Material properties and geometric analysis of WAAM ER110S tubular and open section members

Wire arc additive manufacturing (WAAM) has recently gained attention in the civil engineering industry for its potential to produce complex-shaped structures in a both flexible and efficient manner. This paper presents the geometric analysis of WAAM ER110S cruciform section, square and circular hollow section members and material properties of WAAM ER110S plate. A total of 24 specimens, with each 8 respectively for cruciform section, square hollow section and circular hollow section, were manufactured, involving a broad range of cross-sectional width-to-thickness ratios. 3D laser-scanning was conducted to capture the geometric characteristics of all the 24 WAAM ER110S members, while an innovative method using the acrylonitrile-butadiene-styrene (ABS) replicas was used to address the issue of incomplete inner scans inside the square hollow section and circular hollow section members. Moreover, the new approach to define the initial local geometric imperfections is proposed in this paper; the initial local geometric imperfections based on the longitudinal line, cross-section and plate levels of curved surface members, were respectively derived, with the derivation processes detailed in this paper. The initial local geometric imperfection magnitudes derived by three approaches were found to be coherent with the current codified limit, but more tests need to be conducted to ensure this limit more accurately. The scanning electron microscopy (SEM) test was employed to study the surface morphology and microstructure of the WAAM ER110S plate, while an energy dispersive spectrometer (EDS) analysis was conducted in the SEM area to determine the distribution of the analysed elements. Subsequently, material testing with coupons cut from various orientations of WAAM ER110S plate was performed to obtain the fundamental material properties of WAAM ER110S at different angles to the print layer direction and further investigate material anisotropy. The WAAM ER110S plate is observed to be rough and significantly different from previous machined specimens, with acicular grains and analysed elements showing a uniform distribution. Meanwhile, the material properties exhibit anisotropy to some extent, and the test coupons fractured at (or near) the cross-section with the smallest area. Overall, the experimental results will help establish the data bank on the initial local geometric imperfections of WAAM cruciform section, square and circular hollow section, and the research findings in this paper will put the basis for the development of the further relevant design rules.