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The present study investigates buckling characteristics of cut-out borne stiffened hyperbolic paraboloid shell panel made of laminated composites using finite element analysis to evaluate the governing differential equations of global buckling of the structure. The finite element code is validated by solving benchmark problems from literature. Different parametric variations are studied to find the optimum panel buckling load. Laminations, boundary conditions, depth of stiffener and arrangement of stiffeners are found to influence the panel buckling load. Effect of different parameters like cut-out size, shell width to thickness ratio, degree of orthotropy and fiber orientation angle of the composite layers on buckling load are also studied. Parametric and comparative studies are conducted to analyze the buckling strength of composite hyperbolic paraboloid shell panel with cut-out. [ABSTRACT FROM AUTHOR]

The tensile properties at elevated temperatures (780, 800 and 820 ℃) for the laminated CuAl10Fe3Mn2-intermetallics composites have been investigated. The bronze-intermetallics laminated composites were transformation superplastic at 800 ℃. When the initial strain-rate was 0.7 × 10-3 s-1 fracture elongation of 455% was achieved. An excursion through the transformation range α→β and back β→α resulted in a finite, irreversible strain increment on each thermal cycle. These strains were accumulated without fracture of intermetallic layers. A small amount of cavities were formed during superplastic deformation of aluminum bronze which were nucleated at the iron-rich particles and grew along the force axis. At 780 and 820 ℃, the expected superplastic behavior of laminated composites was not realized because α and β phase grains were too coarse to allow deformation by grain-boundary sliding through microstructural superplasticity and cracking in the intermetallic layers began.

Composites have been extensively used in the modern era in wide range of applications. This article deals with the study of vibration characteristics of natural fiber reinforced composite beam in which Aloe vera fiber is reinforced in epoxy matrix and is used in combination with glass-epoxy. Finite element method of analysis is adopted using Ansys software. Effects of several parameters like laminate stacking sequence, support conditions, material hybridization, and number of layers, etc. on the natural frequency of natural fiber reinforced composite beam are analyzed. Experimental study on Aloe vera fiber reinforced composite beam is also conducted for validation.

This paper presents a static analysis of laminated composite doubly-curved shells using refined kinematic models with polynomial and non-polynomial functions recently introduced in the literature. To be specific, Maclaurin, trigonometric, exponential and zig-zag functions are employed. The employed refined models are based on the equivalent single layer theories. A simply supported shell is subjected to different mechanical loads, specifically: bi-sinusoidal, uniform, patch, hydrostatic pressure and point load. The governing equations are derived from the Principle of Virtual displacement and solved via Navier-Type closed form solutions. The results are compared with results from Layer-wise solutions and different higher order shear deformation theories available. It is shown that refined models with non-polynomial terms are able to accurately predict the through-the-thickness displacement and stress distributions maintaining less computational effort compared to a Layer-wise models.

In this paper, wave propagation in multi-scale hybrid glass fiber (GF)/carbon nanotube (CNT)/polymer nanocomposite plates is studied for the first time by means of refined higher-order plate theory. The hybrid nanocomposite consists of CNTs and glass fibers (GF) as reinforcing components distributed within a polymeric matrix. A hierarchical micromechanical approach is used to predict the effective mechanical properties of the hybrid nanocomposite, including the three-dimensional (3D) Mori-Tanaka method and the rule of mixture. Moreover, a refined-type higher-order shear deformation theory (HSDT) is implemented to take into account the influence of the shear deformation on the motion equations of the system. Then, the governing equations are achieved on the basis of the energy-based Hamilton’s principle. Finally, the derived equations will be solved analytically for the purpose of extracting the natural frequency of the continuous system. A set of numerical examples are provided to cover the effects of various parameters on the wave dispersion characteristics of the plate. It can be declared that the hybrid nanocomposite system can achieve higher wave frequencies compared with other types of composite structures. Additionally, it is found that the selection of the lay-ups and length-to-diameter ratio plays a significant role in the determination of the sandwich plate’s acoustic response.

