Finite Element Simulation of Dimensional Shrinkage and Residual Stresses in Material Extrusion of a Highly Filled Metal-Polymer Feedstock (17-4PH)

Abstract

This preprint presents a staged thermo-mechanical finite element model of the printing, cooling, and detachment stages of material extrusion (MEX) for a highly filled 17-4PH stainless-steel feedstock (95.5 wt.% metal loading, paraffin-wax/stearic-acid binder). Extending the sequential-activation framework of Farh and Gribniak, validated for unfilled PLA, to a metal-filled feedstock for the first time to the authors' knowledge, the model couples a transient thermal simulation with a birth-and-death element activation scheme and a mechanical analysis incorporating temperature-dependent elastic-plastic properties and an explicit detachment stage. The thermal simulation predicts a peak temperature of 95.6 °C. The mechanical simulation predicts a maximum displacement of 0.113 mm (0.068% relative to specimen length) and a maximum von Mises residual stress of 0.306 MPa, localized at the specimen fillets — below the material's room-temperature yield strength but approaching or exceeding it when compared to the assumed local, temperature-dependent yield strength. This work has not undergone external peer review and is shared as a first predictive baseline for the green-state mechanical response of this feedstock, pending experimental validation and intended to support a future extension to spatially graded metal-polymer compositions. The temperature-dependent mechanical properties used in the model are, with one exception, engineering estimates rather than measured data; this and other limitations are discussed explicitly in the manuscript.