scholarly journals Experimental Study of the Relaxation Properties of Carbon Fiber Cloth

Materials ◽  
2020 ◽  
Vol 13 (16) ◽  
pp. 3603
Author(s):  
Qiang Wang ◽  
Hua-Lin Song ◽  
Chun-Ling Lu ◽  
Wan-Xu Zhu ◽  
Jia-Zhu Huang
Keyword(s):  
Carbon Fiber ◽  
Relaxation Rate ◽  
Calculation Model ◽  
Test Results ◽  
Relaxation Properties ◽  
Reinforced Plastics ◽  
Axial Tension ◽  
Carbon Fiber Cloth ◽  
Relaxation Loss ◽  
Rate Calculation

In this study, a new method was proposed to study the relaxation properties of carbon fiber reinforced plastics (CFRP) fabric under axial tension. Under the condition of constant temperature and humidity, six groups of 168 h stress relaxation tests were conducted. Considering the influence of the prestress level, the size of CFRP cloth, and the surface coating of CFRP cloth on the relaxation performance, the measures to reduce the relaxation loss were proposed. The relaxation rate calculation model was established based on the test results of the authors and other scholars and was validated through comparisons with the test results. The results indicate that the relaxation rate of CFRP cloth was between 1.92% and 6.1%. When the prestress level was smaller than 0.3 fu, the relaxation rate of CFRP cloth decreased with the increase of prestress level. When the prestress level was greater than 0.3 fu, the relaxation rate increased with the increase of the prestress level. Under the same conditions, the relaxation rate of the CFRP specimens coated with glue was smaller than the uncoated samples by 3.21–6.28%. The calculation model could well estimate the relaxation rate of CFRP cloth.

INCREASING SENSITIVITY OF EDDY CURRENT NON-DESTRUCTIVE TESTING OF DELAMINATION IN CARBON-FIBER REINFORCED PLASTICS

2021 ◽  
pp. 28-37
Author(s):  
P. N. Shkatov ◽  
G. A. Didin ◽  
A. A. Ermolaev
Keyword(s):  
Carbon Fiber ◽  
Eddy Current ◽  
Calculation Model ◽  
Fiber Reinforced ◽  
Destructive Testing ◽  
Carbon Fiber Reinforced Plastics ◽  
Reinforced Plastics ◽  
Fiber Reinforced Plastics ◽  
Carbon Fiber Reinforced ◽  
The Difference

The paper is concerned with increasing sensitivity of eddy current nondestructive testing of most dangerous delamination in carbon-fiber reinforced plastics (CFRP). Increased sensitivity is achieved by separate registration and comparison of eddy current signals obtained from a set of stratifications of carbon fibers with the same orientation. The separation of eddy current signals is possible due to pronounced anisotropy of the electrical conductivity of the layers dominant in the direction of the fibers of the corresponding layer. Eddy-current signals are registered by eddy current probes with maximum sensitivity in a given angular direction. Prior to the scan eddy current signals of the probe are leveled on a defect-free area. The influence of the working gap on the difference between the eddy current signals of the probe is suppressed by normalizing it according to one of the signals. The analysis of the registered signals from delamination has been performed using an approximate calculation model. The reliability of the obtained results has been confirmed by comparison with experimental results and calculations using the finite element method.

Study on Stress Relaxation Properties of GFRP Rebars/Bolts

2010 ◽  
Vol 168-170 ◽  
pp. 1821-1826
Author(s):  
Guo Qing Yuan ◽  
Guo Hua Dong ◽  
Jian Ma
Keyword(s):  
Stress Relaxation ◽  
Relaxation Rate ◽  
Construction Projects ◽  
Test Time ◽  
Relaxation Properties ◽  
Reinforced Plastics ◽  
Glass Fiber Reinforced ◽  
Fiber Reinforced Plastics ◽  
Superior Corrosion Resistance ◽  
Gfrp Rebars

Glass fiber reinforced plastics (GFRP) rebars / bolts are more and more being applied in construction projects with its superior corrosion resistance. To improve the economical efficiency of their application it is very significant to develop the prestressed GFRP rebars/bolts structure system. Therefore it is very valuable to probe the stress relaxation properties of GFRP rebars/bolts. With an innovation ends anchoring method for stress relaxation specimens of GFRP rebars/bolts, the stress relaxation properties has been tested in this paper. Results show that the relaxation rate of GFRP rebars/bolts increases with the initial stress increasing and with test time prolonging. It is increasing more rapidly at the beginning stage and it becomes slow after 24 hours. The relaxation law of GFRP rebars/bolts is similar to the law of CFRP and AFRP rebars/bolts. The relation between the relaxation rate and the logarithm of test time in hour follows also better linear law. The relaxation rate of GFRP rebars/bolts is bigger than CFRP ones and smaller than AFRP ones. The mechanical properties do not change obviously after 120h relaxation test.

