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This paper proposes a study on the thermal buckling of Variable Angle Tow (VAT) composite plates using high-order theories. Here, the governing equations are derived via the principle of virtual work. Under the assumption of linear pre-buckling, the stability problem is reduced to a linear eigenvalue analysis considering proportional geometric stiffness. In contrast, a constant thermal load is assumed to be known along the plate thickness, and the uncoupled thermo-mechanical formulation is used, where the thermal effects are described as external loads. The plate is discretized using the Finite Element Method (FEM) and high-order theories are developed using the Carrera Unified Formulation (CUF). Using the CUF, the equations are expressed as an invariant of the plate theory approximation order. Therefore, Equivalent Single Layer (ESL) and Layer-Wise (LW) models can be easily implemented. Several geometries and lamination cases are considered for verification purposes, including different side-to-thickness ratios and fiber orientations, which result in various anisotropy effects. In addition, the effect of changing constraints and materials is evaluated. Particular attention is paid to the effect of the structural theory approximation on the evaluation of the thermal buckling load. It is shown that the correct evaluation is highly dependent on the edge-to-thickness ratio and on the anisotropy given by both the fiber orientation and the material properties. As a final remark, sensitivity analysis and best fiber angle solutions are discussed to highlight the importance of the LW modeling approach. [ABSTRACT FROM AUTHOR]

· Novel composite ABHs act as efficient trapped-energy resonators. · Highly-localized trapped modes drive strong scattering of composite ABHs in infinite plates. · Large impedance mismatch and intensified interaction between composite ABHs guarantee efficient vibration isolation. · Various lattice configurations achieve significant bandgap performance and expand vibration-damping regions. Drawing upon the advantages of lightweight nature and highly efficient energy harvesting capabilities, acoustic black holes (ABHs) serve as local resonator units with significant potential in constructing phononic plates. In this paper, we introduce a novel composite ABH structure made of different materials, and extends this composite concept to the infinite plate model. Analytical results reveal that the composite ABH exhibits a stronger local resonance effect and more localized trapped modes compared to traditional homogeneous types. By employing linear algebraic equation systems derived from boundary conditions and utilizing the closed-form solutions of the varying-thickness Kirchhoff plate, we compare the wave propagating behaviors of different ABH scatterers. Numerical results highlight that the enhanced trapped modes resulting from material inhomogeneity lead to more pronounced peaks in scattering energy. Moreover, we address the multiple scattering problem for composite ABH array in the infinite plate using the T -matrix relationship between the scattering and exciting energy. Displacement spectra and wave field results demonstrate that the larger impedance mismatch and increased interaction caused by periodic composite ABHs in the plate result in more effective vibration isolation. Our discussion on array configurations concludes that the ABH square array, incorporating both rows and columns, produces a significant bandgap for flexural vibration, while also expanding the larger and more efficient vibration-attenuated region. [Display omitted] [ABSTRACT FROM AUTHOR]

This paper investigates the vibrational characteristics of functionally graded porous (FGP) nanocomposite plates reinforced with graphene platelets (GPL), incorporating internal line supports, and in contact with fluids on both sides. The nanocomposite plate functions as a vertical wall, separating two rigid tanks containing quiescent, inviscid, irrotational, and incompressible fluids. Three porosity distribution types and three GPL dispersion patterns are examined. The effects of various parameters, such as GPL weight fraction and porosity coefficient, on natural frequencies are investigated, and for the first time, the effect of porosity cell type on the vibrational behavior of the nanocomposite plate is studied. Finally, the impact of fluids' depth on the plate's natural frequencies, mode shapes, and mode order is also discussed. To achieve this, a model for the displacement field, kinetic energy, and strain energy of the nanocomposite plate accounting for both open and closed cell porosity types is developed, employing first-order shear deformation theory (FSDT). This model, in tandem with a fluid-solid interaction model that takes into account both sloshing and bulging modes of the fluids, leads to the formulation of a symmetric eigenvalue problem. Solving this problem via the Rayleigh-Ritz method leads to natural frequencies and mode shapes for the nanocomposite plate. [ABSTRACT FROM AUTHOR]

In this paper, the fatigue failure of engineered cementitious composites (ECC) and concrete laminated structure was investigated by using a model based on the peridynamics (PD) method. The model enhances efficiency by incorporating "residual life" and "cyclic blocks," utilizing the fully discrete method for ECC interfaces and the energy-based PD model for bimaterial interfaces. Its effectiveness, accuracy, and versatility have been validated through various numerical examples. Furthermore, the study examines crack propagation in ECC pavement overlays under four-point bending and investigates the impact of ECC layer thickness and fiber content on the fatigue characteristics of laminated structures. • A fully discrete fatigue model of ECC is constructed based on PD. • The energy-based PD model for the interfaces in ECC-concrete laminated structures was built. • The established model simulated the fatigue failure of ECC-concrete laminated structures. [ABSTRACT FROM AUTHOR]

Reduced-order homogenization (ROH) and related methods are important computational tools for simulating the material behavior of composites. These methods generally sacrifice accuracy in exchange for superior computational efficiency, relative to methods such as classical computational homogenization (CCH). In this study, building on the recently developed solver-free CCH, we propose a fine-scale solver-free reduced order homogenization approach that avoids solving the fine-scale equilibrium equations and approximates the phase-average eigenstrains by sampling the fine-scale eigenstrain at a small number of points. The proposed method, which we call solver-free ROH, works by pre-computing history-dependent eigenstrain influence function tensors and sampling point contribution factors based on training data from a small set of CCH simulations. Then, during the online stage of the computation, phase-average eigenstrains are computed from sampling point eigenstrains and used to compute homogenized stresses and strains. Focusing on small-deformation problems, this paper formulates and verifies the solver-free ROH approach for nonlinear periodic heterogeneous media. First, in the formulation, we delineate a sampling point approximation of the phase eigenstrains and describe the use of this approximation within the coarse-scale stress update. Next, we verify the solver-free ROH using loading cases outside the training data set. Finally, we use the proposed method to simulate a multilayer composite plate in three point bending (3pt-bend) and open hole tension (OHT), demonstrating the method's efficiency and accuracy relative to the CCH. [ABSTRACT FROM AUTHOR]

