Sandwich Plates Research Articles

Moving-Load Dynamic Analysis of Thick Sandwich Plates with Titanium Alloy Face Sheets and a Porosity-Dependent FG-GPLRC Core

Moving-Load Dynamic Analysis of Thick Sandwich Plates with Titanium Alloy Face Sheets and a Porosity-Dependent FG-GPLRC Core

Analysis of FGM-type porous sandwich plates subjected to free vibration using Student Order Theory

This research adopts a high-order shear deformation theory to explore the free vibration characteristics of square porous sandwich plates constructed from functionally graded materials (FGMs). This theory effectively addresses shear deformation effects without necessitating a shear correction factor. The material properties of the FGMs change continuously throughout the plate's thickness, following a power-law distribution (P-FGM) based on the volume fractions of the component materials. The outer layers are metal, while a uniform ceramic layer constitutes the core. The governing equations are derived from the principle of virtual displacements. This study examines three different porosity distributions. By utilizing Hamilton's principle, the equations of motion were formulated. The numerical analysis demonstrates how the distribution of materials, geometry, and porosity affect the free vibration responses of FGM sandwich plates. The validity of the present theory is studied by comparing certain results obtained with other results published in the literature.

Topological elastic wave transport and manipulation in three-dimensional metamaterials stacked with sandwich plates

Topological metamaterials demonstrate unprecedented wave manipulation abilities with topologically protected robustness, which have been extensively investigated in one-dimensional (1D) and two-dimensional (2D) mechanical systems, but less explored in three-dimensional (3D) systems. In this study, a 3D topological mechanical metamaterial with periodically stacked sandwich metamaterial plates is proposed to achieve 2D topological surface wave transport in a relatively low-frequency range. An innovative chiral compression-torsion coupling core is employed on the sandwich metamaterial plate to lower the band frequency. Analogous to the quantum valley Hall effect, the two-fold topological nodal line is lifted by breaking the spatial inversion symmetry, opening a topological band gap. By supercell analysis, the topological interface state is demonstrated to appear at the interface of two topologically different domains, and the topological boundary state can also be excited under appropriate free or fixed boundary conditions. Taking advantage of the 3D periodicity, the wave propagation based on both topological interface states and boundary states is examined in both 2D flat plates and 3D structures, realizing 1D topological waveguide and 2D topological surface wave transport respectively. It is found that mode symmetry matching is crucial for constructing the topological wave transport with both interface and boundary states. Leveraging the dependence of boundary states on boundary conditions, this work innovatively presents route-switchable and layer-selective wave manipulation by controlling boundary conditions without complicated structure design, enriching the strategies for tunable elastic wave manipulation. Besides, the topologically protected surface wave transport is demonstrated by introducing defects and disorders. These findings provide new insights into the topological transport of elastic waves in 3D mechanical metamaterials and contribute to the development of intelligent and robust devices for various purposes, such as vibration mitigation, energy harvesting, and signal sensing.

Free vibration and nonlinear transient analysis of blast-loaded FGM sandwich plates with stepped face sheets: Analytical and artificial neural network approaches

This study investigates the free vibration and transient dynamic response of functionally graded material (FGM) sandwich plates with stepped face sheets (FGM-SPSFS) supported by viscoelastic foundation under blast loading. The research focuses on the effects of geometric configurations and material property variations across segments. Each plate comprises three layers: a homogeneous hard core and two FGM face sheets, divided horizontally into two segments with differing face sheet thicknesses, which enhance structural stiffness while maintaining a consistent total thickness. The material properties of the sandwich plates follow a power-law distribution. The formulations are based on higher-order shear deformation plate theory and von Kármán geometric nonlinearity, and are solved using Galerkin’s method. Validation is achieved by comparing the results with published literature and finite element analysis (FEA). Artificial neural network (ANN) models are developed to predict natural frequencies without extensive computational runs, employing Bayesian Regularization (BR) and Levenberg–Marquardt (LM) algorithms in MATLAB. A new graphical user interface (GUI) tool facilitates frequency predictions using the proposed ANN model. Key findings indicate that modifications to the stepped face sheets and core layers affect stiffness, natural frequency, and vibration amplitudes. Increasing the core-to-total thickness ratio enhances stiffness, resulting in higher frequencies and reduced displacement amplitudes. The LM algorithm outperforms the BR algorithm, with errors generally below 1%, compared to 2% to 4% for BR with the log-sigmoid function. This study offers valuable insights into the design and analysis of FGM sandwich structures for engineering applications.

