Hybrid Composite Plates Research Articles

Cast-in-situ vs prefabricated solution based on NSM-CFRP reinforced SHCC for seismic retrofitting of severely damaged substandard RC beam-column joints

In this study, the effectiveness of two retrofitting solutions for the repair and upgrading of severely damaged substandard RC beam-column joints is examined and compared. Both solutions are made of CFRP reinforced SHCC (Strain Hardening Cementitious Composite). However, whilst one of the solutions follows a cast-in-situ retrofitting strategy, the other is based on bonding prefabricated Hybrid Composite Plates (HCP). Chemical anchors were used to prevent or delay debonding of the retrofitting layer.

Effect of patch dimension and fiber orientation on non-linear buckling of hybrid composites

AbstractIn this study, first circular hole layered hybrid composite plates were repaired by wet patch method, and then buckling behavior was investigated experimentally and numerically. In the experimental study, composite plates were produced by vacuum infusion method using hybrid fabrics made of carbon and aramid. Circular holes were drilled in the produced plates and then these holes were repaired with the same material. In the wet patch repair method, wet hybrid fabrics impregnated with epoxy resin were placed around the hole and then this area was subjected to pressure and temperature by vacuum infusion method. In experimental tests, pressure force was applied to the fixed sides and force-displacement graphs were obtained. In a numerical study, non-linear buckling analysis was performed by creating numerical models of plates and patches using the finite element method. As a result, experimental and numerical load-displacement graphs were obtained in accordance with pre- and post-buckling. Thanks to the repair in accordance with practical applications, no interface debonding damage occurred in ideal samples. Increasing the patch length from 30 mm to 40 mm increased the maximum damage load by 6 %, while increasing the patch length to 50 mm increased damage load by 12 %. Increasing the patch thickness from 0.65 mm to 1.1 mm increased the load by 67 %, while increasing it to 2.16 mm increased the load to 247 %. Fiber orientation was found to be a more influencing factor in critical buckling and damage load than the ply sequence.

Eigenfrequency Behavior of Banana/Glass/Epoxy Hybrid Composite-A Numerical and Experimental Investigation

ABSTRACT In the present work, a finite element model in conjunction with higher-order shear deformation theory was developed to investigate the eigenfrequency responses of hybrid composite (banana-glass-epoxy) flat-panel structures. First of all, five different sets of banana-glass-epoxy hybrid composite plates were fabricated using an in-house fabrication facility. The test specimen for elastic property evaluation was prepared according to the ASTM standard. The necessary elastic properties were obtained by tensile test and utilized in numerical analysis. Furthermore, to develop the mathematical model of hybrid laminated composite, higher-order displacement kinematics were used that eliminates the consideration of shear correction factor. The model of plate was divided into several small parts using 2D nine noded elements. The elemental mass and stiffness of the panel were obtained and assembled to get the global mass and stiffness. The global values were substituted further into the governing equation derived from Hamilton principle. Furthermore, constraints conditions were imposed and the governing equation was solved to get the natural frequency. First, the numerical model’s sensitivity and accuracy were checked by stability and validation study. After that new numerical examples were solved and influences of different parameters including hybridization on frequency responses were studied and discussed in detail.

Effect of the use of a hybrid material on stress reduction in an adhesive used for a single lap joint; bending loading effect

Composite materials are increasingly widely used in high-tech industries in recent decades and are now affecting more and more fields, especially in aeronautics. Their success is due to the many advantages they offer compared to traditional materials: lightness, good resistance to fatigue, good resistance to corrosion, the possibility of obtaining complex shapes. The bonding assembly of composite materials is all the more interesting since the durability of the assemblies and essentially the adhesive joint strongly depends on the nature of the fiber as well as the stacking sequence. Therefore, the introduction of the hybrid composite in recent years brings a great advantage in the stiffness flexibility compensation of composite plates. However, the behavior of composite plate assemblies has been the concern of researchers for several years, the analysis of their behavior is generally studied in tension-shear stress, but in reality, these assemblies are subjected to different types of stress. As in the case of bending, the behavior of the adhesive is poorly understood and few studies have been conducted in this area of research. The objective of our work is to analyse by the finite element method the variation of the stresses in the adhesive joint used for the assembly of two hybrid composite plates. These hybrid composite sheets consist of alternating 0.25 mm thick aluminum sheets and carbon or unidirectional glass prepregs, bonded with an epoxy adhesive. These hybrid composites have shown their efficiency compared to the metal plate and composites by their resistance to fatigue and impact. The results of our numerical analysis show the variation of the various stresses in the adhesive joint for an assembly of hybrid composite plates type aluminum-carbon and aluminum-glass. The location of the reinforcing layers in the composite relative to the base layers was varied in order to see the optimum position for which the stresses in the glue joint are lowest under the bending test.

