28 - Numerical study of first cyclic loadings on additively manufactured 316L stainless steel using a compartmentalized finite element model
Abstract
The research has shown that as-built parts fabricated through the Laser Powder Bed Fusion (LPBF) additive manufacturing (AM) process exhibit heterogeneous anisotropy and demonstrate a nonlinear mechanical behavior that is challenging to predict. In the initial step, in order to account for this behavior, a home-made compartmentalized finite element model was developed in order to simulate the first uniaxial load-controlled cyclic loadings (R = 0.1) of stainless steel 316L along three directions (0◦, 45◦ and 90◦). The characteristic of this model is its ability to take into account the natural heterogeneity of the material, by assigning a distinct material behavior to each element. In this study, a linear elastic J2 viscoplastic behavior was applied. All parameters were determined through tensile and creep experiments. The yield stress parameters were randomly and statistically distributed across each element. The selected probability distribution was a Gaussian distribution with two parameters : the mean (µ) representing the yield stress with an offset of 0.2%, and the standard deviation (σ). In total, the model used six parameters, two for elastic behavior (Young’s modulus and Poisson’s coefficient) and four for viscoplastic behavior (mean, standard deviation, hardening modulus and viscoplastic coefficient). The numerical results were compared with experimental findings in terms of stress-strain curves. The AM process produces 3D objects by building them one layer at a time. The LPBF process, characterized by its observation of a section of melt pools for each layer and layer interface between layers in parallel plane to the building direction (BD), or some weld beads to represent the laser’s passage for just one layer in a perpendicular plane to the BD. To account for this phenomenon, the FE model’s structure will be built layer by layer. For each layer, a distinct statistical distribution of the yield stress parameter will be assigned. The standard deviation parameter will be the sole element altered in each distribution, with the hope of accurately reproducing the experimental results. The addition of layer heterogeneities to the model is expected to, hopefully, improve the predictions of numerical simulation results.
Speaker
Axel Monnier
Discover speaker profilePhD student in SYMME Laboratory
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28 - Numerical study of first cyclic loadings on additively manufactured 316L stainless steel using a compartmentalized finite element model
Date/Time
20/03/2024
12:15 pm -12:35 pm
Location
Room 7