Over the last two decades, several experimental and numerical studies have been performed in order to investigate the acoustic behavior of different muffler materials. However, there is a problem in which it is necessary to perform large, important, time-consuming calculations particularly if the muffler was made from advanced materials such as composite materials. Therefore, this work focused on developing the concept of the indirect dual-chamber muffler made from a basalt fiber reinforced polymer (BFRP) laminated composite, which is a monitoring system that uses a deep learning algorithm to predict the acoustic behavior of the muffler material in order to save effort and time on muffler design optimization. Two types of deep neural networks (DNNs) architectures are developed in Python. The first DNN is called a recurrent neural network with long short-term memory blocks (RNN-LSTM), where the other is called a convolutional neural network (CNN). First, a dual-chamber laminated composite muffler (DCLCM) model is developed in MATLAB to provide the acoustic behavior datasets of mufflers such as acoustic transmission loss (TL) and the power transmission coefficient (PTC). The model training parameters are optimized by using Bayesian genetic algorithms (BGA) optimization. The acoustic results from the proposed method are compared with available experimental results in literature, thus validating the accuracy and reliability of the proposed technique. The results indicate that the present approach is efficient and significantly reduced the time and effort to select the muffler material and optimal design, where both models CNN and RNN-LSTM achieved accuracy above 90% on the test and validation dataset. This work will reinforce the mufflers’ industrials, and its design may one day be equipped with deep learning based algorithms.

The post-impact residual behaviour of a modified-matrix glass fiber laminated composite is analysed. The matrix of the laminate was modified by mixing it with 1/4” long chopped glass fibers in up to 4% volume fractions. Beam impact tests were performed at 7.5 J and 12.5 J impact energies with fixed boundary conditions. The data suggest that the impact resistance as well as the elastic response of the laminates increase with increasing chopped fiber content. Flexural test results showed improved residual properties in the case of reinforced epoxy laminates. Microscopic damage analysis shows a good correlation with laminates’ impact performance parameters.

This paper evaluates the fracture of notched epoxy matrix composites using the Brazilian disk (BD) test from both numerical and experimental points of view. The study began with a comprehensive experimental program covering three different composite lay-ups (quasi-isotropic, unidirectional, and cross-ply) and various geometries of U and V notches. Specifically, the BD samples combined the three layouts, four different notch angles, and three notch radii with three specimens per combination, leading to an overall number of 108 fracture tests. The experiments showed the appropriateness of the BD test for the study of the fracture behavior of composite materials and provided a good pool of data for further investigations. Subsequently, the virtual isotropic material concept (VIMC) was applied in combination with two fracture criteria to theoretically predict the experimentally acquired fracture loads. This study demonstrated that using the VIMC approach can provide robust predictions while incurring much lower computational costs compared to the conventional approaches found in the literature.

In this paper, the sub-laminate local buckling, global buckling and delamination propagation behavior of composite laminates with circular embedded delamination were studied numerically. First, linear buckling analyses were performed and buckling loads and modes of local sub-laminate and global buckling were identified. Next, geometrically nonlinear post-buckling and delamination propagation analyses were performed. Buckling deformation was instigated by seeding finite element meshes with a small amount of combined linear buckling modes. In-plane failure and interface delamination were accounted for by a continuum damage mechanics method and cohesive zone modeling, respectively. Analyses were performed to investigate the interaction between local sub-laminate buckling, global buckling, in-plane failure, and delamination propagation. The dependence of buckling behavior on the size and depth of location of pre-delamination was also investigated by a series of parametric studies. [ABSTRACT FROM AUTHOR]

Laminated composites are complex multifunctional materials and often endure barely visible damage which is characterised by matrix cracks and fiber damage leading to delamination. These composites are often used in safety-critical industries such as aeronautical and automotive industries which makes it crucial to have techniques to assess damage before and during use. This paper presents full-field digital image correlation (DIC) as a method for damage detection in laminated composites under static loading conditions. Full-field DIC is an optical measuring system used to assess deformation data (i.e. displacement and strain) in any component under various loading conditions. Assuming that the damage changes the mechanical properties, the method is applied here to detect changes in stiffness caused by barely visible impact damage in laminated composites. It is shown in the experimental findings that full-field DIC has the capability to detect barely visible damage caused by various impact energies in laminated composites, provided that the excitation or form of loading is applied near the impacted area. [ABSTRACT FROM AUTHOR]

This article presents a free vibration analysis of laminated sandwich plates under various boundary conditions by using an efficient C0 eight‐node quadrilateral element. This new element is formulated based on the recently proposed layerwise model. The present model assumes an improved first‐order shear deformation theory for the face sheets while a higher‐order theory is assumed for the core maintaining an interlaminar displacement continuity. The advantage of this model relies on its number of variables is fixed, does not increase when increasing the number of lamina layers. This is a very important feature compared to the conventional layerwise models and facilitates significantly the engineering analysis. Indeed, the developed finite element is free of the shear locking phenomenon without requiring any shear correction factors. The governing equations of motion of the sandwich plate are derived via the classical Hamilton's principle. Several examples covering the various features such as the effect of modular ratio, aspect ratios, core‐to‐face thickness ratio, boundary conditions, skew angle, number of layers, geometry and ply orientations are solved for laminated composites and sandwich plates. The obtained results are compared with 3D, quasi‐3D, 2D analytical solutions, and those predicted by other advanced finite element models. The comparison studies indicate that the developed finite element model is of fast convergence to the reference and valid for both thick and thin laminated sandwich plates. Finally, it can be concluded that the present model is not only simple and accurate than the conventional ones, but also comparable with refined analytical solutions found in the literature. [ABSTRACT FROM AUTHOR]

