Mechanical performance and damage evolution of MWCNT modified filament wound glass/epoxy composite pipes under burst pressure, low velocity impact (LVI) and compression after impact (CAI) loading

TAŞYÜREK M., GEMİ L., YAZMAN Ş.

COMPOSITES PART A-APPLIED SCIENCE AND MANUFACTURING, cilt.213, 2027 (SCI-Expanded, Scopus)

Özet

Filament-wound glass/epoxy composite pipes may experience hidden low-velocity impact damage that compromises both pressure-bearing capacity and post-impact residual strength. This study presents an integrated experimental investigation of the effects of multi-walled carbon nanotube (MWCNT) matrix modification on burst performance, low-velocity impact response, compression after impact (CAI) behavior, and damage evolution of f 55 degrees filament-wound GFRP pipes. Neat, 0.5 wt% MWCNT-modified, and 1.0 wt% MWCNT-modified epoxy matrices were used to manufacture identical six-layer pipe specimens. The addition of 1.0 wt% MWCNT increased epoxy tensile strength and fracture strain by 10.2 % and 33.3 %, respectively, and improved the pipe hardness and burst strength by 5.2 % and 9.3 %. Under impact loading, MWCNT modification increased peak contact force and improved bending stiffness, while CNT1.0-GFRP generally exhibited lower maximum displacement values, particularly at low and intermediate impact velocities. CAI results revealed a damage-statedependent response: CNT1.0-GFRP showed the highest non-impacted compressive strength, whereas CNT0.5GFRP provided the most stable post-impact residual compression performance. After 3.0 m/s impact, the compressive strength loss was limited to 8.9 % for CNT0.5-GFRP, compared with 15.6 % for GFRP-N and 17.5 % for CNT1.0-GFRP. Damage observations further showed that MWCNT modification altered post-impact damage evolution rather than simply producing a proportional improvement with increasing nanotube content. These results demonstrate that matrix-level reinforcement and post-impact structural damage tolerance do not necessarily evolve in parallel, revealing a damage-state-dependent role of MWCNT modification in filamentwound GFRP pipes.