Abstract: A detailed experimental study is performed for piezo resistance damage sensing on conductive glass fiber/epoxy composites under mode-I fracture conditions. The conductive composites are fabricated by homogeneously dispersing carbon nanotubes (CNTs) within the epoxy matrix and electro-flocking short carbon fibers onto the laminates along with a vacuum infusion process. A parametric study is done on the in-situ damage sensing properties by varying the carbon fiber lengths (150 µm and 350 µm) and the car… Show more
“…The fracture surfaces are relatively smooth due to the lack of carbon fibers being present in between the layers of fiberglass. 17 Some of the glass fibers can be seen within the epoxy and appear to remain mostly intact, with some small amounts of breakage occurring. Based on the SEM images, it is apparent that the crack propagated relatively easily, resulting in lower fracture toughness compared to the flocked composites.Figure 10.SEM images of control specimens under (a) static and (b) dynamic fracture conditions.…”
Section: Resultsmentioning
confidence: 99%
“…The surfaces of these composites are much rougher than those of the control composites, showing evidence that more energy was required for the crack to propagate through them, hence the larger fracture toughness compared to the control specimens. 17 Epoxy by itself does not offer as much resistance to crack growth as it does when reinforced with milled carbon fibers.Figure 11.SEM images of (a) 80–1000, (b) 80–2000, (c) 150–1000, (d) 150–2000 for static fracture conditions.Figure 12.SEM images of (a) 80–1000, (b) 80–2000, (c) 150–1000, (d) 150–2000 for dynamic fracture conditions.…”
Section: Resultsmentioning
confidence: 99%
“…The surfaces of these composites are much rougher than those of the control composites, showing evidence that more energy was required for the crack to propagate through them, hence the larger fracture toughness compared to the control specimens. 17 Epoxy by itself does not offer as much resistance to crack growth as it does when reinforced with milled carbon fibers.…”
Section: Crack Initiation Toughnessmentioning
confidence: 99%
“…O’Donnell et al reinforced fiberglass epoxy composites with milled carbon fibers with lengths of 150 and 350 microns. 17 Flocking of carbon fibers improved quasi-static mode-I fracture loading compared to unflocked composites. Many of the composites displayed a correlation between load drops and increases in electrical resistance as unsteady crack propagation occurred.…”
An experimental study was performed to investigate damage sensing and fracture toughness of multifunctional conductive glass fiber composites under dynamic mode-I fracture loading. Carbon nanotubes (CNTs) were dispersed within the epoxy matrix using a shear mixing and sonicating process. An electrostatic wet flocking process was used to reinforce milled short PAN-based carbon fibers onto each of the layers of glass fiber fabric along the thickness direction in the composites. These layers of flocked fabric were stacked, and a vacuum infusion process was employed to fabricate the composites. The parametric study consisted of two carbon fiber lengths (80 μm and 150 μm) and two fiber densities (1000 fibers/mm2 and 2000 fibers/mm2) and was performed to investigate the damage sensing capabilities of a three-dimensional conductive network generated through CNTs and carbon fibers. A double cantilever beam (DCB) configuration was considered, and a modified Hopkinson pressure bar setup along with a high-speed camera was used to investigate dynamic fracture toughness of the composites. The piezo-resistance response of the composites during dynamic fracture was measured using a modified system of four probes. For comparison, composites were also characterized for fracture toughness and piezo-resistance under quasi-static fracture loading conditions. The addition of short, milled PAN-based carbon fibers significantly increased the fracture toughness of glass/epoxy composites. The piezo-resistance response of the composites was easily correlated with instances of sudden crack growth during static fracture loading.