Application of machine learning algorithm and Carrera unified formulation in thermal buckling analysis of a functionally graded graphene origami enabled auxetic metamaterial sandwich plate with an auxetic concrete foundation

This study presents a comprehensive thermal buckling analysis of sandwich plates composed of functionally graded graphene origami-enabled auxetic metamaterial (FG-GOEAM) face sheets on an auxetic concrete foundation, using Carrera’s unified formulation (CUF) as the theoretical framework. FG-GOEAM materials are emerging as advanced composites, combining exceptional mechanical resilience, tunable auxetic behavior, and high thermal stability, making them suitable for extreme environments. By employing CUF, a powerful and adaptable modeling approach, this work accurately captures the complex mechanical interactions within the FG-GOEAM sandwich structure under thermal loads, incorporating both material gradation and auxetic properties. To further enhance the precision and efficiency of this thermal buckling analysis, a deep neural network (DNN) is developed as a machine learning algorithm to predict critical temperature differences, based on a dataset generated through mathematics simulation. The DNN model demonstrates excellent predictive capability, validated by close alignment between its estimates and CUF results, thus reducing computational costs while maintaining high accuracy. Parametric studies are conducted to assess the effects of material gradation, aspect ratios, and foundation properties on thermal buckling performance. The results highlight the superior thermal stability of FG-GOEAM structures and the potential of DNNs to serve as reliable, computationally efficient tools for advanced structural analysis. This study provides a novel, integrated framework for high-fidelity thermal buckling prediction in complex auxetic composites, paving the way for broader applications in engineering fields requiring lightweight, thermally stable structures.

Effects of spring oscillators on the vibroacoustic properties of porous sandwich plates under elastic constraints

Effects of spring oscillators on the vibroacoustic properties of porous sandwich plates under elastic constraints

Nonlinear free vibrations of sandwich plates with FG GPLR face sheets based on the full layerwise finite element method

Nonlinear free vibrations of sandwich plates with FG GPLR face sheets based on the full layerwise finite element method

Low-frequency propagating and evanescent waves in strongly inhomogeneous sandwich plates

The paper aims at studying dispersion of elastic waves in a sandwich plate with the parameters, characteristic of aerogel core and hard skin layers, typical for aerospace applications including optimal design of fuselage structural components. The proposed approach relies on multiparametric analysis, taking into account the effect of strong transverse inhomogeneity. It is demonstrated that both an additional low-frequency propagating wave and a slowly decaying evanescent one appear due to a high contrast in geometric and mechanical parameters of the layers. The key findings include the derivation of two-mode asymptotic expansions of the full dispersion relation at the low-frequency limit, as well as elucidation of the non-trivial link between long-wave evanescent and propagating modes. A sophisticated composite nature of the obtained expansions involving various shortened forms is investigated. The range of validity for each of these forms over frequency and wave-number domains is evaluated. Comparison of asymptotic results with the numerical solution of the full dispersion relation is presented.

Low-velocity impact on a CFRP sandwich plate with a reentrant auxetic core

Theoretical analysis is utilized to model the low-velocity impact (LVI) on a Carbon-Fiber Reinforced Polymer (CFRP) sandwich plate with reentrant auxetic core. The Zig-Zag theory is employed to formulate the displacement field of the sandwich plate. The mechanical characteristics of the reentrant auxetic core unit cell are determined through the application of Gibson’s equations. The influences of the unit cell thickness, the unit cell angle, the number of layers of the unit cell along the plate thickness, the impactor radius, and the impactor initial velocity on the LVI study of CFRP sandwich plate with reentrant auxetic core are investigated in detail.

