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Investigation of Interlayer Interface Strength and Print Morphology Effects in Fused Deposition Modeling 3D-Printed
Daniel B Perez1, Emrah Celik1, Ryan L Karkkainen1
1Department of Mechanical and Aerospace Engineering, University of Miami, Coral Gables, Florida, USA.
3D Printing and Additive Manufacturing
|January 19, 2023
Summary
Fused deposition modeling 3D printing of Polylactic Acid (PLA) shows reduced strength due to interlayer weaknesses. Optimizing printing to reduce gaps can significantly improve part stiffness and strength.
Area of Science:
- Materials Science
- Additive Manufacturing
- Polymer Engineering
Background:
- Fused Deposition Modeling (FDM) is a popular 3D printing technique.
- Layer-by-layer deposition in FDM can lead to anisotropic mechanical properties and weak interlayer adhesion.
- Understanding and improving the interface strength is crucial for enhancing component performance.
Purpose of the Study:
- To quantify the interface strength of 3D-printed Polylactic Acid (PLA).
- To investigate the correlation between microstructure (interlayer gaps, voids) and mechanical properties.
- To explore simulation-based strategies for improving the strength of FDM-printed parts.
Main Methods:
- Tensile testing of custom-designed PLA specimens to measure stiffness and strength.
- Microstructural analysis using digital microscopy to identify and measure defects.
- Finite Element Method (FEM) simulations incorporating microstructural features and cohesive surfaces to model interface behavior.
Main Results:
- 3D-printed PLA specimens exhibited significantly reduced stiffness (32.4%) and tensile strength (47.8%) compared to bulk filament.
- Tensile fracture was primarily caused by interlayer debonding.
- FEM simulations determined an average interface strength of 33.75 MPa, a 22.5% reduction from bulk properties.
- Reducing interlayer gaps in simulations improved stiffness and strength, with complete gap elimination yielding potential improvements of 16.1% and 19.8%, respectively.
Conclusions:
- The interlayer interface is a critical weak point in FDM-printed PLA components.
- Microstructural defects, particularly interlayer gaps and voids, significantly degrade mechanical performance.
- Optimizing the 3D printing process to minimize or eliminate these defects offers a viable pathway to substantially enhance the mechanical properties of printed parts.
