Thermal Modeling of BAAM for Tailoring Residual Stresses and Strength
Abstract
Additive manufacturing (AM) offers the potential for the fabrication of complex structuresthat could not previously be achieved, or" which could only be achieved with significant waste. Bigarea additive manufacturing (BAAM) is a large-scale form of polymer AM in which a filament isextruded layer-by-layer onto a bed. BAAM is a versatile technology that could be used tomanufacture structures" of naval relevance. However, residual stresses in large scale AM structurescan lead to distortions or delamination, and fundamenta""l science-based approaches tocharacterizing and eliminating residual stresses do not currently exist. There is, therefore, a needf"or improved fundamental understanding of the underlying effects of processing conditions andlayer/interfacial characteristics on the residual stresses and the mechanical properties of polymercomposite structures produced by BAAM. Such understanding could provide the basis for thefuture design of AM processes for the fabrication of robust military and civilian structures.The proposed program will develop a fundamental understanding of the effects of BAAMmaterial and processing parameters on the interlayer bonding and residual stresses in large scaleadditively manufactured composite parts. Thermal finite element modeling of the BAAM processwill be performed collaboratively with ongoing experimental as well as 1-D and 2-D simulationefforts. This approach will allow for rapid v"alidation of simulations, synergies between simulationsof varying complexity/detail, and new insights into process sensitivity and" design of improvedprocesses.Three major research tasks are proposed: Develop a robust 3-D simulation of thermalprofiles during BAAM; perform bead parameterization and sensitivity analysis; investigatescalability and optimization of modeling resources. Task 1 will focus on creation of a thermalmodel as well as the correlation of the model outputs to interlayer weld strength and residual"stresses. In Task 2, the BAAM simulation will be used to determine the most important featuresof the extrudate/bead for performance"", while comparison of simulation-derived performancecriteria with experimental results will allow us to determine the limits of the" current model anddevelop ways of accounting for other relevant physics. Task 3 focuses on identifying boundaryconditions for domi"nance of different modes of heat transfer, as well as for different levels ofmodeling complexity.The proposed research will advanc"e BAAM and other extrusion-based method of polymerAM through contributing to answering fundamental questions about the effects of BAAM materialand processing parameters on interlayer bonding and residual stresses in large scale additivelymanufactured composite" parts. Specifically, the proposed research will develop a method forrelating thermal profiles to interlayer bonding and residual s""tress, and harness this ability tounderstand the source of residual stresses in BAAM and develop strategies to mitigate residualst""resses and improve interlayer bonding. In the process, the proposed research will advanceunderstanding of the fundamental science u"nderlying this manufacturing technique and contributeto the development of design rules for BAAM.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jul 07, 2017
- Source ID
- N000141712672
Entities
People
- Amy M Peterson
Organizations
- Office of Naval Research
- United States Navy
- Worcester Polytechnic Institute