Characterisation of the anisotropic response of wire and arc additively manufactured stainless steel

Abstract

In contrast to conventional structural steel and stainless steel, wire and arc additively manufactured (WAAM) material can exhibit a strongly anisotropic response. To investigate the degree of anisotropy in WAAM sheet material, data obtained from tensile tests on machined and as‐built stainless steel coupons are utilised. The WAAM material was tested in three different loading directions relative to the deposition direction and the response was captured using digital image correlation; a summary of the key results is presented. In the elastic range, the observed mechanical response is characterised using an orthotropic plane stress material model, which requires the definition of two Young's moduli, the Poisson's ratio and the shear modulus. Good agreement between the test results and the theoretical predictions based on the orthotropic material model is demonstrated. In the inelastic range, to describe the anisotropic yielding of the material, the well‐known Hill's criterion utilising the 0.2% proof stresses is employed. Overall, the elastic and inelastic properties of the studied material are shown to vary significantly with the direction of loading.

Dynamic testing and analysis of the world's first metal 3D printed bridge

“…In the elastic material range, anisotropy was captured by means of an orthotropic material model, while, in the inelastic range, the Hill yield criterion was employed. [55] In ABAQUS, the *LAMINA and *POTENTIAL keywords [50] were used for the elastic and plastic material range, respectively. More details of the FE model used herein, including details of the material properties and modelling of the material anisotropy, can be found in Kyvelou et al [49].…”

Blended structural optimization for wire-and-arc additively manufactured beams

“…The general reference system describes the orientation of the printed layers, while the symmetry axes of the orthotropic medium are denoted as L (longitudinal direction) and T (transversal direction). Previous studies revealed a specific anisotropic relationship between the relative printing orientation and the mechanical response of WAAM-produced stainless steel plates, then modelled as an orthotropic material (as explained in the next section) [12,32].…”

“…This suggests the adoption of an orthotropic material model, whose symmetry axes x and y are the main deposition directions and the orthogonal one (longitudinal and transversal direction, L and T, respectively). As such, previous research has been carried out to calibrate an orthotropic plane stress material model for WAAM stainless steel, validated through experimental tests [12,32].…”

“…Figure 9 reports the stress-strain curves for both printing orientations (0° and 45°) in terms of mean engineering values, e.g., calibrated from experimental results, and the corresponding true values, adopted for the analysis. For more accurate analyses, a calibrated orthotropic material model for both elastic and post-yielding behavior should be implemented (see, e.g., [32]).…”