# Flexural response of concurrently 3D printed sandwich composite

**Authors:** Bharath H S, Dileep Bonthu, Suhasini Gururaja, Pavana Prabhakar, Mrityunjay Doddamani  
**arXiv:** [2007.11669](https://arxiv.org/abs/2007.11669)  
**Date:** 2020-07-22  
**Summary page:** https://www.summarizepaper.com/en/paper/2007.11669v1/

## Key points

- Study focuses on flexural response of concurrently 3D printed sandwich composites with a syntactic foam core
- Sandwich structures with syntactic foam cores are promising in marine applications due to lower water uptake in the foam core when faced with damage to face-sheets
- High-density polyethylene (HDPE) filament used to 3D print skin of sandwich
- Glass microballoon (GMB) reinforced HDPE syntactic foam filaments used for the core
- Blends of GMB in HDPE prepared at different volume percentages: 20%, 40%, and 60%
- Foamed blends extruded into filament form for use in commercially available fused filament fabrication (FFF) based 3D printers
- Defect-free syntactic foam core sandwich composites concurrently 3D printed for characterization of flexural behavior
- Addition of GMB increases specific modulus and strength in sandwich composites, highest improvement observed in sandwiches containing a core with a volume percentage of 60% GMB
- Flexural strength, fracture strength, and strain of foam core sandwiches exhibit superior response compared to their respective cores
- Experimental results align well with theoretical predictions
- Failure mode of printed sandwich discussed in detail
- Study provides valuable insights into flexural response of concurrently 3D printed sandwich composites, optimizing material composition, and understanding mechanical properties
- Findings contribute to advancements in lightweight materials for marine applications and demonstrate potential benefits of using syntactic foam cores in sandwich structures.

## Summary

The study focuses on the flexural response of concurrently 3D printed sandwich composites with a syntactic foam core. Sandwich structures with syntactic foam cores are considered promising in marine applications due to their lower water uptake in the foam core when faced with damage to the face-sheets. In this research, high-density polyethylene (HDPE) filament is used to 3D print the skin of the sandwich, while glass microballoon (GMB) reinforced HDPE syntactic foam filaments are utilized for the core. To optimize the parameters, blends of GMB in HDPE are prepared at different volume percentages: 20%, 40%, and 60%. These foamed blends are then extruded into filament form for use in commercially available fused filament fabrication (FFF) based 3D printers. The defect-free syntactic foam core sandwich composites are concurrently 3D printed to characterize their flexural behavior. The printed HDPE, foam cores, and sandwiches undergo testing under a three-point bending mode. The results show that the addition of GMB increases both specific modulus and strength in the sandwich composites, with the highest improvement observed in sandwiches containing a core with a volume percentage of 60% GMB. Additionally, the flexural strength, fracture strength, and strain of foam core sandwiches exhibit a superior response compared to their respective cores. The experimental results align well with theoretical predictions. Finally, the failure mode of the printed sandwich is also discussed in detail. Overall, this study provides valuable insights into the flexural response of concurrently 3D printed sandwich composites with a focus on optimizing material composition and understanding their mechanical properties. The findings contribute to advancements in lightweight materials for marine applications and demonstrate the potential benefits of using syntactic foam cores in sandwich structures.