A novel hybrid composite phononic crystal plate with multiple vibration band gaps at low frequencies

The low-frequency vibration isolation of a new hybrid phononic crystal plate are numerically and experimentally demonstrated in this paper. The proposed structure is composed of two types of periodic double-sided composite resonators deposited on a two-component plate. The dispersion relations, transmission spectra, and displacement fields of the eigenmodes are calculated by the finite element method. Compared to the classical phononic plate, the proposed structure can generate multiple flexural and longitudinal band gaps (BGs) at low frequencies. The formation mechanisms of the BGs can be explained by the corresponding “analogous-rigid modes”. The results of the parametric analyses show that the BGs can be significantly modulated by adjusting the material and geometric parameters. Furthermore, shake tests on a fabricated specimen were performed to verify the attenuation performance for elastic waves of specific frequency ranges. This research indicates that the proposed structure is a promising option for broadband low-frequency vibration insulation.

Dynamic Response of Functionally Graded Carbon Nanotube-Reinforced Hybrid Composite Plates

Dynamic instability behavior of functionally graded carbon nanotube reinforced hybrid composite plates subjected to periodic loadings is studied. The governing equations of motion of Mathieu-type are established by using the Galerkin method with reduced eigenfunctions transforms. With the Mathieu equations, the dynamic instability regions of hybrid nanocomposite plates are determined by using the Bolotin’s method. Results reveal that the dynamic instability is significantly affected by the carbon nanotube volume fraction, layer thickness ratio, bending stress, static and dynamic load parameters. The effects of important parameters on the instability region and dynamic instability index of hybrid nanocomposite plates are discussed.

Modeling and simulation of the static and vibratory behavior of hybrid composite plate off-axis anisotropic

This study presents the static and vibratory behavior of a hybrid sandwich plate with a magnetorheological elastomer core. In order to improve the static and vibrational behavior of the plate, the pseudo-fibers formed by the effect of the magnetic field on the elastomer charged by the ferromagnetic particles are oriented at 45° with respect to the direction of the magnetic field at 0°. Ritz's approach is taken to solve the physical problem. In order to verify and compare the results obtained by the Ritz approach, an analysis using the finite element method was carried out. The effect of the magnetic field on bending displacements, normal stresses, shear stresses, and static strain modes of the off-axis anisotropic hybrid sandwich plate are discussed. The rheological property of the MRE material at 0° and at 45° are determined experimentally, and are exploited in the two numerical approaches. The natural frequencies and the modal damping of the sandwich plate are calculated and discussed for various magnetic field intensities. The results obtained by the two methods are compared. These off-axis anisotropic MRE structures could open up new opportunities in various fields of aeronautics, aerospace, mechanical engineering and civil engineering.

Numerical modeling of hygrothermal effect on the dynamic behavior of hybrid composite plates

Numerical modeling of hygrothermal effect on the dynamic behavior of hybrid composite plates

Experimental study on magnesium wire–polylactic acid biodegradable composite implants under in vitro material degradation and fatigue loading conditions

This study investigated the fatigue life of biodegradable magnesium wire–polylactic acid (Mg/PLA) composite implants during the initial patient rehabilitation period under physiological loads through experimental and finite element methods. Under a simulated body fluid condition, the fatigue life was observed to be completely affected by material degradation, which accelerated the pitting corrosion of the composite bone plate. The mechanical behaviour of Mg/PLA composite bone plate was investigated under physiological loading conditions for the case of a tibial fracture with a 3 mm gap. A three-point bending fatigue test setup was employed to validate the fatigue characteristics of composite specimens. Finally, to alleviate the generated stress and enhance the fatigue resistance of fully biodegradable composites, a hybrid composite bone plate is proposed. At the screw section, the hybrid composite is partly composed of a comparatively more fatigue-safe non-degradable glass–polypropylene composite, which improves the healing performance of the fractured tibia.

