Cure Monitoring of Composites Based on Embedded Fiber Bragg Gratings

2011 ◽  
Vol 211-212 ◽  
pp. 585-589 ◽  
Author(s):  
Xiao Yan Shen
Keyword(s):  
Fiber Reinforced Polymer ◽  
Carbon Fiber Reinforced Polymer ◽  
Cure Process ◽  
Cfrp Laminates ◽  
Cure Monitoring ◽  
Fbg Sensor ◽  
Reinforced Polymer ◽  
Before And After ◽  
Fbg Sensors ◽  
The Difference

Cure-induced strain is produced inevitably during the fabrication of the composite. To measure the strain, undamaged methods such as using fiber Bragg grating(FBG) sensor are employed. In this paper, nine unidirectional carbon fiber-reinforced polymer(CFRP) laminates are autoclaved produced, with FBGs embedded in different layers through the thickness (0-layer, 5-layer, 10-layer and 13-layer). The experiment measures the difference of the FBGs’ Bragg wavelengths before and after the cure which is linearly relevant to the cure-induced strain, to explore the distribution of strains through the thickness. The experimental results indicate a certain strain in neural plane of approximately 370με under the designed size of the laminates. The results also show that the cure-induced strains in different layers through the thickness are less than 1000με even including all errors, however they do not display distinct regular in thickness direction. Moreover, through the FBG sensors and the thermocouples, the cure process with the strain and temperature variations is understood well. The result verifies that the cure-induced strain is mainly generated at the end of the cure when the temperature cools down.

scholarly journals Strain Transfer Characteristic of a Fiber Bragg Grating Sensor Bonded to the Surface of Carbon Fiber Reinforced Polymer Laminates

2018 ◽  
Vol 8 (7) ◽  
pp. 1171
Author(s):  
Zhongyu Wang ◽  
Hongyang Li ◽  
Li Zhang ◽  
Jingfeng Xue
Keyword(s):  
Carbon Fiber ◽  
Strain Measurement ◽  
Fiber Reinforced Polymer ◽  
Carbon Fiber Reinforced Polymer ◽  
Transfer Model ◽  
Strain Transfer ◽  
Cfrp Laminates ◽  
Reinforced Polymer ◽  
Host Materials ◽  
Fbg Sensors

Structural health monitoring is of great importance for the application of composites in aircrafts. Fiber Bragg grating (FBG) sensors are very suitable for structure strain measurement. However, the strain measured by FBG sensors is different from the original strain in host materials. The relationship between them is defined as strain transfer. As composites are anisotropic, the traditional strain transfer model, which regards the elasticity modulus of host materials as a constant, is inadaptable. In this paper, a new strain transfer model is proposed for FBG sensors bonded to the surface of carbon fiber reinforced polymer (CFRP) laminates. Based on the measurement structure, the model is established and the transfer function is derived. The characteristics influencing the strain transfer are analyzed. The stacking directions, stacking numbers, and stacking sequences of CFRP laminates have a distinct effect on the transfer efficiency, which is different from the isotropy host materials. The accuracy of the proposed model was verified by experiments on a nondestructive tensile system, and the maximum model error is less than 0.5%. Moreover, the model was applied to the strain measurement of CFRP wing skin, which indicates that measurement errors decrease by 11.6% to 19.8% after the compensation according to the model.

scholarly journals Experimental Study of Aged and Seriously Damaged RC Beams Strengthened Using CFRP Composites

2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
Ning Zhuang ◽  
Honghan Dong ◽  
Da Chen ◽  
Yeming Ma
Keyword(s):  
Mechanical Properties ◽  
Fiber Reinforced Polymer ◽  
Carbon Fiber Reinforced Polymer ◽  
Rc Beams ◽  
Yield Load ◽  
Cfrp Laminates ◽  
Load Growth ◽  
Reinforced Polymer ◽  
Bonding Length ◽  
Damaged Beams

This paper presents results from experiments on aged and seriously damaged reinforced concrete (RC) beams strengthened with different arrangements of external carbon fiber-reinforced polymer (CFRP) laminates and end anchorages. Seven RC beams from an old bridge, measuring 250 × 200 × 2300 mm, were tested. All specimens were loaded to yield load to evaluate initial mechanical properties. Then, these seriously damaged specimens were repaired using different CFRP-reinforcing schemes and reloaded to failure. The yield load growth due to CFRP reinforcement ranged from 5% to 36%. Different parameters including CFRP dimension and position, bonding length, and end anchorage were investigated and facilitated conclusions on beam ductility, load-midspan deflection response, and failure mode. This research contributes to knowledge about the CFRP repair of aged and seriously damaged beams to ensure better performance in overloaded conditions.

