다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

It is widely known that the availability of lightweight structures with excellent energy absorption capacity is essential for numerous engineering applications. Inspired by many biological structures in nature, bio-inspired structures have been proved to exhibit a significant improvement over conventional structures in energy absorption capacity. Therefore, use of the biomimetic approach for designing novel lightweight structures with excellent energy absorption capacity has been increasing in engineering fields in recent years. This paper provides a comprehensive overview of recent advances in the development of bio-inspired structures for energy absorption applications. In particular, we describe the unique features and remarkable mechanical properties of biological structures such as plants and animals, which can be mimicked to design efficient energy absorbers. Next, we review and discuss the structural designs as well as the energy absorption characteristics of current bio-inspired structures with different configurations and structures, including multi-cell tubes, frusta, sandwich panels, composite plates, honeycombs, foams, building structures and lattices. These materials have been used for bio-inspired structures, including but not limited to metals, polymers, fibre-reinforced composites, concrete and glass. We also discussed the manufacturing techniques of bio-inspired structures based on conventional methods, and adaptive manufacturing (3D printing). Finally, contemporary challenges and future directions for bio-inspired structures are presented. This synopsis provides a useful platform for researchers and engineers to create novel designs of bio-inspired structures for energy absorption applications.

A review of recent research on bio-inspired structures and materials for energy absorption applications

The review outlines modern trends in theoretical developments, novel designs and modern applications of sandwich structures. The most recent work published at the time of writing of this review is considered, older sources are listed only on as-needed basis. The review begins with the discussion on the analytical models and methods of analysis of sandwich structures as well as representative problems utilizing or comparing these models. Novel designs of sandwich structures is further elucidated concentrating on miscellaneous cores, introduction of nanotubes and smart materials in the elements of a sandwich structure as well as using functionally graded designs. Examples of problems experienced by developers and designers of sandwich structures, including typical damage, response under miscellaneous loads, environmental effects and fire are considered. Sample applications of sandwich structures included in the review concentrate on aerospace, civil and marine engineering, electronics and biomedical areas. Finally, the authors suggest a list of areas where they envision a pressing need in further research.

Review of current trends in research and applications of sandwich structures

Over the past several decades, a noticeable amount of research efforts has been directed to minimising injuries and death to people inside a structure that is subjected to an impact loading. Thin-walled (TW) tubular components have been widely employed in energy absorbing structures to alleviate the detrimental effects of an impact loading during a collision event and thus enhance the crashworthiness performance of a structure. Comprehensive knowledge of the material properties and the structural behaviour of various TW components under various loading conditions is essential for designing an effective energy absorbing system. In this paper, based on a broad survey of the literature, a comprehensive overview of the recent developments in the area of crashworthiness performance of TW tubes is given with a special focus on the topics that emerged in the last ten years such as crashworthiness optimisation design and energy absorbing responses of unconventional TW components including multi-cells tubes, functionally graded thickness tubes and functionally graded foam filled tubes. Due to the huge number of studies that analysed and assessed the energy absorption behaviour of various TW components, this paper presents only a review of the crashworthiness behaviour of the components that can be used in vehicles structures including hollow and foam-filled TW tubes under lateral, axial, oblique and bending loading.

https://myresearchspace.uws.ac.uk/ws/files/1765038/Paper_2.pdf

On the crashworthiness performance of thin-walled energy absorbers: Recent advances and future developments

Innovative honeycomb-based structures have been paid substantial attention in recent years due to their superb mechanical performances and specific functions. The presented study made acomprehensive overview on the development of the innovative honeycomb-based structures in the past two decades, including filled-type, embedded, tandem, hierarchical, auxetics with Negative Poisson's Ratio (NPR), etc. Mechanical performances of these structures were commented with advantages and disadvantages, related on their geometric configurations, mechanical performance and dynamic response, respectively. The challenges as well as future directions were also analyzed. The achievements provide significant guidelines in designing of new generation light-weight honeycomb-based structures.

