Particle- based Simulation of Crack Propagation in Structural Connections Produced with Direct Energy Deposition 3D- Printing

                                
==Abstract==

This paper explores how Force Flux Peridynamics (FFPD) can support the design of lightweight metal components in building structures produced with Direct Energy Deposition (DED) Additive Manufacturing (AM). DED is a relatively new technology that deposit metal layer-by-layer to create three-dimensional structures without the need for support structures. This process has the potential to significantly reduce the embodied carbon in building structures by reducing the weight of the structural connections and hence the weight of all other structural components [4]. However, the process applied in AM for metals can make the printed objects susceptible to defects which may compromise their structural integrity and may even lead to fracture [5]. In this paper we describe a design process for the creation of lightweight structural components while including modelling of anisotropy, yielding and brittle fracture. The central core of the process is the application of a particle method called Force Flux Peridynamics (FFPD) which is used to predict yielding and fracture. The paper thus builds upon strategies developed and defined in other publications including; the derivation of the FFPD particle method [2], a strategy for calibration of materials in paper [1], a motivation to apply this concept in the context of nodal connections for spatial structures as described in paper [3]. The specific nodal connection that is analysed in this paper is designed for rotational DED printing which creates a component with radial anisotropic mechanical properties. The node is analysed using an axial tensile and an axial compression load case where the load is applied by imposing incremental translations to the attachments where the structural members would be connected. The susceptibility to fracture in relation to the anisotropy of the printed metal is discussed.