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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]

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]

Aiming at the problem about misjudging sheet fracture in hydroforming process, the different mechanisms between drawing and hydraulic bulging are analyzed. In this paper, a method to test the forming limit diagram (FLD) based on uniform load in thickness direction is adopted by using laminated plate hydroforming, and the quality of hydroforming process is judged more accurately. By the numerical simulation analysis, the shape of the specimen on five different linear paths is preliminarily determined, and the forming limit diagram of the sheet is obtained under the stretch-compression condition. At the same time, the influence of method of lubrication such as non-lubrication, oil, grease, and thin film on FLD is analyzed. The results show that the first principal strain and the second principal strain increase, and the bulging height decreases with the decrease of friction factor. Among them, the friction factor of thin film is reduced to the lowest. In the process of laminated sheet hydroforming, the thin film lubrication between pieces is more relatively accord with the experimental condition of stretch-compression bulging, and the FLD is more reliable to judge the quality of component formed by hydroforming. [ABSTRACT FROM AUTHOR]

A novel method is proposed in this paper for simultaneously locating and quantifying damage in composite plates by employing Lamb waves and the algorithm of convolution neural network. The interaction between Lamb wave and damage of different degrees is also studied by simulation. The experiments on Lamb wave are carried out by employing a square array which is composed of four piezoelectric wafers. First of all, the sensor array collects response signals of Lamb wave as training data, and then de-noises them adopting the method of the wavelet transform. In the process, the damage caused to the composite can be realized through mass blocks. Besides, the Fourier transform is applied for the extraction of the characteristics shown by the signals. After that, the spectrum with the characteristics of damage and corresponding damage modes are employed as input and output of the convolutional neural network, respectively, and accordingly, the model of damage identification is established. Finally, 191 samples (from a total of 192) were identified accurately and the correct recognition rate achieved is 99.5%, which consequently demonstrates that the convolution neural network can be employed to establish the complex mapping relationship between signal and damage, and further proves that the proposed method performs well in high accuracy and great potential in simultaneous localization and quantitative identification of damage existing in composite plate. [ABSTRACT FROM AUTHOR]

Most of random dynamic loading identification research studies are about the original inverse pseudoexcitation method which does not fundamentally reduce the negative effect of ill-conditioned frequency response function matrix on accuracy of loading identification. This paper describes a new improved method based on weighted average technique to reduce peak errors between identified load spectrum and the actual load spectrum near some natural frequencies. Meanwhile, relative error of root mean square value between identified load and the actual load is reduced. The introduced selection method of threshold value is innovative which is the key of weighted average technique. This improved loading identification method is successfully applied to experiments of cantilever beam and thermal protection composite plate structure. Identification results prove that the proposed method is valid by good agreement between identified power spectrum density and the actual one. Moreover, this method has higher accuracy than inverse pseudoexcitation method in low-frequency band. [ABSTRACT FROM AUTHOR]

Purpose The purpose of this paper is to consider divergence of composite plate wings as well as slender wings with thin-walled cross-section of small-size airplanes. The main attention is paid to establishing of closed-form mathematical solutions for models of wings with coupling effects. Simplified solutions for calculating the divergence speed of wings with different geometry are established.Design/methodology/approach The wings are modeled as anisotropic plate elements and thin-walled beams with closed cross-section. Two-dimensional plate-like models are applied to analysis and design problems for wings of large aspect ratio.Findings At first, the equations of elastic deformation for anisotropic slender, plate-like wing with the large aspect ratio are studied. The principal consideration is delivered to the coupled torsion-bending effects. The influence of anisotropic tailoring on the critical divergence speed of the wing is examined in closed form. At second, the method is extended to study the behavior of the large aspect ratio, anisotropic wing with box-like wings. The static equations of the wing with box-like profile are derived using the theory of anisotropic thin-walled beams with closed cross-section. The solutions for forward-swept wing with box-like profiles are given in analytical formulas. The formulas for critical divergence speed demonstrate the dependency upon cross-sectional shape characteristics and anisotropic properties of the wing.Research limitations/implications The following simplifications are used: the simplified aerodynamic theory for the wings of large aspect ratio was applied; the static aeroelastic instability is considered (divergence); according to standard component methodology, only the component of wing was modeled, but not the whole aircraft; the simplified theories (plate-lime model for flat section or thin-walled beam of closed-section) were applied; and a single parameter that defines the rotation of a stack of single layers over the face of the wing.Practical implications The simple, closed-form formulas for an estimation of critical static divergence are derived. The formulas are intended for use in designing of sport aircraft, gliders and small unmanned aircraft (drones). No complex analysis of airflow and advanced structural and aerodynamic models is necessary. The expression for chord length over the span of the wing allows for accounting a board class of wing shapes.Social implications The derived theory facilitates the use of composite materials for popular small-size aircraft, and particularly, for drones and gliders.Originality/value The closed-form solutions for thin-walled beams in steady gas flow are delivered in closed form. The explicit formulas for slender wings with variable chord and stiffness along the wing span are derived. [ABSTRACT FROM AUTHOR]