• Develops a new strain energy-based homogenization model to determine equivalent stiffness properties of cellular cores. • Provides a unified approach for different cellular core shapes and material configurations. • Derives equations to calculate strain energy density of a RVE based on classical laminate theory and deformation assumptions. • Validates the model against FE analysis for honeycomb and other core shapes with different composite wall configurations. • Provides simplified design plots to enable engineers to calculate effective properties without complex calculations efficiently. • Opens the door to optimizing composite sandwich panel designs by considering core shape, geometry, and materials. The performance of cellular core sandwich panels is influenced significantly by the choice of geometric and material parameters of the cellular core and skins. In order to determine the optimal design of sandwich panels, it is important to relate the geometric and material parameters of the cellular core to the resulting performance of the sandwich panel. Theoretical homogenisation models are computationally efficient and plays an important role in the inverse design of sandwich panel. This paper presents a methodology to determine the equivalent homogenised properties for composite cellular core systems. The methodology was developed based on a strain energy-based homogenisation approach. Unlike other existing models, the proposed model in this paper is applicable to different core shapes and different composite wall layer configurations. An existing model was further extended for comparison purposes to determine the equivalent properties of hexagonal composite honeycomb core. Results from both models were compared with finite element (FE) results for hexagonal honeycomb cores, and the predictions from the proposed model are also compared with FE results for different cellular core shapes. A good agreement was found between the predicted and FE results. The proposed model was found to be superior to existing models in its ability to consider different core shapes and composite wall layer configurations. [ABSTRACT FROM AUTHOR]

In this study, a laminated composite (Ti–6Al–4V (wt%)/Ti–44Al–8Nb–0.2 W–0.2B–0.03Y (at.%) (Ti–44Al–8Nb)) was successfully fabricated via a hot-pack rolling process. The microstructure and mechanical properties of the composite were investigated. No defects were observed at the interfacial region, thereby indicating a high bonding strength between Ti–44Al–8Nb and Ti–6Al–4V alloys. Electron back-scattered diffraction analysis exhibited a few dislocations, sub-structures, and residual stress in the interfacial region. The flexural strength of the composite in the arrester orientation (AO) was 2001.7 MPa, which was 53% higher than that of the Ti–44Al–8Nb alloy. The fracture toughness of the composite in AO (44.5 MPa·m1/2) was 3.4 times to that of Ti–44Al–8Nb alloy. Tensile test at 25 °C indicated higher ultimate tensile strength (802 MPa), yield strength (688 MPa), and tensile plastic strain of the composite (0.94%) than those of the monolithic Ti–44Al–8Nb alloy. The toughening, strengthening, and fracture mechanisms of the composite were discussed in detail. • Ti6Al4V (wt.%)/Ti-44Al-8Nb-0.2 W-0.2B-0.03Y (at.%) laminated composite is successfully fabricated by hot-pack rolling. • The interfacial region of composite can be divided into three parts and few dislocations, sub-structures and residual stress are stored. • Compared with TiAl alloy, the flexure strength and toughness of composite in arrester orientation are much improved. • Due to the defect free interfacial region, the room temperature tensile plastic strain of composite is enhanced. [ABSTRACT FROM AUTHOR]

This study presents the effect of curvature ratio on transient vibration analysis of simply supported antisymmetric thick cross-ply laminated composite shells (LCS) on elastic foundation. In the analysis, the foundation is modeled with two parameters. These models are Pasternak and Winkler models. The equation of motion for laminated rectangular shells resting on elastic foundation is obtained through Hamilton’s principle. The analysis is achieved in Laplace domain. By using modified Durbin’s algorithm, calculations are transformed from Laplace domain to the time domain. The numerical results are presented in the form of graphics.

