Biological materials-fish scales exhibit ultra-flexibility due to its functionally graded materials. Inspired by the hierarchical gradient structure of fish scales, a new flexible gradient model that can adequately describe the characteristics of the bioinspired hierarchical structures is proposed in this work. To assess the flexibility of the proposed gradient model, a combination of extended finite element method (XFEM) and stabilized discrete shear gap (DSG) is established to analyze the vibration of bioinspired gradient plates with/without cracks. The DSG technique is employed to eliminate the shear locking phenomenon, while the XFEM is used for a mesh-independent modelling of crack. The combined approach is applicable to both moderately thick and thin plates, and is insensitive to mesh distortion. Functionally gradient plates take two types: power law function (Type I) and bioinspired hierarchical mode (Type II). For Type I, the natural frequencies decrease by increasing the gradient factor, i.e., the exponent of the power law. When the gradient factor is larger than one, the improvement of the plate stiffness by material gradient is restricted. For Type II, the natural frequencies are mostly independent of the step smoothing factor, yet quite sensitive to the number of step layers, providing an additional degree of freedom in tailoring the material properties. In addition, the natural frequencies of the bioinspired gradient plate are lower than that of the homogeneous ceramic plate. By using Type II, the stiffness of the plate can be reduced effectively, making the plate prone to deformation, which coincides with the flexible scale design. Therefore, the present study provides an incisive method and instructive guideline for a new era of artificially designed flexible materials inspired by natural (or biological) materials and structures.
Abstract The main aim of this paper is to investigate the mechanical buckling behavior of functionally graded materials and carbon nanotubes-reinforced composite plates and curved panels. The governing equations are established using a double directors finite element shell model which induces a high-order distribution of the displacement field and takes into account the effect of transverse shear deformations. The effective material properties of functionally graded materials are estimated using...
This paper aims to investigate the effect of the Winkler-Pasternak elastic foundation on the natural frequencies of Carbon Nanotube (CNT)-reinforced laminated composite plates and shells. The micromechanics of reinforcing CNT particles are described by a two-parameter agglomeration model. CNTs are gradually distributed along the thickness direction according to various functionally graded laws. Elastic foundations are modeled according to the Winkler-Pasternak theory. The theoretical model consi...
#1Zengqian Liu(CAS: Chinese Academy of Sciences)H-Index: 17
#2Marc A. Meyers(UCSD: University of California, San Diego)H-Index: 97
Last. Robert O. Ritchie(University of California, Berkeley)H-Index: 132
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Abstract Living organisms have ingeniously evolved functional gradients and heterogeneities to create high-performance biological materials from a fairly limited choice of elements and compounds during long-term evolution and selection. The translation of such design motifs into synthetic materials offers a spectrum of feasible pathways towards unprecedented properties and functionalities that are favorable for practical uses in a variety of engineering and medical fields. Here, we review the ba...
The main aim of the present paper is to solve numerically the free vibration problem of sandwich shell structures with variable thickness and made of Functionally Graded Materials (FGMs). Several Higher-order Shear Deformation Theories (HSDTs), defined by a unified formulation, are employed in the study. The FGM structures are characterized by variable mechanical properties due to the through-the-thickness variation of the volume fraction distribution of the two constituents and the arbitrary th...
The cylindrical bending condition for structural models is very common in the literature because it allows an incisive and simple verification of the proposed plate and shell models. In the present paper, 2D numerical approaches (the Generalized Differential Quadrature (GDQ) and the finite element (FE) methods) are compared with an exact 3D shell solution in the case of free vibrations of functionally graded material (FGM) plates and shells. The first 18 vibration modes carried out through the 3...
Last. Erasmo Viola(UNIBO: University of Bologna)H-Index: 57
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Abstract The paper shows the free vibration investigation of simply supported functionally graded material (FGM) shells. Spherical and cylindrical shell geometries are investigated for two different material configurations which are one-layered FGM structures and sandwich structures embedding an internal FGM core. A three-dimensional (3D) exact shell model and different two-dimensional (2D) computational models are compared in terms of frequencies and vibration modes. The proposed numerical solu...
This paper presents a very flexible variable kinematics modeling technique for composite structures. The key point is the subdivision of the multilayered cross-section into numerical sublaminates, each consisting of one or more physical plies, and the formulation of model assumptions independently in each sublaminate according to the compact index notation known as Generalized Unified Formulation. Reference is made to the classical displacement-based and the mixed RMVT variational frameworks. Fo...
#2Tinh Quoc Bui(TITech: Tokyo Institute of Technology)H-Index: 54
Last. Sohichi Hirose(TITech: Tokyo Institute of Technology)H-Index: 15
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Abstract We present new numerical results in buckling failure analysis of cracked composite functionally graded plates subjected to uniaxial and biaxial compression loads. An accurate extended 3-node triangular plate element in the context of the extended finite element method (XFEM) is developed, integrating the discrete shear gap method (DSG) to eliminate shear-locking. The plate kinematics is based on the Reissner–Mindlin theory, and material properties are assumed to vary through thickness d...
Last. Phuc Phung-Van(Ton Duc Thang University)H-Index: 29
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Abstract A cell-based smoothed discrete shear gap method (CS-DSG3) using triangular elements was recently proposed for static and free vibration analyses of Mindlin plates. In this paper, the CS-DSG3 is extended for free vibration analysis of cracked Mindlin plates by integrating the original CS-DSG3 with discontinuous and crack-tip singular enriched functions of the extended finite element method (XFEM) to give a so-called extended cell-based smoothed discrete shear gap method (XCS-DSG3). Three...
A cell-based smoothed finite element method with discrete shear gap technique is employed to study the static bending, free vibration, and mechanical and thermal buckling behaviour of functionally graded material (FGM) plates. The plate kinematics is based on the first-order shear deformation theory and the shear locking is suppressed by the discrete shear gap method. The shear correction factors are evaluated by employing the energy equivalence principle. The material property is assumed to be ...
#1Ahmed Raza(IIT Mandi: Indian Institute of Technology Mandi)H-Index: 1
#2Mohammad Talha(IIT Mandi: Indian Institute of Technology Mandi)H-Index: 17
Last. Himanshu Pathak(IIT Mandi: Indian Institute of Technology Mandi)H-Index: 63
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In this study, the influence of material uncertainty on the vibration characteristics of the cracked functionally graded materials (FGM) plates is investigated. Extended stochastic finite element f...
Abstract With an exquisite design that allows the elastic modulus to decrease in the surface layer and vary periodically inside, the stomatopod dactyl club can easily penetrate a hard and tough conch shell. Inspired by this idea, in this paper, a surface gradient target and a periodic layered target were designed. The failure processes of the two bionic targets and a uniform target under impact were studied with the finite element method (FEM), and the mechanism that allows the bionic designs of...
#1J.L. Liu(NUS: National University of Singapore)H-Index: 4
#2Ashish Singh(NUS: National University of Singapore)H-Index: 7
Last. Vincent B. C. Tan(NUS: National University of Singapore)H-Index: 45
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Abstract Helicoidal laminates mimicking the shells of mantis shrimp crustaceans have been found to be able to bear higher loads than conventional laminate configurations primarily through quasi-static or low-speed out-of-plane loads. However, mantis shrimps are known to withstand high speed impacts and there is a lack of such studies on helicoidal laminates. A study into the ballistic performance of helicoidal laminates was undertaken. The laminae of chitin fibers forming the shell were simulate...
