Narrow Results

The objective of this study was to investigate a novel remediation methodology for GFRP manufactured wind turbine blades for improving their maintenance under different environment and loading conditions. The fundamental specimens that were fabricated using wet prepreg manufacture technic were pre-damaged then repaired by attaching external glass fiber patches. The repair patches were penetrated by epoxy or UV resin, followed by ambient, $80^{\circ }\mathrm{\text{C}}$ curing or ultraviolet irradiation curing, respectively. Tensile, flexure, short beam shear tests and end notch flexure (ENF) test were conducted both in room and low temperature according to ASTM standards. The UV cured resin repaired specimens revealed better properties than epoxy in low temperature. The higher external-fundamental laminate interfacial bonding strength and lower velocity of crack diffusion, as well as the initiation of thermal residual stress, resulted in better mechanical properties under low temperature environment. In addition, the outstanding performance of UV resin was thought as the high crystallinity content curing by ultraviolet irradiation and the great inherent strength of itself.

The photopolymerizable resin repair method was investigated for the high altitude location and harsh remediation condition of wind turbine blades, because of its short operation time and low equipment requirement. This paper demonstrates the durability under ultraviolet (UV) irradiation environment of a photo- or thermal-polymerizable resin repaired GFRP, which is the essential material for manufacturing wind turbine blades. During the experiments, the fundamental GFRP specimens fabricated by wet prepreg manufacture technique were pre-damaged, and then repaired by attaching external photo- or thermal-polymerizable resin-impregnated glass fabric patches, followed by UV curing and room temperature (RT) curing, respectively. Long-term UV ageing (over 1300 h) was conducted to repaired specimens by employing a 365 nm wavelength UV lamp. The mechanical properties, thermal properties and surface morphology were evaluated before and after ageing. The results revealed that the UV cured specimens have better mechanical properties and stability compared to RT cured specimens in UV ageing environments.

Fiber reinforced plastics (FRPs) are extensively utilized in various applications due to their excellent comprehensive properties. However, the weak interlaminar property and durability of FRPs have been repeatedly mentioned as limitations in applications that include complex loading conditions. The remediation of FRPs has recently become a research focus for lifetime extension and strength reversion. Photopolymerizable resins, as a novel matrix material and an alternative for thermal polymerizable resins, have the advantages of short operation time, low price, and low equipment requirements. This study investigated the durability in long-term acid atmosphere exposure environment of photo and thermal polymerizable resin repaired GFRP. External glass fabric patches impregnated with the photo or thermal polymerizable resins were attached to pre-damaged fundamental specimens to conduct the remediation, followed by room temperature (RT) or UV irradiation for curing processing. The repaired specimens were positioned in the laboratory-fabricated hermetically-sealed condensation device. The 10 vol.% sulphuric acid (pH$=$0.76) was chosen as the source to generate the acidic atmosphere. The total ageing time was sustained for eight weeks (over 1300 h), and ILSS and DCB tests were performed every seven days, together with morphology observation. Better interlaminar properties retention and stability were revealed after eight weeks ageing for UV repaired specimens. The hardener is a factor that tends to increase the acid penetration rate, which is thought of as the mechanism of the better acid resistance of the UV repaired specimens.