Numerical and Experimental Studies on the Deformation of Missing‐Rib and Mixed Structures under Compression

Abstract

Auxetic materials are an active research area with many potential applications. [1-8] There are many mechanisms/structures that have been developed to generate negative Poisson's ratio behaviors, including re-entrant structures, chiral structures, rotating rigid/semirigid units and angle-ply laminates. [7-15] These established mechanisms and the capacity of designing Poisson's ratio through controlled heterogeneity have opened up the possibility of developing material systems with targeted Poisson's ratios. The unique properties of auxetic structures lead to a wide range of applications, such as novel fasteners, biomedical applications, energy-absorbing devices, acoustic dampers, membrane filters with variable permeability, personal protective equipment, smart implant, actuators, and sensors. [12-16] These applications targeted require a detailed understanding of deformation of auxetic structures at both local cell level (beam bending, rotation, buckling, and contact) and macroscales (e.g., sample deformation) to balance the mechanical requirements as well as the functional properties. [17-27] In addition, the stability of Poisson's ratio and auxeticity under different loading modes and strain levels is also important. The deformation of porous materials under a compression load is more complex than simple uniaxial tension loading. The deformation of different auxetic structures under compression has been increasingly studied, [28-37] such as negative Poisson's convex-concave foams, [30] re-entrant unit cell, [31-34] disordered auxetic metamaterials, [35] cellular frameworks, [36] arrowhead structures, [29] and missing-rib (MR) auxetic structures. [29-37] Yang et al. [29] studied the behavior of auxetic structures under compression using both static model and dynamic finite-element (FE) modeling. The results show that auxetic materials could be effective in reducing the shock forces. The properties, such as stiffness, Poisson's ratio, and efficiency in shock absorption were found to be dependent on the structure and material combinations. Dong et al. [31] studied the compressive mechanical properties of the metallic auxetic re-entrant honeycomb. The work found that the modeling results were affected by the number of cells used in the FE model. Wang et al. [33] compared the characterization of composite 3D re-entrant auxetic cellular structures made from carbon fiber-reinforced polymer and single materials. The composite re-entrant auxetic structure showed the potential to significantly increase the specific stiffness of the structure. Remennikov et al. [34] studied the quasi-static compression and drop hammer impact tests of sandwich panel with re-entrant honeycomb design. The results suggest that sandwich panels with a re-entrant honeycomb core have a strong potential for enhancing the performance of lightweight impact-resistant protective systems. Apart from research on single mechanism structures, several works have been reported, exploring the use of mixed structures (MSs), which combined auxetic structures o...

Three-Dimensionally Printed Expandable Structural Electronics Via Multi-Material Printing Room-Temperature-Vulcanizing (RTV) Silicone/Silver Flake Composite and RTV

“…Patterns that possess a negative Poisson's ratio, such as re-entrant, rotational, chiral, and crumpled sheets, can be used for this purpose. The missing-rib structure was chosen because it divided the pattern into rows and columns and allowed for its systematic design and modification [61][62][63][64]. We demonstrated the fabrication of expandable structural electronics via multi-material printing, such as capacitor-type strain sensors and resistor-type heaters.…”

Experimental investigation of the in-plane quasi-static mechanical behaviour of additively-manufactured polyethylene terephthalate/organically modified montmorillonite nanoclay composite auxetic structures

“…Several structures have been used to mimic auxetic behaviour in the microscopic and macroscopic scales. Some of them include re-entrant honeycomb structures, 7-10 missing-rib structures, [11][12][13][14] chiral structures, [15][16][17][18] and arrowhead structures, [19][20][21][22] among many others. In addition, unconventional and highlytailored structures have also been researched extensively to obtain highly specific requirements for the intended application.…”

“…Despite their wide usage, these structures have been extensively altered in terms of their geometrical constraints and structural members to extract maximum functionality in recent times. Studies by Tang et al 13 to assess the effects of sample sizes and strain rates on the NPR stability of missing-rib structures showed that the deformation and the instability of the structures resulted from the contact among corner-edge walls. The study proposed a mixed model approach to improve the stable auxeticity range and shape retention.…”

Investigation of a Novel Chiral S‐Shaped Auxetic Structure under Large Tensile Deformation

“…The analyses resulted in different deformation patterns and stability strain ranges for the varied shapes and sizes of the chiral auxetic models. [ 59 ] The mechanical responses of a chiral shape structure were evaluated extensively for the varied compressive loading velocities. The high strain rate of loading resulted in an enhanced specific strength and shock absorbance as compared with quasistatic (slow strain rate) loading.…”