Thesis
Characterization of interlayer adhesion and fracture resistance in additively manufactured thermoplastic parts
Washington State University
Master of Science (MS), Washington State University
2017
Handle:
https://hdl.handle.net/2376/100998
Abstract
The quality of fused deposition modeling (FDM) 3D printed parts are primarily influenced by the process conditions and mesostructural features. This study aims to establish the relationships between the process parameters/mesostructural features and the fracture resistance of printed parts. A fracture-mechanics-based methodology is developed and used to characterize the interlayer adhesion strength and the overall fracture resistance of FDM 3D printed materials. Double cantilever beam (DCB) specimens of acrylonitrile butadiene styrene (ABS) were designed and printed with a precrack at the layers' interface. Specimens were printed at different nozzle and bed temperatures, and with different layer heights and layer widths. The DCBs were loaded in an opening mode and the load-displacement curves were synchronized with the optical visualization of the crack tip to detect the critical load at the crack initiation. A finite element model, coupled with J-integral method and fracture surface analysis was then developed to obtain the apparent fracture resistance (Jcr,a) and the interlayer fracture resistance (Jcr,i), as a measure of the interlayer adhesion. The results indicated that nozzle temperature has the most significant effect on both the apparent and the interlayer fracture resistances of FDM printed materials. The apparent fracture resistance increased by ~38% with 20°C increase in the nozzle temperature from 220°C to 240°C. Similarly, the interlayer fracture resistance also increased by ~15% from 3391.04±69.83 to 3907.54±143.13 J/m2 . Bed temperature also affected the fracture resistance albeit with a milder rate. The interlayer fracture resistance increased by 7.6% from 3527.91±221.16 to 3798.54±204.04 J/m2 by a 20°C increase in the bed temperature from 85 to 105°C. The layer width appeared to be a less significant factor, compared to the nozzle and bed temperatures. Furthermore, a huge drop from 2130.73±108.37 to 731.82±47.22 J/m2 was observed in the apparent fracture resistance of printed ABS samples when the layer height was increased from 0.1 mm to 0.3 mm. This significant decrease was attributed to the mesostructure consideration through scanning electron microscopy and density investigation. Overall, this work proposes a methodology to quantify the fracture resistance of layer-by-layer printed materials and provides insights toward the design and analysis of printed materials for structural and functional applications.
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Details
- Title
- Characterization of interlayer adhesion and fracture resistance in additively manufactured thermoplastic parts
- Creators
- Nahal Aliheidari
- Contributors
- Amir Ameli (Degree Supervisor)
- Awarding Institution
- Washington State University
- Academic Unit
- Electrical Engineering and Computer Science, School of
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University; [Pullman, Washington] :
- Identifiers
- 99900525131701842
- Language
- English
- Resource Type
- Thesis