Resistance Welding of Thermoplastic Composites for Industrial Scale Wind Turbine Blades
Wind blades are currently made from thermosetting fiber-reinforced polymer (FRP) composite materials. Thermoplastic FRP materials offer many benefits in both material properties and manufacturability relative to thermoset FRP materials. The first objective of the thesis is to compare the advantages and disadvantages of both thermoplastic materials and thermoset materials in blade applications. Identifying potential blade manufacturing processes that incorporate the inherent benefits from a thermoplastic material system is also part of this objective. The second thesis objective is to help demonstrate the feasibility of welding thermoplastic materials for use in industrial scale wind turbine blades. This can be accomplished by adapting technology used currently in aerospace structures for use in megawatt-scale wind turbine blades. The research methods employed in this thesis include experimental characterization of thermoplastic composites to meet wind industry material standards set by classification societies for thermoplastic material selection. Identifying potential blade manufacturing processes that incorporate the inherent benefits from a thermoplastic material system is also an objective of this research. With a thermoplastic material and a feasible processes selected, an investigation of resistance welding of thermoplastic parts is conducted for use as a joining method for larger structures. Experimental parameters obtained from both the material characterization study and from literature are used to assess the quality of welded joints. Welds are evaluated in a lap shear configuration. The findings and contributions help to demonstrate the feasibility of welding thermoplastic composite materials to manufacture wind turbine blades.