Numerical study of smart honeycomb core using shape memory polymers

This paper presents an experimental investigation on the effect of structural (geometrical) design on the thermomechanical behavior of shape memory polymers. Three beams with identical dimensions (length, width, and thickness), material, and mass, but with different geometrical cells (honeycomb, diamond, and rounded rectangle) are designed by solving a set of nonlinear equations and produced using additive manufacturing method. Then, thermomechanical tests under bending and tensile loading at different temperatures are conducted. As a result, shape recovery and force recovery of the beams, due to the shape memory behavior of the material, are measured. In bending and tensile tests, shape and force recovery results of each beam are compared with their own pre-force and other beams. According to the results, the beam with rounded rectangle cells has the most shape recovery and force recovery ratios (compared to its applied pre-force). Shape recovery for this beam type in bending and tensile tests is 93.03% and 87.86%, respectively. The beam with honeycomb cells requires more pre-force in bending and tensile modes for programming, which leads to a higher maximum force recovery, due to its higher strength.

Section: Introductionmentioning

confidence: 99%

An experimental investigation on structural design of shape memory polymers

Roudbarian

Baniasadi

Mojtaba

et al. 2019

“…Here the concept may rather be qualified as semi-active [26,27] or simply adaptive, since the characteristic time required to pass from one configuration to another (a few seconds) is much larger than the periods associated to the dynamical effects to be controlled. Recent works on damping control of sandwich structures based on magneto-elastic couplings [28,29], or smart honeycomb composite cores based on shape memory polymers [30] can also be considered as related to the investigations reported here.…”

Section: Introductionmentioning

confidence: 78%

In-core heat distribution control for adaptive damping and stiffness tuning of composite structures

Butaud

Renault

Verdin

et al. 2020

In this work, a smart composite structure with damping and stiffness control ability is proposed. The multilayered arrangement has a shape memory core, whose damping and stiffness are tuned by temperature control. The structure is divided in several zones, each of them can be heated in real time using temperature regulation to reach the expected mechanical properties provided by the strong temperature and frequency dependency of the stiffness and loss factor of the viscoelastic core. The heat flux, which is used to tune the mechanical properties, is provided by copper tracks printed on an electronic board used as skin of the sandwich. The paper presents a model-based design process, including thermal and mechanical simulations, providing the gradient temperature fields which are required to obtain a specific damping and stiffness. Experimental tests are finally presented, considering three configurations with various temperature sets corresponding to three different compromises between static stiffness and dynamic damping.

“…So far, many lattice structures with different unit cells including pyramidal [13], 3D kagome [14,15], octet structure [2,16], tetrahedral structure [14,17], etc, have been constructed and the corresponding mechanical behaviors have been studied, respectively. However, most previous studies have only dealt with the lattice structures made of metals [12,18] and ceramics [19][20][21], and only a few papers have focused on lattice structures made of polymers [10,22,23]. As compared to metals or ceramics, polymers usually show stronger time and temperature dependence for outdoor load bearing structures, and should be taken into account.…”

Section: Introductionmentioning

confidence: 99%

Design oriented constitutive modeling of amorphous shape memory polymers and Its application to multiple length scale lattice structures

Yan

2019

Shape memory polymer (SMP) based lattice structures have been drawing increasing attention because of their tune-ability, high specific strength and stiffness, substantial energy absorption capability, and ease of manufacturing by 3D printing. While a number of studies have been conducted to model and design simple SMP structures such as beams, there is currently a lack of effort towards modeling SMP lattice structures. In this study, a design oriented constitutive model based on the concept of phase evaluation law was revisited. Because traditional iso-stress or iso-strain assumption does not capture the physical transition between the active phase and frozen phase, we developed a new two-phase sphere model based on the physical growth process of the frozen phase from nuclei. The constitutive model was validated by modeling the thermomechanical response of amorphous SMP dog-bone specimen, plate specimen, and cubic lattice specimen by using user-defined subroutine UMAT in ABAQUS. The validated model was then used to predict the thermomechanical behaviors of three lattice structures with different unit cells and further used to predict the structural behavior of self-similar multiple length scale lattice structures. It is found that, under uniaxial loading, square unit cell yields the highest load carrying capacity, and lattice structures with higher orders of structural hierarchy fail by rib local buckling with much higher buckling load. This study may help design multiple length scale SMP lattice structures for engineering structures and devices.