# Mechanical and Vibration Performance of Novel Lightweight Sandwich Structures with EPS Beads Filled Syntactic Foam Cores

## TL;DR

This paper introduces a new lightweight sandwich composite with improved mechanical and vibration performance using EPS beads and GFRP face sheets.

## Contribution

A novel hybrid syntactic foam core with EPS beads and HGMs is proposed, offering enhanced mechanical properties and vibration performance.

## Key findings

- Increasing EPS bead density improves compressive and flexural strengths and natural frequencies.
- The sandwich architecture increases flexural load-bearing capacity up to five times compared to standalone cores.

## Abstract

This study introduces
a new class of lightweight sandwich
composites
featuring syntactic foam cores filled with expanded polystyrene (EPS)
beads and reinforced by single-layer glass fiber-reinforced polymer
(GFRP) face sheets. The hybrid core structure was formulated by embedding
hollow glass microballoons (HGMs) and EPS beads of varying densities
(10, 18, and 30 kg/m3) into an epoxy matrix, enabling precise
control over core morphology and mechanical behavior. The structural
performance was comprehensively evaluated through uniaxial compression,
three-point bending, and free vibration tests. To complement the experimental
investigations, a finite element model based on third-order shear
deformation theory was developed to simulate the vibrational response.
The model exhibited strong agreement with experimental data, confirming
its predictive accuracy. Results reveal that increasing EPS bead density
significantly enhances the core and overall composite density, leading
to improved compressive and flexural strengths, elevated natural frequencies,
and reduced damping capacity. Notably, the sandwich architecture dramatically
boosted the flexural load-bearing capacity of the syntactic coresachieving
up to a 5-fold improvement over the standalone core materials. These
findings underscore the effectiveness of EPS bead-filled syntactic
foams in tailoring the mechanical and dynamic properties of sandwich
composites. The proposed design strategy offers a scalable and versatile
approach for developing lightweight structural components with enhanced
performance, suitable for demanding aerospace, automotive, and marine
applications.