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Lightweight structures with bioinspired metamaterials, with their uniquely engineered properties not found in naturally occurring materials, have garnered significant attention for their potential in various engineering applications. This study explores the mechanical behavior of sandwich plate structures utilizing the Kresling origami pattern, fabricated through a straightforward 3D printing process. By conducting 3-point bending and compression tests, as well as simulations with Abaqus software, the research investigates the distinctive mechanical properties and performance enhancements these origami-inspired structures offer under mechanical loading. This study is noteworthy for being the first to investigate the bending characteristics of sandwich structures utilizing the two cell Kresling pattern or double Kresling, an area that has not been previously explored. Utilizing the Kresling structure in sandwich panels poses a challenge due to its rotational behavior. To address this, we employ a double Kresling pattern, which confines the rotation to the middle layer. This approach ensures that the outer layers remain stable, maintaining the overall integrity of the sandwich panel structure during deformation under mechanical loading. The findings reveal that the 3D-printed Kresling origami core significantly reduces weight while maintaining structural integrity, making it especially beneficial for aerospace engineering, where lightweight yet strong materials are crucial. This research highlights the potential of Kresling-patterned sandwich plates to improve efficiency and performance in supersonic vehicles, providing valuable insights into their structural efficiency and applicability in advanced engineering fields. 

Abstract Fish scale-like features on substrates arranged periodically produce peculiar mechanical behavior. These include nonlinear stiffness, anisotropy in deformation, and finally jamming behavior. These smart structures can be fabricated by partially embedding stiffer plate-like segments on softer substrates to create a bi-material system, with overlapping scales. The dynamic response shows remarkable geometrical-material interplay and anisotropies in damping. Especially interesting is the damping behavior that is distinct from typical damping found in mechanical structures which are often approximated as Rayleigh-Damping. Here we discuss some of these dynamic behaviors that include material-geometry distinction in damping, multiple damping scenarios and interplay of dissipation possibilities. We performed experimental analysis and compared the results with simple mathematical laws that govern architecture-dissipation relationships that can help understand the vibrating response of pillar/scale-covered membranes/thin plates. We conclude by noting the applicability these metastructure in structural damping with other forms currently in use in practice. 

The fouling of submerged surfaces detrimentally alters stratum properties. Inorganic and organic foulers alike attach to and accumulate on surfaces when the complex interaction between numerous variables governing attachment and colonization is favourable. Unlike naturally evolved solutions, industrial methods of repellence carry adverse environmental impacts. Mammal fur demonstrates high resistance to fouling; however, our understanding of the intricacies of such performance remains limited. Here, we show that the passive trait of fur to dynamically respond to an external flow field dramatically improves its anti-fouling performance over that of fibres rigidly fixed at both ends. We have previously discovered a statistically significant correlation between a group of flow- and stratum-related properties, and the quantified anti-fouling performance of immobile filaments. In this work, we improve the correlation by considering an additional physical factor, the ability of hair to flex. Our work establishes a parametric framework for the design of passive anti-fouling filamentous structures and invites other disciplines to contribute to the investigation of the anti-fouling prowess of mammalian interfaces. 

Abstract Fish scales inspired materials platform can provide advanced mechanical properties and functionalities. These materials, inspired from fish scales take the form of either composite materials or multi-material discrete exoskeleton type structures. Over the last decade, they have been under intense scrutiny for generating tailorable and tunable stiffness, penetration and fracture resistance, buckling prevention, nonlinear damping, hydrodynamic and camouflaging functions. Such programmable behavior emerges from leveraging their unique morphology and structure-property relationships. Several advanced tools of characterization, manufacturing, modeling and computation have been employed to understand and discover their behavior. With the rapid proliferation of additive manufacturing (AM) techniques, and advancing envelope of modeling and computational methods, this field is seeing renewed efforts to realize even more ambitious designs. We present a review and recapitulation of the state-of-the art in fish scale inspired materials in this paper. 

Fouling of surfaces in prolonged contact with liquid often leads to detrimental alteration of material properties and performance. A wide range of factors which include mass transport, surface properties and surface interactions dictate whether foulants are able to adhere to a surface. Passive means of foulant rejection, such as the microscopic patterns, have been known to develop in nature. In this work, we investigate the anti-fouling behaviour of animal fur and its apparent passive resistance to fouling. We compare the fouling performance of several categories of natural and manufactured fibres, and present correlations between contamination susceptibility and physio-mechanical properties of the fibre and its environment. Lastly, we present a correlation between the fouling intensity of a fibre and the cumulative impact of multiple interacting factors declared in the form of a dimensionless group. Artificial and natural hair strands exhibit comparable anti-fouling behaviour in flow, however, the absence of flow improves the performance of some artificial fibres. Among the plethora of factors affecting the fouling of fur hair, the dimensionless groups we present herein provide the best demarcation between fibres of different origin.