The purpose of this paper is to test ten identical reinforced concrete haunched beams (RCHBs) to determine the effectiveness of pre-cast strain-hardening cementitious composite (PSHCC) plates for shear strengthening. For this purpose, the PSHCC plates have been manufactured in accordance with the test parameters, let to cure for roughly 30 days, and then dipped into the strengthened RCHBs' concrete cover at the critical shear span. The used PSHCC plates are rectangular in shape with a 20 mm thickness and a 100 mm width, and they are reinforced with a single layer of steel wire mesh. The considered key parameters were the effect of shear reinforcement in the test region, the PSHCC plate orientation angle (450, 600, or 900), and the spacing between PSHCC plates (200, 250, or 300 mm). In addition, it was interesting to observe how the strengthening plates, if they exist, are positioned in relation to the inner stirrups (aligned, un-aligned, or inclined). The application of PSHCC substantially enhanced the ultimate shear capacity of the strengthened beams, according to the results of experimental tests. Moreover, the inclined configuration of the PSHCC demonstrated higher shear performance than the vertical configuration, both in terms of the shear cracks characteristics and ultimate capacity. As well, the ductility and serviceability characteristics of the strengthened RCHBs were obviously affected by the application of PSHCC plates. Finally, a proposed analytical model was developed to estimate the shear capacity of the strengthened RCHBs using PSHCC plates. • PSHCC plates were investigated for shear strengthening of RC haunched beams. • The effect of web reinforcement, plates orientation angle and spacing were investigated. • Ten RC haunched beams under four-point loading have been experimentally tested. • A shear capacity increase of 48.8-148.5% was achieved. • A proposed analytical model was developed for predicting the ultimate shear capacity of the strengthened RCHBs. [ABSTRACT FROM AUTHOR]

• The nonlinear vibrations and control are investigated for the PFG-GRLCCR variable cross-section plate with NPPF controller. • The dynamic mode is derived for the PFG-GRLCCR variable cross-section plate. • The NPPF controllers are designed according to the similarity principle. • The frequency responses under the simultaneous resonance are analyzed. • Chaotic dynamics are investigated by the bifurcation diagrams. This paper studies the nonlinear vibrations and control of the piezoelectric functionally graded graphene-reinforced laminated composite cantilever rectangular (PFG-GRLCCR) variable cross-section plate with the NPPF controller under the simultaneous resonant cases. The nonlinear dynamic governing equations of motion for the PFG-GRLCCR variable cross-section plate are obtained by using the extended Halpin-Tsai mode, linear constitutive equations of the piezoelectric materials, classical laminated plate theory, von Karman large deformation theory, and Hamilton principle. Considering Galerkin method, the nonlinear ordinary differential governing equations are obtained. The nonlinear positive position feedback (NPPF) controllers are designed according to the similarity principle. The multiple scale method is used to investigate the nonlinear vibration characteristics of the stable motion for the PFG-GRLCCR variable cross-section plate with the NPPF controllers. The amplitude-frequency response curves, force-amplitude response curves, time histories, phase portraits, and bifurcation diagrams are given to investigate the nonlinear dynamic characteristics of the PFG-GRLCCR variable cross-section plate with the NPPF controller. The results demonstrate that the NPPF controller can suppress the nonlinear vibrations of the structure well, and the effectiveness of the controllers is best when the NPPF controller has a similar nonlinear characteristic with the structure. The complex nonlinear vibration characteristics appear for the PFG-GRLCCR variable cross-section plate with the NPPF controller. [ABSTRACT FROM AUTHOR]

Defect detection of laminated composite plates using ultrasonic guided waves is of great interest nowadays. Nevertheless, it is still a challenging problem to reconstruct the true shape of defects in anisotropic materials. The inverse method proposed in this paper can directly reconstruct the specific shape of defects. Moreover, this method does not need iteration, is simple in form and easy to use. A three-step strategy of this method is performed as follows: Firstly, based on boundary integral equation and Born approximation assumption, flaw shape function and reflection coefficients form a set of Fourier transform pairs; Secondly, we propose an efficient way to quickly obtain Green's function and bring it to step 1. Finally, the actual shape and location of flaws can be inversely reconstructed by reflection coefficients in the whole frequency domain obtained by modified boundary element method (BEM). This method is implemented to reconstruct cavity-type flaws at the interface in a laminated composite plate. The correctness and effectiveness of the proposed method is finally validated for several benchmark problems, and the effect of frequency range, flaw size and mode selection on accuracy of the inverse reconstruction are discussed in detail. [Display omitted] • Accurate reconstruction of locations and shapes of multiple defects. • Finer flaw shape images with high-frequency range scattering data. • Sensitivity to small defects. • Fundamental guided wave mode recommended for flaw reconstruction. [ABSTRACT FROM AUTHOR]

• SH waves in a piezoelectric semiconductor/piezomagnetic half-space are studied. • Effects of semiconduction and material properties on SH waves are investigated. • The development of various electromechanical fields are discussed in detail. • The influences of piezoelectric and piezomagnetic constants are highlighted. • The results are useful in multiferroic composite semiconductor structures. Piezoelectric semiconductors (PSs) possess the physical properties of piezoelectric and semiconductor simultaneously. When a piezomagnetic (PM) material is added to the PS, the composite structures will exhibit the comprehensive mageto-electro-semiconductive (MES) coupling effects. In this paper, the propagation characteristics of shear horizontal (SH) waves in a multiferroic composite semiconductor structure are investigated, where a n-type PS thin plate is perfectly bonded to a semi-infinite PM substrate. Based on the three-dimensional macroscopic theory for PS and PM, the dispersion equations are derived analytically. Numerical examples are presented to study the effects of steady-state carrier density, cover thickness, and material properties on the phase velocity and attenuation of SH wave systematically. The developments of various electromechanical fields through the thickness of the layers are discussed. The results show that initial electron concentration (n 0) has an important effect on the distribution of most physical quantities such as displacement, stress, electric potential and electric polarization, but magnetic potential and magnetic flux density are insensitive to n 0. The piezoelectric constant e 15 and piezomagnetic constant f 15 have different effects on the SH wave propagation and magnetic potential distribution. The theoretical results could be helpful for the analysis and design of PS-PM structures or related surface acoustic wave (SAW) devices. [ABSTRACT FROM AUTHOR]

• Thermo-elastic solutions for laminated plates with different supports are derived. • The method is suit for composite plates with arbitrary thickness and layer numbers. • The influences of physical and geometric parameters are thoroughly investigated. This paper aims to investigate thermal behaviors of composite laminated plates with different supports under non-uniform temperature boundary conditions. The thermo-elastic solutions of temperature, displacements, and stresses for the laminated plate with arbitrary layer numbers and thickness are obtained based on the three-dimensional theory of thermoelasticity. By applying the Fourier law of heat conduction and the thermoelastic equations, the state-space equations are established by employing the temperature, heat flux, displacements, and stresses as state variables without the hypothesis of displacement form. The differential quadrature method is introduced to discretize the in-plane state variables. On the basis of the continuities of state variables at the interfaces in the laminated plate, the relationships of temperature, heat flux, displacements, and stresses between the top and bottom surfaces can be derived. By simultaneously considering temperature and mechanical boundary conditions applied to the surfaces of the laminated plate, the initial state variables for temperature, displacements, and stresses can be determined uniquely. The errors in the temperature, displacements and stresses resulting from the differential quadrature method can be eliminated by incrementally augmenting the number of sampling points in the convergence study. The accuracy of the present method is thoroughly verified by comparing the current results with both the finite element solutions and the findings reported in previous literature. Finally, the influences of surface temperature, length-to-thickness ratios, material properties, layer numbers, and support types for the distributions of the temperature field, displacements, and stresses in the laminated plate are discussed in detail. [ABSTRACT FROM AUTHOR]

