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Glass fiber-reinforced polymer (GFRP) reinforcing bars have relatively low shear strength, which limits their possible use in civil infrastructure applications with high shear demand, such as concrete reinforcing dowels. We suggest that the horizontal shear strength of GFRP bars can be significantly improved by nanomodification of the vinyl ester resin prior to pultrusion. The optimal content of functionalized multiwalled carbon nanotubes (MWCNTs) well dispersed into the vinyl ester resin was determined using viscosity measurements and scanning electron micrographs. Longitudinal tension and short beam shear tests were conducted to determine the horizontal shear strength of the nanomodified GFRP reinforcing bars. While the tensile strength of the GFRP reinforcing bars was improved by 20%, the horizontal shear strength of the bars was improved by 111% compared with the shear strength of neat GFRP bars pultruded using the same settings. Of special interest is the absence of the typical broom failure observed in GFRP when MWCNTs were used. Differential scanning calorimetry measurements and fiber volume fraction confirmed the quality of the new pultruded GFRP bars. Fourier-transform infrared (FTIR) measurements demonstrated the formation of carboxyl stretching in nanomodified GFRP bars, indicating the formation of a new chemical bond. The new pultrusion process using nanomodified vinyl ester enables expanding the use of GFRP reinforcing bars in civil infrastructure applications.
Shreya Vemuganti; Rahulreddy Chennareddy; Amr Riad; Mahmoud M. Reda Taha. Pultruded GFRP Reinforcing Bars Using Nanomodified Vinyl Ester. Materials 2020, 13, 5710 .
AMA StyleShreya Vemuganti, Rahulreddy Chennareddy, Amr Riad, Mahmoud M. Reda Taha. Pultruded GFRP Reinforcing Bars Using Nanomodified Vinyl Ester. Materials. 2020; 13 (24):5710.
Chicago/Turabian StyleShreya Vemuganti; Rahulreddy Chennareddy; Amr Riad; Mahmoud M. Reda Taha. 2020. "Pultruded GFRP Reinforcing Bars Using Nanomodified Vinyl Ester." Materials 13, no. 24: 5710.
The use of fiber-reinforced polymer (FRP) composite materials are continuously growing in civil infrastructure due to their high strength, low weight, and manufacturing flexibility. However, FRP is characterized by sudden failure and lacks ductility. When used in construction, gradual failure of FRP components is desired to avoid catastrophic structural collapse. Due to its mechanical orthotropy, the behavior of FRP relies significantly on fiber orientation and stacking sequence. In this paper, a novel multi-angled glass fiber reinforced polymer (GFRP) composite laminate showing pseudo ductile behavior is produced using 3D-printing. This is accomplished by varying fiber orientation angles, stacking sequence, and thickness of lamina. Single-angled GFRP composite specimens were 3D-printed with different fiber orientation angles of 0°, 12°, 24°, 30°, 45°, and 90° using continuous and fused filament techniques. The tension test results of the single-angled specimens were then used to aid the design of multi-angled laminate for potential progressive failure behavior. A 3D finite element (FE) model was developed to predict the response of the experimental results and to provide insight into the failure mechanism of the multi-angled laminate. The experimental observations and the FE simulations show the possibility of producing pseudo ductile FRP-by-design composite using 3D-printing technology, which leads the way to fabricate next-generation composites for civil infrastructure.
Shreya Vemuganti; Eslam Soliman; Mahmoud Reda Taha. 3D-Printed Pseudo Ductile Fiber-Reinforced Polymer (FRP) Composite Using Discrete Fiber Orientations. Fibers 2020, 8, 53 .
AMA StyleShreya Vemuganti, Eslam Soliman, Mahmoud Reda Taha. 3D-Printed Pseudo Ductile Fiber-Reinforced Polymer (FRP) Composite Using Discrete Fiber Orientations. Fibers. 2020; 8 (9):53.
Chicago/Turabian StyleShreya Vemuganti; Eslam Soliman; Mahmoud Reda Taha. 2020. "3D-Printed Pseudo Ductile Fiber-Reinforced Polymer (FRP) Composite Using Discrete Fiber Orientations." Fibers 8, no. 9: 53.