Effect Of Peel Ply On Bonding Quality Of The Composites For Wind Power Blade

In recent years,during the production of wind turbine blades,the caps of wind blades are formed by piling pultruded belts into a vacuum mold cavity.Afterwards,the resin is poured in a vacuum to achieve the pultruded strips bonding each other,this molding method greatly improves the production efficiency of caps and saves costing,however how to improve the bonding strength between pultruded strips in the production is a problem that has been widely studied recently.The purpose of this experiment is to explore how to improve the bonding strength between the pultruded strips during the formation of the caps of wind power blades.Since the gaps between the pultruded strips are narrow,It's not easy to flow when the resin is poured into the vacuum chamber,eventually resulting in non-uniform adhesive layer during using.For pultruded strips,changing the surface roughness can not only increases the gap between the strips,but also increases the surface energy of the pultruded strips and improves the bonding strength between the interfaces.Since this experiment was carried out under laboratory conditions,it was impossible to explore using real pultruded strips.Therefore,a unidirectional carbon fiber prepreg with a high carbon fiber content was used to prepare a simulated carbon fiber pultrusion by vacuum bag forming.And selected five different types of peel ply,which were nylon 66 peel ply with a basis weight of 52g/m2?85 g/m2?105 g/m2 and PET with basis weight of 58 g/m2?85 g/m2.Peel ply were used to simulate the formation of unidirectional carbon fiber pultruded plies.Before forming,they were applied to the surface of carbon fiber prepreg to prepare five simulated pultruded plates with different surface roughness.The surface morphology of the plate was analyzed by means of a metallographic microscope to observe the microscopic surface and the measurement of the surface profile roughness.It was found that the surface roughness of the pultruded sheet was related to the relative buckling wave height of the peel ply.The larger the relative buckling height of the peel ply,the larger the surface roughness of the corresponding pultruded sheet was.In order to simulate the bonding method between pultruded strips in the actual production process,a vacuum bag and sealant were used in this experiment to create a vacuum area for the pultruded sheet.The resin was poured into the sheet to achieve the secondary bonding of the pultruded sheet.Then,the secondary bonding method selected in this experiment is double overlap,and then the four-point bending strength and tensile strength of the double-lapped sample obtained by secondary bonding are measured.According to the result of strength testing,the surface roughness of the pultrusion plate was 2.34?m,which is for the best bonding strength,and the type of peel ply that can be used to obtain this degree of roughness was summarized as nylon 66(85 g/m2),and summed up the best way for the secondary bonding composition,which is using the same rough surface of pultrusion plate to bond.