Evaluation of energy absorption capabilities and mechanical properties in FDM printed PLA TPMS structures

Abstract

Additive manufacturing is an advanced technology used to fabricate complex geometries with unique properties like cellular structures which accommodate repeated unit cells located in the x, y and z direction. These structures can be used as infill patterns due to their self-supporting structure. Among the cellular structures, Triply Periodic Minimal Surface (TPMS) structures such as Gyroid, Diamond and Schwarz Primitive (SchwarzP) structures can be tailored to produce complex structures for various applications like tissue engineering scaffolds and replace the conventional polymeric foams. TPMS structures are designed and manufactured by using the Fused Deposition Modelling (FDM) technique using Poly-Lactic Acid (PLA) as material. Among TPMS structures, Gyroid is having a unique property like structurally symmetric which design was modified to enhance the mechanical properties. The modified Gyroid or deformed Gyroid undergone a quasi-static compression test and compare the results with Diamond and SchwarzP structures. Porosity and permeability coefficients are evaluated and an optical microscope is used to verify the fabricated components. As well as, Failure patterns of the structures were evaluated and energy absorption capabilities determined. The main objective of this paper is to evaluate the impact of design and porosity on the mechanical and morphological properties of TPMS structures. In conclusion, the deformed Gyroid has more energy absorption capability up to the 11.6% strain than other TPMS structures. After 11.6% of strain, SchwarzP structure dominates.

Prediction of Cellular Structure Mechanical Properties with the Geometry of Triply Periodic Minimal Surfaces (TPMS)

“…Based on the results obtained, it can be argued that polyamide-12 and polylactide are more promising materials for the manufacture of energy-absorbing structures than photocured polymers based on acrylates. 31 The physical and mechanical properties of the tested samples are presented in Tables 3−5.…”

3D-Printed PEEK/Silicon Nitride Scaffolds with a Triply Periodic Minimal Surface Structure for Spinal Fusion Implants

“…One advantage of TPMS structures over strut-based cellular structures is that the strut size varies linearly from one node to another, resulting in a gradual change in the material distribution. This eliminates the sudden increase/decrease in material distribution, which improves the mechanical properties . In addition, the unique geometry of the surface-based lattices reduces stress concentrations, thus producing a smoother crush behavior as they undergo compressive loading .…”

“…This eliminates the sudden increase/decrease in material distribution, which improves the mechanical properties. 22 In addition, the unique geometry of the surface-based lattices reduces stress concentrations, thus producing a smoother crush behavior as they undergo compressive loading. 20 Therefore, the PEEK/SiN TPMS scaffold limits the risk of implant failure and has demonstrated sufficient loadbearing capacity to function as a substitute for trabecular vertebral bone.…”

“…The surface is partitioned into two infinitely intertwined domains, while the whole structure remains an open cavity . The TPMS structure possesses several notable advantages, including a large surface area, a favorable strength-to-weight ratio, a uniform stress distribution under load-bearing conditions, and a high energy absorption capacity with low relative density. , …”

“…20 The TPMS structure possesses several notable advantages, including a large surface area, a favorable strength-to-weight ratio, a uniform stress distribution under load-bearing conditions, and a high energy absorption capacity with low relative density. 21,22 PEEK is one of the main materials clinically used for fusion cages, and it is a polymer that is biomechanically similar to cortical bone, offering advantages in terms of load distribution. 23,24 However, PEEK does not bind directly to bone due to its chemical inertness and hydrophobicity.…”