The location optimization of sensors is a essential problem in structural health monitoring systems. Taking the cost of sensors into account, it is uneconomical to install sensors on every part of a structure and moreover in aeronautical industry, the weight is a crucial factor. In this paper, a optimal placement optimization of sensor locations for structural health monitoring systems is studied. Several techniques of optimization of sensors are approached and applied in a shell structure. The structure, a laminate of carbon fiber, was modeled by the finite element method (FEM) and then subject to free vibration. Genetic algorithms (GAs) are then employed to locate the best sensor distribution to cover a specific number of low frequency modes. Numerical results have demonstrated the overall efficiency of sensor delivery methods. Specific problems occurred, especially regarding the method of effective independence, being less efficient and discrepant in relation to the other methods employed. In summary, the results obtained in this paper provide an optimal position for sensors in real SHM systems and experiments. [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]

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]

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]

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]

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]

Buckling and postbuckling behavior of carbon nanotube (CNT) reinforced thick composite plates resting on elastic foundations and subjected to thermomechanical loads are investigated in this paper. The plates are subjected to uniform uniaxial compression in a thermal environment or the combined action of nondestabilizing preexisting uniaxial compression and uniform temperature rise. CNTs are reinforced into matrix through functionally graded distributions. The properties of constitutive materials are assumed to be temperature dependent and effective properties of CNT-reinforced composite are determined according to an extended rule of mixture. Governing equations are based on a higher order shear deformation theory taking von Kárman nonlinearity, initial geometrical imperfection, elasticity of tangential restraints of unloaded edges and plate-foundation interaction into consideration. Analytical solutions are assumed to satisfy simply supported boundary conditions and Galerkin method is applied to obtain nonlinear load-deflection relations. Numerical analyses are carried out to show the effects of CNT distribution patterns, preexisting loads, initial imperfection, degree of in-plane constraint, and elastic foundations on the nonlinear thermomechanical stability of CNT-reinforced composite plates. [ABSTRACT FROM AUTHOR]

Applications of skew plates in the practical civil engineering are well-established. A look into the papers about the failure of laminated composite structural elements revealed that composite skew plates have not been studied for failure in detail. The first-ply failure load and frequency reduction due to such a failure are reported considering practical parametric variations of composite skew plates. Different well-established failure criteria, including the most recent Puck failure criterion, are used to investigate the first-ply failure response by the finite-element method. The results obtained are postprocessed to formulate specific recommendations regarding the relative behavior of different skew plate combinations in terms of the first-ply failure. [ABSTRACT FROM AUTHOR]

Discrete response of structures often is a key probabilistic quantity of interest. For example, one may need to identify the probability of a binary event, such as whether a structure has buckled. This study used an adaptive domain-based decomposition and classification method, combined with sparse grid sampling, to develop an efficient classification surrogate modeling algorithm for such discrete outputs. An assumption of monotonic behavior of the output with respect to all model parameters, based on the physics of the problem, helps to reduce the number of model evaluations and makes the algorithm more efficient. As an application problem, this paper developed a computational framework for generation of a probabilistic penetration response of S- 2 glass/SC -15 epoxy composite plates under ballistic impact. This enables the computationally feasible generation of the probabilistic velocity response (PVR) curve, or the V0−V100 curve, as a function of the impact velocity, and prediction of the ballistic limit velocity as a function of the model parameters. The PVR curve incorporates the variability of the model input parameters and describes the probability of penetration of the plate as a function of impact velocity. [ABSTRACT FROM AUTHOR]

Nonlinear progressive failure analysis (PFA) of piezolaminated composite shell panel under mechanical out-of-plane loading in the hygro-thermal environment is performed. The higher-order shear deformation theory (HSDT) with von-Karman nonlinear kinematics are used for basic formulation. Using variational principle governing equation for panel structure obtained by Newton's Raphson approach through finite element method is employed to compute the necessary PFA. The second-order perturbation technique (SOPT) is utilized to obtain statistics in terms of mean and corresponding coefficient of variance (COV) of first ply and last ply failure load (FPFL and LPFL) through ply-by-ply failure counting by assuming random input system parameters. Convergence and validation analysis is performed to check the exactness of MATLAB version 2013a code. Shell panels are subjected to environmental conditions with uniform temperature and moisture distribution over entire shell panels. Initially, the paper presents the response of the composite plate and shell with the application of uniformly distributed flexural loading in the form of transverse central deflection (TCD) and mean FPFL and LPFL using a deterministic approach. Then, statistics in terms of mean and corresponding COV of FPFL and LPFL are obtained using a probabilistic approach through PFA. The effect of thickness and aspect ratio, types of loading, lamination sequences, curvatures, temperature increment, moisture content, the position of piezoelectric layers, and voltage variation on statistics of PFA has been examined. [ABSTRACT FROM AUTHOR]

• A bottom-up multiscale model of graphene/PMMA composite is established from atomic scale to macroscopic structure. • The nano scale effects of finite-size graphene on the FG-GRC quadrilateral plate is considered via the multiscale analysis. • The efficiency parameters of graphene/PMMA composite are derived by the extended Halpin-Tsai micromechanics model. • The effects of geometrical parameter, graphene volume fraction and distribution are explored on the vibration behaviors. In this paper, a molecular dynamics (MD)-based multiscale analysis is employed to investigate the free vibration of graphene reinforced laminated composite plates from the atomic scale to the macroscopic behavior. The atomic models of graphene with different sizes, poly (methyl methacrylate) (PMMA) and graphene/PMMA composites with different graphene volume fractions are constructed, and Poisson's ratio as well as elastic moduli are in good agreements with the MD results. Then the efficiency parameters of the Young's and shear moduli of graphene/PMMA composites are derived at the micro scale via the extended Halpin-Tsai micromechanics model, and are employed subsequently to the vibration analysis at the macro scale. Based on the first order shear deformation theory and meshless method, the governing equation of functionally graded graphene reinforced composite (FG-GRC) quadrilateral plates is derived and discretized to analyze the vibration behavior. The effects of geometrical parameter, graphene volume fraction and distribution pattern are investigated on the dimensionless frequency of FG-GRC quadrilateral plates. The multiscale analysis in this paper combines the simulation of material properties at the atomic scale and the response of structure at the macro scale, which provides a feasible way to study the vibration behavior of composite structures. [ABSTRACT FROM AUTHOR]