Design and Evaluation of Hybrid Composite Plates for Ballistic Protection: Experimental and Numerical Investigations.

In this paper, hybrid composite plates for ballistic protection were investigated experimentally and numerically, with a target to reduce the weight of currently used body armor inserts and, at the same time, satisfy the requirements of the National Institute of Justice’s (NIJ) ballistic protection standards. The current study has three phases to improve the ballistic plate’s energy absorption capability. The first phase is devoted to studying the effect of the material types, including three different fibers: carbon fiber, date palm fiber, and Kevlar fiber. The second phase is dedicated to studying the effect of hybridization within layers. The two previous phases’ results were analyzed to optimize the material based on the hybrid composite ballistic plate’s maximum energy absorption capability. The commercial finite element software package LS-DYNA was employed for numerical modeling and simulation. The hybrid composite ballistic plate could absorb more impact energy than the non-hybrid Kevlar plate with the same area density from the numerical simulation results. This study provides lighter-weight ballistic inserts with a high protection level, making movement easier for the wearer. The numerical results were verified by comparing results of a plate made of 40 layers of Kevlar with an actual ballistic test. The results indicated that the simulation results were conservative compared to the ballistic test.

A numerical investigation on low velocity impact response of polymer-based nanocomposite plates containing multiscale reinforcements

The hybridization of carbon fibers (CFs) with carbon nanotubes (CNTs) is a new way of improving the mechanical and physical performances of composite materials. The aim of this work is to evaluate the low velocity impact response of polymer-based hybrid composite plates reinforced by the chopped CFs and CNTs using finite element method (FEM). A nested micromechanical FEM considering interphase region created by the non-bonded van der Waals interactions between the CNTs and polymer is developed for predicting the mechanical properties of hybrid composites. The predictions of the proposed numerical model are compared with the results of experiment and other numerical methods. It is demonstrated that adding a small amount of CNTs into the chopped CF-reinforced polymer composites can increase the contact force and decrease the center deflection of hybrid composite plates. The influences of volume fractions of CF and CNT, thickness and elastic modulus of interphase region, diameter and initial velocity of projectile, dimensions and boundary conditions of plate on the dynamic response of hybrid composite structures are discussed.

Numerical modeling of hygrothermal effect on the dynamic behavior of hybrid composite plates

In this work, the hygrothermal effect on the behavior of hybrid laminated composite plate has been investigated using high-order shear deformation theory and finite element analysis. The equation of motion of the laminated plate is obtained using Hamilton's principle, and the mathematical expressions are obtained using Navier's solution for different boundary conditions. The engineering moduli for the different cases: non-hybrid composite and hybrid composite are calculated using the law of mixtures. The mechanical properties of hybrid composite plate are considered as temperature and humidity dependent. The results obtained with finite element analysis using Abaqus and analytical approach show a good agreement in predicting the fundamental frequencies of hybrid cross-ply laminated plates under hygrothermal loading.

Multi-objective optimal design of hybrid composite laminates under eccentric loading

Laminated composites are being used in many engineering applications since they provide significant weight reduction, better fatigue and corrosion resistance. In this study, design optimization of a hybrid composite laminate subjected to eccentric loading was carried out using multi-objective genetic algorithm (MOGA). The ply material (carbon fiber or E glass) and fiber orientations (−90 ≤ θ ≤ 90) were considered as design variables. The objective function was to minimize cost and weight with the maximization of the stiffness. The design constraints were the maximum Tsai-Wu failure index, first mode natural frequency. The numerical analyses were carried out by using ANSYS software package. Genetic aggregation model was used to generate the response surfaces which were used to obtain the optimum design variables. The optimum lay-up sequence and ply materials were determined for weight saving and cost reduction of hybrid composite plates. It was shown that the hybridization of carbon fiber and E glass fiber provided the optimal designs offers lower cost and higher mechanical performance. MOGA method was very effective to optimize the structural performance of the hybrid composite plates under eccentric loading.

