Thermal Conductivity Properties and Heat Transfer Analysis of Multi-re-entrant Auxetic Honeycomb Structures

Abstract

In this work, the static and transient conductivity properties of a novel centersymmetric honeycomb structure are evaluated using analytical and finite element (FE) models. The honeycomb structure features a unit cell geometry allowing in-plane auxetic (negative Poisson’s ratio) deformations, and geometry parameters to be used to design the honeycomb configurations for multifunctional applications. The equivalent thermal conductivity along the two principal directions of the multi-re-entrant unit cell is calculated using a theoretical approach based on Fourier’s law and electric-thermal analogy. To validate the theoretical models, a FE analysis has been carried out on periodic unit cells under thermal steady-state conditions, showing an excellent agreement with the theoretical results. A transient thermal analysis, considering convection and radiation, has been performed numerically to evaluate the possible use of this honeycomb configuration for sandwich panels in thermal protection systems. Parametric analysis on the thermal conductivity and maximum temperatures acquired during convection-radiation is performed vs. the nondimensional geometry parameters of the honeycomb cell. The auxetic honeycomb configurations show higher out-of-plane conductivity, strong in-plane thermal anisotropy, and the lowest peak temperatures during heat transfer between the bottom and top faces of honeycomb panels.

Phononic band gap design in honeycomb lattice with combinations of auxetic and conventional core

“…2. These geometries include the reentrant, multi-reentrant, chiral and anti-chiral structures [5,6,7,8,9,10,11]. Different variations of the chiral and antichiral lattices like hexachiral, tetrachiral etc.…”

Novel design of honeycombs using a seamless combination of auxetic and conventional cores toward phononic band gap engineering

“…2 and include reentrant, multi-reentrant, chiral and anti-chiral structures. [5][6][7][8][9][10][11] There are, again, different variations of chiral and antichiral lattices like hexachiral, tetrachiral etc.…”

“…These topologies mainly involve reentrant, multi-reentrant, chiral and anti-chiral structures. [5][6][7][8][9][10][11] With growing technological capabilities in fabricating structures with more complicated geometries, research on auxetics has gained further momentum. However, in spite of enormous opportunity in potentially tweaking different properties to have more freedom in availing desired behavior, attention has scarcely been given to the analysis and design of structures involving combined conventional and auxetic cores, and such rare efforts mainly involve combining them along one dimension only.…”

Experimental and numerical study of distortion in flat, L‐shaped, and U‐shaped carbon fiber–epoxy composite parts

“…As such, several studies reported in the literature have tried to establish the correlation between these properties and the curing temperature and the degree of cure [37][38][39][40][41][42][43][44][45].…”

“…They reported similar findings for thermal conductivity. Johnston [42] and Innocenti et al [45] described thermal conductivity of composite materials as a vector quantity which is directionally dependent. …”