Bu çalışmada, elastik zemin üzerine oturan basit mesnetli antisimetrik çapraz-katlı dizilimli tabakalı kompozit silindirik kalın kabukların (LCS), zorlanmış titreşim analizi üzerine eğrilik oranının etkisi sunulmaktadır. Bu analizlerde, zemin iki parametre ile modellendi. Bu modeller Pasternak ve Winkler modelleridir. Hamilton prensipleri ile elastik zemin üzerindeki tabakalı kompozit dikdörtgen kabukların hareket denklemleri elde edilmiştir. Analizler, Laplace alanında elde edilmiştir. Modifiye Durbin yöntemi ile çözümler Laplace alanından zaman alanına dönüştürülmüştür. Sayısal sonuçlar grafikler şeklinde sunulmuştur.

Thermal buckling study on the symmetric laminated composite trapezoidal plate with a circular cutout subjected to a uniform increase in temperature for various boundary conditions is explored in this paper. In a mathematical model, the first-order shear deformation principle is employed in accordance with the variational energy system. For acquiring the thermal buckling temperature, a nine-node heterosis plate relation has been used in the finite element formulation. By correlating the present findings with accessible literature, the effectiveness of the present formulation is verified. The impact of different parameters, such as trapezoidal shape, cutout size, ply-orientation, plate edge conditions and plate width to thickness ratio have been considered to study the effect of each parameters on the buckling characteristics of plate under various temperatures. It is observed from the study that each parametric investigation significantly affect the thermal buckling behaviour of trapezoidal plates. [ABSTRACT FROM AUTHOR]

A novel structure-optimized SiC fiber reinforced metal-intermetallic-laminated composite (SiCf-Ti/Al3Ti) without intermetallic centerline defect has been fabricated by vacuum hot pressing using stacked fibers and foils as well as Ti barrier layer. Through microstructure characterization by SEM and EBSD, the mechanisms of centerline formation and structural optimization were investigated detailedly. The mechanical properties and fracture behaviors of the optimized and non-optimized SiCf-Ti/Al3Ti composites were studied via quasi-static compression tests. The experimental results indicated that the intermetallic centerline region existing at the mid-plane of Al3Ti layer in non-optimized composite mainly contains newly-formed Kirkendall voids and gathered metallic oxides. Additionally, owing to the similar moving trails of fibers, oxides and voids in molten Al during hot pressing, SiC fiber is always accompanied with centerline, which causes the poor bonding of SiCf/Al3Ti interface. Unlike that, due to the adding of Ti barrier layer, SiC fibers are separated from centerline and metallurgically bonded with Al3Ti intermetallic in the optimized composite. The compression testing results proved that the optimized SiCf-Ti/Al3Ti composite possesses superior strength and toughness compared with those of the non-optimized composite. Besides, the extending of cracks along centerline often leads to large-scale centerline splitting and untimely SiCf/Al3Ti interface debonding in non-optimized composite. Nevertheless, cracks formed in optimized composite tend to propagate at the interfacial zone between layers instead of cutting off Al3Ti layer along its mid-plane. Moreover, ascribed to the well-bonded SiCf/Al3Ti interface, SiC fibers play an important role in strengthening and toughening the optimized SiCf-Ti/Al3Ti composite by fiber bridging mechanism. [ABSTRACT FROM AUTHOR]

This work focuses on the fabrication and characterisation of epoxy composites reinforced with natural fibre layers extracted from the inner bast (phloem) of the papaya plant (Carica papaya) under tensile and three-point bending loading. The papaya phloem is composed of fibrous laminas that wrap and reinforce the stem of the plant. A set of quasi-periodically arranged holes disrupt the continuity of these layers, through which the branches emerge. The fibres in each layer constitute an anisotropic honeycomb-like structure, whose elongated cells align along a single preferential direction. Papaya-reinforced epoxy composites are fabricated by hand lay-up and evaluated using two full-factorial designs based on the fibre-to-load direction in longitudinal (0°) and transverse (90°) conditions, for configurations without holes and alternating holes. Composites made with randomly-oriented short fibres are also evaluated along with the first experiment. The tensile and flexural properties obtained are compared to other materials in the literature to assess its potential as a structural material. The results show that the papaya bast fibre layers can be a promising reinforcement for polymeric composites.

