cured at 130°C and 0.6 MPa for 90 min.…”

Section: Specimens and Experimentsmentioning

confidence: 99%

Using Electrical Resistance Change to Monitor the Damage in a Thick CFRP Plate Caused by a Dent

Shimazu

Mizutani

et al. 2011

JMMP

An impact load on a thick carbon fiber reinforced plastic (CFRP) plate usually causes a dent. The dent results in a decrease of electrical resistance. Our previous paper demonstrated the effect of the dent in the measurement of electrical resistance change of a thick CFRP plate subjected to impact loading. The present paper focuses on the electrical resistance decrease caused by the dent. Numerous FEM analyses were performed, and the relationship between electrical resistance changes and delamination location was constructed, by measuring the response surfaces. Several experiments were conducted and the measured electrical resistance changes were used to predict damage location from the response surfaces. The present study shows that the dent decreases the electrical resistance change ratio even in the adjacent segments, and the electrical resistance changes caused by the dent enable us to monitor the damage location. FEM analyses for a projected area model are sufficient to construct the relationships without resorting to many experiments.