“…The fracture surfaces are relatively smooth due to the lack of carbon fibers being present in between the layers of fiberglass. 17 Some of the glass fibers can be seen within the epoxy and appear to remain mostly intact, with some small amounts of breakage occurring. Based on the SEM images, it is apparent that the crack propagated relatively easily, resulting in lower fracture toughness compared to the flocked composites.Figure 10.SEM images of control specimens under (a) static and (b) dynamic fracture conditions.…”
Section: Resultsmentioning
confidence: 99%
“…The surfaces of these composites are much rougher than those of the control composites, showing evidence that more energy was required for the crack to propagate through them, hence the larger fracture toughness compared to the control specimens. 17 Epoxy by itself does not offer as much resistance to crack growth as it does when reinforced with milled carbon fibers.Figure 11.SEM images of (a) 80–1000, (b) 80–2000, (c) 150–1000, (d) 150–2000 for static fracture conditions.Figure 12.SEM images of (a) 80–1000, (b) 80–2000, (c) 150–1000, (d) 150–2000 for dynamic fracture conditions.…”
Section: Resultsmentioning
confidence: 99%
“…The surfaces of these composites are much rougher than those of the control composites, showing evidence that more energy was required for the crack to propagate through them, hence the larger fracture toughness compared to the control specimens. 17 Epoxy by itself does not offer as much resistance to crack growth as it does when reinforced with milled carbon fibers.…”
Section: Crack Initiation Toughnessmentioning
confidence: 99%
“…O’Donnell et al reinforced fiberglass epoxy composites with milled carbon fibers with lengths of 150 and 350 microns. 17 Flocking of carbon fibers improved quasi-static mode-I fracture loading compared to unflocked composites. Many of the composites displayed a correlation between load drops and increases in electrical resistance as unsteady crack propagation occurred.…”
An experimental study was performed to investigate damage sensing and fracture toughness of multifunctional conductive glass fiber composites under dynamic mode-I fracture loading. Carbon nanotubes (CNTs) were dispersed within the epoxy matrix using a shear mixing and sonicating process. An electrostatic wet flocking process was used to reinforce milled short PAN-based carbon fibers onto each of the layers of glass fiber fabric along the thickness direction in the composites. These layers of flocked fabric were stacked, and a vacuum infusion process was employed to fabricate the composites. The parametric study consisted of two carbon fiber lengths (80 μm and 150 μm) and two fiber densities (1000 fibers/mm2 and 2000 fibers/mm2) and was performed to investigate the damage sensing capabilities of a three-dimensional conductive network generated through CNTs and carbon fibers. A double cantilever beam (DCB) configuration was considered, and a modified Hopkinson pressure bar setup along with a high-speed camera was used to investigate dynamic fracture toughness of the composites. The piezo-resistance response of the composites during dynamic fracture was measured using a modified system of four probes. For comparison, composites were also characterized for fracture toughness and piezo-resistance under quasi-static fracture loading conditions. The addition of short, milled PAN-based carbon fibers significantly increased the fracture toughness of glass/epoxy composites. The piezo-resistance response of the composites was easily correlated with instances of sudden crack growth during static fracture loading.
“…The addition of micro carbon fibers enhanced the electrical network of the composites but also introduced micro-cracks with the matrix, reducing the strength in most cases. In a separate parametric study, O’Donnell et al 12 explored glass FRPCs embedded with CNTs and varying micro carbon fibers lengths and densities. The inclusion of micro-carbon fibers increased the mode-I fracture toughness in all cases, with the greatest increase residing with 350 µm at 2000 fibers/mm 2 (106%) followed by 150 µm at 500 fibers/mm 2 (75%).…”
A comprehensive experimental investigation is performed to understand the damage sensing capabilities of thermoplastic intra-ply carbon/glass laminated composites embedded with Carbon Nanotubes (CNTs) under quasi-static interlaminar shear and mode-I fracture loading conditions. CNTs are dispersed in thermoplastic Elium® resin using a combination of ultrasonication and shear mixing processes. This resin mix is used in a vacuum infusion process to fabricate four different intra-ply laminated composites orientations; G-0-C-90 [Carbon fibers are in the longitudinal direction], G-90-C-0 [Glass fibers are in the longitudinal direction], G-45-C-45(R) [carbon and glass fibers are at +45°, and −45° from the longitudinal direction and form a repeating layup], and G-45-C-45(A) [carbon and glass fibers are at +45°, and −45°, but with alternating directions for each lamina in the layup]. Four-circumferential probes are utilized to obtain the piezo-resistance measurements associated with damage inside the composites under shear and mode-I loadings. In the shear experimentation, the G-45-C-45(A) orientation demonstrated the largest interlaminar shear strength, at 50% greater than the G-45-C-45(R) orientation. Both G-45-C-45(A) and G-45-C-45(R) had significantly larger shear strains compared to the G-90-C-0 and G-0-C-90 orientations. However, the best resolution in shear damage sensing was seen with the G-0-C-90 composites. In the mode-I fracture experiments, the greatest fracture initiation toughness is shown with the G-0-C-90 orientation, which is 80% greater than the G-90-C-0 orientation. Compared to all orientations, the G-0-C-90 orientation also provided the most sensitive electrical response.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