Ceramic/metal laminated composite armor systems have great importance and potential in defence technology due to their high ballistic performance and lightweight. In this study, it was aimed to determine the ballistic performances, limits, and perforation types of light metals (with densities below 5.0 g/cm³) used as ductile backing plates in laminated composite armor systems. In the numerical analysis, SiC tiles of 5 and 10 mm thickness were used as the front layer. Al5083-H116, Mg AZ31B, and Ti6Al4V light metal alloys in different thicknesses were used as the backing layer. While using the Johnson and Holmquist (JH-1) material model in SiC ceramic tiles, the Johnson-Cook (JC) material model was applied for ".30 APM2" bullet components and metal layers. The analyzes were performed with Ansys/Autodyn software. As a result of the simulations, among all the laminated armor systems providing full protection against ".30 APM2" ballistic threats with a collision speed of 878 m/s, the lowest areal density was determined as 54.245 kg/m² in 10 mm SiC/5 mm Ti6Al4V laminated composite armor. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Aeronautical Materials is the property of Editorial Board of Journal of Aeronautical Materials 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.)

Metal-intermetallic laminated composites not only retain the high temperature strength of intermetallics, but also possess the high toughness and ductility of metal at room temperature which are gradually becoming the research priorities of domestic and overseas researchers. In this article, authors introduced Ti-Al, Ni-Al, Fe-Al, Nb-Al and other common metal-intermetallic laminated composites and emphasized on the advantages and disadvantages of synthesis methods, such as hot-pressing, explosive welding, spark plasma sintering and so on. The toughening mechanisms inside and outside of metal-intermetallic laminated composites were summarized. Finally, the deficiencies about the research of metal-intermetallic laminated composites at present were analyzed. The research must focus on the Ti-Al laminated composite. Improving the ductility and toughness at room temperature, researching the toughening mechanism and optimizing the fabrication process are the key issues to the engineering application of metal-intermetallic laminated composites.

In this study, we present a material-orientation optimization method for tailoring the thermal displacements of laminated composite shell structures to required target values. The square displacement error norm between the displacements and the target values is minimized by varying the distributed anisotropic material orientation of each layer. The optimum design problem is formulated as a distributed-parameter, or a design parameterization-free optimization problem, and the sensitivity function with respect to the material orientation variation is theoretically derived based on the variational method. The optimal material orientation variation is determined by the H1 gradient method with Poisson’s equation, where the sensitivity function is applied as the Robin condition to vary and optimize the material orientation distribution. Then, the optimal material orientation variation is determined as the temperature distribution by the Poisson’s equation, which ensures the continuous material distribution. The optimal design examples show that the proposed optimization method can effectively produce the optimum material orientation with a smooth curvilinear distribution for tailoring thermal or static deformation of a laminated composite shell structure.

Bu çalışmada, laminat kompozitler üzerine cep işlemede kontrol faktörlerinin (takım yolu stratejisi, takım tipi ve malzemesi, kesme hızı, ilerleme miktarı, kesici takımın yana kayma mesafesi) yüzey pürüzlülüğü ve boyutsal tamlık üzerindeki ana etkileri, % katkıları ve optimum değerleri Taguchi Metodu, ana etki grafikleri, Varyans analizi ve Gri İlişkisel Analiz yöntemi kullanılarak belirlenmiştir. Çalışma sonuçlarına göre, yüzey pürüzlülüğü üzerinde en etkili parametreler sırasıyla kesici takım geometri ve malzemesi (% 70.90), kesme hızı (%9.40) ve yana kayma mesafesi (%8.20) olmuştur. Aynı şekilde, boyutsal tamlık üzerinde de kesici takım tipi ve malzemesinin (%99.35) anlamlı bir etkisi gözlemlenmiş iken diğer parametrelerin toplam etkisi % 1’in altında kalmıştır. Hem minimum yüzey pürüzlülüğü ve hem de nominal ölçülere daha yakın boyutsal tamlıkta cepler elde etmek için kontrol faktörlerinin optimum seviyeleri; TPS2:Doğrusal cep işleme, Ct3:Yuvarlak uçlu helisel HSS parmak freze, Vc3:350 m/dak, f2:0.011 mm/dev ve SO1:3 mm olarak belirlenmiştir. Diğer taraftan, kompozit laminatlar üzerine cep işlemede yüzey pürüzlülüğü ve boyutsal tamlık üzerinde karbür takımların performansı zayıf bulunmuştur.

This paper presents the results of microstructural analysis of novel preceramic paper-derived SiCf/SiC composites fabricated by spark plasma sintering. The sintering temperature and pressure were 2100/2200 °C and 60/100 MPa, respectively. The content of fibers in the composites was approx. 10 wt %. The SiCf/SiC composites were analyzed by positron annihilation methods, X-ray diffraction technology, scanning electron microscopy, and Raman spectroscopy. Longer sintering time causes the proportion of the 6H-SiC composition to increase to ~80%. The increase in sintering temperature from 2100 °C to 2200 °C leads to partial transition of 4H-SiC to 6H-SiC during the sintering process, and the long-life component of positrons indicates the formation of Si vacancies. The Raman characteristic peaks of turbostratic graphite appear in the Raman spectrum of SiC fibers, this is caused by the diffusion of carbon from the surface of the SiC fiber and the preceramic paper during the high-temperature sintering process.