Physics-driven and data-driven methods are commonly used for impact force identification. Due to system identification errors, physics-driven methods often suffer from force oscillations and peak underestimations, leading to poor accuracy. Data-driven methods generally require massive experimental data, incurring expensive costs. Hence, achieving accurate and low-cost impact force identification in the presence of system identification errors remains a significant challenge. In this paper, we proposed a data-physics hybrid-driven deep learning method for impact force identification, named DPH-TrLSTM. The method utilizes the time-reversed long short-term memory (TrLSTM) network to establish the causal relationship from response to force. The data-physics hybrid (DPH) loss function is employed to mitigate the adverse effect of system identification errors. The DPH-TrLSTM method only requires the transfer matrix and a small amount of experimental data obtained from the system identification step, eliminating the need for additional experiments. Experimental results from 40 impact forces at eight locations on a composite plate demonstrated that the DPH-TrLSTM method could achieve mean peak and relative errors below 1.0% and 2.5%, respectively, significantly outperforming the three regularization methods. This result suggests that the proposed method can perform high-accuracy impact force identification even when system identification errors exist. Moreover, the effect of system identification errors on the method's performance can be evaluated using the min–max curve, thereby determining its applicable scope. The study further reveals that system identification errors are the key reason for the poor performance of the three regularization methods. The choice of measurement points may affect the performance of DPH-TrLSTM, primarily due to system identification errors rather than the condition number of the transfer matrix. [ABSTRACT FROM AUTHOR]

This paper presents an investigation into the free vibration and nonlinear dynamic analyses of new complex edge contour plate structures, known as single-variable-edge (SVE) plates. Cracks emerge at the center of the plate's surface, and the effects of edge crack orientation and depth on the dynamical characteristics of the laminated nanocomposite SVE plates have been considered in this study. The functionally graded graphene nanoplatelet reinforced composite (FG-GPLRC) material was utilized for the edge-cracked plate that rests on a Winker-Pasternak elastic foundation. The Halpin-Tsai micromechanical model is used to predict the material characteristics, which are presumptively temperature-dependent. The rule of mixtures is employed to determine Poisson's ratio, density mass, and thermal expansion. The governing equations are established based on the theory of elasticity, and Von Karman-Donnell geometric nonlinearity assumption. To confirm the reliability and accuracy of this approach, the acquired findings are validated with those produced using Finite Element Analysis (FEA). Furthermore, the geometrical and material parameters, fracture properties, and environmental (temperature and elastic foundation) factors are also investigated in the study. The research findings hold significant implications for applications in aerospace and aeronautical, civil, and mechanical engineering. • The crack orientation and depth have been built in laminated nanocomposite structure. • The dynamics of cracked complex plates have been scrutinized in two aspects: linear and nonlinear responses. • The periodic and chaotic status of the complex structure in critical points have been investigated. [ABSTRACT FROM AUTHOR]

The piezoelectric unimorphs are essential resonant components of many oscillating systems including electroacoustic devices. The unimorph spectral properties are namely dependent on geometric dimensions, applied materials and mounting. Preliminary dimensioning and optimization of unimorph shape are usually carried out prior to comprehensive design work mostly based on finite element method. Simple analytical model is a suitable tool for initial design phase. This paper presents a derivation of calculation model describing natural vibrations of a circular unimorph with the piezoelectric layer diameter smaller than the elastic layer diameter. The system of equations with closed-form solution is instrumental to calculation of resonant frequencies and mode shapes for unimorphs with clamped, simply supported and free circumference. The theoretical results are compared with vibration velocity measurement of clamped unimorph sample in a wide frequency range. Analytical model derived in this paper is used to assess the effect of the thickness tolerance on unimorph resonant frequencies. [ABSTRACT FROM AUTHOR]

The application of the sampling surfaces (SaS) method to the three-dimensional (3D) stress analysis of laminated composite plates is presented in a companion paper (Kulikov GM, Plotnikova SV. Strong sampling surfaces formulation for laminated composite plates. Compos Struct 2017;172:73–82). In this paper, we extend the strong SaS formulation to the 3D vibration analysis of laminated plates. The SaS formulation is based on choosing the arbitrary number of SaS parallel to the middle surface in order to introduce the displacements of these surfaces as basic plate unknowns. Such choice of unknowns with the use of the Lagrange polynomials in spatial approximations of displacements through the layer thicknesses leads to a robust laminated plate formulation. The feature of the proposed approach is that all SaS are located inside the layers at Chebyshev polynomial nodes. The use of outer surfaces and interfaces is avoided that makes it possible to minimize uniformly the error due to the Lagrange interpolation. Therefore, the strong SaS formulation based on direct integration of equations of motion of the elastic body can be applied efficiently for the 3D free and forced vibration analyses of laminated composite plates. [ABSTRACT FROM AUTHOR]

This paper addresses the influence of material and fabrication uncertainties on natural frequencies of curvilinear fiber laminate. Material properties and fiber orientation are considered uncertain. The sensitivity of input parameters to natural frequencies is obtained using high-dimensional model representation tool, and the results are compared with Monte Carlo simulation. This sensitivity pattern is established through various parametric studies. Highly sensitive parameters are identified and analyzed. Further stochastic analysis of natural frequencies of curvilinear fiber laminate is performed using polynomial neural network. The accuracy and efficiency of polynomial neural network are compared and conclusions are drawn. [ABSTRACT FROM AUTHOR]

Graphene platelets (GPLs) can be used to enhance the mechanical and electrical properties of the matrix material, which efficiently determines and improves the dynamic behavior in composite structures. Based on the first-order shear deformation theory, this paper investigates the vibration and wave problems in a functionally graded graphene-reinforced composite plate. The composite plate is composed of the polymer matrix reinforced with GPLs that are dispersed along the thickness direction, following four kinds of functionally graded patterns. The governing equation of dynamic problems in the composite plate can be described in the state space formulation, and be solved using the method of reverberation-ray matrix (MRRM). Unlike the traditional state space method, this method is unconditionally stable due to introducing the dual coordinates, which can inherently avoid the numerical instability. After a validation study to verify the present analysis, a parametric study is conducted to analyze the effect of weight fraction, size and distribution patterns of the reinforments, as well as the boundary conditions and aspect ratios on the dynamic behaviors of the composite plate, hence providing a better way to achieve improved dynamic resistances of the GPLs composite plates. [ABSTRACT FROM AUTHOR]

