Method for the Microstructural Characterisation of Unidirectional Composite Tapes

The outstanding properties of carbon fibre-reinforced polymer composites are affected by the development of its microstructure during processing. This work presents a novel approach to identify microstructural features both along the tape thickness and through the thickness. Voronoi tessellation-based evaluation of the fibre volume content on cross-sectional micrographs, with consideration of the matrix boundary, is performed. The method is shown to be robust and is suitable to be automated. It has the potential to discriminate specific microstructural features and to relate them to processing behaviour removing the need for manufacturing trials.

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A Comparative Analysis on the Methods of Strengthening Isolated Reinforced Concrete Columns

IOP Conference Series Materials Science and Engineering ◽

10.1088/1757-899x/1203/2/022037 ◽

2021 ◽

Vol 1203 (2) ◽

pp. 022037

Author(s):

Mungur Ved Vritesh ◽

Seeboo Asish

Keyword(s):

Reinforced Concrete ◽

Cross Section ◽

Wire Mesh ◽

Steel Plates ◽

Experimental Investigations ◽

Cross Sectional ◽

Short Columns ◽

Reinforced Polymer ◽

Carbon Fibre Reinforced Polymer ◽

Fibre Reinforced Polymer

Abstract In the construction industry, there are several methods which have been used to improve the capacity and effectiveness of structural concrete structures. Engineers can extend the life of the structures by implementing strengthening techniques. One of the techniques to strengthen columns and beams is the use of jacketing. The strength of the structural members is enhanced through the surface structural bonding of materials such as Carbon-Fibre Reinforced Polymer (CFRP), Glass-Fibre Reinforced Polymer (GFRP), ferrocement, steel angles, steel plates, wire mesh and so on. In this study, 18 reinforced concrete short columns of cross-sectional size 60 mm × 60 mm and 500 mm height were cast using concrete grade 30 MPa. The columns were subjected to compressive axial loads till failure. Moreover, the damaged columns were strengthened using three structural strengthening techniques namely, Reinforced Concrete Jacketing (RCJ), Reinforced Concrete Wire Mesh Jacketing (RCWJ) and, Steel Jacketing (SJ). The columns strengthened using RCJ and RCWJ had a cross section of 120 mm × 120 mm while SJ had a cross section of 66 mm × 66 mm. Six different configurations were used for each technique. The experimental investigations showed a minimum increase of 48.0%, 48.7% and 35.2% in the axial compressive strength when strengthened using RCJ, RCWJ and SJ respectively. Among the three strengthening techniques, SJ was determined to be the effective technique on considering structural design, time production and costs.

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Carbon fibre reinforced polymer wrapping for the rehabilitation of masonry columns

Canadian Journal of Civil Engineering ◽

10.1139/l03-015 ◽

2003 ◽

Vol 30 (4) ◽

pp. 734-744 ◽

Cited By ~ 18

Author(s):

Mark J Masia ◽

Nigel G Shrive

Keyword(s):

Carbon Fibre ◽

Single Layer ◽

Strength Increase ◽

Cross Sectional ◽

Unit Type ◽

Reinforced Polymer ◽

Significant Strength ◽

Carbon Fibre Reinforced Polymer ◽

Fibre Reinforced Polymer ◽

Cfrp Wrapping

The use of carbon fibre reinforced polymer (CFRP) wrapping to strengthen existing cracked masonry columns was investigated experimentally. The study was aimed at quantifying the increase in strength that can be achieved and assessing the effect of column size on the strength increase. Eighteen columns were tested, with three different square cross-sectional sizes (290 mm × 290 mm, 390 mm × 390 mm, 490 mm × 490 mm) and two different types of clay masonry unit. Six columns were constructed in each size, two columns using unit type 1 and four columns using unit type 2. Strengthening was achieved by wrapping the square section columns directly with a single-layer CFRP laminate or by wrapping the columns after first casting a circular concrete jacket around the column. The latter treatment was applied to two of the small-sized columns and two of the intermediate-sized columns. All other square section columns were wrapped directly. Significant strength increases were achieved, particularly when the columns were provided with the cylindrical concrete jacket. These preliminary tests indicate that the use of CFRP wrapping is an effective technique for rehabilitating damaged masonry columns. Decisive conclusions could not be made regarding the effect of column size (cross-sectional area) on the strength increase achieved. Further tests together with nonlinear finite element modelling aimed at duplicating the experimental observations would greatly enhance the information provided by the current tests.Key words: masonry, columns, rehabilitation, strengthening, fibre reinforced polymer, experimental.

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Fibre Bridging and Nozzle Clogging in 3D Printing of Discontinuous Carbon Fibre Reinforced Polymer Composites: Coupled CFD-DEM Modelling

10.21203/rs.3.rs-439471/v1 ◽

2021 ◽

Author(s):

Hao Zhang ◽

Lixing Zhang ◽

Haoqi Zhang ◽

Jiang Wu ◽

Xizhong An ◽

...