Effect of temperature and moisture on free vibration characteristics of skew laminated hybrid composite and sandwich plates

This paper is concerned with the effect of variation in temperature and moisture concentration on free vibration response of skew laminated hybrid composite and sandwich plates. The coupled thermo-elastic and hygro-elastic finite element model is formulated using the first-order shear deformation theory (FSDT). Uniform temperature and moisture concentration rise is considered for the analysis. Soft-core viscoelastic materials are considered for the sandwich plates and are modeled using the complex modulus approach. Linear strain-displacement relations are used to develop a mechanical stiffness matrix, and the initial stress stiffness matrix is generated using non-linear strain-displacement relations to represent the non-mechanical stiffness matrix. Numerical examples for the generated finite element model are presented and discussed comprehensively to understand the effect of temperature, moisture concentration, skew angle, length to width ratio, length to thickness ratio, and boundary conditions on the vibration response of the laminated hybrid composite and sandwich plates. Further investigation is devoted to studying the influence of temperature and moisture concentration-dependent material properties, stacking sequence, core to face sheet thickness ratio, and fiber orientation on vibration behavioral response of sandwich and hybrid composite plates.

Vibration Analysis of Carbon Fiber-Graphene-Reinforced Hybrid Polymer Composites Using Finite Element Techniques.

In this study, a computational procedure for the investigation of the vibration behavior of laminated composite structures, including graphene inclusions in the matrix, is developed. Concerning the size-dependent behavior of graphene, its mechanical properties are derived using nanoscopic empiric equations. Using the appropriate Halpin-Tsai models, the equivalent elastic constants of the graphene reinforced matrix are obtained. Then, the orthotropic mechanical properties of a composite lamina of carbon fibers and hybrid matrix can be evaluated. Considering a specific stacking sequence and various geometric configurations, carbon fiber-graphene-reinforced hybrid composite plates are modeled using conventional finite element techniques. Applying simply support or clamped boundary conditions, the vibrational behavior of the composite structures are finally extracted. Specifically, the modes of vibration for every configuration are derived, as well as the effect of graphene inclusions in the natural frequencies, is calculated. The higher the volume fraction of graphene in the matrix, the higher the natural frequency for every mode. Comparisons with other methods, where it is possible, are performed for the validation of the proposed method.

Parametric instability of functionally graded carbon nanotube-reinforced hybrid composite plates in thermal environments

This paper studies the parametric instability of hybrid nanocomposite plates under an arbitrary periodic load in thermal environments. The hybrid nanocomposite plate is a three-layer board. It has metal layers on both surfaces and one core reinforced with functionally graded (FG) carbon nanotubes (CNTs). The Galerkin method with a reduced eigenfunction transformation is applied to establish the governing equations of motion. According to the Bolotin method, a set of Mathieu-type differential equations is formed to determine dynamic instability regions and dynamic instability index (DII). The in-plane periodic stress is taken to be a combination of pulsating axial and bending stresses in the example problems. The effects of the layer thickness ratio, CNTs volume fraction, CNTs distribution type, temperature, bending stress, static and dynamic load on the dynamic instability of hybrid nanocomposite plates are investigated and discussed.

Effect of graphene nanoplatelets on the impact response of a carbon fibre reinforced composite

In the present paper, experimental investigations were conducted to assess the effect of nanomodification on the impact behaviours of hybrid composite plates. Graphene nanoplatelets (GNPs) of two different sizes, 5 and 30 μm, were used to modify a composite material made with 64 wt.% of unidirectional fibres and a low-viscosity epoxy resin. The effect of the nanomodification with 30 μm GNPs was also studied on composite plates prepared with a higher viscosity resin. Three laminate thicknesses (4, 8, and 16 layers) were tested with a standard drop dart testing technique. The peak forces as well as the absorbed energy and the fracture surfaces, observed with a Scanning Electron Microscope (SEM), were compared. Experimental results showed that nano-modification with 5 μm particles had a detrimental effect on both the peak forces and the absorbed energy, whereas the addition of 30 μm GNPs increased the absorbed energy, especially for a laminate thickness of 16 layers. Overall, the experimental results demonstrated that the size of graphene nanoparticles has a significant effect on the impact response of composite laminates.