Explosive welding technique is widely used in many industries. This technique is useful to weld different kinds of metal alloys that are not easily welded by any other welding methods. Interlayer plays an important role to improve the welding quality and control energy loss during the collision process. In this paper, the Ti6Al4V plate was welded with a copper plate in the presence of a commercially pure titanium interlayer. Microstructure details of welded composite plate were observed through optical and scanning electron microscope. Interlayer-base plate interface morphology showed a wavy structure with solid melted regions inside the vortices. Moreover, the energy dispersive spectroscopy analysis in the interlayer-base interface reveals that there are some identified regions of different kinds of chemical equilibrium phases of CueTi, i.e. CuTi, Cu2Ti, CuTi2, Cu4Ti, etc. To study the mechanical properties of composite plates, mechanical tests were conducted, including the tensile test, bending test, shear test and Vickers hardness test. Numerical simulation of explosive welding process was performed with coupled Smooth Particle Hydrodynamic method, Euler and Arbitrary Lagrangian-Eulerian method. The multi-physics process of explosive welding, including detonation, jetting and interface morphology, was observed with simulation. Moreover, simulated plastic strain, temperature and pressure profiles were analysed to understand the welding conditions. Simulated results show that the interlayer base plate interface was created due to the high plastic deformation and localized melting of the parent plates. At the collision point, both alloys behave like fluids, resulting in the formation of a wavy morphology with vortices, which is in good agreement with the experimental results. [ABSTRACT FROM AUTHOR]

In this paper, a mathematical procedure is elaborated based on large deformation, finite element and perturbation methods for thermo-large amplitude analysis of anisotropic laminated and sandwich FGM plates with temperature-dependent properties. Nonlinear thermal dependence distribution following a power law is adapted. Various types of multilayered composite plates with position and temperature-dependent material properties are considered. Mathematical formulations and explicit relationships are presented in the frame of finite element methods. The structure is subjected to linear and uniform temperature variations. The temperature and the displacement are expanded in power series with unknown terms, and the numerical solution is obtained by the finite element method. The homotopy method is used for nonlinear thermal buckling, and a continuation procedure is elaborated for nonlinear thermal–displacement responses. The nonlinear thermal critical buckling load is first computed and the postbuckling equilibrium path of FGM and laminated plates under thermal loading is investigated. Temperature-dependent properties and geometry effects as well as boundary conditions on the nonlinear thermal buckling and postbuckling behaviors are analyzed. [ABSTRACT FROM AUTHOR]

Perforated composite laminates are frequently encountered in multiple engineering applications as sub-components of complicated structures. In many of these applications, the primary objective of using the panel is to resist buckling under diverse environmental and loading conditions. This paper is mainly focused on the vibration and buckling responses of composite laminates with elliptical cutouts subjected to localized edge loads under different hygrothermal environments. Toward this, a nine-noded heterosis plate element has been utilized to discretize the plate by adopting a refined meshing pattern around the elliptical cutout. The geometric nonlinearity has been incorporated to predict free vibrations under the hygrothermal environment. Considering the plethora of applications of composite laminates in hygrothermal conditions, a new temperature/moisture-dependent model is presented by taking into consideration various mechanical loadings. For a given environmental and loading condition, the stress distribution within the perforated panel is highly non-uniform in nature and hence, a novel dynamic approach has been proposed to solve buckling problems by adopting two sets of boundary conditions. A MATLAB program has been developed to investigate the effect of various parameters such as elliptical cutout size, elliptical orientation, elliptical cutout eccentricity, thickness and boundary conditions of the laminated composite plate under diverse hygrothermomechanical loading conditions. A notable difference in the critical buckling load is observed when the locally prestressed perforated panels are subjected to complex hygrothermal environments, especially at larger elliptical cutouts and hence the importance of localized edge loads under hygrothermal environment is emphasized. [ABSTRACT FROM AUTHOR]

Planar composite plate shear walls/concrete filled (C-PSW/CF) consist of two steel web plates and two flange (or closure) plates making up a long hollow box section that is filled with concrete. The web plates are connected to each other using regularly spaced steel tie bars. Steel headed stud anchors (shear studs) may be added to reduce the steel plate slenderness for local buckling considerations in the composite phase. This paper presents the results of experimental investigations conducted to evaluate the behavior of five planar C-PSW/CF specimens subjected to constant axial compression and cyclic lateral loading. Parameters included are the axial load level, steel plate slenderness ratio, and tie reinforcement ratio. The cyclic lateral load-deflection responses of the composite wall specimens are discussed along with their lateral stiffness, strength, and deformation capacity. Experimental results indicate that the lateral load capacity of composite walls is governed by flexural yielding of the steel plates followed by plate inelastic local buckling and concrete crushing. All the wall specimens developed and exceeded the flexural capacity calculated using the plastic stress distribution method (while including the effects of axial compression). The post-peak strength degradation of wall specimens is governed by the initiation and propagation of fracture through the steel flange plates and web plates. A fiber-based model was developed and used to calculate the section moment-curvature response of the specimens. Comparing the experimental and numerical moment-curvature responses indicates that the section flexural stiffness and flexural capacity can be estimated using the fiber-based analysis method. [ABSTRACT FROM AUTHOR]

