Title: Microscale Thermal Management and Effect of Defects in Fused Deposition Modeling of Continuous Carbon Fiber PLA Composite

Authors: Nima Moazami, Massoud Kaviany, Harsh Baid, Reza Hajiha, Cody Godines, and Frank Abdi

DOI: 10.33599/nasampe/c.19.0728

Abstract: Current material options and Additive Manufacturing (AM) printing techniques (e.g. fused deposition modeling (FDM), known as 3D printing) lead to the creation of substantial voids in the built parts, which have a negative effect on the attainable strength of composites. These voids are categorized into three different types in 3D printed carbon fiber composites: 1) gas bubbles 2) interbead voids and 3) fiber pull-out. In fact, thermal history (temperature vs. time), meltpool, and thermo-physical properties play a significant role in how the material flows through the nozzle and more importantly, how the final interface between the beads is formed. The objective is to predict 1) through-the-thickness transient temperature (melting, sintering, and cooling periods) in a microscale level and 2) Material States (i.e. transient changes in density, voids volume ratio, and Volume of Solid (VOS)) of Continuous Fiber Reinforced Thermoplastic Composites (CFRTPCs) using the developed novel algorithm and advanced thermal code. Continuous carbon fiber and PLA filament were utilized as reinforcing phase and matrix, respectively. This multi-physics multi-phase (solid, liquid, and powder) model aims to compensate for the systematic physical property variabilities of the layer-by-layer build-up of a part such as formation of voids, shrinkage, liquid formation and movement due to melting and solidification/sintering. This tool can be used to control the depth/width of the meltpool and Heat Affected Zone (HAZ) to deliver more energy to partially melted regions or less energy to overheated regions. Also, the tool enables tracking of the material temperature, swelling and sintering as a function of various printing parameters to improve the flow behavior. This can be used to define main parameters for good surface contact and temperature conditions to enable optimal polymer sintering conditions. The thermal history was validated against literature data of Filled Chopped Carbon Fiber Composite (CF-ABS) and it is used to track the void formations in microscale level. The model was used to model the experimental condition found in literature for CFRTPCs in FDM process. Two types of defect have been implemented in current simulation study: i) micro-voids predicted by thermal code and ii) fiber waviness that resulted in degraded properties. Nano-assisted micro mechanics was used to implement the effect of void contents inside the neat PLA structure. A Finite Element (FE) is then developed to simulate ISO 14125 bending test on Carbon Fiber Reinforced Polymers (CFRP) and the flexural strength of these virtual models with different fiber loadings are predicted and validated by using a commercially available FE Solver bonded with a Multi-Scale Progressive Failure analyzer.

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Conference: CAMX 2019

Publication Date: 2019/09/23

SKU: TP19-0728

Pages: 14

Price: $28.00