Composite materials facilitate the control of specific properties in components while varying the type, angle, and order of individual fiber weaves in the laminate. This possibility of synthesizing material properties has aroused great interest in musical instrument making since the availability of synthetic fiber composites in the 1970s. However, when arranging plies, the combination of weave types and angles can lead to vibroacoustic effects which are unusual for makers used to working with wood. The mechanics behind these effects are described, starting with an outline of the theory of vibrations in thin plates. Further, the consequences of rotating fibers are theoretically derived and, subsequently, examined in a series of measurements on rectangular thin plates as well as assembled violin top plates. From the findings obtained, it can be concluded that the specific characteristics have to be taken into account for a successful use of composite materials in musical instrument making. This paper, therefore, concludes with easy-to-understand recommendations for musical instrument makers when using fiber composites. [ABSTRACT FROM AUTHOR]

Variable angle tow laminates (VAT) and stiffeners are known to redistribute the in-plane load distribution and tailor the buckling mode shapes, respectively, for improving structural performance. To leverage the benefits of using VAT laminates in the practical applications, in the present paper, we discuss buckling load maximization conducted for a stiffened VAT laminated plate with a central cutout considering VAT laminate manufacturing constraints. Three representative boundary conditions as seen in the aerospace structures are considered: in-plane axial displacement, in-plane pure shear, and in-plane pure bending displacements. Two common manufacturing constraints, the one on the automatic fiber placement (AFP) manufacturing head turning radius and the other on the tow gap/overlap, while fabricating VAT laminates are considered in the laminate design. These two manufacturing constraints are modeled by controlling the fiber path radius of curvature and tape parallelism in optimizing the fiber path orientations for the VAT laminates. Stiffener layout and fiber path angle for the VAT laminated plates are both considered in the buckling load maximization study. To avoid using a fine mesh in modeling the stiffened VAT laminates with a cutout when employing the finite element analysis during the optimization, the VAT laminated plate and the stiffeners are modeled independently. The displacement compatibility is enforced at the stiffener–plate interfaces to ensure that the stiffeners move with the plate. Particle swarm optimization is used as the optimization algorithm for the buckling load maximization study. Optimization results show that, without considering AFP manufacturing constraints, the VAT laminates can increase the buckling loads by 21.2% and 12.4%, respectively, comparing to the commonly used quasi-isotropic laminates and traditionally straight fiber path laminates for the structure under the in-plane axial displacement case, 19.7% and 12.5%, respectively, for the in-plane shear displacement case, and 62.1% and 26.6%, respectively, for the in-plane bending displacement case. The AFP manufacturing constraints are found to have different impacts on the buckling responses for the VAT laminates, which cause the maximum buckling load to be 9.3–10.1%, 3.0–3.2%, and 23.2–29.8% less than those obtained without considering AFP manufacturing constraints, respectively, for the present studied model under in-plane axial, shear, and bending displacements. [ABSTRACT FROM AUTHOR]

This paper explores the performance of low-cost unidirectional carbon fibre towpregs with respect to line production speed and fibre volume fraction. Using an automated production line, towpregs were produced at different production speeds, resulting in modified fibre volume fractions. The towpregs were used to manufacture unidirectional composite plates, which were then tested to evaluate mechanical performance. The fibre straightness and interfacial void ratio of the composite plates were determined by statistical analysis of the samples' optical micrographs. The results demonstrate that adjusting the line production speed enables targeted fibre volume fractions (FVF) to be reached, resulting in the composites having different mechanical performances (2039 MPa and 2186.7 MPa tensile strength, 1.26 and 1.21 GPa flexural strength for 59.8% and 64.4% FVF, respectively). It was shown that at lower production speeds and FVF, composites exhibit good consolidation and low porosity, which is highlighted by the better interlaminar shear strength performances (8.95% increase), indicating the limitations of manufacturing very high FVF composites. Furthermore, it was concluded that fibre straightness plays a key role in mechanical performance, as samples with a lesser degree of fibre straightness showed a divergence from theoretical tensile properties. [ABSTRACT FROM AUTHOR]

This paper analyses the influence of face milling process parameters on the surface properties of carbon fibre reinforced polymer. The influence of milling speed and feed per tooth on the surface properties was determined. The influence of cutting speed and feed per tooth on surface energy properties was determined. The object of research was a carbon fiber reinforced plastics (CFRP) composites plate made of carbon fibre in epoxy matrix. The too l used in the study was a double-edged end mill. The machining parameters used were variable: cutting speeds of 100 m·min-1, 120 m·min-1, 140 m·min-1 and 160 m·min-1, and feeds per tooth of 0.015 mm/tooth, 0.020 mm/tooth, 0.025 mm/tooth and 0.03 mm/tooth. The axial depth of cut and radial depth of cut was a constant parameter. After milling, tests were carried out on the surface contact angle, which was used to determine the surface free energy. Based on the contact angle measurements carried out with the sitting-drop method and the calculation of the surface free energy with the Owens-Wendt model, it was observed, that the increase in the value of the surface free energy is significantly influenced by the increase in the cutting speed. [ABSTRACT FROM AUTHOR]

The composite materials are remarkably increasing in many industry sectors like aircraft, automobiles, oil pipes, and marine boats. This attention comes from their excellent properties, such as lightweight and high strength. However, these materials expose many damages like fiber-matrix debonding, matrix crack, and delamination. The composite structures risked damage through the service life and therefore need to repair to achieve their function with a good performance. This paper focuses on the analysis during the tensile test of samples of fi berglass epoxy composite materials exposed to damage before and after repair. Experimental and numerical investigations are performed to determine and identify mechanical properties and failure analysis between repaired and unrepaired composite plates. Five samples are selected: without hole, 4 mm hole-repaired, stepped hole from 4 to 8 mm, and stepped hole from 4 to 8 mm-repaired. Simulation models are created using the finite element (FE) method to compare them with Abaqus's practical experiments to predict damage during the tensile test. To simulate damage models, interlaminar and intralaminar damage, were used to study initiation and propagation of the samples failure. Results show that the experimental and numerical investigations of the repaired samples have a significant effect on the mechanical properties and failure behavior of the holed and stepped plates compared with unrepaired samples. Also, maximum stress and strain are concentrated around and on both sides of the hole, while the most significant damage occurs around the hole and the axial direction. [ABSTRACT FROM AUTHOR]

In this paper, a progressive damage analysis of two-dimensional C/SiC composites and superalloy mechanically fastened joint with countersunk bolt is implemented to simulate the uniaxial tensile loading process by using a user-defined subroutine UMAT embedded into the general package Abaqus. On basis of the developed damage model, a parametric study is carried out to illustrate the effects of countersunk parameters on tensile performance for the hybrid bolted joint. It is found that there are negligible changes in the stiffness of the bolted joint, as the countersunk height varies from 1.5 to 2.5 mm for the considered bolt-head diameter cases. However, the failure load of the ceramic matrix composite and superalloy hybrid joint exhibits significant changes under different combinations of countersunk parameters. Increasing the countersunk height of the bolt intensifies the initial stress concentration and results in the redistribution of stress around the hole-edge area of the composite material plate. For the bolt-head diameter and countersunk height equal to 9.4 and 1.5 mm, respectively, the joint structure ensures the maximum load-bearing capacity for the studied joint with a countersunk bolt. [ABSTRACT FROM AUTHOR]