Keyword(s):

3D Printing ◽

Polymer Matrix ◽

Volume Fraction ◽

Fibre Volume Fraction ◽

Fibre Length ◽

Fibre Volume ◽

Nozzle Clogging ◽

Reinforced Polymer ◽

Carbon Fibre Reinforced Polymer ◽

Fibre Reinforced Polymer

Abstract A coupled multiphase model based on computational fluid dynamics (CFD) and discrete element method (DEM) is developed to numerically investigate the extrusion-based 3D printing process of discontinuous carbon fibre reinforced polymer composites. Short carbon fibres are modelled as rigid bodies by clumping discrete spheres in DEM, while polymer matrix is treated as an incompressible Newtonian fluid in CFD. A fluid-particle interaction model is adopted to couple DEM and CFD and represent the dynamic fibre/matrix interaction. Collisions between fibres are considered naturally in DEM by using the Hertz-Mindlin contact law. The coupled CFD-DEM is validated, both qualitatively and quantitatively, against X-ray microtomography (µCT) experimental results for the T300/PA6 composite. Parametric study on various fibre lengths, fibre volume fraction and resin viscosity using the CFD-DEM model shows that the nozzle clogging tends to occur when the fibre length and/or the fibre volume fraction are increased. Use of a polymer matrix with a lower viscosity can be effective to eliminate the clogging issue when printing composites with relatively short fibres. The fibre length is dominating when long fibres are used and the clogging is largely independent on the viscosity of the polymer matrix. Finally, a potential solution of using a cone sleeve insert located above the shrinking region to address the nozzle clogging issue is proposed and numerically assessed.

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Size effects in axially loaded square-section concrete prisms strengthened using carbon fibre reinforced polymer wrapping

Canadian Journal of Civil Engineering ◽

10.1139/l03-064 ◽

2004 ◽

Vol 31 (1) ◽

pp. 1-13 ◽

Cited By ~ 61

Author(s):

Mark J Masia ◽

Trevor N Gale ◽

Nigel G Shrive

Keyword(s):

Carbon Fibre ◽

Axial Strain ◽

Plain Concrete ◽

Cross Sectional ◽

Reinforced Polymer ◽

Carbon Fibre Reinforced Polymer ◽

Cross Sectional Size ◽

Fibre Reinforced Polymer ◽

Cfrp Wrapping ◽

Strength And Ductility

The use of carbon fibre reinforced polymer (CFRP) wrapping to strengthen plain concrete prisms of square cross section was investigated experimentally. The study was aimed at quantifying the increase in axial compressive strength and ductility that can be achieved and assessing the effect of cross-sectional size on the increases. Thirty prisms of three different square cross-sectional sizes (100 mm × 100 mm × 300 mm, 125 mm × 125 mm × 375 mm, 150 mm × 150 mm × 450 mm) were tested. Ten prisms were constructed in each size. Five prisms in each size were left unwrapped as control specimens, and five were wrapped with two layers of unidirectional CFRP laminate. All prisms were loaded in axial compression until failure. Significant increases in strength and ductility were achieved by wrapping. The effectiveness of the wrap, as measured by the percentage increases in strength and peak axial strain, reduced with increasing cross-sectional size. These tests indicate that the use of CFRP wrapping is an effective technique for strengthening and (or) rehabilitating concrete columns. Test results available in the literature by other authors are also summarized. Although these results are highly scattered, they are consistent with the findings of the current tests.Key words: concrete, prism, column, square, rehabilitation, strengthening, FRP, experimental.

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Fibre bridging and nozzle clogging in 3D printing of discontinuous carbon fibre-reinforced polymer composites: coupled CFD-DEM modelling

The International Journal of Advanced Manufacturing Technology ◽

10.1007/s00170-021-07913-7 ◽

2021 ◽

Author(s):

Hao Zhang ◽

Lixing Zhang ◽

Haoqi Zhang ◽

Jiang Wu ◽

Xizhong An ◽

...

Keyword(s):

3D Printing ◽

Polymer Matrix ◽

Volume Fraction ◽

Fibre Volume Fraction ◽

Fibre Length ◽

Fibre Volume ◽

Nozzle Clogging ◽

Reinforced Polymer ◽

Carbon Fibre Reinforced Polymer ◽

Fibre Reinforced Polymer

AbstractA coupled multiphase model based on computational fluid dynamics (CFD) and discrete element method (DEM) is developed to numerically investigate the extrusion-based 3D printing process of discontinuous carbon fibre-reinforced polymer composites. Short carbon fibres are modelled as rigid bodies by clumping discrete spheres in DEM, while polymer matrix is treated as an incompressible Newtonian fluid in CFD. A fluid-particle interaction model is adopted to couple DEM and CFD and represent the dynamic fibre/matrix interaction. Collisions between fibres are considered naturally in DEM by using the Hertz-Mindlin contact law. The coupled CFD-DEM is validated, both qualitatively and quantitatively, against X-ray microtomography (μCT) experimental results for the T300/PA6 composite. Parametric study on various fibre lengths, fibre volume fraction and resin viscosity using the CFD-DEM model shows that the nozzle clogging tends to occur when the fibre length and/or the fibre volume fraction are increased. Use of a polymer matrix with a lower viscosity can be effective to eliminate the clogging issue when printing composites with relatively short fibres. The fibre length is dominating when long fibres are used and the clogging is largely independent on the viscosity of the polymer matrix. Finally, a potential solution of using a cone sleeve insert located above the shrinking region to address the nozzle clogging issue is proposed and numerically assessed.

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