Whole Field Structural Health Monitoring by Polymer-Matrix Carbon Fiber Smart Layer

2010 ◽  
Vol 148-149 ◽  
pp. 812-817 ◽  
Author(s):  
Hua Sheng Zheng ◽  
Si Rong Zhu ◽  
Zhuo Qiu Li ◽  
Lian Ye
Keyword(s):  
Carbon Fiber ◽  
Polymer Matrix ◽  
Health Monitoring ◽  
Effective Strain ◽  
Strain Sensor ◽  
Resistance Response ◽  
Resistance Change ◽  
Fiber Mats ◽  
Structure Damage ◽  
Three Point Bending

With epoxy reinforced by short carbon fiber mats, a skin-like strain sensor, polymer-matrix smart layer was developed, which can continuously cover the structural surface to sense strain for the whole filed. The smart layer was proved to be an effective strain sensor for tensile strain up to 0.8% by a monotonic tension experiment, exceeding this limit cause nonlinearity in the resistance response. The damage sensitivity of the smart layer was revealed by the monitoring for a FRP beam with prefabricated defect. Based on its sensitivities, the smart layers was applied in the health monitoring for a concrete beam under three-point bending, the result showed a good correlation between the resistance change of the smart layer and the load applied on the structure. The emergency of structure damage can be monitored by the turning point on the resistance-deflection curve of the smart layer.

Shape Memory Behavior of Carbon Composites With Functional Interlayer

2018 ◽  
Author(s):  
L. Santo ◽  
L. Iorio ◽  
G. M. Tedde ◽  
F. Quadrini
Keyword(s):  
Carbon Fiber ◽  
Shape Memory ◽  
Polymer Composites ◽  
Polymer Matrix ◽  
Smart Materials ◽  
Shape Memory Polymer ◽  
Shape Memory Polymers ◽  
Carbon Composites ◽  
Three Point Bending ◽  
Functional Behavior

Shape Memory Polymer Composites (SMPCs) are smart materials showing the structural properties of long-fiber polymer-matrix together with the functional behavior of shape memory polymers. In this study, SM carbon fiber reinforced (CFR) composites have been produced by using a SM interlayer between two CFR prepregs. Their SM properties have been evaluated in comparison with traditional structural CFR composites without the SM interlayer by using an especially designed test. Active and frozen forces are measured during a thermo-mechanical cycle in the three-point bending configuration. Experimental results show that SMPCs are able to fix a temporary deformed shape by freezing high stresses.

scholarly journals Two-Dimensional Piezoresistive Response and Measurement of Sensitivity Factor of Polymer-Matrix Carbon Fiber Mat

Polymers ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 3072
Author(s):  
Min Wu ◽  
Li Huang ◽  
Xiaoyu Zhang ◽  
Jianzhong Chen ◽  
Yong Lv
Keyword(s):  
Carbon Fiber ◽  
Polymer Matrix ◽  
Longitudinal Direction ◽  
Experimental Results ◽  
Sensitivity Factor ◽  
Poisson Effect ◽  
Lateral Direction ◽  
Resistance Change ◽  
Change Rate ◽  
Tension Loading

Based on the piezoresistive effect, the piezoresistive constitutive relation of a carbon fiber mat under orthogonal strain was deduced. Considering the Poisson effect, the piezoresistive responses and measurement of the sensitivity factor of a polymer-matrix carbon fiber mat under bidirectional strain were studied by a two-times uniaxial tension loading method in different directions, which was pasted in the center area of a cruciform aluminum substrate. The relations between the resistance change rate and the orthogonal strains were established, the reasonability of which was confirmed by comparison with the experimental results. The results show that the longitudinal piezoresistive sensitivity factor C11 is 21.55, and the lateral piezoresistive sensitivity factor C12 is 24.15. Using these factors, the resistance change rate of another polymer-matrix carbon mat was predicted, which was made by the same technique, and the error between the predicted and the experimental results was 1.3% in the longitudinal direction and 6.1% in the lateral direction.

Crack Detecting by Carbon Fiber Polymer-Matrix Layer

2011 ◽  
Vol 52-54 ◽  
pp. 1747-1751
Author(s):  
Xi Fang ◽  
Zhuo Qiu Li ◽  
Si Rong Zhu ◽  
Yong Lv
Keyword(s):  
Carbon Fiber ◽  
Uniaxial Tension ◽  
Polymer Matrix ◽  
Bending Test ◽  
Functional Material ◽  
Fiber Layer ◽  
Resistance Change ◽  
Matrix Layer ◽  
Sensing Application ◽  
Embedded Crack

Carbon fiber (CF) is an essential functional material focused on widely, especially in civil engineering. The mechano-electric character of carbon fiber layer based on the polymer-matrix and its sensing application to the pre-embedded crack detecting were experimentally discussed in this paper. Through the uniaxial tension the CF layer reveals a good performance by resistance changing with response to the loading. By three-points bending test, the crack of the structure would lead to an evident increasing of the resistance change ratio of CF layer. From the experimental results, the ratio of resistance increasing of CF layer laid on crack will be higher by 14.25% in average than that of CF layer with no crack laid. Thus carbon fiber mat composed with polymer will provides a new kind of potential sensor which can detect the defects of the structure.

