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.

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.

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.

Experimental Nondestructive Testing Using Magnetostrictive Particles Embedded in Carbon Fiber Reinforced Polymer Beams

2012 ◽  
Author(s):  
Jonathan Rudd ◽  
Dustin Spayde ◽  
Oliver Myers
Keyword(s):  
Carbon Fiber ◽  
Fiber Reinforced Polymer ◽  
Carbon Fiber Reinforced Polymer ◽  
Fiber Reinforced ◽  
Secondary Circuit ◽  
Release Agent ◽  
Cfrp Laminates ◽  
Reinforced Polymer ◽  
Magnetostrictive Strain ◽  
Carbon Fiber Reinforced

In this paper, the experimental sensing results of damage testing using magnetostrictive particulate sensors, embedded in fiber reinforced polymer laminates, are presented. Carbon fiber reinforced polymer (CFRP) laminates (Hexcel AS4/3501-6) are embedded with terfenol-d particles and the ply count is varied to observe the change in the sensing. Sensing is observed using a non-contacting magnetostrictive strain sensor setup. The sensing parameter observed is the voltage induced in the secondary circuit. Two of the three batches presented have laminates that are embedded with .5″×.5″, release agent coated patches that prevent bonding between the terfenol-d and the CFRP layer. The laminate ply count ranges from 2–14 unidirectional plies. Two fabrication methods are used to distribute the particles in the laminate. The experimental results from the three batches reveal that the fabrication technique has a significant effect on the sensing signal. The effect of particle accumulation near the sensor dominates the sensing signal and makes the presence of a delamination difficult to assess. The experiments also show that when the ply count is varied, there is not much variation in the sensing signal.

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