ABSTRACT
Auxetic textiles are emerging as an enticing option for many advanced applications due to their unique deformation behavior under tensile loading. This study reports the geometrical analysis of three-dimensional (3D) auxetic woven structures based on semi-empirical equations. The 3D woven fabric was developed with a special geometrical arrangement of warp (multi-filament polyester), binding (polyester-wrapped polyurethane), and weft yarns (polyester-wrapped polyurethane) to achieve an auxetic effect. The auxetic geometry, the unit cell resembling a re-entrant hexagon, was modeled at the micro-level in terms of the yarn's parameters. The geometrical model was used to establish a relationship between the Poisson's ratio (PR) and the tensile strain when it was stretched along the warp direction. For validation of the model, the experimental results of the developed woven fabrics were correlated with the calculated results from the geometrical analysis. It was found that the calculated results were in good agreement with the experimental results. After experimental validation, the model was used to calculate and discuss critical parameters that affect the auxetic behavior of the structure. Thus, geometrical analysis is believed to be helpful in predicting the auxetic behavior of 3D woven fabrics with different structural parameters.
ABSTRACT
Numerous applications of DNA origami nanotubes for load-bearing purposes necessitate the improvement of properties and mechanical behavior of these types of structures, as well as the use of innovative structures such as metamaterials. To this end, the present study aims to investigate the design, molecular dynamics (MD) simulation, and mechanical behavior of DNA origami nanotube structures consisting of honeycomb and re-entrant auxetic cross-sections. The results revealed both structures kept their structural stability. In addition, DNA origami based-nanotube with auxetic cross-section exhibits negative Poisson's ratio (NPR) under tensile loading. Furthermore, MD simulation results demonstrated that the values of stiffness, specific stiffness, energy absorption, and specific energy absorption in the structure with an auxetic cross-section are higher than that of a honeycomb cross-section, similar to their behavior in macro-scale structures. The finding of this study is to propose re-entrant auxetic structure as the next generation of DNA origami nanotubes. In addition, it can be utilized to aid scientists with the design and fabrication of novel auxetic DNA origami structures.Communicated by Ramaswamy H. Sarma.