In this paper, higher order closed-formed analytical solutions for the buckling analysis of functionally graded sandwich rectangular plates are obtained using a unified shear deformation theory. Three-layered sandwich plates with functionally graded skins on top and bottom; and isotropic core in the middle are considered for the study. The material properties of skins are varied through the thickness according to the power-law distribution. Two types of sandwich plates (hardcore and softcore) are considered for the detail numerical study. A unified shear deformation theory developed in the present study uses polynomial and non-polynomial-type shape functions in terms of thickness coordinate to account for the effect of shear deformation. In the present theory, the in-plane displacements consider the combined effect of bending rotation and shear rotation. The parabolic shear deformation theory of Reddy and the first-order shear deformation theory of Mindlin are the particular cases of the present unified formulation. The governing differential equations are evaluated from the principle of virtual work. Closed-formed analytical solutions are obtained by using the Navier's technique. The non-dimensional critical buckling load factors are obtained for various power-law coefficients, aspect ratios and skin-core-skin thickness ratios. [ABSTRACT FROM AUTHOR]

In this paper, the dynamic behavior of the nanoparticle low-velocity impact on viscoelastic laminated composite nanoplate has been investigated. To determine the impact force between nanoparticle and laminated composite nanoplate, the van der Waals interaction force is considered based on the description of Lennard-Jones. The material properties of each layer of laminated composite nanoplate are supposed to be viscoelastic based on the Kelvin–Voigt model. The governing equations of the system are derived based on the first-order shear deformation plate theory and the nonlocal strain gradient theory by employing Hamilton's principle. Galerkin's method is employed to solve differential equations of nanoplate with different boundary conditions. Afterward, the system of time-dependent equations is solved by applying the Newmark's method. The parametric study is presented to examine the effect of particle initial velocity, particle radius, viscoelastic modulus, fiber orientation, nonlocal parameter, length scale parameter, and different boundary conditions on the impact response of nanoplate. [ABSTRACT FROM AUTHOR]

In this paper, a three-dimensional static deformation of arbitrary functionally graded multilayered multiferroic composites plates with weakly and highly conducting imperfect interfaces is derived. The magnetoelectroelastic properties of each layer of the composite plates have been assumed varying throughout the thickness direction. The imperfect interfaces between the layers are assumed to be mechanically compliant, dielectrically and magnetically weakly or highly conducting. In each layer, the state-space approach is firstly applied leading to space variable. Cauchy's problem and adapted Runge-Kutta numerical procedure is used to solve the established state-space equation. The elaborated semi-analytical solution has been propagated throughout the multilayered multiferroic composites plates using the propagator matrix method and accounting the transfers matrices at each imperfect interface. The developed formulas have been programmed and the numerical obtained results have been well compared with available ones. For the computation process, the piezoelectric material BaTi O 3 and piezomagnetic material CoF e 2 O 4 are used. In addition, these numerical tests showed that the proposed solution is in good agreement with the available 3D asymptotic approach, the modified Pagano method, the pseudo-Stroh formalism, the finite elements method and the Peano series solution. Furthermore, the effects of mechanically compliant, dielectrically and magnetically weakly or highly conducting imperfect interface on the static response and the magnetoelectric coupling coefficient of the functionally graded multilayered multiferroic composites plates for various configurations have been also analyzed. It has been carried out that, the bending response and the magnetoelectric coupling coefficient of the multiferroic composites plates remarkably depend on the kind of imperfect interface, the used sequences as well as on the loadings conditions namely mechanical, electric or magnetic, respectively. [ABSTRACT FROM AUTHOR]

This paper defines in-plane displacement functions of a composite lattice rectangular plate, which is assumed to be a Kirchhoff-Love plate. It presents an approximate method based on the continuous model of conducting a progressive failure analysis for predicting material failure and post-failure behavior of the composite lattice rectangular plate with various boundary and load conditions. To define the approximate method, we use the Ritz method and Hashin's failure criteria. The validity of the present method is verified by comparing the results of the finite element analysis. Finally, we perform parametric and sensitivity analyses to investigate the effects of the design parameters on the failure characteristics of the composite lattice rectangular plates based on the present method. The results allow a database to be obtained on the structural characteristics of composite lattice rectangular plates. Consequently, it is concluded that the present method is well suited to progressive failure analysis of composite lattice rectangular plates due to their relative simplicity and computational efficiency. [ABSTRACT FROM AUTHOR]

This study aims to improve the impact protection performance of composite structures by combining a honeycomb core with negative Poisson's ratio and graphene platelets reinforced (GPR) face sheets. The paper investigates the nonlinear repeated low-velocity impact responses of auxetic honeycomb composite plates, taking into account loading-unloading-reloading processes. Effective material properties of the auxetic honeycomb core and GPR face sheets are obtained by using the proposed modified Gibson function and Halpin-Tsai model. Then, taking into account geometric nonlinearity, the nonlinear equations of motion for the system were derived by Hamilton's principle. Afterward, the time-varying contact force between the composite plate and a spherical impactor is defined by the modified nonlinear Hertz contact theory. The Galerkin method and variable-step Runge-Kutta algorithm are selected to obtain nonlinear impact responses. The proposed methods are verified by finite element simulation and experiment. Finally, the study evaluates the effects of key parameters on the nonlinear repeated low-velocity impact responses. [ABSTRACT FROM AUTHOR]

