Performance Evaluation of Sandwich Structures Printed by Vat Photopolymerization

Abstract

Additive manufacturing such as vat photopolymerization allows to fabricate intricate geometric structures than conventional manufacturing techniques. However, the manufacturing of lightweight sandwich structures with integrated core and facesheet is rarely fabricated using this process. In this study, photoactivatable liquid resin was used to fabricate sandwich structures with various intricate core topologies including the honeycomb, re-entrant honeycomb, diamond, and square by a vat photopolymerization technique. Uniaxial compression tests were performed to investigate the compressive modulus and strength of these lightweight structures. Sandwich cores with the diamond structure exhibited superior compressive and weight-saving properties whereas the re-entrant structures showed high energy absorption capacity. The fractured regions of the cellular cores were visualized by scanning electron microscopy. Elastoplastic finite element analyses showed the stress distribution of the sandwich structures under compressive loading, which are found to be in good agreement with the experimental results. Dynamic mechanical analysis was performed to compare the behavior of these structures under varying temperatures. All the sandwich structures exhibited more stable thermomechanical properties than the solid materials at elevated temperatures. The findings of this study offer insights into the superior structural and thermal properties of sandwich structures printed by a vat photopolymerization technique, which can benefit a wide range of engineering applications.

Compression and Bending Properties of Short Carbon Fiber Reinforced Polymers Sandwich Structures Produced via Fused Filament Fabrication Process

“…The sandwich structures with a C core had the lowest compression performance (5.6 Mpa compressive strength and 0.256 Gpa modulus of elasticity for compression), and the composite sandwich structures with a Hat core had the highest performance (14 Mpa compressive strength and 0.44 Gpa modulus of elasticity for compression). The values of the compressive strength of the Hat core sandwich structure are higher compared to the results obtained in other studies for different types of materials manufactured by additive processes, such as the compressive strength of the diamond core sandwich structure (3 Mpa) manufactured by the FFF process from PLA-PHA material [40]; compressive strength of sandwich structures with diamond core (6.97 Mpa) manufactured by the Vat Photopolymerization process [54]. Loaddisplacement curves typical of compression tests present similar evolutionary patterns, which can be divided into three different stages: elastic deformation, deformation plateau, and densification [55][56][57].…”

Estimation of three-point bending behavior using finite element method for 3D-printed polymeric sandwich structures with honeycomb and reentrant core

“…This phenomenon is often referred to as snap-through instability. Due to this type of failure, this structure tends to have a higher flexure strength compared to honeycomb [8,14]. The flexure stress of the PETG sandwich structure with reentrant core (~56 MPa) was the highest followed by the PETG sandwich structure with honeycomb core (~49 MPa).…”

Rational Design and Characterization of Materials for Optimized Additive Manufacturing by Digital Light Processing

“…One of the earliest introductions of suspensions was in the form of ceramic powder, such as alumina and zirconia, in freeform fabrication using SLA [ 12 ]. This was also extended for DLP [ 13 ], for indirect fabrication of solid complex parts with good surface quality and high precision [ 14 ], after a two-step thermal treatment: (i) debinding, for removing photopolymer matrix, and (ii) sintering, for material consolidation [ 15 ]. Similar to ceramics, metal suspensions have also been proposed for the high-speed fabrication of metal parts after thermal treatment [ 16 ].…”