Reverse design and application of phononic crystals based on deep learning

Abstract This paper reverse-design phononic crystals with band gaps within a targeted frequency band using the trained Conditional Variational Autoencoder (CVAE) and further studies the vibro-acoustic characteristics of a composite sandwich plate with a phononic crystal panel as the core layer. Firstly, a matrix composed of 0s and 1s, representing scatterers and substrates, is randomly generated by MATLAB to represent two-dimensional phononic crystals. The three-dimensional phononic crystals are obtained by stretching the two-dimensional phononic crystals along the average direction, and COMSOL Multiphysics is used to calculate the band gap. In order to maximize the production of phononic crystals with a band gap distribution, the Convolutional Neural Network (CNN) is trained to predict whether the generated phononic crystals have band gaps. Finally, using data on the structures of phononic crystals and their band gap distributions, the CVAE is trained to achieve the reverse design of artificial periodic structures based on the target band gap. To verify the effectiveness of the structures obtained through the reverse design method on vibration and noise reduction, the submerged vibro-acoustic characteristics of a composite sandwich plate consisting of a phononic crystal panel and carbon fiber panels are studied. The model of the composite sandwich plate is fabricated, and its submerged vibro-acoustic characteristics are tested and compared with numerical results. Finally, the submerged vibro-acoustic response levels of composite sandwich plates with phononic crystal panels and honeycomb panels as core layers are compared using numerical methods to assess the phononic crystal panel's vibration and noise reduction effects.

Nonlinear vibration analysis of sandwich plates with inverse-designed 3D auxetic core by deep generative model

Building on a deep generative model (DGM), this paper introduces an innovative sandwich plate structure featuring an inverse-designed auxetic 3D lattice core and conducts a detailed investigation of its nonlinear vibration characteristics and effective Poisson's ratios under various parameter settings. By incorporating a conditional estimator and quality loss evaluation functions, the enhanced conditional generative adversarial networks are capable of designing 3D truss auxetic topologies that achieve customized negative Poisson's ratios without reliance on subjective experience. Additionally, lattice specimens are created using 3D metal printing, and the mechanical properties of these DGM-based 3D auxetic structures are validated through vibration experiments and finite element models. These structures exhibit significantly superior natural frequencies compared to those obtained through conventional topology optimization methods reported in existing literature. The study also explores the impact of different functionally graded configurations, temperature variations, boundary conditions, and dimensional parameters on the natural frequency, nonlinear vibration response, and effective Poisson's ratio of the inverse designed auxetic sandwich plates.

Research on low-velocity impact performance of polyurethane foam-filled M-type GFRP foldcore sandwich plate

The M-type GFRP (Glass Fiber Reinforced Polymer) foldcore was prepared by thermal pressing method, and was bonded with the panel to obtain the complete foldcore sandwich structure and filled the core with polyurethane foam. The influence of foam filling, impact energy and impact position on the damage mode and impact dynamic response under the low-velocity impact of GFRP M-type foldcore sandwich structure is studied through low-velocity experiment. The results show that the impact resistance of N-side impact is better than the B-side impact. Foam filling could effectively closing the gap between the N-side impact and B-side impact. In addition, foam filling could absorb about 15%-25% more energy than the empty core sandwich plate.

Comprehensive transverse shear stress analysis for FG-GRC sandwich plates based on a refined higher-order zigzag theory

Comprehensive transverse shear stress analysis for FG-GRC sandwich plates based on a refined higher-order zigzag theory

Study on the Process of Preparing Aluminum Foam Sandwich Panel Precursor by Friction Stir Welding

In recent years, high-performance lightweight and multifunctional aluminum foam sandwiches (AFSs) can be successfully applied to spacecraft, automobiles, and high-speed trains. Friction stir welding (FSW) has been proposed as a new method for the preparation of AFS precursors in order to improve the cost-effectiveness and productivity of the preparation of AFS. In this study, the AFS precursors were prepared using the FSW process. The distribution of foaming agents in the AFS precursors and the structure and morphology of AFS were observed using optical microscopy (OM), scanning electron microscopy (SEM), and X-ray energy dispersive spectroscopy (EDS). The effects of the temperature and material flow on the distribution of the foaming agent during the FSW process were analyzed through experimental study and numerical simulation using ANSYS Fluent 19.0 software. The results show that the uniform distribution of the foaming agent in the matrix and excellent densification of AFS precursor can be prepared when the rotation speed is 1500 r/min, the travel speed is 25 mm/min, the tool plunge depth is 0.2 mm, and the tool moves along the retreating side (RS). In addition, the experimental and numerical simulations show that increasing the welding temperature improves the uniformity of foaming agent distribution and the area of AFS precursor prepared by single welding, shortening the thread length inhibits the foaming agent from reaching the upper sandwich plate and moving along the RS leads to a more uniform distribution of the foaming agent. Finally, the AFS with porosity of 74.55%, roundness of 0.97, and average pore diameter of 1.192 mm is prepared.

