Abstract: The paper deals with the extension **of** isotropic **plates** problem to the case **of** **composite** **plates**. In order to perform it, the Kirchhoff-Love hypotheses were “softened” by some additional ones. Considering the constitutive laws for **composite** materials the stress functions were eliminated by using Cauchy equations. As a result a partial derivative equation in displacements was obtained. Finally the boundary condition formulation was extended for the case **of** complex **composite** **plates**.

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Finite Strip **Method** (FSM) is another universally applicable **method** for buckling and post-buckling analyses **of** **plates** and plate structures. It can be considered as a particular kind **of** simplified finite element **method** in which a special element called strip is used. Finite strip **method** is based on discretization **of** the domain into lon- gitudinal strips and interpolates the behavior in the longitudinal direction by different functions and in the trans- verse direction by polynomial functions. Cheung (1976) may be considered as the pioneer who ﬁrst proposed the concept **of** FSM. Cheung established FSM for the analysis **of** simply supported **plates**. The studies presented by Smith and Sridharan (1978) proposed FSM for buckling **of** isotropic plate under edge loading. Recently, Ovesy, Ghannadpour and their co-workers (Ovesy et al. 2005) have made a contribution by introducing two different versions **of** finite strip methods, namely the full-energy and semi-energy finite strip approaches. Two other differ- ent versions **of** finite strip **method**, namely spline and semi-analytical methods are also developed by them for predicting the response **of** rectangular laminates with non-symmetric and symmetric forms **of** initial imperfec- tion. They used both formulations to predict the non-linear response **of** channel sections when subjected to uni- form end-shortening in their **plane** (Ovesy et al. 2006). An exact finite strip is introduced by Ghannadpour and Ovesy (2008) to investigate the exact relative post-buckling stiffness **of** I-section struts. To extend their works, they developed a high accuracy finite strip for the buckling and post-buckling analyses **of** moderately thick sym- metric cross-ply **composite** **plates** based on FSDT (Ovesy et al. 2016).

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The bending problem **of** thin **plates** can be modelled by the Classical Plate Theory (CPT) (or Kirchhoff-Love theory) when the out-**of**-**plane** displacement is small and shear deformations are negligible. The first works using BEM to analyze the bending **of** thin **plates** with Kirchhoff-love's theory were presented in the 1970s. Some **of** those works can be found in Bézine (1978), Altiero and Sikarskie (1978), and Stern (1979). More recently, Dirgantara and Aliabadi (1999, 2006) investigated the bending and the large deflection **of** shells. Albuquerque et al. (2006) studied the bending **of** laminated **composite** Kirchhoff **plates**. Katsikadelis and Babouskos (2009) used BEM with the analog equation **method** to study bending and vibration **of** thick **plates**.

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Batra and Liang 11 used a three-dimensional linear theory **of** elasticity to find the optimal location **of** an actuator on a simple-supported rectangular laminated plate with embedded PZT layers. The optimal design is obtained by fixing the applied voltage and the size **of** the actuator and moving it around in order to find the maximum out-**of**-**plane** displacement. Liang et al. 12 proposed a model for the optimization **of** the induced-**strain** actuator location and configuration for active vibration control. Correia et al. 13 presented refined finite element models based on higher order displacement fields applied to the optimal design **of** laminated **composite** **plates** with embedded or surface bonded piezoelectric actuators and sensors.

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shear deformation through the thickness direction **of** the **plates**. In particular, The HSDTs do not required shear correction factor and it can generally guarantee zero transverse shear stress values on the top and bottom surfaces **of** the plate. Some important and early works on HSDT can be found in the open literatures [1-5] where more realistic representation **of** transverse shear deformation were generally tried to be provided. Later, Zhang and Yang [6] described some recent developments **of** the FEs based on various laminated **composite** plate theories. Reddy [1] suggested a simple but very useful HSDT for laminated **composite** **plates**. His version **of** HSDT is based on equivalent single layer plate theory and it allows parabolic variation **of** transverse shear stress and also satisfies zero shear stress boundary conditions at the top and bottom surfaces **of** the plate. Moreover, it does not involve any unknown fields which do not have any physical meaning. Bose and Reddy [7, 8] ana- lyzed laminated **plates** by using a unified third-order laminate plate theory that contains classical, first-order and third-order theories and they presented analytical **method** using the Navier and Levy equations and the FE **method** using the unified third order laminate plate theory. A review on the various methods used in the estimation **of** transverse and inter-laminar stresses for laminated com- posite **plates** and shell including both analytical and numerical methods was provided by Kant and Swaminathan [9]. Kant and Manjunatha [10] provided the FE based on HSDT having twelve de- grees **of** freedom per node. They presented three-dimensional stress and **strain** states to investigate the flexure-membrane coupling behavior **of** unsymmetrical laminated plate. Akhars and Li [11] de- veloped a spline finite strip **method** for static and free vibration analysis **of** **composite** **plates** using Reddy’s HSDT. Pervez et al [12] developed a two dimensional serendipity FE based on a refined HSDT having seven degrees **of** freedom per node to perform the linear static analysis **of** laminated orthotropic **composite** **plates**. Latheswary et al [13] studied the behavior **of** laminated **composite** **plates** under static loading by using a four-node nonconforming element based on HSDT. Goswami [14] presented a simple C^0 FE formulation for nine-node FE with six degrees **of** freedom based on HSDT.