This paper presents the seismic response analysis of a cylindrical container made of laminated composite. The analytical homogenization is used for calculation of the material properties of unidirectional fiber‐reinforced composite layer. Constitutive relations for laminate within the classical laminate theory are considered. Effective modulus of elasticity is obtained and put into a calculation of internal forces of the laminated composite cylindrical tank. The seismic analysis of liquid storage facilities has to have different approaches as the analysis of typical structures. Because of an earthquake, the hydrodynamic impulsive and convective pressures are generated in addition to hydrostatic pressure. The solved liquid‐filled container made of the laminated composite was situated for the region of Slovak Republic and was analyzed in respect of Eurocode 8 recommendations. [ABSTRACT FROM AUTHOR]

Propagation of Lamb waves in both laminated and functionally graded (FG) composites is analyzed. Anomalous dispersion at high frequencies is observed revealing substantial discrepancy in the high frequencies asymptotes for quasi-flexural and quasi-symmetric fundamental modes. The applied methodology is based on a variant of sextic complex formalism. [ABSTRACT FROM AUTHOR]

The aim of this numerical and statistical study was to investigate the buckling analysis of laminated composite plates containing functionally graded fiber orientation angles. The laminated composite plates had functionally graded fiber orientation angles based on Taguchi's L18 (21 × 32) orthogonal array. The fiber orientation angles were considered to be control factors. Numerical analyses were performed using finite element software ANSYS. The optimum critical buckling load and the effects of fiber orientation angles for maximum data were determined using the analysis of the signal-to-noise ratio. The importance levels of laminates and their percent contribution on the buckling characteristics were calculated using analysis of variance. Regression analysis was employed to investigate the effects of control factors on buckling responses mathematically. The effects of laminate stacking sequence, mesh size, element type, mode number, and boundary condition were carried out using laminates with the optimum levels. [ABSTRACT FROM AUTHOR]

In the present study, values of yield strength of individual layers of layered composites based on different strength mild steels obtained by explosion welding followed by cold rolling and heat treatment were determined. The effect of cold rolling with a total reduction of 50% and heat treatment at a temperature of 500 °C on the change of the deformational resistance of Fe-2Mn-Si and Fe-11Cr-9Ni-2Mo-1Ti steels' layers in the composite was established. It was shown that additional cold deformation of the layered composite leads to an increase in yield strength of Fe-2Mn-Si and Fe-11Cr-9Ni-2Mo-1Ti steels' layers by 20% and 24%, respectively, and additional heat treatment of the cold-deformed composite contributes to strengthening of the Fe-11Cr-9Ni-2Mo-1Ti steel layers by 17% and softening of the Fe-2Mn-Si steel layers by 6%. It was shown that the level of strengthening of the Fe-11Cr-9Ni-2Mo-1Ti steel layers after cold rolling corresponds to the level of strengthening of this steel after heat treatment. It was determined that the maraging steel layers with initial ultrafine-grained microstructure are intensely strengthened (35%) by conducting combined heat-deformational processing of a layered composite, including cold rolling with a total reduction of 50% and subsequent heat treatment at a temperature of 500 °C. [ABSTRACT FROM AUTHOR]

The tensile properties at elevated temperatures (780, 800 and 820 ℃) for the laminated CuAl10Fe3Mn2-intermetallics composites have been investigated. The bronze-intermetallics laminated composites were transformation superplastic at 800 ℃. When the initial strain-rate was 0.7 × 10-3 s-1 fracture elongation of 455% was achieved. An excursion through the transformation range α → β and back β → α resulted in a finite, irreversible strain increment on each thermal cycle. These strains were accumulated without fracture of intermetallic layers. A small amount of cavities were formed during superplastic deformation of aluminum bronze which were nucleated at the iron-rich particles and grew along the force axis. At 780 and 820 ℃, the expected superplastic behavior of laminated composites was not realized because α and β phase grains were too coarse to allow deformation by grain-boundary sliding through microstructural superplasticity and cracking in the intermetallic layers began. [ABSTRACT FROM AUTHOR]

