Application of Electric Resistance Change Method to Damage Detection of CFRP Bolted Joints

Bolted joints are widely used for composite structures. As is well known, excessive bearing load gives rise to bearing failure at hole boundaries. Detecting bearing failure is important for assuring integrity of composite structures. Conventional nondestructive inspection methods are expensive, cumbersome, time-consuming, and not suitable for health monitoring, and a simple, low-cost inspection method for bearing failure must be developed. Authors have experimentally demonstrated detection bearing failure by an electrical resistance change method. In this study, detectablity of remote damage, which includes bearing failure, using an electric resistance change method is investigated analytically. The results show that fiber breaking and delamination induce permanent increase in the electric resistance of the bolted composite joints, and that the proposed method, which involves measuring electric resistance, is effective for detecting bearing failure.

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Detectability of Bearing Failure of Composite Bolted Joints by Electric Resistance Change Method

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.321-323.957 ◽

2006 ◽

Vol 321-323 ◽

pp. 957-962 ◽

Cited By ~ 10

Author(s):

Yoshinobu Shimamura ◽

Keiko Oda ◽

Akira Todoroki ◽

Masahito Ueda

Keyword(s):

Health Monitoring ◽

Composite Structures ◽

Low Cost ◽

Nondestructive Inspection ◽

Bolted Joints ◽

Bearing Failure ◽

Electric Resistance ◽

Resistance Change ◽

Inspection Method ◽

Bearing Load

Bolted joints are widely used for composite structures. As is well known, excessive bearing load gives rise to bearing failure at hole boundaries. Detecting bearing failure is important for assuring integrity of composite structures. Since conventional nondestructive inspection methods are expensive, cumbersome, time-consuming, and not suitable for health monitoring, a simple, low-cost inspection method for bearing failure must be developed. Authors have demonstrated the feasibility of detecting bearing failure by using an electric resistance change method. In this study, more detailed analyses were carried out to investigate the detectability in terms of the damage size and the distance between damage and electrodes. The results show that bearing failure of less than 10mm square causes the electric resistance change of a few hundred ppm and thus can be easily detected, and that the electrodes can be mounted more than 10 mm far from a bolt hole.

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Toward Structural Health Monitoring of Civil Structures Based on Self-Sensing Concrete Nanocomposites: A Validation in a Reinforced-Concrete Beam

International Journal of Concrete Structures and Materials ◽

10.1186/s40069-020-00451-8 ◽

2021 ◽

Vol 15 (1) ◽

Author(s):

Diego L. Castañeda-Saldarriaga ◽

Joham Alvarez-Montoya ◽

Vladimir Martínez-Tejada ◽

Julián Sierra-Pérez

Keyword(s):

Reinforced Concrete ◽

Damage Detection ◽

Direct Current ◽

Health Monitoring ◽

Electrical Resistance ◽

Concrete Beam ◽

Reinforced Concrete Beam ◽

Structural Member ◽

Rc Beam ◽

Electric Resistance

AbstractSelf-sensing concrete materials, also known as smart concretes, are emerging as a promising technological development for the construction industry, where novel materials with the capability of providing information about the structural integrity while operating as a structural material are required. Despite progress in the field, there are issues related to the integration of these composites in full-scale structural members that need to be addressed before broad practical implementations. This article reports the manufacturing and multipurpose experimental characterization of a cement-based matrix (CBM) composite with carbon nanotube (CNT) inclusions and its integration inside a representative structural member. Methodologies based on current–voltage (I–V) curves, direct current (DC), and biphasic direct current (BDC) were used to study and characterize the electric resistance of the CNT/CBM composite. Their self-sensing behavior was studied using a compression test, while electric resistance measures were taken. To evaluate the damage detection capability, a CNT/CBM parallelepiped was embedded into a reinforced-concrete beam (RC beam) and tested under three-point bending. Principal finding includes the validation of the material’s piezoresistivity behavior and its suitability to be used as strain sensor. Also, test results showed that manufactured composites exhibit an Ohmic response. The embedded CNT/CBM material exhibited a dominant linear proportionality between electrical resistance values, load magnitude, and strain changes into the RC beam. Finally, a change in the global stiffness (associated with a damage occurrence on the beam) was successfully self-sensed using the manufactured sensor by means of the variation in the electrical resistance. These results demonstrate the potential of CNT/CBM composites to be used in real-world structural health monitoring (SHM) applications for damage detection by identifying changes in stiffness of the monitored structural member.

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A Study on Thermal and Electrical Conductivities of Ethylene-Butene Copolymer Composites with Carbon Fibers

International Polymer Processing ◽

10.1515/ipp-2020-4003 ◽

2021 ◽

Vol 36 (4) ◽

pp. 417-422

Author(s):

Y. Hamid ◽

P. Svoboda

Keyword(s):

Mechanical Properties ◽

Thermal Conductivity ◽

Carbon Fiber ◽

Electric Conductivity ◽

Carbon Fibers ◽

Mechanical Strain ◽

Electric Resistance ◽

Resistance Change ◽

Electrical Conductivities ◽

Fiber Sample

Abstract Ethylene-butene copolymer (EBC)/carbon-fiber (CF) composites can be utilized as an electromechanical material due to their ability to change electric resistance with mechanical strain. The electro-mechanical properties and thermal conductivity of ethylene butene copolymer (EBC) composites with carbon fibers were studied. Carbon fibers were introduced to EBC with various concentrations (5 to 25 wt%). The results showed that carbon fibers’ addition to EBC improves the electric conductivity up to 10 times. Increasing the load up to 2.9 MPa will raise the electric resistance change by 4 500% for a 25% fiber sample. It is also noted that the EBC/CF composites’ electric resistance underwent a dramatic increase in raising the strain. For example, the resistance change was around 13 times higher at 15% strain compared to 5% strain. The thermal conductivity tests showed that the addition of carbon fibers increases the thermal conductivity by 40%, from 0.19 to 0.27 Wm–1K–1.

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