Optimal design of vibration resistance of fiber-reinforced composite sandwich plates embedded in a viscoelastic square honeycomb core

This work focuses on investigating the optimal design of composite sandwich plates (FCSPs) with a viscoelastic square honeycomb core (VSHC). Firstly, using the cross-fill theory, the complex modulus technique, the first-order shear deformation theory, the minimum strain energy principle, and the Newmark-β method, a theoretical model of the VSHC-FCSPs under half-sine pulse excitation is formulated to calculate the inherent frequencies, the peak and vibration decay time of the transient response in time domain. The peak and vibration decay time are taken as the indexes of the anti-vibration performance. Considering an index of structural stiffness performance, the average value of the inherent frequencies is adopted to calculate the overall stiffness. After a set of literature validations and optimization validations, the multi-objective genetic algorithm is employed to study the optimization issue of VSHC-FCSPs. The optimization objectives are to minimize the three design variables of the transient response peak, vibration decay time, and reciprocal of overall stiffness. Then, the fiber laying angle of each layer, the core thickness ratio and the modulus ratio are assumed as optimization variables. Finally, the results with good vibration resistance and structural stiffness in the Pareto front are chosen as references, and these corresponding variations of the design variables and optimization objectives are obtained. The optimization results have revealed that the optimization variables corresponding to the intermediate points should be selected as references to improve the anti-vibration capacity and ensure the structural stiffness performance.

Vibration and stability of functionally graded porous (FGP) sandwich plates under moving mass

Vibration and stability of functionally graded porous (FGP) sandwich plates under moving mass

Influence of Transverse Normal Strain on Buckling and Vibration of Sandwich Plates

This study presents the buckling and free vibration behavior of simply supported square and rectangular sandwich plates. A third-order shear deformation theory considering both the transverse shear and normal deformations is used. The condition of zero transverse shear stresses on the top and bottom surfaces of the plate is satisfied. Hence, the present theory does not require the shear correction factor generally associated with the first-order shear deformation theory. Governing equations and boundary conditions are obtained using the principle of minimum potential energy. The closed-form solutions of simply supported sandwich plates are obtained. The effect of the side-to-thickness ratio and plate aspect ratio on buckling and free vibration responses of simply supported square and rectangular sandwich plates is examined. Parametric effects of face sheet thickness ratios and load factor upon the critical buckling load for uniaxial and biaxial buckling analysis of square and rectangular sandwich plates for different staking sequences are studied. All numerical solutions are obtained using MATLAB® programs. The results obtained from the present theory are compared with those from classical plate theory, first-order shear deformation theory, higher-order shear deformation theories, and the exact three-dimensional elasticity solutions as applicable.

Probing uncertainty in low-velocity impact behaviour of hybrid functionally graded (FG)—sandwich plate and spherical shell structures

Probing uncertainty in low-velocity impact behaviour of hybrid functionally graded (FG)—sandwich plate and spherical shell structures

Lamb waves in sandwich plates: group velocity not equal to velocity of energy transport

Lamb waves in sandwich plates: group velocity not equal to velocity of energy transport

Experimental study on the ballistic performance of CFRP/AFB sandwich plate

Lightweight bulletproof plate is highly demanded in the field of security field. A novel plate of carbon fiber reinforced plate (CFRP)/aramid filament bundles (AFB) sandwich plate is manufactured through winding methods in this paper. The ballistic performance is evaluated and failure mechanism is explored on the designed six CFRP/AFB sandwich plates. It is found that the sandwich structure of 3-4 × 16 is the best structure by comprehensively considering the energy absorption, Coefficient of Variation(CV) and shaping difficulty, of which the v50 and the average energy absorption are 225.26 m/s and 150.60 J, respectively. In addition, for the case that the number of filaments in the first entanglement is more and the number of first entanglement in the secondary entanglement is less, the ballistic performance would be better. To the failure mechanism, the upper CFRP is damaged by shear failure and the bottom CFRP shows delamination and separation in the impact process. The filament bundle plate in the core layer is benefit in resistance to projectile impact and it fails mainly by the disintegration and bending. This novel CFRP/AFB sandwich plate is a new direction for producing ballistic proof plate.