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Owing to the fact that the stiffened plate elements **of** ships are thin-walled, their out-**of**-**plane** stress is negligible but their in-**plane** stress is determinant. Hence, the modeling **of** these components is precise enough with shell elements. Therefore, the element Shell 181, that is appropriate for mod- eling the thin and relatively thick **plates** and is constructed based on Classic Plate **Strain** and Mindlin theories, was used in the analyses. These elements are composed **of** 4 nodes and each node has 6 degrees **of** freedom. This element is appropriate for linear and nonlinear solutions with large deformations and great angle variations. Also, this element can be used for modeling the **composite** and laminated materials.

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Here In this study, the **composite** laminates subjected to transverse impact with consideration interlaminar and intralaminar damage based on Cohesive Zone Model (CZM) and Progressive Damage Model (PDM) are investigated by numerical analysis using ABAQUS commercial finite element code. The delamination in stacking ply with the same fiber orientation is considered as interlaminar damage and the delamination in an inner layer **of** any cluster is ignored. Hashin criterion is used for intralaminar damage initiation and evolution without using any subroutine. First, the appropriate procedure for delamination on **composite** specimen was suggested based on CZM approach in double cantilever beam to verify the intralaminar damage simulation. Then by considering several case studies with different impact energies, the results **of** present simulation is verified with the relevant and available experimental results and numerical references in the existing literature. According to the available experimental results the present simulation results are more acceptable and accurate than the results **of** similar numerical works, especially in higher impactor velocity.

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In this work a **method** **of** obtaining a **composite** material based on small-dispersed particles is consid- ered. Proposed **method** consists **of** two steps **of** separation, mechanical – rough separation and plasma – soft separation, and also **of** step **of** deposition a catalytic nanolayer by wet impregnation **of** separated parti- cles in an aqueous solution **of** nickel nitrate. During such procedure a **composite** powder **of** small-dispersed zeolite particles with average diameter **of** 5 m and catalytic nickel layer was obtained. All obtained sam- ples were studied on a Quanta 3D 200i scanning electron microscope. Microscopic analysis and obtained experimental results show, that increasing **of** dispersion **of** separated powder allows for increasing a mass **of** catalyst in the **composite**, and the used separation **method** in plasma for obtaining **of** particles with high dispersion do not erode a catalytic layer.

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Figure 7 exhibits the interface microstructure **of** magnesium alloys in the rolled sample under various annealing conditions. Figure 7a is the microstructure **of** magnesium alloys in the rolled sample without annealing. It shows the typical nonuniform bimodal microstructure, fine grain sharing the submicrometer dimensions in comparison with the largest elongated grain with the size **of** 29.2 µm, indicating nonuniform deformation during hot rolling process. Figure 7b is the OM images **of** the middle zone **of** Mg alloys obtained from rolled sample without annealing. Due to incomplete dynamic recrystallization in the process **of** hot rolling, a certain amount **of** fine recrystallization structure appeared. Figure 7c-e exhibits the optical micrographs **of** Mg alloys near the interface in the rolled samples annealed at different temperatures for 1 h. Figure 7c and d shows small Figure 4. SEM images **of** the **composite** interfaces after explosive welding (a) big waveform (c) mini waveform.