Mechanical, low-velocity impact, and hydrothermal aging properties of flax/carbon hybrid composite plates

A hybrid of flax and carbon fibers was considered as an effective way to enhance the mechanical and hydrothermal resistance of flax-reinforced polymer composites. In this study, hybrid composites based on three layers of cross-ply flax fabrics, two layers of unidirectional carbon fabrics, and an epoxy resin were investigated in terms of the tensile, three-point bending, impact, and water absorption properties. The flax fabric reinforcement of the hybrid composites contributed to an improvement in the toughness, whereas the carbon fabric contributed to an improvement in their hydrothermal resistance and overall strength and stiffness. The hybrid composites with carbon fibers on the surface (CFFFC) exhibited brittle failure in the tensile test, whereas those with alternating layers (FCFCF) exhibited greater plastic deformation. In addition, the failure strain of the CFFFC samples showed a negative hybrid effect, whereas that of the FCFCF samples improved 63.5% compared with that of carbon-fiber-reinforced polymer composites. A positive hybrid effect on the impact performance of hybrid reinforced epoxy composites containing the unidirectional carbon fabric and cross-ply flax fabric was observed. At 40 °C and 80% relative humidity, the diffusion rate of water molecules in the FCFCF samples was 16 times that in the CFFFC samples.

Bending, free vibration, and buckling responses of chopped carbon fiber/graphene nanoplatelet-reinforced polymer hybrid composite plates: An inclusive microstructural assessment

This paper presents a finite element analysis of the bending, buckling, and free vibration of the chopped carbon fiber/graphene nanoplatelet reinforced polymer hybrid composite plates. Both rectangular and circular composite plates are considered. The effective material properties of the chopped carbon fiber /graphene nanoplatelet reinforced hybrid composites are predicted using a multistep micromechanical model based on the Halpin–Tsai homogenization scheme. An inclusive microstructural assessment is accomplished by the evaluation of the influences of the volume fraction, length, thickness, and agglomeration of graphene nanoplatelets as well as the volume fraction, aspect ratio, and the alignment of the chopped carbon fibers on the mechanical behaviors of the chopped carbon fiber/graphene nanoplatelet hybrid composite plates. It is found that the bending, buckling, and vibration characteristics of hybrid composite structures are highly affected by the microstructural features. The addition of graphene nanoplatelets improves the stability of the chopped fiber-reinforced hybrid composite structures. The agglomeration of the graphene nanoplatelet into the polymer matrix leads to a degradation in the composite plate mechanical performances. Aligning the chopped carbon fibers significantly decreases the deflections, and increases the critical buckling loads and the natural frequencies of hybrid composite plates. Comparisons are conducted with the numerical results reported in literature that indicate good agreement with our results.

Postbuckling response of functionally graded hybrid plates with cutouts under in-plane shear load

The present study deals with the investigation of buckling and postbuckling responses of functionally graded hybrid square plates which are symmetric about its mid plane. The cutouts of various sizes and shapes located at the center of the plate are considered. The plate is subjected to positive and negative in-plane shear loads. The boundary conditions used are simply supported on all the four edges of the plate. Three stacking sequences are considered to investigate the optimum stacking sequence at which the critical buckling and first failure loads are highest. Functionally graded hybrid plates (FH) subjected to negative in-plane shear load is more effective compared to plates subjected to positive in-plane shear load. Diamond shaped cutout with small sized perforation has the highest critical buckling and first ply failure loads amongst the FH plates with cutouts. It is observed that the direction of applied in-plane shear load, fiber stacking sequence; cutout shape and size substantially influence the strength and failure characteristics of functionally graded hybrid composite plates.