• The vibration suppression study of the plate structure based on the nonlinear piezoelectric shunt damping is proposed. • The modified Ritz method and complexification-averaging method are adopted to obtain dynamic responses of the system. • The effects of the negative capacitance and nonlinear capacitance on the vibration suppression performance are discussed. This paper proposes a nonlinear piezoelectric shunt damping circuit to mitigate the vibration of the plate structures subjected to the aerodynamic and harmonic excitations. The nonlinear piezoelectric shunt damping circuit consisting of the piezoelectric patch, inductor, resistor, negative capacitor and nonlinear capacitor is considered. Firstly, the governing equations of the electro-mechanical coupling nonlinear system are formulated based on the energy method and modified Ritz method. Furthermore, the complexification-averaging method combined with pseudo arc-length continuation method is adopted to analyze the steady-state response of the coupled system with aerodynamic and harmonic forces. A considerable number of numerical cases are performed to validate the proposed model and the time domain and frequency domain dynamic responses of the plate structures with and without control are further compared to validate the effectiveness of the proposed control strategy. Meanwhile, the energy transfer analysis between the plate structure and external piezoelectric shunt damping circuit is investigated. Finally, the effects of key parameters of the nonlinear piezoelectric shunt damping circuit including the negative capacitance and nonlinear capacitance on the vibration suppression performance of the piezoelectric shunt damping are discussed. [ABSTRACT FROM AUTHOR]

This paper aims at numerical finite element (FEM) research of guided Lamb waves propagation in multidirectional composite plates. All simulations were conducted in the Abaqus/CAE software by using the dynamic/explicit solver. The material considered in this work was carbon/epoxy composite laminate with [90⁰/θ/θ/θ/-θ/-θ/-θ/90⁰] stacking sequence where θ set was equal 0⁰, 30⁰, 45⁰, 60⁰ and 90⁰. The main goal of the analysis was to evaluate the influence of fiber orientation angles θ on propagation behavior of the separate symmetric S0 and asymmetric A0 Lamb wave modes. Numerical model was created by using the C3D8R brick element. The Lamb waves were generated by using concentrated force with 200 kHz frequency. The acoustic signal generated by travelling wave was registered at two nodes that representthe acoustic emission sensors. Obtained results were presented in tabular form where separate mode velocities were collected and on the normalized displacement versus time plots depicted registered wave signals. In addition, the contour diagrams and through-thickness deformations plots were created to present behavior of the extensional and the flexural modes. The greatest value of the S0 mode velocity was obtained for unidirectional laminates whereas the lowest for composite plate with 45⁰ fiber orientation angle. The asymmetric mode found to generate slightly greater deformation of plate in XZ plane than the symmetric. Recognition of the Lamb wave behavior in multidirectional laminates will allow to better planning the experimental acoustic emission tests. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Ordnance Equipment Engineering is the property of Chongqing University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Contact lenses are currently a practical and effective solution for the correction of refractive errors but also for the application of orthokeratology procedures in cases of keratoconus or high myopia pathologies. In orthokeratology procedures, the contact lenses used are rigid (hard) and are made of biocompatible materials resulting in a composite structure together with the cornea of the human eye. Thus, the contact lenses for orthokeratology have the effect of deforming the corneal surface, in the latter inducing a series of residual and inertial stress states through which changes in the refractive power of the entire eyeball are obtained. This paper presents aspects related to the approach of the corneal‐contact lens composite structure as a thin curved plate set. Also, the study is completed with the determination of the different aspects in section and an anisotropic structure which implies an approach of biomechanical behavioral analyzes both in terms of the elastic component and the viscosity component manifested in the corneal structure. As shown by specialists, the cornea topography is determined by the balanced state between the internal and external forces acting on it and its mechanical rigidity, which is, in turn, defined by the cornea geometry, the biomaterial thickness, and rigidity. Therefore, the development of studies on the corneal‐contact lens combination in orthokeratology as a composite structure is closest to the real behavior of the whole. [ABSTRACT FROM AUTHOR]

In this paper, the non-destructive testing (NDT), structural health monitoring (SHM), and scanning laser Doppler vibrometer (SLDV) techniques were presented to quantify three simulated delaminations inserted at different depths of a unidirectional composite plate. First, the RollerFORM and Omniscan equipment were sufficiently used to identify the delaminations. Second, in conjunction with guided waves, the developed imaging method was successfully used to detect and quantify the interested delaminations. The tuning curves were determined experimentally to define the dominant Lamb wave modes of incident waves. Third, multi-physics three-dimensional finite element simulations of propagating and interacting Lamb waves with delaminations were implemented to extract the wavefield data for wavenumber analysis. The experimental part was conducted to validate the numerical results using SLDV. The effect of the delamination depth on the trapped waves generated over the delamination region was studied numerically and experimentally. The results showed that trapped waves could be affected by the delamination depth. Both numerical and experimental results demonstrated that the near surface delamination has strong trapped waves over the delamination region while the far surface delamination has weak trapped waves. The energy distribution maps of numerical and experimental wavefields data sufficiently quantified the interested delaminations. A good agreement was achieved between the numerical and experimental results. [ABSTRACT FROM AUTHOR]

