Climate change and the growing need for energy independence have resulted in a quickly expanding offshore wind energy industry. Foundations of these structures made from welded steel hollow sections are prone to fatigue. The wrapped composite joints omit welds, greatly increasing fatigue life. But is this technology equipped to handle the harsh offshore environment?

This research aims to gain first insight into a subject not studied in the context of the wrapped composite joint before, the effect of freeze-thaw cycles. A broad overview is created by including a vast range of experimental and numerical subjects discussing the external degradation and internal degradation, through (microscopic) surface investigation, gravimetric measurements, quasi-static tensile tests and a numerical evaluation of heat transfer and developing strains on joint geometries.

This Additional Graduation Work consists of two different fields of research: experimentally determining the linear coefficient of thermal expansion, and by Finite Element Modelling determining salt water diffusion coefficients. The research is centered around the wrapped composite joint: an innovative technology using a composite wrap connecting steel hollow sections instead of traditional welds.

Linear Coefficient of Thermal Expansion