Magnetoelectric (ME) coupling is of interest for a variety of applications, but it is weak in a single-phase material. Strain-coupled laminates are an efficient way to achieve a high ME coupling. In this paper, we first derive an exact solution for a simply supported multilayered anisotropic magneto-electro-elastic plate with interfacial magneto-electro-elasticity. It is expressed in terms of the extended pseudo Stroh formalism along with the propagator matrix method. The interface modulus and stress are considered by constructing an interface matrix. Based on this solution, sandwich plates made of different layups of piezoelectric and piezomagnetic materials are numerically studied. Our results indicate that for the given layup, it is possible to tune the ME coupling by the interface modulus and stress. Considering interface effect is common in nanoplate, this study could provide an extra channel for turning the ME coupling in the layered magneto-electro-elastic plates with possible device applications. [ABSTRACT FROM AUTHOR]

In this study, three types of viscoelastic laminated composite dampers (VLCDs) were fabricated and experimentally analyzed. The dampers were fabricated by adding mesh skeleton materials to acrylic rubber to increase its stiffness; this can provide greater restoring force to passive control structures under the same strain conditions. The mechanical properties of the VLCDs were studied by measuring the maximum shear stress, storage shear modulus, loss factor, and equivalent viscous damping ratio under the same ambient temperature and different loading schemes. The experimental results showed that: (1) the addition of aramid mesh skeleton material to the damper can improve its stiffness without changing the matrix of the damping material; (2) the strain amplitude significantly affects the mechanical properties of VLCDs; (3) the excitation frequency has a slight impact on these mechanical properties; and (4) the influence of large-strain low-cycle fatigue on these mechanical properties is significant during the first 15 cycles and less significant during the next 15 cycles. Furthermore, hysteresis curves were calculated and simulated using the Bouc-Wen-Baber-Noori model. The simulation and experimental results agreed well with each other. [ABSTRACT FROM AUTHOR]

Composites have been extensively used in the modern era in wide range of applications. This article deals with the study of vibration characteristics of natural fiber reinforced composite beam in which Aloe vera fiber is reinforced in epoxy matrix and is used in combination with glass-epoxy. Finite element method of analysis is adopted using Ansys software. Effects of several parameters like laminate stacking sequence, support conditions, material hybridization, and number of layers, etc. on the natural frequency of natural fiber reinforced composite beam are analyzed. Experimental study on Aloe vera fiber reinforced composite beam is also conducted for validation. [ABSTRACT FROM AUTHOR]

Copyright of Acta Materiae Compositae Sinica is the property of Acta Materiea Compositae Sinica Editorial Department 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 work, minimum weight optimization of laminated composite is performed using a newly developed enhanced bat algorithm (EBA). Bat algorithm (BA) is a recently developed swarm-based optimization technique which is inspired by the echolocation behavior of bats. The standard BA shows premature convergence and reduced convergence speeds under some conditions. So, the EBA is used to perform the design optimization of laminated composites. The laminate analysis based on classical laminate theory is utilized for the stress calculations. Tsai–Wu failure curve is considered as the constraint in this constrained optimization problem. Number of plies at each orientation angle are considered as the design variables. The design optimization has been carried out for both conventional and unconventional (dispersed plies) stacking sequences considering different loading configurations: uniaxial tension, biaxial tension with and without shear loadings. Ply angles dispersed in the range of 5 ∘ – 85 ∘ , 25 ∘ – 65 ∘ and 0 ∘ – 90 ∘ at intervals of 5 ∘ are considered for the unconventional stacking sequence to increase damage tolerance. In addition, a new mathematical function is proposed to measure the dispersion of ply angles in the laminate called the dispersion function. Also, the performance of EBA is compared with standard BA in the optimum weight design of composite laminates. [ABSTRACT FROM AUTHOR]

In this study, the composite parts subjected to tensile load were combined with a doubleacting adhesive connection and analyzed using the 3D finite element method (FEM). The joint design is important to ensure that the joint is durable, does not take up too much space and has a long service life. In the analysis, carbon / epoxy (AS4 / 3501-6) composite parts with different orientation angles were used and DP410 was used as adhesive. Models for numerical analysis were created using ANSYS 14.5 package program. Finite element analyzes were performed to determine the damage loads. In general, because the damages occur in the adhesive region, the stresses in all directions on the adhesive, shear stresses, von-Mises stress and peel stresses were obtained at the specified failure loads. As a result, the effects of orientation angles, overlap dimensions of the bonded area and adhesive layer were investigated. The most effective parameters were determined for the composite parts joined with embedded double-acting adhesive. Furthermore, it is stated that embedded adhesive connection is important for industrial applications. [ABSTRACT FROM AUTHOR]