The finite element method is used to develop a computational algorithm for solving a limited class of problems on the bending of composite plates reinforced with systems of unidirectional high-strength fibers. It is assumed that a neutral plane exists in the region of the plate and behaves similarly to a flexible nondeformable membrane. The displacements of the plate in the longitudinal direction are linear in thickness. In the case of fiber composites with different elastic moduli in tension and compression, the neutral plane, generally speaking, does not coincide with the median plane. The problem of minimizing the elastic energy functional in accordance with the Lagrange variational principle yields a fourth-order elliptic differential equation for the deflection. The bending stiffnesses of the plate included in the coefficients of the equation are calculated with account for the fact that the elastic characteristics of the reinforcing fibers under tension and compression are significantly different. The numerical solution of the equation is obtained via the finite element method with the help of a Bell triangular element. The paper presents computational results for the bending of rectangular laminated plates in which the fibers are laid in different directions. [ABSTRACT FROM AUTHOR]

This paper presents a novel investigation on the robustness of Acoustic Emission (AE) technique on the characterization of indentation-induced Damage Mechanisms (DMs) in scaled laminated composites. AE is used to monitor a comprehensive series of scaled Quasi-Static Indentation (QSI) tests performed on Quasi-Isotropic (QI) S-glass/8552 epoxy composite plates, with in-plane and intra-plane scaling. A detailed assessment of the damage evolution is carried out through clustering of the monitored AE signals. The AE results indicated the existence of different DMs such as delamination, matrix cracking and fiber breakage. Ultrasonic C-scan and visual observations were also used to verify the AE based results. It was observed that both in-plane and intra-plane scaling alter the induced DMs, and the AE analysis was able to accurately identify and quantify the DMs in each case. However, the AE features (frequency, energy and count) were found to be dependent on different variables such as size, geometry and stacking sequence of the investigated samples. This research highlights the potential and challenges to develop AE as a reliable structural health monitoring system for impact/indentation damage monitoring of composite plates over a range of sizes and complexities. [ABSTRACT FROM AUTHOR]

This paper deals with the improvement in patch loading resistance achieved by a bottom triangular cell attached to a steel T‐shaped girder flange. As local introduction of the reaction from the bearings onto the webs during incremental launching is a specific limit state for structures designed with steel webs, the attachment of a bottom triangular cell allows using wider launching pads since T‐flange transverse bending is no longer critical; web panel slenderness is also reduced, achieving an increase in critical buckling load of the web panel. But, in addition and most important, a supplementary resistant mechanism is generated, as the bottom triangular cell also works a continuous beam in bending, spanning the vertical stiffeners, so that part of the local concentrated load is directly transmitted to the stiffeners, significantly increasing patch loading resistance of the web. The analyses carried out by hybrid beam and plate non‐linear finite element models show both resistant mechanisms: web resistance and the additional contribution of vertical stiffeners through the triangular cell bending stiffness. Finally, a numerical model is proposed for evaluating the contribution of vertical stiffeners to patch loading resistance, in order to improve present formulation. [ABSTRACT FROM AUTHOR]

In this paper a Mindlin's plate model is developed for the Bending, buckling and vibration analysis of a graphene nanoplate based on a modified couple stress theory. The bending rates and dimensionless bending values under uniform surface traction and sinusoidal load, the dimensionless critical force under a bi-axial surface force in x and y directions and dimensionless frequencies of different modes are all obtained for various plate's dimensional ratios and material length scale to thickness ratios. The results are presented and discussed in details. [ABSTRACT FROM AUTHOR]

This paper presents a static analysis of laminated composites plates by employing a novel higher-order shear deformation theory with stretching effect (quasi-3D HSDT). This theory accounts for both transverse shear and normal strains effects by a parabolic variation of all displacements through the thickness and satisfies the stress-free boundary conditions on the top and bottom surfaces of the plate without using shear correction factor. The displacement field of the proposed theory has only five unknowns, which is even less than the other existing high-order shear deformation plate theories. The principle of virtual works is used to derive the governing equations and boundary conditions. The closed form solutions are obtained by using Navier procedure for cross-ply laminated composite plates subjected to sinusoidal load for simply supported boundary conditions. The numerical results are compared with those predicted by other theories to show the effects of shear deformation and thickness stretching on displacement and stresses. [ABSTRACT FROM AUTHOR]

The rock plate (RP) method can be used to identify the size and location of potentially dangerous bed separation space (BSS) in coal mines. The RP method is performed in three steps: (1) The rock strata above the coal seam is simplified as a composite plate calculation model; (2) The deflection of rock strata is expressed as a double trigonometric series and obtained using the energy method; (3) The internal-forces and deformation of the RP are solved to determine the size and location of the BSS based on elasticity and a BSS identification process. This requires that the BSS be unbroken, and the BSS upper rock stratum be an aquifer. In this study, the Yuanzigou coal mine was taken as a study case and the RP method was used to determine the size and location of BSS water (BSS-W) above the coal goaf of working face 1,012,001. BSS usually occurs at the contact surface between hard and soft rock strata; at this mine, BSS-W exists between the Yijun conglomerate and the Anding mudstone formations. The results predicted that when the working face advanced 350 m, the third BSS will break, allowing BSS-W to flood into the goaf. These results were verified by borehole video observation. Therefore, two control methods were used: inclined drainage holes drilled from the roadway and spaced holes drilled from the surface in areas with abundant water. This paper thus provides a way to locate the BSS-W and prevent an inrush hazard. [ABSTRACT FROM AUTHOR]

