Improving fracture strength of fused filament fabrication parts via thermal annealing in a printed support shell

  • R. M. Dunn
  • K. R. Hart
  • E. D. WetzelEmail author
Full Research Article


Polymeric structures fabricated using fused filament fabrication (FFF) have limited use in engineering applications as a result of their poor inter-laminar bonding. In this study, we utilize a dual-material print head to encase a low glass transition temperature (Tg) polymer (acrylonitrile butadiene styrene) within a high-Tg shell (polycarbonate). The resulting structure, if annealed at a temperature between the core and shell polymer Tg values, creates a tough interior with high inter-laminar strength while retaining the as-printed three-dimensional geometry of the part. Fracture toughness of annealed, shelled parts was evaluated using single edge notch bend (SENB) fracture specimens and reached values more than 1800% higher than unannealed specimens. Importantly, the annealed specimens exhibited consistent ductile failure and plastic deformation, unlike the as-printed parts which exhibited brittle inter-laminar fracture. Parts with complex geometries are presented to demonstrate geometric stability during annealing and a practical load bearing application.


Additive manufacturing Fused deposition modelling Fracture mechanics Annealing 



This research was supported in part by an appointment to the Postgraduate Research Participation Program at the U.S. Army Research Laboratory administered by the Oak Ridge Institute for Science and Education through an interagency agreement between the U.S. Department of Energy and USARL.

Compliance with ethical standards

Conflict of interest

On behalf of all authors, the corresponding author states that there is no conflict of interest.


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Copyright information

© This is a U.S. government work and not under copyright protection in the U.S.; foreign copyright protection may apply 2019

Authors and Affiliations

  1. 1.Materials and Manufacturing Sciences Division, U.S. Army Research LaboratoryAberdeenUSA

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