Analysis of process-induced deformation on the spring-in of carbon fiber-reinforced polymer thin laminates

2019 ◽  
Vol 53 (20) ◽  
pp. 2901-2907 ◽  
Author(s):  
Andrea Corrado ◽  
Wilma Polini
Keyword(s):  
Carbon Fiber ◽  
Fiber Reinforced Polymer ◽  
Carbon Fiber Reinforced Polymer ◽  
Fiber Reinforced ◽  
Cure Process ◽  
Reinforced Polymer ◽  
Numerical Tool ◽  
Carbon Fiber Reinforced ◽  
Polymer Laminates ◽  
Flange Angle

The cure process of carbon fiber-reinforced polymer laminates induces residual stress inside the parts that causes geometrical unconformities. The most important unconformity is the spring-in that means the deviation of the flange-to-flange angle from the design angle. The spring-in value depends on some process parameters, such as the lay-up sequence of the plies, as demonstrated in previous works. The aim of this work is to study the dependence of the spring-in on the deviations in the orientation of the plies due to a hand process. A numerical tool was developed and experimentally tested.

scholarly journals Influence of ties on the behavior of short reinforced concrete columns strengthened by external CFRP

2018 ◽  
Vol 162 ◽  
pp. 04005
Author(s):  
Kaiss Sarsam ◽  
Raid Khalel ◽  
Mohammed Hadi
Keyword(s):  
Carrying Capacity ◽  
Concrete Columns ◽  
Fiber Reinforced Polymer ◽  
Carbon Fiber Reinforced Polymer ◽  
Load Carrying Capacity ◽  
Cfrp Sheets ◽  
Reinforced Polymer ◽  
Load Carrying ◽  
The Difference ◽  
Normal Strength

An experimental study was carried out to investigate the behavior of normal strength reinforce concret (RC) circular short column strengthned with “carbon fiber reinforced polymer (CFRP) sheets”. Three series comprising totally of (15) specimens loaded until failure under concentric compresion load. Strengthening was varied by changing the number of CFRP strips, spacing and wrapping methods. The findings of this research can be summarized as follows: for the columns without CFRP, the influence of the tie spacing was significant: compared with 130 mm tie spacing, dropping the spacing to 100 mm and 70 mm increased the load carrying capacity by 18% and 26%, respectively. The columns with less internal confinement (lesser amount of ties) were strengthened more significantly by the CFRP than the ones with greater amount of internal ties. As an example of the varying effectiveness of the fully wrapped CFRP, the column with ties at 130 mm was strengthened by 90% with the CFRP. In contrast, the ones with 70 mm spaced ties only increased in strength with CFRP by 66%. Compared with the control specimen (no CFRP), the same amount of CFRP when used as hoop strips led to more strengthening than using CFRP as a spiral strip- the former led to nearly 9% more strengthening than the latter in the case of 130 mm spaced internal steel ties. In the case of 100 mm internal steel ties, the difference (between the hoops & spiral CFRP strengthening) is close to 4%. In contrast, there is no difference between the two methods of strengthening in the heavily tied columns (70 mm tied spacing).