Featured Application: The grille-type steel plate concrete composite wall (GSPCW) is an innovative shear wall system that has recently been developed. This type of shear wall is characterized by large vertical and lateral load capacity while maintaining large deformation capability. Since barely any traditional reinforcing bars are needed, the structural measures for wall construction are simple and can be easily implemented. Based on both experimental and numerical investigations of the GSPCW wall components, the seismic performance of GSPCW walls have been verified to be satisfactory in terms of load-bearing capacity, stiffness and deformation capacity, energy dissipation, etc. Moreover, further analysis on the application of GSPCW walls in a super-high-rise building as a case study show the excellent performance of the system. Based on these findings, it can be inferred that GSPCW wall could be used as an alternative system for conventional steel concrete composite wall, and is expected to be a promising system for high-rise buildings in seismic regions. The grille-type steel plate concrete composite wall (GSPCW) is an innovative shear wall system that mainly consists of steel faceplates, steel tie plates and infilled concrete. Compared to traditional steel plate concrete composite shear walls, the advantages of GSPCW walls include: (1) relatively high lateral and buckling resistance; and (2) simple structural measures for convenient construction and implementation. This paper presents the results of extensive numerical investigations regarding GSPCW systems, examining both GSPCW wall components and their application in a super-high-rise building as a case study. First, typical GSPCW wall models are established using DIANA software, and the numerical models are validated on the basis of comparison with results from previously reported experimental tests. The verified models are further used to perform parametric analyses with the aim of further understanding the effects of various design parameters on the seismic performance of GSPCW systems, including steel ratio, axial load ratio, height-to-width ratio, aspect ratio of the grille steel plate, and concrete compressive strength. Second, a super-high-rise building was selected for application to perform a case study of a GSPCW system. The seismic performance of the tall building in the case study was comparatively evaluated on the basis of both nonlinear time history analysis and modal pushover analysis (MPA), and the results from both of these methods validated the use of GSPCW is an efficient structural wall system appropriate for use in super-high-rise buildings. Finally, a simple economic assessment of the GSPCW building was performed, and the results were compared with those obtained for conventional reinforced concrete wall buildings. [ABSTRACT FROM AUTHOR]

The present paper deals with an effort to model impact damage in 3D-FE simulation. In this work, we studied the scattering behavior of an incident A0 guided wave mode propagating towards an impacted damaged zone created within a quasi-isotropic composite plate. Besides, barely visible impact damage of the desired energy was created and imaged using ultrasonic bulk waves in order to measure the size of the damage. The 3D-FE frequency domain model is then used to simulate the scattering of an incident guided wave at a frequency below an A1 cut-off with a wavelength comparable to the size of the damaged zone. The damage inside the plate is modeled as a conical-shaped geometry with decayed elastic stiffness properties. The model was first validated by comparing the directivity of the scattered fields for the A0 Lamb mode predicted numerically with the experimental measurements. The modeling of the impact zone with conical-shape geometry showed that the scattering directivity of the displacement field depends significantly on the size (depth and width) of the conical damage created during the point-impact of the composite with potential applications allowing the determination of the geometric characteristics of the impacted areas. [ABSTRACT FROM AUTHOR]

In this research, the characterization test on nonlinear vibration of a fibre-reinforced composite thin plate is studied. First, in order to improve the efficiency and precision of the test, a laser scanning vibration system is designed and developed. Then, test methods and procedures of the harmonic distortion and nonlinear time-varying damping of such thin plates are proposed from the time-domain perspective. Corresponding test methods and procedures of nonlinear vibration properties such as the hard/soft stiffness and amplitude-dependent damping are also presented from the frequency-domain perspective. Finally, the TC500 carbon fibre/resin composite plate is selected as an example for the research to carry out a case study. Potential nonlinear vibration phenomena of such plates are characterized by the proposed test methods. It has been proved that the related test system and techniques adopted in this paper can provide an important reference for the establishment of the nonlinear vibration test methodology of fibre-reinforced composite structures. [ABSTRACT FROM AUTHOR]

In this paper, the free vibration behaviors of composite laminated annular and circular plates under complex elastic boundary constraints are investigated. Firstly, Reddy's high-order shear deformation theory (HSDT) and Jacobi polynomial method are effectively combined to establish the unified vibration analysis model of composite laminated annular and circular plates. Secondly, the simulation of complex elastic boundary and coupling boundary is realized by using artificial virtual spring technology. Then, the energy equation of the composite laminated plate is established by using Rayleigh–Ritz energy technology. Finally, the free vibration solution equation of the laminated plate is obtained through the Hamilton differential principle. The fast and uniform convergence of this method and the accuracy of the calculated results are verified by numerical examples and the model experimental method. On this basis, the parameterization study is conducted, and the effects of material parameters, geometric parameters, spring stiffness values, and lamination scheme on the vibration characteristics of the annular or circular plate are fully discussed, which can provide a theoretical basis for future research. [ABSTRACT FROM AUTHOR]