An effective peak stress formula for concrete confined with carbon fiber reinforced plastics

2003 ◽  
Vol 30 (5) ◽  
pp. 882-889 ◽  
Author(s):  
Chih-Tsung Lin ◽  
Yeou-Fong Li
Keyword(s):  
Carbon Fiber ◽  
Peak Stress ◽  
Confined Concrete ◽  
Test Results ◽  
Fiber Reinforced ◽  
Carbon Fiber Reinforced Plastics ◽  
Reinforced Plastics ◽  
Concrete Cylinders ◽  
Fiber Reinforced Plastics ◽  
Carbon Fiber Reinforced

The uniaxial compression test results of three different strengths and three different sizes of concrete cylinders confined with different layers of carbon fiber reinforced plastics (CFRP) are used to develop an effective peak stress formula for predicting the strength of confined concrete. The theory of this peak stress formula was based on the triaxial confined test of soil and rock, and the lateral confinement of the concrete was assumed to be due to the CFRP. The peak stress of the confined concrete can be explicitly expressed as a function of the unconfined concrete strength and the lateral CFRP confined strength. Experiments were done on 108 concrete cylinders, and the test results show the accuracy and effectiveness of this peak stress formulation of confined concrete.Key words: confined concrete, peak stress, carbon fiber reinforced plastics.

scholarly journals A self-boosting microwave plasma strategy tuned by air pressure for the highly efficient and controllable surface modification of carbon

RSC Advances ◽  
2021 ◽  
Vol 11 (17) ◽  
pp. 9955-9963
Author(s):  
Yanjing Liu ◽  
Jiawei He ◽  
Bing Zhang ◽  
Huacheng Zhu ◽  
Yang Yang ◽  
...  
Keyword(s):  
Surface Modification ◽  
Carbon Fiber ◽  
High Efficiency ◽  
Microwave Plasma ◽  
Air Pressure ◽  
Air Plasma ◽  
Highly Efficient ◽  
Carbon Fiber Cloth

Microwave enabled air plasma was boosted by a carbon fiber cloth (CFC) and used for the high-efficiency surface modification of the CFC, yielding CFCs with tunable contents of oxygen and each O-containing group.

scholarly journals Absorption and Strength Properties of Short Carbon Fiber Reinforced Mortar Composite

Buildings ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 300
Author(s):  
Md. Safiuddin ◽  
George Abdel-Sayed ◽  
Nataliya Hearn
Keyword(s):  
Tensile Strength ◽  
Carbon Fiber ◽  
Water Absorption ◽  
Carbon Fibers ◽  
Strength Properties ◽  
Fiber Content ◽  
Test Results ◽  
Air Content ◽  
Entrapped Air ◽  
Short Carbon

This paper presents the water absorption and strength properties of short carbon fiber reinforced mortar (CFRM) composite. Four CFRM composites with 1%, 2%, 3%, and 4% short pitch-based carbon fibers were produced in this study. Normal Portland cement mortar (NCPM) was also prepared for use as the control mortar. The freshly mixed mortar composites were tested for workability, wet density, and entrapped air content. In addition, the hardened mortar composites were examined for compressive strength, splitting tensile strength, flexural strength, and water absorption at the ages of 7 and 28 days. The effects of different carbon fiber contents on the tested properties were observed. Test results showed that the incorporation of carbon fibers decreased the workability and wet density, but increased the entrapped air content in mortar composite. Most interestingly, the compressive strength of CFRM composite increased up to 3% carbon fiber content and then it declined significantly for 4% fiber content, depending on the workability and compaction of the mortar. In contrast, the splitting tensile strength and flexural strength of the CFRM composite increased for all fiber contents due to the greater cracking resistance and improved bond strength of the carbon fibers in the mortar. The presence of short pitch-based carbon fibers significantly strengthened the mortar by bridging the microcracks, resisting the propagation of these minute cracks, and impeding the growth of macrocracks. Furthermore, the water absorption of CFRM composite decreased up to 3% carbon fiber content and then it increased substantially for 4% fiber content, depending on the entrapped air content of the mortar. The overall test results suggest that the mortar with 3% carbon fibers is the optimum CFRM composite based on the tested properties.

Machining quality of high speed helical milling of carbon fiber reinforced plastics

2021 ◽  
pp. 095440622199673
Author(s):  
Adel Abidi ◽  
Sahbi Ben Salem ◽  
Mohamed Athmane Yallese
Keyword(s):  
Surface Roughness ◽  
Carbon Fiber ◽  
High Speed ◽  
Hole Diameter ◽  
Feed Speed ◽  
Carbon Fiber Reinforced Plastics ◽  
Reinforced Plastics ◽  
Machining Quality ◽  
Fiber Reinforced Plastics

Among advanced cutting methods, High Speed Milling (HSM) is often recommended to improve the productivity and to reduce the costs of machining parts. As every cutting process, HSM is characterized by some defects like surface roughness and delamination are the main defects generated in composite materials. The aim of this experimental work is the studying of the machining quality of woven Carbon fiber reinforced plastics (CFRP) using the HSM technology. Experiments were done using different machining parameters combinations to make opened holes in CFRP laminates. This study investigated the effect of cutting speed, orbital feed speed, hole diameter on the delamination defect and surface roughness responses generated in the drilled holes. The design of experimental tests was generated using the approach of Central Composite Design (CCD). The characterization of these responses was treated with the Analysis of variance (ANOVA) and Response surface methodology (RSM). Results showed that the surface roughness is highly affected by the orbital feed speed (F) with contribution of 22.45%. The delamination factor at entry and exit of holes is strongly influenced by the hole diameter D (25.97% and 57.43%) respectively. The developed model equations gave a good correlation between the empirical and predicted results. The optimization of the milling parameters was treated using desirability function to minimize the surface roughness (Ra) and the delamination factor simultaneously.

Sign in / Sign up

Export Citation Format

Share Document