Defects Study on Drilling of Carbon Fiber Reinforced Polymer (CFRP) Laminates

2014 ◽  
Vol 800-801 ◽  
pp. 61-65 ◽  
Author(s):  
Kun Xian Qiu ◽  
Cheng Dong Wang ◽  
Qing Long An ◽  
Ming Chen
Keyword(s):  
Carbon Fiber ◽  
Feed Rate ◽  
High Speed ◽  
Fiber Reinforced Polymer ◽  
Carbon Fiber Reinforced Polymer ◽  
Fiber Reinforced ◽  
Cfrp Laminates ◽  
Drilling Performance ◽  
Reinforced Polymer ◽  
Carbon Fiber Reinforced

The new developed carbon fiber reinforced polymer laminates are widely used in main structural components of big commercial aircrafts. Generally drilling is the final operations in manufacturing structure, which is the most important operation during assembly. Defects such as burrs and delamination always appear in the process of drilling, which makes it hard to control the drilling quality. In this research, the drilling defects of T800 CFRP laminates are evaluated by using a brad point drill and a multifacet drill in terms of drilling forces, burr defect and delamination detection. The results show that the spindle speed is the most significant factor affecting the delamination defect followed by the feed rate. High speed drilling and low feed rate could improve the surface quality and reduce the delamination. The multifacet drill showed excellent drilling performance than the brad point drill and generated smaller defects.

scholarly journals Strengthening of Reinforced Concrete Slab-Column Connections with Carbon Fiber Reinforced Polymer Laminates

2019 ◽  
Vol 10 (1) ◽  
pp. 265 ◽  
Author(s):  
Cheng-Chih Chen ◽  
Shun-Long Chen
Keyword(s):  
Compressive Strength ◽  
Shear Strength ◽  
Reinforced Concrete ◽  
Carbon Fiber ◽  
Concrete Slab ◽  
Fiber Reinforced Polymer ◽  
Punching Shear ◽  
Carbon Fiber Reinforced Polymer ◽  
Cfrp Laminates ◽  
Reinforced Polymer

This study presents the structural behavior and punching shear strength of the concrete slab-column connections strengthened with carbon fiber reinforced polymer (CFRP) laminates. The variables considered for the twelve specimens included the compressive strength of the concrete, the ratio of the tensile steel reinforcement, and the amount of the CFRP laminates. Square concrete slabs were simply supported along four edges. During the test, monotonically concentrated load was applied to the stub column located at the center of the slab. The punching shear strength, stiffness, and mode of failure were investigated. Test results demonstrated that increasing the compressive strength of concrete, ratio of the steel reinforcement, and amount of the CFRP laminates led to an increase in the punching shear strength of the slabs. Moreover, the CFRP laminates were effective in appreciably increasing the punching shear strength of the slab-column connections. An analytical approach was conducted to calculate the punching shear strength of the slab-column connections strengthened with CFRP laminates. Based on the theory of reinforced concrete members, the application of the CFRP laminates increased the flexural strength of the slab and resulted in an increase of the effective depth of the slab section. Consequently, the punching shear strength was increased. The results of the analytical calculation revealed that the analytical work accurately predicted the experimental punching shear strength.

scholarly journals Characteristics of Eddy Current Distribution in Carbon Fiber Reinforced Polymer

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
Shaoni Jiao ◽  
Jian Li ◽  
Fei Du ◽  
Lei Sun ◽  
Zhiwei Zeng
Keyword(s):  
Carbon Fiber ◽  
Eddy Current ◽  
Fiber Reinforced Polymer ◽  
Electrical Anisotropy ◽  
Carbon Fiber Reinforced Polymer ◽  
Fiber Direction ◽  
Fiber Reinforced ◽  
Cfrp Laminates ◽  
Reinforced Polymer ◽  
Carbon Fiber Reinforced

The paper studies the characteristics of eddy current (EC) distribution in carbon fiber reinforced polymer (CFRP) laminates so as to guide the research and operation of eddy current testing of CFRP. To this end, an electromagnetic field computation model of EC response to CFRP based on the finite element method is developed. Quantitative analysis of EC distribution in plies of unidirectional CFRP reveals that EC changes slowly along the fiber direction due to the strong electrical anisotropy of the material. Variation of EC in plies of multidirectional CFRP is fast in both directions. The attenuation of EC in the normal direction in unidirectional CFRP is faster than that in isotropic material due to faster diffusion of EC. In multidirectional CFRP, EC increases near the interfaces of plies having different fiber orientations. The simulation results are beneficial to optimizing sensor design and testing parameters, as well as damage detection and evaluation.

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