An analytical approach is developed in this paper to investigate the wave propagating in graphene oxide powder (GOP) reinforced nanocomposite plates under thermal loading. The plate is embedded on a two parameter elastic substrate to make this research more realistic. The structure is exposed to thermal loadings with various temperature rises such as sinusoidal temperature rise (STR), linear temperature rise (LTR) and uniform temperature rise (UTR). The governing differential equations are derived via incorporation of the Hamilton's principle and refined higher order plate theory then solved analytically to obtain the wave frequency and phase velocity of the GOP reinforced nanocomposite plate. The GOPs are dispersed in a polymeric matrix through the thickness of the plate by considering different functionally graded (FG) patterns. Moreover, the effective material properties of the structure are predicted on the basis of Halpin–Tsai micromechanical scheme. Furthermore, the accuracy of the present model is verified with previous works and also the influences of various parameters on the wave propagation behavior of the structure are covered too. The graphical results declare that wave propagation in GOP reinforced nanocomposite plates dramatically depends on these parameters. [ABSTRACT FROM AUTHOR]

A damage localization method based on natural frequency was proposed in order to complete the nondestructive diagnosis of a composite plate. The relationship between the damage position and the natural frequency of the composite plate was studied both qualitatively and quantitatively. Furthermore, the damage localization method proposed in this paper was proved by simulation and experimentation, with the results showing that this method can locate the position where the stiffness of the composite plate decreased in both simulation and experiment. Finally, the damage localization method based on natural frequency can be applied for non-destructive diagnosis of a delamination composite plate. [ABSTRACT FROM AUTHOR]

This paper investigates the performance of several meta-heuristic algorithms, including Particle Swarm Optimisation (PSO), different variants of Differential Evolution (DE), Biogeography-Based Optimisation (BBO), Cultural Algorithm (CA), Optics-Inspired Optimisation (OIO), and League Championship Algorithm (LCA), for optimum layup of laminated composite plates. The study provides detailed Pseudo codes for different algorithms. The buckling capacity maximisation of a 64-layer laminated composite plate under various load scenarios has been considered as the benchmark problem, in which the design variables are the stacking sequences of layers. A Deep Statistical Comparison (DSC) method is employed to rank the performance of different algorithms. The DSC uses a nonparametric two-sample Kolmogorov-Smirnov test to conduct the performance comparisons between the algorithms. The overall performance rankings obtained from the DSC suggest that the LCA, OIO, and PSO algorithms perform remarkably better in comparison to other algorithms. The comparisons provide some interesting conclusions on the performance of different algorithms. [ABSTRACT FROM AUTHOR]

This paper investigates the aeroelastic flutter and vibration reduction of functionally graded (FG) multilayer graphene nanoplatelets (GPLs) reinforced composite plates with piezoelectric patch subjected to supersonic flow. Activated by the control voltage, the piezoelectric patch can generate the active mass and active stiffness that can accordingly increase the base plate's stiffness and mass. As a result, it changes the GPLs reinforced plate's dynamic characteristics. The motion equation of the plate-piezoelectric system is derived through the Hamilton principle. Based on the modified Halpin–Tsai model, the effects of graphene nanoplatelets weight fraction and distribution pattern on the dynamic behaviors of the plate are numerically studied in detail. The result illustrates that adding a few amounts of grapheme nanoplatelets can effectually enhance the aeroelastic properties of the plates. Two kinds of control strategies, including the displacement and acceleration feedback control, are applied to suppress the occurrence of the flutter of the plate. It shows that the displacement and acceleration feedback control can improve the critical flutter Mach number of the plate by attaching active stiffness and active mass, respectively. Furthermore, the combined displacement and acceleration feedback control has a better control effect than that of considering only one of them. [ABSTRACT FROM AUTHOR]

In this paper, the nonlinear dynamics behavior of the bending deflection of a stiffened composite laminated plate is suppressed using beam stiffeners at different fiber volume fractions and different aspect ratios. The non-periodic motion and chaos in a stiffened composite laminated plate is detected using the largest Lyapunov exponent parameter and power density function of a fast Fourier transform (FFT). The critical buckling load is calculated at different thickness ratios, numbers of stiffeners, lamination angles and stiffener–depth ratios based on different boundary conditions. The nonlinear response of the bending deflection is analyzed analytically, numerically and experimentally. The analytic solution has been derived using Levy and Navier solutions of classical laminate plate theory at different boundary conditions (CLPT). The numerical simulation was conducted using the ANSYS program while the experiment test was carried out using a strain gauge through a strain meter device. Experimentally, a Southwell plot is used to investigate the value of the critical buckling load. The combined loading are the in-plane compression mechanical load and shear force. All the values of the largest Lyapunov exponent are positive, which gives indication to non-periodic motion and chaos. The nonlinear dynamics behavior of the bending deflection is decreased with the increasing of number of stiffeners in which the value of largest Lyapunov exponent has been decreased. The nonlinear dynamics behavior is increased with the increasing of aspect ratios and fiber volume fractions. The system with an aspect ratio (2.5) and fiber volume fraction ( υ f = 80%) for an un-stiffened plate is more chaotic than the other systems. [ABSTRACT FROM AUTHOR]

A novel finite element model for geometrically nonlinear analysis of laminated composite plates is proposed in this paper. It is based on a seven-variables higher-order shear deformation theory that only requires a C0-type continuity. The finite element method with mixed interpolation of tensorial components approach (MITC) is considered in which an MITC3 three-node triangle element with seven degree-of-freedoms per nodes, cell- and edge-based strain smoothing techniques is developed. The geometrical nonlinearity of the plates involving by von Karman strain is formed in the total Lagrange approach based on the small strain assumptions. Numerical examples of cross-ply laminated composite plates are provided to investigate the validation of the proposed method. [ABSTRACT FROM AUTHOR]

In this paper, the interface microstructure, elements' diffusion features at the interface, and bonding properties in nickel-based alloy/carbon steel clad composite prepared by vacuum hot-roll bonding were investigated, comprehensively. The influence of element distribution on the interface bonding strength was revealed as well. The results showed that there was a 13 μm thick diffusion layer at the interface of nickel-based alloy/carbon steel composite plate, which was beneficial to a strong bond between nickel-based alloy and carbon steel, as well as the stable transition of mechanical properties in the thickness direction. Kirkendall voids and fine-grained structure (the grain size is about 41.5 nm) were observable by peeling off the nickel-based alloy cladding, which greatly promoted element diffusion and enhanced the interfacial bonding strength of the nickel-based alloy/carbon steel composite plate. The diffusion coefficient of Ni at the interface was about 2 orders of magnitude larger than that of nanocrystalline Fe. The shear strength reached up to 453 MPa, which was much higher than the minimum of 140 MPa defined in ASTM A-264 specifications. Furthermore, in the shear test, the fracture occurred on the X52 carbon steel side at the contact rather than at the composite plate interface. [ABSTRACT FROM AUTHOR]

