Orthotropic plate buckling method for the design of stainless steel structures manufactured by wire-arc directed energy deposition

Abstract

Wire-arc directed energy deposition (DED-Arc) offers significant advantages for manufacturing stainless steel plates, but the inherent material anisotropy of DED-Arc stainless steel challenges the isotropic assumptions underlying current design standards (e.g., AISC 360, EN 1993-1-4, GB 50017). This paper proposes an Orthotropic Plate Buckling Method (OPBM) for predicting the local buckling resistance of DED-Arc stainless steel plate elements in compression. Analytical solutions for the elastic critical buckling stress of orthotropic plates were first derived for simply-supported (SS) and simply-supported–free (SF) boundary conditions. A comprehensive experimental database comprising 595 tensile coupon test results was established to characterise the anisotropic material properties of common DED-Arc stainless steel grades. Based on this database, empirical correlations for estimating directional Young’s moduli and Poisson’s ratios were proposed and used to determine the orthotropic material properties for stub column tests for which a full set of material test data was unavailable. Using 101 collated stub column test results, new local buckling design curves were developed for SS and SF plates, with the plate slenderness determined based on the orthotropic material assumption. Comparative assessments demonstrate that the OPBM significantly improves accuracy over the conventional isotropic design rules in EN 1993-1-4, with the mean test-to-predicted resistance ratio decreasing from 1.30 to 1.10 for SS plates and from 1.47 to 1.17 for SF plates. Two worked examples are provided to illustrate the practical implementation of the OPBM. The proposed OPBM provides a mechanics-based design framework for DED-Arc stainless steel plate elements and can be extended to other AM metallic materials exhibiting anisotropy, supporting their safe and efficient application in structural engineering.