Modeling the mechanical behavior of fused deposition acrylonitrile-butadiene-styrene polymer components

The development of mechanics/materials-based understanding of the relations between the Fused Deposition manufacturing parameters—extrusion flow rate, fiber-to-fiber gap, and manufacturing temperatures—and the resulting material properties of unidirectional FD-ABS materials was studied. Resulting mechanical properties were incorporated into a computer-based manufacturing design tool for optimizing the mechanical performance of unidirectional FD-ABS components. The investigation was conducted using a Stratasys, Inc. FDM1600 Fused Deposition Modeler with P400-ABS as modeling material. The mesostructure of unidirectional FD-ABS materials is characterized as a function of four manufacturing variables: extrusion flow rate, fiber-to-fiber gap, extrusion temperature and envelope temperature in terms of the aerial void and fiber bond densities. In addition, the fiber-to-fiber bond strength is characterized as a function of the manufacturing temperatures. Results showed these two mesostructural variables to be strongly dependent on the fiber-to-fiber gap and extrusion flow rate and very little on the manufacturing temperatures. Manufacturing temperatures influence, however, the fiber-to-fiber bond strength, with the envelope temperature playing an important role. Further improvements in the fracture strength were found after heat treatment of the specimens.; Three particular mesostructures were selected for experimental/analytical-computational characterization of the mechanical stiffness and strength. Experiments conducted on specimens under plane-stress conditions are used to validate the analytical/computational models developed for stiffness and strength predictions. Results showed anisotropy in both stiffness and strength, with the latter being more significant. It was also found that molecular orientation effects during the FD extrusion process reduce the elastic properties of extruded ABS fibers. These experimental results were used to validate theoretical models for the stiffness and strength of FD-ABS materials. Differences with experimental in-plane moduli of less than 10% were obtained in most cases. Strength of FD-ABS material in plane stress showed excellent agreement with theoretical predictions from a multi-axial theory. These models are then incorporated into the ABAQUS Finite Element model of a coat-hook and further linked to a global convergent optimization tool. The optimal fiber layout orientation which maximizes the load carrying capacity of the component was found.