Recent advances in novel metallic honeycomb structure

Metamaterials have unprecedented properties that facilitate the development of advanced devices and machines. However, their interconnected building structures limit their applications, especially in the fields that require large deformation, rich programmability and efficient shape-reconfigurability. To break this limit and exploit more potentialities of metamaterials, an innovative material design strategy is proposed, named mechanical pixel (MP) array design. Similar to a screen that displays images by adjusting the colors of pixels, the metamaterials can form and reconfigure 3D morphologies by tuning the heights (lengths) of the MPs in the array. The strategy is demonstrated in a multistable metamaterial by experimental tests, theoretical analysis, and numerical simulations. Using this strategy, a large macroscopic shear deformation is obtained, and remarkable enhancements in the mechanical programmability, shape-reconfigurability and adaptability, and reusable shock-resistance are exhibited. Moreover, mechanical design and property prediction for the metamaterials are both greatly simplified due to the pixelated design. For a piece of the 3D pixel metamaterial with m n-unit MPs, the number of programmable displacement-force curves increases from n+1 to 2m∙n +1 , and the number of stable morphologies grows from n+1 to at least (n+1)m . This strategy can be used to enhance the merits and further excavate the potential of versatile metamaterials.

3D Pixel Mechanical Metamaterials.

Crashworthiness investigation of the bio-inspired bi-directionally corrugated core sandwich panel under quasi-static crushing load

Numerous composite structures with excellent integrative performance that can replicate the mechanical properties of biological materials have been created to fill gaps in material-property charts, and these bio-inspired structures have crucial implications in a wide range of engineering communities. In this paper, a series of novel bio-inspired aluminum honeycombs consisting of horseshoe mesostructure have been proposed on the basis of triangular honeycomb, square honeycomb, hexagonal honeycomb and kagome honeycomb to improve the energy absorption capacity. The three-dimensional finite element models of the bio-inspired horseshoe-shaped aluminum honeycombs are developed in order to explore the mechanical behaviors under the out-of-plane uniform compression. The simulation results are validated based on the compression experiments of regular hexagonal honeycombs. Besides, parametric investigations are carried out to understand the influences of the wave amplitude, wave number and cell-wall thickness on the out-of-plane crashworthiness. The numerical results demonstrate that adding the horseshoe mesostructure to the regular honeycombs can increase the plateau force greatly compared with the traditional honeycomb structure, leading to the higher specific energy absorption although increasing the initial peak force as well. Finally, a multi-objective optimization is carried out to seek for the optimal honeycombs with the maximum specific energy absorption together with the minimum initial peak force simultaneously.

Out-of-plane crashworthiness analysis of bio-inspired aluminum honeycomb patterned with horseshoe mesostructure

The paper presents a theoretical, numerical and experimental investigation into the dynamic behavior of internally nested tube systems subjected to lateral impact loading. A theoretical model based on rigid, perfectly plastic material idealization is proposed, in which the effects of strain-hardening and strain-rate are considered. The analytical solutions to the crushing behavior of nested tube systems are obtained. Numerical simulations based on finite element method using the explicit code LS-DYNA and experiments are performed and the response of force and displacement versus time impacted by a drop hammer are compared with the theoretical predictions, resulting in good agreement.

Internally nested circular tube system subjected to lateral impact loading

In this paper, the size-dependent vibrational behaviors of functionally graded (FG) magneto-electro-viscoelastic nanobeams in the presence of porosities and embedded in the viscoelastic medium are studied based on the nonlocal Timoshenko beam theory in conjunction with the Kelvin-Voigt viscoelastic model. The viscoelastic medium is modeled as a visco-Pasternak foundation with consideration of both shear modulus and medium damping coefficient. The FG material properties are supposed to vary along the thickness direction in a power-law exponent form, and two types of porosity distributions are considered. The present model is validated by comparison with several existing theories and a good agreement is achieved. Parametric studies are carried out to investigate the coupling influences of the nonlocal parameter, FG power-law index, porosity volume fraction, porosity distribution, boundary condition, structural damping coefficient and viscoelastic foundation parameters, as well as electric voltage and magnetic potential on the vibrational performance of FG magneto-electro-viscoelastic porous nanobeams. The results are helpful for the design and applications of nano-electro-mechanical systems (NEMS).

Jialing Yang

Papers

3D Pixel Mechanical Metamaterials.

Crashworthiness investigation of the bio-inspired bi-directionally corrugated core sandwich panel under quasi-static crushing load

Out-of-plane crashworthiness analysis of bio-inspired aluminum honeycomb patterned with horseshoe mesostructure

Internally nested circular tube system subjected to lateral impact loading

Vibration of FG magneto-electro-viscoelastic porous nanobeams on visco-Pasternak foundation