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Figure 8 presents the variation **of** the maximal thermal stresses in the plate and the **composite** patches as a function **of** the ratio c/R deined previously for comparison between circular and elliptical patches. The stresses are calculated in the ibre direction (parallel to the direction **of** the applied load). We can see the process **of** adhesive curing involves relatively high level **of** thermal stresses along the ibre axis in the plate and the sign **of** this stresses is positive. It means that, according to the ibre direction, the aluminum plate is under tensile stresses. This is due to the fact that during the cooling the **composite** patch prevents the return **of** the aluminum plate to its initial position after dilatation. This behavior leaves the plate in tension.

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O principal objetivo deste trabalho é apresentar de forma clara e concisa a aplicação de padrões de projeto de software com a linguagem PHP. Durante o trabalho são apresentados os principais conceitos que envolvem a orientação a objetos e sua aplicação na linguagem PHP. É apresentado também um breve histórico da linguagem PHP, mostrando sua evolução rumo ao suporte à orientação a objetos, suporte este que passa a ser bem completo na versão 5 da linguagem. Durante o desenvolvimento do trabalho são apresentados exemplos de cada categoria dos padrões de projeto, sendo eles o padrão Singleton, **Method** Factory e Abstract Factory entre os padrões de criação, **Composite**, Decorator e Façade entre os padrões Estruturais e Iterator, Observer e Template **Method** como representantes dos padrões Comportamentais. Os padrões são utilizados em conjunto para a formação de uma aplicação exemplo.

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Abstract. A finite element formulation for active vibration control **of** thin plate laminated structures with integrated piezoelectric layers, acting as sensors and actuators is presented. The finite element model is a nonconforming single layer triangular plate/shell element with 18 degrees **of** freedom for the generalized displacements and one electrical potential degree **of** freedom for each piezoelectric element layer, and is based on the Kirchhoff classical laminated theory. To achieve a mechanism **of** active control **of** the structure dynamic response, a feedback control algorithm is used, coupling the sensor and active piezoelectric layers, and Newmark **method** is used to calculate the dynamic response **of** the laminated structures. The model is applied in the solution **of** several illustrative cases, and the results are presented and discussed.

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The dynamic behavior **of** variable stiffness **composite** laminated (VSCL) plate with curvilinear fiber orientation subjected to in- **plane** end-loads is investigated. A variable stiffness design can increase the laminated **composite** structural performance and also provides flexibility for trading-offs between various structural prop- erties. In each ply **of** the VSCL plate, the fiber-orientation angle assumed to be changed linearly with respect to horizontal geometry coordinate. The spline finite strip **method** based on both classical as well as higher order shear deformation plate theories is formulated to explain the structural behavior. The panel is assumed containing internal square delamination regions with friction and contact conditions at delaminated interfaces are not considered. In order to demonstrate the capabilities **of** the developed **method** in predicting the structural dynamic behavior, some representing results are obtained and compared with those available in the literature. The effects **of** change in curvilinear fiber orientation angles on the struc- tural stability is studied. The obtained results show very good conformity in comparison with those exists in the available litera- ture .

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In order to evaluate the performance **of** the developed element for the study **of** free vibration response **of** irregular **plates**, a five layer symmetric cross-ply skew laminated **plates** (90/0/90/0/90) with simply supported edges is considered. The geometry **of** the skew **plates** is shown in Figure 7. The material properties MM5 **of** Table 2 is used for this analysis. The skew angle α is varied from 0°, 15°, 30°, 45° and 60°. The non-dimensional natural frequencies for the first four modes are reported in Table 6, considering the thickness ratios (a/h) as 10. A mesh size **of** 12×12 is considered for the analysis. The first six flexural mode shapes obtained for α = 45° are shown in Figure. 8. The comparison was made with the analytical solutions **of** Wang (1997) using B-spline Rayleigh-Ritz **method**, the solution **of** Ferreira et al. (2005) based on Radial Basic Function (RBF), as well as with the finite element models **of** Nguyen-Van (2009) and Garg et al. (2006). The results **of** the comparison show the effectiveness **of** the present element in the analysis **of** this type **of** structures.