Copyright of FME Transactions is the property of University of Belgrade, Faculty of Mechanical Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this research, nonlinear thermal buckling and post-buckling behaviors of composite plate with the circular/elliptical cut-out are investigated using particle semi-energy (PSE) method. The semi-energy method is based on the solution of compatibility equation via an Airy force function and out-of-plane displacement function. The unknown parameters of these functions are determined by minimizing the potential energy. The integral of potential energy are replaced with summation of particles energy at perforated plate. The cut-out is modeled easily using these particles. The advantages of this method are easily cut-out modeling by particles and proposing just one of the displacement fields (i.e. out-of-plane). Based on the results, there is a good agreement (1.25%) between the post-buckling loads derived from PSE of this paper and experimental test of other literature. The accuracy of the finite element method (FEM) is 7.5% with respect to experimental test. The influences of temperature distribution, the cut-out size and elliptical cut-out rotating on post-buckling load and deflection of perforated plate are investigated. [ABSTRACT FROM AUTHOR]

The thermo mechanical buckling and post-buckling behavior of layered composite shell type structure are considered with the finite element method under the combination of temperature load and applied mechanical loads. To account for through-thickness shear deformation effects, the thermal elastic, and higher-order shear deformation theory is used in this study. The refined higher order theories, that takes into account the effect of transverse normal deformation, is used to develop discrete finite element models for the thermal buckling analysis of composite laminates. Attention in this study is focused on analyzing the temperature effects on buckling and post-buckling behavior of thin shell structural components. Special attention in this paper is focused on studying of values of the hole in curved panel on thermal buckling behavior and consequently to expend and upgrade previously conducted investigation. Using finite element method, a broader observation of the critical temperature of loss of stability depending on the size of the hole was conducted. The presented numerical results based on higher-order shear deformation theory can be used as versatile and accurate method for buckling and post-buckling analyzes of thin-walled laminated plates under thermo mechanical loads. [ABSTRACT FROM AUTHOR]

Stacking sequence design is indispensable to make efficient use of the material properties of laminated composite materials. These laminated composites are usually fabricated from unidirectional plies of given thickness with fiber orientations limited to a small set of angles (e.g., 0°, +45°, –45°, and 90°). This leads to a combinatorial optimisation problem, which is rather complex to solve. In this paper, a new multi-population-based harmony search algorithm with dynamic interaction of populations, hybridised with a customised neighborhood algorithm to solve the layup sequence design problem of laminate composite plate is presented. Numerical experiments have been carried out by first considering the buckling and failure load optimisation of a laminate composite plate and later studies have been carried out using hybrid laminate plates for maximisation of buckling load and fundamental frequency with varied levels of hybridisation and for various plate aspect ratios. Numerical studies carried out in this paper clearly indicate that proposed dynamic hybrid adaptive harmony search algorithm is an effective combinatorial optimisation tool for stacking sequence optimisation of laminate composite structures and the computational performance is found to be superior when compared to other popular implementations of harmony search algorithm. [ABSTRACT FROM PUBLISHER]

The paper is dedicated to the research of the dynamic behaviour of heat protection tiles made of composite material and connected to an elastic base. Such structural elements are one of the types of thermal protection for a spacecraft during the prelaunch period. A mathematical model, which makes it possible to determine the stress-strain behaviour of a ceramic tile structure made of composite material is represented, taking into account the formation of liquid at elevated temperatures or ice accumulation. As a result of the research, the values of deflection, shear force, and normal stresses in the structure were obtained, which is necessary for calculating the strength and performance of the tiled thermal protection during the active stages of the flight of a spacecraft. The task is modeled by the boundary-value problem of deformation of a circular composite plate, connected with an elastic base. The effect of the temperature field was taken into account. The plate material is modeled by composite sandwich plates with a lightweight core. To describe the kinematics of a plate package asymmetric in thickness, the hypotheses of a broken normal are adopted. Kirchhoff's hypotheses are valid in thin bearing layers. In a relatively thick core, the normal does not change its length, it remains straightforward, but it rotates by some additional angle. The reaction of the base is described by the Winkler model. The system of equilibrium equations and its solution in displacements are obtained. A numerical parametric analysis of the solution was conducted. [ABSTRACT FROM AUTHOR]

The NM500/Q345/NM500 composite plates were subjected to different hot rolling and heat treatment processes in this paper. The influence of hot rolling and heat treatment on the microstructure, element distribution and defect composition of the bonding interface of the as-rolled clad plates was studied by using optical microscope, scanning electron microscope, electron backscattered diffraction and transmission electron microscope. Meanwhile, the mechanical properties of wear-resistant steel were analyzed by microhardness and tensile tests. It was revealed that the increase in rolling reduction promoted the metallurgical bonding between NM500 and Q345 steels. The composite texture components of {112} ~ {113} < 110 > , {332} < 113 > , {223} < 110 > , {554} < 225 > and < 110 > ∥RD were formed in the tissue when the reduction rate was 70%. γ/α phase transformation reinforced the texture components and thus increased {332} < 113 > and {554} < 225 > after quenching treatment. Typical lath martensites were present in the structure, and there were high-density dislocations and substructures between the laths. Tempering treatment at 200 °C facilitated the deposition of some needle-like or rod-like ε precipitates in the martensite. The best tensile strength (1432.28 MPa) and elongation (22.68%) in the composite plate could be achieved by post-rolling treatment of quenching at 900 °C and tempering at 200 °C. [ABSTRACT FROM AUTHOR]