Additive Manufacturing Simulation

The Extrusion Deposition Additive Manufacturing (EDAM) process is a manufacturing process used to produce three-dimensional objects made by deposition of molten polymer composite in a layer-by-layer fashion. Printing with fiber reinforced, semi-crystalline polymers provides for the manufacture of molds that can be used in high-temperature composite prototype molding applications. Further, the EDAM is scalable and can provide printed geometries in the centimeter to meter scales. However, in plane (X-Y) fiber orientation of the extrudate results in mechanical properties in the stacking orientation (Z) that are governed by the bond formed between adjacent extrudate layers. The quality of this interlayer bond is strongly influenced by the processing conditions, namely temperature and printing history.

Customer Papers

In this paper, the commercial finite element software package Abaqus is used to simulate the FDM process. A Mobius arm part is used to illustrate the simulation procedure and a sequentially coupled thermo-mechanical analysis is performed. The heat transfer analysis calculates the temperature history which is mapped onto and used to predict residual stress and potential part distortion in the subsequent structural analysis. The tool path patterns dictate how material is progressively added to the part during the build and directly influence the accumulation of residual stresses within the part. Independent tool path events are characterized using event series data such as time, location and bead cross-sectional area.

Community News

Although additive manufacturing was first developed in the 1980’s, the technology is mainly applied for prototyping and tooling. The printing process is not well understood and controlled to be confidently used for printing of load bearing parts. Due to the complex geometry and the layer by layer printing process, parts as printed may show distortion, residual stress, delamination and failure that render the part unusable at the moment that it comes out of the machine. Finite element simulations of additive manufacturing can be very effective in understanding the cause of these defects and predicting the in-service performance of the printed parts. However, most finite element codes are not designed for simulating additive manufacturing processes.

Customer Papers

Metal Big Area Additive Manufacturing (mBAAM) is a new additive manufacturing (AM) technology based on the metal arc welding. A continuously fed metal wire is melted by an electric arc that forms between the wire and the substrate, and deposited in the form of a bead of molten metal along the predetermined path. Objects are manufactured one layer at a time starting from the base plate. The final properties of the manufactured object are dependent on its geometry and the metal deposition path, in addition to depending on the basic welding process parameters.

Customer Papers

Additive manufacturing, specifically the extrusion deposition process, involves the progressive addition of material at elevated temperatures following a prescribed machine path at prescribed speed. Utilizing the newly available features of Abaqus 2017, specifically element activation and event series, progressive element activation is performed by implanting the user subroutine UEPActivationVol. In this work, the system at Purdue University for extrusion deposition of highly filled, high temperature thermoplastics is modeled through a user subroutine suite which coordinates element activation according to machine instructions, assigns appropriate local coordinate systems for using anisotropic material properties, and sets relevant initial state variables for user material models.

Customer Papers

A UMATHT user subroutine was developed in Abaqus to combine a non-isothermal dual crystallization kinetics model with a statistical melting model in order to describe the simultaneous solidification/re-melting behavior of 3D printed parts during the Extrusion Deposition (ED) process. This subroutine is described in detail. Results indicate that crystallization behavior is significant and strongly dependent on the utilized polymer. As an outlook, the interaction with a second UMAT user subroutine that will be employed to predict residual stresses and deformations is explained.

Customer Papers