Multifunctionality of Nanoengineered Self‐Sensing Lattices Enabled by Additive Manufacturing

Abstract

Lightweight cellular materials are engineered to enhance performance attributes such as energy absorption, specific stiffness, negative Poisson's ratio, negative thermal expansion coefficient, etc. However, self‐sensing functionality of such architected materials is seldom explored. Herein, a combined experimental and numerical study on additive manufacturing (AM)‐enabled self‐sensing cellular composites processed via fused filament fabrication, utilizing in‐house engineered multiwall carbon nanotube (MWCNT)/polypropylene random copolymer (PPR) filament feedstocks, is reported. The tunable self‐sensing and enhanced mechanical performance of PPR/MWCNT lattices are experimentally demonstrated by varying their architectural parameters in addition to the MWCNT content. The lattices reveal strain and damage sensitivity gauge factors of 12 and 1.2, respectively, comparable to bulk materials’ commercial gauge factors. Furthermore, self‐sensing lattices exhibit 200%, 155%, 153%, and 137% increase in stiffness, energy absorption capacity (as high as 4.7 MJ m−3), specific energy absorption (20.5 J g−1), and energy absorption efficiency (90%), respectively, compared with their non‐reinforced counterparts. The tunable multifunctional performance of AM‐enabled cellular composites demonstrated here provides guidelines for the design and development of composite lattices with advantaged structural and functional properties for an array of applications such as patient‐specific biomedical devices capable of measuring comfort in prosthetics.

Piezoresistive behavior of DLP 3D printed CNT/polymer nanocomposites under monotonic and cyclic loading

“…Subsequently, structure continues to crush at a nearly constant stress of ≈ 1 MPa until densification commences at ε ≈ 55%, which is associated with a steep increase in the slope of the stress-strain curve. The piezoresistive functionality imparted to the structure by the addition of CNTs helps in monitoring the deformation and damage state of structure [51], as discussed in the following. During the initial (elastic) phase of the response, we observe a sharp decrease in ΔR/R 0 with a gauge factor value of 20 as the CNTs move closer to each other within the cell walls, increasing the conductivity of cell wall material.…”

Influence of Core Cellular Structures on Collapse Mechanisms Maps of Sandwich Beams

“…where the σ xx , σ yy and τ xy are the stresses inside the core instead the ε xx , ε yy and γ xy are the core strains. In this study, the foundation has an orthotropic behaviour so the foundation elastic properties are defined following the core stiffness matrix, equation (1) . The total strain energy definition is unchanged.…”

“…Nowadays, Additive Manufacturing (AM) enables the manufacturing of intriguing material architectures inspired by the nature. These cellular materials achieve excellent mechanical properties and functional performances [1,2]. However, it is a challenge to define the best cellular structure inside a complex mechanical system.…”

“…The conventional structure is the hexagonal structure as it is the most used cell inside the sandwich beam. The auxetic structure is the Re-Entrant structure as it is widely studied in literature and it is getting more and more used for energy absorption applications [1,3]. The Gyroid structure is an extremely stiff structure with a shear modulus slightly higher than an isotropic material with the same Young's modulus and Poisson's ratio.…”

Recent Advancements in Design Optimization of Lattice‐Structured Materials

“…FDM has the advantages of low cost and simplicity which make it broadly implemented in the area of lattice-structured materials. [31][32][33][34][35][36] For instance, Andrew et al [36] explored the energy absorption characteristics of PlasGRAY thermoplastic and polypropylene random copolymer multiwalled carbon nanotube (PPR/MWCNTs) and high-density polyethylene plate lattices [31] processed via FDM. Figure 1e depicts the SC plate lattice made of PPR/MWCNTs.…”