Piezoresistivity of Modified Carbon Fiber Polymer-Matrix Composites

2011 ◽  
Vol 214 ◽  
pp. 607-611 ◽  
Author(s):  
Yong Lv ◽  
Si Rong Zhu ◽  
Zhuo Qiu Li ◽  
Xi Fang
Keyword(s):  
Carbon Fiber ◽  
Polymer Matrix ◽  
Polymer Matrix Composites ◽  
Strain Sensor ◽  
Matrix Composites ◽  
Fiber Glass ◽  
Reinforced Plastics ◽  
Dynamic Tracking ◽  
Continuous Carbon Fiber ◽  
Stability Frequency

Treat continuous carbon fiber with special technology, followed by pasting the electrode pole to it and in epoxy resin, a high resistance-strain sensitivity of polymer-matrix carbon fiber strain sensor can be achieved. Paste this element on the beam of fiber glass reinforced plastics, we tested its linearity、sensitivity、stability, frequency response etc. The results indicate that the sensitivity of this component is more than 400 as well as load frequency less than 10Hz. Its dynamic tracking performance is in relatively sound with no significant response lag.

scholarly journals Effect of Mechanical Pretreatments on Damage Mechanisms and Fracture Toughness in CFRP/Epoxy Joints

Materials ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1512
Author(s):  
Chiara Morano ◽  
Ran Tao ◽  
Marco Alfano ◽  
Gilles Lubineau
Keyword(s):  
Fracture Toughness ◽  
Carbon Fiber ◽  
Carbon Fibers ◽  
Polymer Matrix ◽  
Mechanical Tests ◽  
Adhesive Joints ◽  
Fiber Reinforced Polymers ◽  
Composite Joints ◽  
Damage Mechanisms ◽  
Grit Blasting

Adhesive bonding of carbon-fiber-reinforced polymers (CFRPs) is a key enabling technology for the assembly of lightweight structures. Surface pretreatment is necessary to remove contaminants related to material manufacturing and ensure bond reliability. The present experimental study focuses on the effect of mechanical abrasion on the damage mechanisms and fracture toughness of CFRP/epoxy joints. The analyzed CFRP plates were provided with a thin layer of surface epoxy matrix and featured enhanced sensitivity to surface preparation. Various degrees of morphological modification and fairly controllable carbon fiber exposure were obtained using sanding with emery paper and grit-blasting with glass particles. In the sanding process, different grit sizes of SiC paper were used, while the grit blasting treatment was carried by varying the sample-to-gun distance and the number of passes. Detailed surveys of surface topography and wettability were carried out using various methods, including scanning electron microscopy (SEM), contact profilometry, and wettability measurements. Mechanical tests were performed using double cantilever beam (DCB) adhesive joints. Two surface conditions were selected for the experiments: sanded interfaces mostly made of a polymer matrix and grit-blasted interfaces featuring a significant degree of exposed carbon fibers. Despite the different topographies, the selected surfaces displayed similar wettability. Besides, the adhesive joints with sanded interfaces had a smooth fracture response (steady-state crack growth). In contrast, the exposed fibers at grit-blasted interfaces enabled large-scale bridging and a significant R-curve behavior. While it is often predicated that quality composite joints require surfaces with a high percentage of the polymer matrix, our mechanical tests show that the exposure of carbon fibers can facilitate a remarkable toughening effect. These results open up for additional interesting prospects for future works concerning toughening of composite joints in automotive and aerospace applications.

Research on the Performance of Strain Sensors Applied to Bridges

2014 ◽  
Vol 875-877 ◽  
pp. 680-684
Author(s):  
Zhi Liu ◽  
Jing Liu ◽  
Shu Ri Cai
Keyword(s):  
Health Monitoring ◽  
Performance Test ◽  
Strain Sensor ◽  
Safety Monitoring ◽  
Strain Sensors ◽  
Great Role ◽  
Temperature Drift ◽  
Short Life ◽  
Test Analysis ◽  
Health Monitoring System

Strengthening safety monitoring of bridges during service time and improving the capability of emergency support have become the priority of the development of China’s present transportation system. Strain sensors play a great role in bridge detection and health monitoring system. In order to overcome disadvantages of traditional resistance strain sensors, such as big temperature drift, short life and inadaptability in the environment of low temperature and humidity, new arch strain sensors have been developed. This paper mainly discusses the structural and material characteristics of this sensor, as well as the performance test analysis of this strain sensor.

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