Fracture Criterion for Carbon Fiber Reinforced Polymer Sheet to Concrete Interface Subjected to Coupled Pull-Out and Push-Off Actions

2009 ◽  
Vol 12 (5) ◽  
pp. 663-682 ◽  
Author(s):  
Jian-Guo Dai ◽  
Bao-Lin Wan ◽  
Hiroshi Yokota ◽  
Tamon Ueda
2020 ◽  
Vol 23 (8) ◽  
pp. 1644-1655
Author(s):  
Zongquan Liu ◽  
Qingrui Yue ◽  
Rong Li ◽  
Xiaobing Chen

Carbon-fiber-reinforced polymer grids encased with polymer mortar have received much attention lately as an effective technology for strengthening concrete structures. The objective of this study was to investigate the bond-slip behavior of carbon-fiber-reinforced polymer grids to polymer mortar at room and elevated temperatures. First, 20 pull-out specimens were tested at room temperature of 20°C, and the investigated parameters included the type of carbon-fiber-reinforced polymer grids, the embedment length of longitudinal bar, and the transverse bar length. Based on the experimental results, a two-branch bond-slip model at room temperature was proposed, with the characteristic bond stress and the corresponding slip determined by the regression analysis of test data. Second, 24 pull-out specimens were tested at elevated temperatures over a range of 20°C–300°C, and the investigated parameters included the type of carbon-fiber-reinforced polymer grids and the testing temperature. Based on the experimental results, a bond-slip model at elevated temperatures was further proposed by modeling the temperature-dependent reduction factors. The two proposed bond-slip models will be particularly useful in the theoretical analysis of structures with carbon-fiber-reinforced polymer grids and polymer mortar strengthening system under both room and elevated temperatures.


Materials ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 1835
Author(s):  
Paulina Florek ◽  
Magdalena Król ◽  
Piotr Jeleń ◽  
Włodzimierz Mozgawa

Carbon fiber reinforced polymer composites are a dynamically developing group of lightweight composites for applications in the automotive, wind energy, aerospace, and sports sectors. Interfacial connection is the weakest place in these materials. In this study, an attempt was made to improve adhesion between carbon fiber and epoxy resin. For this purpose, nanoparticles of graphene oxide were added to a polymer matrix. The results of the three-point bend test showed that the strength of samples with added graphene oxide increased. Improvement of adhesion between components, reduction of the pull-out effect and change in the method of crack propagation were observed. An attempt was made to explain this effect using spectroscopic methods, both IR and Raman. On the basis of the obtained results, chemical bonds between the individual components of the composites were identified.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Teng Gao ◽  
Yanbin Zhang ◽  
Changhe Li ◽  
Yiqi Wang ◽  
Qinglong An ◽  
...  

AbstractCarbon fiber-reinforced polymer (CFRP) easily realizes the integrated manufacturing of components with high specific strength and stiffness, and it has become the preferred material in the aerospace field. Grinding is the key approach to realize precision parts and matching the positioning surface for assembly and precision. Hygroscopicity limits the application of flood lubrication in CFRP grinding, and dry grinding leads to large force, surface deterioration, and wheel clogging. To solve the above technical bottleneck, this study explored the grindability and frictional behavior of CNT biological lubricant MQL through grinding experiments and friction-wear tests. Results showed that the CNT biological lubricant reduced the friction coefficient by 53.47% compared with dry condition, showing optimal and durable antifriction characteristics. The new lubrication was beneficial to suppressing the removal of multifiber block debris, tensile fracture, and tensile-shear fracture, with the advantages of tribological properties and material removal behavior, the tangential and normal grinding force, and the specific grinding energy were reduced by 40.41%, 31.46%, and 55.78%, respectively, compared with dry grinding. The proposed method reduced surface roughness and obtained the optimal surface morphology by preventing burrs, fiber pull-out, and resin smearing, and wheel clogging was prevented by temperature reduction and lubricating oil film formation. Sa and Sq of the CNT biological lubricant were reduced by 8.4% and 7.9%, respectively, compared with dry grinding. This study provides a practical basis for further application of CNT biological lubricant in CFRP grinding.


2016 ◽  
Vol 20 (6) ◽  
pp. 953-962 ◽  
Author(s):  
Qingrui Yue ◽  
Zongquan Liu ◽  
Rong Li ◽  
Xiaobing Chen

Carbon-fiber-reinforced polymer grids have received much attention lately because of many advantages. The force transfer behavior and development length of carbon-fiber-reinforced polymer grid reinforcement were evaluated using a pull-out test method. A total of 18 pull-out specimens of carbon-fiber-reinforced polymer grid reinforcement were tested under monotonic static loading, and the investigated parameters included the concrete compressive strength, the number of embedded transverse bars, with or without transverse bars, and the number of adjacent longitudinal bars. The slips between the reinforcing carbon-fiber-reinforced polymer grids and the concrete were measured at both the free end and the loaded end during the whole loading process. The test results indicated that first, the concrete compressive strength and the adjacent longitudinal bars had little influence on the force transfer behavior, second, the wedge action of the transverse bars was very important for transferring force; thus, increase in number of embedded transverse bars increased the force transfer stiffness and reduced the slippage. In the case of tested carbon-fiber-reinforced polymer grids, three embedded transverse bars equal to embedment length of 150 mm were sufficient to develop full tensile strength. Based on this experimental investigation, the preliminary design principles were also discussed.


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