This paper presents the free vibration analysis of laminated functionally graded carbon nanotube reinforced composite (FG-CNTRC) plates. The CNTRC layer consists of single-walled carbon nanotubes (SWCNTs) as reinforcement and polymer as a matrix. The material properties are determined according to the extended rule of mixture. Four different patterns of SWCNTs distribution across the thickness of individual layers are considered. Based on the first-order shear deformation theory (FSDT), the equations of motion are derived and then solved by employing the pb2-Ritz method. The accuracy of the present approach is verified by comparing the obtained results with those available in the literature and commercial ANSYS software. The significant influences of CNT volume fractions, CNT distribution patterns, plate aspect ratio, plate width-to-thickness ratio, and boundary conditions on the non-dimensional fundamental frequency of symmetric and anti-symmetric laminated FG-CNTR plates has been proven through the numerical examples. Furthermore, the influence of lamination schemes, CNT fiber orientation and the number of layers is also investigated. [ABSTRACT FROM AUTHOR]

Abstract The paper presents the non-polynomial framework for static bending characteristics corresponded with three-phase multi-scale hybrid laminated nanocomposite (MHLN) reinforced plates under initial stresses on the basis of the three-dimensional elasticity theory (3D-elasticity theory). By considering horizontal friction force, the Pasternak type’s two parameters foundation is developed. The multilayer structure with three, five, as well as seven layers are formulated by utilizing compatibility conditions. Composite plates’ bending behavior by considering simply-supported boundary conditions is analyzed with the aid of the state-space-based analytical method (SS-AM). The material properties associated with a multi-scale composite are obtained employing fiber micromechanics in addition to Halpin–Tsai relations. The carbon nanotubes (CNTs) are considered to be uniformly dispersed and randomly oriented in the matrix of epoxy resin. Then, a parametric study is carried out to exhibit the impacts of different kinds of multi-layer plates, various friction forces, stacking sequence, and various initial stresses on the static bending response related to composite plates. [ABSTRACT FROM AUTHOR]

In this paper, a sandwich composite plate with tunable magneto-rheological (MR) fluid core is utilized for analyzing the wave propagation. Sandwich composite plate is made of three layers consisting of the base layer, MR layer and the limiter layer. MR layer is embedded within the base and the limiter layers. Moreover, the upper and the lower layers are made of the elastic materials. This structure is also located on a viscoelastic substrate. At first, for achieving the governing equations of motion, Hamilton's principle and classical plate theory (CLPT) are utilized. Then, exerting an analytical solution, the wave frequency and phase velocity of the propagated waves can be gained by solving eigenvalue problem. By investigating the effect of the magnetic field, the results emphasize that the magnetic field intensity is most important factor for changing the value of the wave dispersion characteristic. Besides, results indicate by enhancing the core-to-top layer thickness ratio, the wave frequency decreases because MR fluid core is softer in comparison to the elastic layers, Hence, MR fluid core operates similar damper. At the end, the effect of the other parameters such as thickness of MR layer, Winkler, Pasternak and damping coefficients are also discussed. [ABSTRACT FROM AUTHOR]

Presence of cracks in mechanical components needs much attention, where the stress field is affected by cracks and the propagation of cracks may be occurred causing the damage. The objective of this paper is to present an investigation of crack type effect on crack severity in a finite plate. Three cases of cracked plate with three different types of cracks are assumed in this work, i.e., single edge crack, center crack and double edge crack. 2D numerical models of cases of cracked plate are established in finite element analysis (FEA), ANSYS software by adopting PLANE 183 element. Values of FEA mode I stress intensity factor SIF and Von-Mises stress at crack apex are determined for cases of cracked plate under tensile stress with different values. To identify the crack severity, the comparison of FEA results for different cracked cases is made. The comparison showed that, single edge cracked plate (SECP) has the maximum values of mode I SIF and Von-Mises stress at crack apex, i.e. the greatest crack severity is considered. Also, values of FEA Von-Mises stress at crack apex for center cracked plate (CCP) are moderate and for double edge cracked plate (DECP) are the minimum. Besides, in case of high crack lengths, it is found that, FEA results of mode I SIF in case of (CCP) are higher than those of in case of (DECP). Consequently, crack severity is considered as moderate in case of (CCP) and the minimum in case of (DECP). Empirical formulas are used to approximately estimate mode I SIF for all the case studies of cracked plate in this study and the results are compared to those of FEA. A good agreement between analytical and FEA results has been showed by this comparison. [ABSTRACT FROM AUTHOR]

This paper provides a finite element analysis of laminated composite plates under the action of a moving vehicle. The vehicle is modeled as a rigid body with four suspension systems, each consisting of a spring- dashpot. Overall, the vehicle possesses three degrees of freedom: vertical, rolling, and pitching motions. The equations of motion of the plate are deduced based on first-order shear deformation theory. Using the Euler- Lagrange equations, the system of coupled equations of motion is extracted and solved by using the Newmark time discretization scheme. The algorithm is validated through the comparison of both the free and forced vibration results provided by the present model and exact or numerical results reported in the literature. The effects are investigated of several system parameters on the dynamic response. [ABSTRACT FROM AUTHOR]

The strongest point about damage identification based on the dynamic measurements, is the ability to perform structural health evaluation globally. Researchers in the last few years payed more attention to damage indicators based on modal analysis using either frequencies, mode shapes, or Frequency Response Functions (FRFs). This paper presents a new application of damage identification in a cross-ply (0°/90°/0°) laminated composite plate based on Force Residual Method (FRM) damage indicator. Considering single and multiple damages with different damage levels. As well as investigating the SSSS and CCCC boundary conditions effect on the estimation accuracy. Moreover, a white Gaussian noise is introduced to test the challenges of the technique. The results show that the suggested FRM indicator provides accurate results under different boundary conditions, favouring the SSSS boundary condition than the CCCC for 3% noise. [ABSTRACT FROM AUTHOR]

How to improve the bonding ability and quality performance of heterogeneous plates has always been one of the difficult problems in the field of high-performance heterogeneous composite sheet forming and manufacturing. In this paper, a new manufacturing method of heterogeneous clad plate, hard plate rolling clad plate, is proposed. The hot rolling process of Al/Mg/Al composite slab with or without hard plate was studied. The results show that the shear stress in the rolling direction (RD) can be transformed into the compressive stress in the normal direction (ND), and then the welding pressure between different composite layers can be increased. This method can suppress the bending and edge crack defects and significantly improve the shape quality and forming ability. At the same time, through the study of the interface structure of the composite plate, it can be known that the metallurgical bonding can be achieved with a small reduction after adding the hard plate. Two clear layers of Al3Mg2 and Al17Mg12 intermetallic compounds appear at the Al/Mg interface. The thickness of the diffusion layer is significantly larger than that of the traditional hot-rolled clad plate, and the thickness of the diffusion layer can reach 38 μm when the reduction is 60%. The yield strength is 172.3 MPa and the elongation is 21.5%. To sum up, the hot rolling of hard-plate provides a new idea for the forming and manufacturing of high performance heterogeneous composite plate. [ABSTRACT FROM AUTHOR]

