# Experimental, numerical, and DIC analysis of high-performance VPP composites with multilayer glass fiber reinforcement

## TL;DR

This study improves the mechanical strength of 3D printed composites by reinforcing them with multiple layers of glass fiber.

## Contribution

The novelty lies in using multilayer glass fiber reinforcement in VPP composites to enhance tensile strength while analyzing mechanical properties.

## Key findings

- Tensile strength increased nearly threefold with four layers of glass fiber reinforcement.
- Flexural strength decreased as the number of glass fiber layers increased.
- FEA and DIC simulations confirmed the experimental results' reliability.

## Abstract

3D printing technology, particularly Vat Photopolymerization (VPP), which includes Digital Light Processing (DLP), has the advantage of producing precise products with good layer quality, but it has a weakness in low mechanical strength. This study aims to improve the mechanical characteristics of composites using standard resin reinforced with glass fiber in variations of 0, 1, 2, 3, and 4 layers. The resulting glass fiber-VPP composite specimens were analyzed through tensile test, flexural test, hardness test, and density test in accordance with ASTM standards. Validation of the experimental results was carried out using FEA (finite element analysis) and DIC (digital image correlation) methods, while evaluation of fracture microstructure phenomena was conducted using SEM testing. The results of this study showed that tensile strength increased by nearly three times. Specimens without reinforcement had an average ultimate tensile strength (UTS) of 20.1 MPa, while specimens with 4 layers of glass fiber had an average UTS of 59.3 MPa. As the number of glass fiber layers increased, the flexural strength of the composite tended to decrease, with the highest flexural strength observed in the specimen with 0 layers of glass fiber at 28.52 MPa, and the lowest in the specimen with 4 layers at 17.58 MPa. The addition of glass fiber led to an increase in density, reaching 1.25 g/cm3 in the specimen with 4 layers of glass fiber. Meanwhile, the hardness value decreased from 61.16 HD in the specimen with 0 layers to 47 HD in the specimen with 4 layers. The FEA and DIC simulations were consistent with the experimental data, supporting the reliability of the research results. This technology can be further applied in real-world applications, particularly in the biomedical, automotive, and aerospace industries.