The microstructural characterization and uniaxial tensile tests of Al/Cu laminated composites were taken to investigate the interface effect and fracture process of the composites. The electron microscopic graphs before and after tensile test were used to evaluate the fracture behavior. Experimental results show that the fracture surfaces of laminated composites mainly present brittle failure characteristics, accompanied with several dimples on the matrixes and a few tearing on the interface. Cracks generally initiate from the interfacial interlayer and variously propagate depending on the interfacial bonding. It is found that Cu/Al interface with enhanced bonding strength generally hinders the propagation of interlayer cracks, while the interface with weak bonding delaminates by the cracks propagation through the interfacial defects. The additional shear stress on the interface between Cu and Al layers due to their different tensile ductilities aggravates the interfacial propagation of cracks. The local plastic deformation of individual matrix layer then occurs after cracks coalesce and failure in the interface. Therefore, the strong bonding interface and matching properties between individual matrix layers are required to improve the fracture performance of Al/Cu laminated composites. [ABSTRACT FROM AUTHOR]

The relations between the stiffness components of a symmetrical or unsymmetrical laminate having trans-verse matrix cracks only in the 90-degree laminas are explored in this work. The crack closure condition for these laminates under membrane and bending deformations is established to obtain the interrelationships. These equations also link the in-plane equivalent Young's moduli and the Poisson's ratios of balanced symmetric laminates. Cracks in off-axis laminas are not considered here. The present relations are validated using numerical data reported in the literature. Each inter-relationship can be used to obtain one elastic property when other property was experimentally measured or analytically calculated. [ABSTRACT FROM AUTHOR]

The present work optimizes Sound Transmission Loss (STL) and weight of double-walled composite cylinder with poroelastic foam employing multi-objective genetic algorithm by offering Variables Chromosome Method (VCM). So, firstly, shell and porous core equations of motion are solved beside acoustic wave equations, simultaneously. Next, optimization of the structure is performed based on VCM in which numbers of outer and inner composite layers are variable. Meanwhile, a number of other design factors such as fiber orientation angles and material types depend on a number of layers that in other researches have been considered constant. Finally, efficiency and reliability of optimized structure are shown. [ABSTRACT FROM AUTHOR]

In this paper, the free vibration and buckling responses of laminated composite and sandwich microbeams with arbitrary boundary conditions are investigated. The governing equations based on the modified couple stress theory are derived by using the total potential energy of a microbeam and employing a transverse shear-normal deformable beam theory. Extensive analysis results in terms of dimensionless fundamental frequencies and dimensionless critical buckling loads are introduced for various boundary conditions, aspect ratios, orthotropy ratios, fiber orientation angles, thickness to material length scale parameter ratios, and core thickness to face layer thickness ratios. [ABSTRACT FROM AUTHOR]

This statistical and numerical study deals with buckling temperature behavior of laminated composite plates with central circular and semicircular holes. Numerical buckling temperature analyses were performed using finite element software ANSYS based on Taguchi L18 orthogonal array. The plates were designed from graphite/epoxy systems. Fiber orientation angles and cutout shapes of the plates were assumed to be the control factors. Analysis of signal-to-noise ratio was used in order to investigate of the effects of fiber orientation angles and cutout shapes on the critical buckling temperature of the plates. Also, analysis of variance was performed in order to see percentage contribution rates and significance levels of control factors. [ABSTRACT FROM AUTHOR]

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Magnetoelectric (ME) composites exhibiting strain-mediated coupling are gaining increasing interest for applications. In this paper, an enhancement of ME response on simple lead-free laminated composites (80Bi0.5Na0.5TiO3-20Bi0.5K0.5TiO3)/CoFe2O4 (BNKT/CFO) prepared by a modified cofiring processing were demonstrated, by analyzing the effect of thickness variation on ME properties. The coexistence of independent BNKT and CFO phase and the presence of a clear and well-bonded interface were confirmed. Specifically, the maximum ME voltage coefficient of laminated composite reached up to 74.59 mV/(cm·Oe) with an optimized BNKT/CFO layer thickness ratio of 1:2. The static elastic model and the equivalent circuit model were used to determine the interface coupling. Also, there is a large magnetodielectric (MD) response up to 5.1% in a magnetic field of 8 kOe. Tuning the layer thickness, the ME response of laminated composite is further optimized, which is of significance in development of magnetic-field-tuned electronic devices. [ABSTRACT FROM AUTHOR]