This paper investigates the thermo-electro-mechanical effects in the nonlinear response of piezoelectric laminated plates exposed to thermal and/or mechanical fields. The mechanics incorporate a) the direct piezoelectric effect through the coupling between electric-mechanical fields, b) the pyroelectric effect through the coupling between electric-thermal fields, and c) the geometric nonlinear effects due to large rotations and initial stresses. Building upon the nonlinear multifield mechanics an eight-node plate finite element is developed to discretize the generalized coupled nonlinear equations, which are subsequently linearized and iteratively solved, using the Newton-Raphson technique. Numerical evaluations demonstrate the capability of the present model to capture both of direct piezoelectric and pyroelectric effects in the nonlinear electromechanical response of piezoelectric composite plates, exposed to thermal and/or mechanical fields. The influence of direct piezoelectric and pyroelectric effects on thermal buckling and postbuckling response of various piezocomposite plates, is investigated. The possibility of pyroelectric effect to promote thermal buckling of piezocomposite plates with attached sensor patches is also quantified. The influence of thermo-electro-mechanical effects on the nonlinear response of smart composite plates, subject to either uniform or gradient temperature variations is finally illustrated. [ABSTRACT FROM AUTHOR]

Present study aims to investigate the mechanical buckling including the shear buckling and the in‐plane mechanical buckling of composite laminated plates reinforced with graphene sheets with temperature dependent features resting on Winkler‐Pasternak elastic foundation in a thermal ambient. The governing equations in the framework of the first order shear deformation theory are attacked by the Ritz method. The plate is subjected to uniaxial, biaxial and shear loads. The innovation of the present paper is considering the temperature dependency and anisotropicity of the material properties of a nanocomposite layer that reinforced with graphene sheets for the purpose of the determination of the mechanical buckling treatment of a graphene reinforced composite (GRC) laminated plate with different boundary condition types. Resorting to the extended Halpin–Tsai micromechanical model, the thermo‐mechanical characteristics of a lamina is defined. Numerical outcomes of the present study are confirmed with the presented data in the literature. The effects of the elastic foundation parameter, the temperature, the plate side to its thickness ratio, the layup scheme, the boundary condition type and the distribution pattern of graphene‐reinforced composites on the critical buckling load are investigated. It is found that, the impact of elastic foundation incorporation is less visible on the critical shear buckling load rather than the critical uniaxial and biaxial mechanical loads. Moreover, the largest critical buckling load belongs to layup [0]10 among the all under studied lamination schemes. [ABSTRACT FROM AUTHOR]

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Rotating machinery has significant applications in the fields of micro and nano meters, such as nano-turbines, nano-motors, and biomolecular motors, etc. This paper takes rotating nano-annular plates as the research object to analyze their free vibration behaviors. Firstly, based on Kirchhoff plate theory, Mindlin plate theory, and Reddy plate theory, combined with nonlocal constitutive relations, the differential motion equations of rotating functionally graded nano-annular plates in a thermal environment are derived. Subsequently, the numerical method is used to discretize and solve the motion equations. The effects of nonlocal parameter, temperature change, inner and outer radius ratio, and rotational velocity on the vibration frequencies of the nano-annular plates are analyzed through numerical examples. Finally, the relationship between the fundamental frequencies and the thickness-to-radius ratio of the nano-annular plates of clamped inner and outer rings is discussed, and the differences in the calculation results among the three plate theories are compared. [ABSTRACT FROM AUTHOR]

• Higher-order layer-wise plate models for composite variable angle tow plate analysis. • Passive damping using viscoelastic inter-layers with frequency-dependent properties. • Mixed interpolation of tensorial components for more efficient and accurate solutions. In this paper, the damped free-vibration and frequency response analysis of variable-angle-tow composite plates embedding viscoelastic layers with frequency-dependent properties are performed. The governing equations are derived from the Principle of Virtual Displacements and higher-order Layer-Wise models are used for the unknown variables description in the thickness direction, furthermore a nine-node finite plate element is employed to solve them. The plate formulation presented in this paper is more efficient with respect to three-dimensional approaches, typically used for this kind of structures, and it is more accurate than existing reduced order methods thanks to the use of the mixed interpolation of tensorial components technique, employed to solve the problem of the shear and membrane locking phenomena. Different multilayered structures have been considered, laminated with unidirectional cross-ply layers or with curvilinear fibers path ones. The use of viscoelastic soft sheets permits to have a passive damping of the structural vibration. The frequency dependent properties of the viscoelastic materials are described through the use of a Kelvin-Voigt model. Numerical solutions are presented for the analysis of variable-angle-tow composites with different boundary-conditions and various lamination schemes. [ABSTRACT FROM AUTHOR]

Multiwall plates consist of parallel thin-walled plates connected by a given number of vertical ribs to yield a light and yet a high strength structure. Unlike composite and sandwich plates, the multiwall plate does not have cross-section material continuity and therefore cannot be analyzed in terms of stress distribution in a simple way. The first order shear deformation theory (FSDT) model is used to obtain a homogeneous plate. Innovative analytic and finite element models were developed to obtain the elastic equivalent constants of the plate. A good matching was obtained between the analytic model results and the numerical ones. It turned out that the analytical approach cannot yield all the elastic equivalent constants, therefore an experimental approach was developed and implemented to obtain all the equivalent elastic constants of a typical multiwall plate. Those results were in good matching with the numerical finite element ones. The structural response to loading for the orthotropic equivalent plate can be easily calculated either analytically, numerically or experimentally. • A homogenization of multiwall plates yielding an orthotropic solid plate with equivalent properties was validated numerically, analytically and experimentally. The authors believe that this was done for the first time for such type of plates. • The output of the present paper is that calculating by FEA the deflection of a rectangular homogenized plate reduces drastically the computation time as compared with the full original plate. This should be hold as the second highlight. • It turned out that a multiwall plate structure has a relatively low transverse shear rigidity in y direction. Therefore, shear deformations must be considered in the design process. Also, the plate's twist rigidity is reduced due to this low rigidity. This conclusion should be considered as the third highlight of the present paper. • It seems than in a multiwall rectangular plate, the Poisson's effect induces a stress in the ribs under y direction tension and bending. This is different from a solid plate, where Poisson's strains are stress less. This interesting conclusion would be the 4th highlight. [ABSTRACT FROM AUTHOR]