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For discrete variable structural problems, a variety **of** methods including simulated annealing can be used [14,23,24]. As pointed out by Correia et al [24,25], among others, the main advantage **of** this **method**, in comparison with gradient-based methods, is the ability to overcome the premature convergence towards a local optimum. By other hand, the main disadvantage is related with the computational lost, because **of** the high number **of** objective function evaluations usually required to reach the optimal solution, which is especially relevant when the objective function evaluation is computationally expensive. The implemented simulated annealing procedure employs a random search that generates feasible sets **of** design variables, accepting not only changes in the design variables that decrease the objective function but also changes that increase it. The latter changes are accepted with a certain probability. The basic functioning **of** the simulated annealing algorithm can de easily described as follows [16,23]:

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In the present work, we extend the internally pressurized two-layer **composite** tube problem to a cyclically loaded two-layer tube in the elastic and elastic-plastic stress states. A detailed analysis is performed for these tubes under one cycle **of** loading, unloading, and reloading **of** internal pressure. This loading cycle under consideration demonstrates an autofrettage process in which a residual stress field is formed inside the tube assembly. In the liter- ature, there are few studies on the cyclic behavior **of** pressurized tubes. Mahbadi and Eslami [32] studied the cyclic loading behavior **of** single-layer thick-walled tubes under different types **of** loading including internal pressure and they used a numerical iterative **method** in their study. Megahed and Abbas [33] studied the influence **of** reverse yield- ing on the residual stresses that developed after autofrettage **of** a single-layer tube. Darijani, Kalgarnovin and Naghd- abadi [34] obtained closed-form solutions **of** the internally pressurized elastoplastic tube problem in which forward and reversed loading is considered. In contrast to those studies, in our work two-layer **composite** thick-walled tubes are analyzed in which the locations **of** the yielding along the tube assembly depend on the tube dimensions. The so- lutions obtained in this study may be used in the analysis and design **of** the two-layer tube assemblies under internal pressure. In addition, the results **of** this analytical work may be used as benchmark problems for numerical solutions. As mentioned above, the geometry considered here consists **of** two tightly fitted concentric tubes. A long tube **of** inner radius a and outer radius b is placed in a tube **of** the same length and **of** inner radius b and outer radius c. The assembly is then constrained axially and at this stage it is stress-free. As the internal pressure is applied, stresses are formed in both **of** the tubes and increase in magnitude with increasing pressures. Depending on the tube dimensions, the yielding commences at the inner surface, at the interface, or at both locations at a critical value **of** pressure P = P e .

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The problem **of** nonlinear vibrations and stability analysis for the symmetric laminated **plates** with complex shape, loaded by static or periodic load in-**plane** is considered. In general case research **of** stability and parametric vibrations is connected with many mathematical difficulties. For this reason we propose approach based on application **of** R-functions theory and varia- tional methods (RFM).The developed **method** takes into ac- count pre-buckle stress state **of** the plate. The proposed ap- proach is demonstrated on testing problems and applied to laminated **plates** with cutouts. The effects **of** geometrical pa- rameters, load, boundary conditions on stability regions and nonlinear vibrations are investigated.

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Today the search for new, recyclable and renewable materials is leading the researchers in new ways. Natural products applications are emerging and some research is starting in this matter. The work presented here analyse the utilization **of** adhesives single lap joints at joining processes to assemble **of** different parts made with natural vegetal sisal fibres reinforced **composite** materials. Some different sisal/epoxy **composite** **plates** are made utilising sisal fibres with different surface treatments, with the purpose **of** increasing the adhesion between the fibres and the matrix, and consequently to improve mechanical behaviour **of** the **composite** material [1,2 and 3] and the adhesives joints. The treatment used is called mercerization, and is described below. Before the treatment application the natural fibres were cleaned in order to remove contaminating agents.

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In recent years, there has been a great growth **of** industrial buildings and residences structured in steel. The steel structures are formed by the connection **of** several structural elements aiming the efficient conduction **of** the external forces acting on the structures for the foundations. The steel has advantageous physical and mechanical characteristics for use in the construction **of** **plane** frames, such as: good relationship between strength and structural weight, adaptability to various architectural forms, wide variety **of** profiles available in the market, great control in the manufacturing process in the mills which results in greater reliability in the use **of** these buildings.

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The optical bandgap energies (OBGE) **of** 3C, 15R, 6H and 4H-SiC have been investigate experimentally by transmission and photoacoustic spectroscopies. The measurements were per- formed on 470 µm thick wafers. The OBGE obtained from both spectroscopies for different polytypes show very good agreement. In order to have a better understanding **of** these materials calculations **of** eletronic band structure were performed by the full-potential linearized augmented **plane** wave (FPLAPW) **method**. For the OBGE the results are compared to the measurements agreeing closely over the energies **of** those polytypes.

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