In this paper the authors compare the experimental load response of several welded aluminum structures with the response of equivalent finite element models. The samples tested represent frame components of NEXUS, a light weight research vehicle. The initial elastic response of thin walled specimens was accurately predicted using quadrilateral shell finite element models. Beam or shell element models were used to predict the elastic response of thick walled tubular samples.The material used to construct all of the samples was 0061-T6 aluminum. Tungsten inert gas welding was used to join the aluminum components. The heat of welding produced a heat affected zone with a large material property variation. The resultant difficulties with the accurate modelling of yield and post yield behaviour are discussed.