Out-of-plane waviness is one of the most common defects which degenerates the strength, stiffness, and fatigue life of hybrid glass–carbon fiber–reinforced polymer composites (FRPs). An accurate and high-speed non-destructive testing method is highly desired for large composite structures in industries. Ultrasonic phased array is a great candidate for such application. This paper applies the wavenumber algorithm to image the waviness in hybrid FRP plates which are a multi-layered medium. The central frequency of 5 MHZ is chosen in order to maximize the ply resonance. Transducers are migrated virtually to each interface between glass and carbon plies in order to overcome the difficulty of wave propagation analysis in such multi-layered system. The wavenumber algorithm demonstrates a better computational performance compared to that of the traditional total focusing method (TFM) in time domain up to 6 times. The glass ply depth and waviness angle can be more accurately presented with relative errors less than 1.5% and 14.8%, respectively. In addition, the resin-rich defect characterization is also achievable with a maximum error of 14.4%. [ABSTRACT FROM AUTHOR]

In this paper, the dynamic and aeroelastic analysis of variable fiber spacing composite (VFSC) laminated plates are carried out. The effects and benefits of changing the fiber distribution pattern on natural frequency and mode shape are explored taking various boundary conditions. Taking cantilever boundary condition flutter characteristics of VFSC plate with different fiber distribution patterns are compared. Further stochasticity of flutter velocity due to randomness in material properties that could arise due to complex manufacturing and fabrication process of VFSC laminates is investigated. The perturbation technique is implemented to perform the stochastic as well as reliability analysis. Various parametric studies are conducted to check the accuracy and efficiency of perturbation technique, by comparing the results with that of Monte Carlo simulation and the first-order reliability method. [ABSTRACT FROM AUTHOR]

In this paper, local damping behaviour of S0 ultrasonic Lamb mode is investigated to determine the reason of amplitude reduction of signals come from a rich resin defect in a composite plate. A four-layer woven glass fibre-epoxy (WGF/epoxy) composite plate, containing a predefined rich resin area as the damage, has been manufactured and inspected with S0 Lamb mode via through transmission and pulse-echo method. Results have shown that there is a considerable amplitude reduction in the transmitted wave while a negligible damage reflected wave has been captured in the related receiver. An experimental based method has been employed in order to extract Rayleigh damping coefficients for the healthy composite plate, followed by a novel methodology to evaluate the damping coefficients at the defected area. Having calculated Rayleigh damping coefficients for both damaged and undamaged areas of the composite plate, several finite element simulations have been carried out, in order to quantify the wave amplitude reduction due to attenuation at the damage. The Amplitude Reduction Ratio (%ARR), obtained from numerical simulation matches closely with experimental ARR, represents that the proposed method for Rayleigh damping coefficients evaluation at the rich resin area can be used for further rich resin defect investigations. [ABSTRACT FROM AUTHOR]

The paper proposes a multi-scale uncertainty quantification framework of composite laminated plates. The micro and macro uncertainty parameters are represented by random and interval variables according to available uncertainty information. The data-driven Polynomial Chaos Expansion model is constructed, where polynomial coefficients of random variables are determined based on their high-dimensional statistical information, and coefficients of interval variables are calculated using sampling analysis method. The proposed framework is applied for multi-scale buckling analysis, natural frequency calculation and reliability estimation. The comparison results with Monte Carlo Sampling method demonstrate the computational superiority of the proposed algorithm to achieve high accuracy in multiple conditions. [ABSTRACT FROM AUTHOR]

Long-term exposure to a harsh environment leads to irreversible degradation of mechanical properties of fiber-reinforced polymer (FRP) profiles. Understanding the aging effects on pultruded FRP composites due to long-term exposure is essential. The moisture diffusion process plays a significant role in understanding material degradation of E-glass/polyester-reinforced polymer composite laminates exposed to hygrothermal environments. In this paper, the moisture diffusion process in pultruded (GFRP) composite bridge members is numerically simulated using the finite-element method. The moisture diffusion parameters were calibrated by gravimetric tests of pultruded composite thin plates. Gravimetric tests of three different rectangular specimens were conducted to investigate three-dimensional moisture diffusion at different temperatures and environments. The calibrated mass diffusion parameters were validated by comparing the average time-dependent moisture concentration obtained from non-Fick finite-element (FE) simulation with experimental results. [ABSTRACT FROM AUTHOR]

This paper reports for the first time the experimental investigation on the free vibration characteristics of angle-ply laminated composite stiffened plates along with the numerical investigation. The natural frequencies of these plates are computed experimentally using an FFT analyzer and numerically by employing the finite element method with combination of isoparametric nine nodded plate and three nodded beam elements. Angle-ply laminated stiffened plates are fabricated using woven glass fiber fabrics and epoxy by hand layup technique. The effects of various support conditions; number, orientation and types of stiffeners; aspect ratios of plates and different fiber orientations on the fundamental frequencies of the angle-ply laminated stiffened plates are investigated. These parameters significantly influence the natural frequencies. It is found that there is a very good agreement observed between the fundamental frequencies obtained from both experimental and numerical investigation. Mode shapes are also presented for angle-ply laminated square stiffened plates with three different support conditions to justify the trend of increasing/decreasing of the modal frequency with the addition of stiffeners. It is observed that the enhancement of the frequencies of the angle-ply plates due to addition of stiffeners is influenced significantly by the position of stiffeners and consequently mode shapes. As the research on the free vibration behavior of angle-ply stiffened plates with experimental analysis is very rare, this study can be considered as the benchmark for future research. [ABSTRACT FROM AUTHOR]

In this paper, shielded metal arc welding on the dissimilar joint between 2205 duplex stainless steel and composite bimetallic plates (304 L stainless steel/10CrNi3MoV steel) with a filler metal E2209 was performed. Furthermore, the microstructure, phase, mechanical properties and intergranular corrosion resistance of the joints were investigated and element distributions of the interfaces were characterized. The results show that austenite transformed to ferrite under the influence of welding thermal cycle, and then a large amount of ferrite appeared in heat affected zone (HAZ) of 2205 duplex stainless steel. Coarse bainite grains were formed in HAZ of the 10CrNi3MoV steel near the fusion line with high temperature welding thermal cycle. Fine granular bainite was also generated in HAZ of 10CrNi3MoV steel due to the relatively short exposure time to the active temperature of grain growth. Local peak temperature near the base 10CrNi3MoV steel was still high enough to recrystallize the 10CrNi3MoV steel to form partial-recrystallization HAZ due to phase change. The filler metal was compatible with the three kinds of base materials. The thickness of the elemental diffusion interfaces layers was about 100 µm. The maximum microhardness value was obtained in the HAZ of 2205 duplex stainless steel (287 ± 14 HV), and the minimum one appeared in HAZ of SS304L (213 ± 5 HV). The maximum tensile strength of the welded joint was about 670 ± 6 MPa, and the tensile specimens fractured in ductile at matrix of the composite bimetallic plates. The impact energy of the weld metal and HAZ of the 10CrNi3MoV steel tested at –20 °C were 274 ± 6 J and 308 ± 5 J, respectively. Moreover, the intergranular corrosion resistance of the weldment including 304 L stainless steel, weld metal, HAZs and 2205 duplex stainless steel was in good agreement with the functional design requirements of materials corrosion resistance. [ABSTRACT FROM AUTHOR]