Hybrid Composite Plates Research Articles

Shear strengthening of damaged reinforced concrete beams with Hybrid Composite Plates

This paper aims to evaluate experimentally the potentialities of Hybrid Composite Plates (HCPs) technique for the shear strengthening and repairing of reinforced concrete (RC) beams. HCP is a thin plate of Strain Hardening Cementitious Composite (SHCC) reinforced with Carbon Fiber Reinforced Polymer (CFRP) laminates. For this purpose, an experimental program composed of four Rectangular and five T-cross section beams was executed to assess the strengthening efficiency of HCPs technique. There were two control beams without any type of shear reinforcement, and seven beams strengthened with HCPs. The HCPs were applied to the lateral faces of the beams by using a combination of epoxy adhesive and mechanical anchors. The bolts were applied with a certain torque in order to increase the concrete confinement. To have a better understanding of the shear behavior of SHCC material, Iosipescu shear tests were carried out, and the results were used to derive their fracture mode II parameters.To further explore the potentialities of the HCPs technique for the shear strengthening, the experimental tests were simulated numerically by a FEM-based computer program considering the material properties obtained experimentally. After demonstration of the good predictive performance of the numerical model, a parametric study was executed to investigate the influence of some parameters on the load carrying capacity of the strengthened beams, namely: i) Use a mortar instead of the SHCC; ii) application of different applied torque level to the mechanical anchors; iii) different bond condition between HCPs and concrete substrate.

Detection of damages in hybrid composite plates with the use of elastic waves generated by PZT active sensors

Detection of damages in hybrid composite plates with the use of elastic waves generated by PZT active sensors

Numerical modeling of defective hybrid composite plates

Numerical modeling of defective hybrid composite plates

The effect of carbon nanotube dispersion on the dynamic characteristics of unidirectional hybrid composites: An experimental approach

Abstract An experimental study on the natural frequencies and damping properties of hybrid composite beams and plates are presented in this paper. Hybrid composites consist of a matrix material along with both nano-fillers and micro fibers. In this research, carbon nanotube (CNT) is used as nano-filler. Epoxy, CNT/epoxy, glass/epoxy, CNT/glass/epoxy, carbon/epoxy and CNT/carbon/epoxy beam-shaped specimens are fabricated. Free vibration analysis of cantilever beams is examined in order to characterize the dynamic behavior of the specimens. 9.4% increase in the fundamental frequency and 12.3% decrease in the damping ratio of the CNT/glass/epoxy beam are observed with respect to those of the glass/epoxy beam specimen. Further, it is observed that CNT/carbon/epoxy beam has degraded fundamental frequency (13.9%) and enhanced damping ratio (31.5%) in comparison with those of carbon/epoxy beam specimen. Moreover, the first bending natural frequencies of the glass/epoxy, CNT/glass/epoxy, carbon/epoxy and CNT/carbon/epoxy plates are obtained experimentally. Plates with all free edges (FFFF) and plates with one edge clamped (CFFF) are investigated. Finite element models confirm the results obtained. Furthermore, the effects of the interfacial adhesion between the CNT/epoxy matrix and micro fibers on the damping properties of the laminated composites are discussed using the obtained results and the scanning electron microscopy (SEM) images.

Experimental investigation of broadband energy harvesting of a bi-stable composite piezoelectric plate

In this work, a bi-stable vibration energy harvester is presented to scavenge energy from ambient vibrations over a wide frequency range. This bi-stable harvester consists of a bi-stable hybrid composite plate as host structure and several pieces of piezoelectric ceramics. Three linear harvesters with the same geometry were employed as the control samples to illustrate the advantages of this bi-stable harvester. The voltage–frequency responses were measured with different g-level excitations, and the output powers across various resistances were measured at different frequencies and accelerations. Unlike the linear harvesters which are effective only near their natural frequencies, the obvious nonlinearities of this bi-stable harvester broaden its working bandwidth. Additionally, the characteristics of this bi-stable host structure contribute to the output power. Under the same condition, when this bi-stable harvester is under cross-well oscillation pattern the maximum output powers are several times higher than those of the linear harvesters. The measured highest output power of this bi-stable harvester is 36.2 mW with 38 Hz frequency and 5g acceleration (g = 9.8 m s−2).

Thermal buckling analysis and stacking sequence optimization of rectangular and skew shape memory alloy hybrid composite plates

Abstract This paper deals with analysis and optimization of rectangular and skew composite plates with embedded Shape Memory Alloy (SMA) wires with respect to thermal buckling. The governing equations are derived based on First Order Shear Deformation Theory (FSDT) and the critical buckling temperatures are calculated using Generalized Differential Quadrature (GDQ) method. The influences of SMA volume fraction, lay-up orientation, pre-strain of SMA fibers, dependency of material properties on temperature, and geometrical parameters like skew angle on thermal buckling of the structure are examined. Results demonstrate that SMAs can play a significant role in delaying buckling when the structure is under thermal loads. Then, in the second part of results, optimization of shape memory alloy hybrid composite (SMAHC) plates is presented in order to maximize critical buckling temperatures. A four-layer composite plates with two SMA-reinforced layers is considered for the optimization problem in which the orientations of fibers are the optimization variables. As the critical buckling temperatures cannot be obtained through a closed-form solution, the optimization process takes a lot of time. Therefore, a powerful meta-heuristic algorithm called Firefly Algorithm (FA) is implemented to find the best answers. A comprehensive verification study is also performed to indicate the accuracy and efficiency of both GDQ solution and optimization process.

Parametric Studies and Numerical Analysis of Low Velocity Impact on Smart Hybrid Composite Laminates

To evaluate the effect of low velocity impact on composite plate using nonlinear explicit finite element software LS-DYNA software. The theoretical basis of the present finite element model is verified by analyzing impact-loaded laminated composite plate previously been studied through analytical. The study of hybrid composite plates are carried were the SMA (shape memory alloy) are used in between the plies to increase the resistance. Also parametric studies were done to find the importance of the Mesh. The present numerical approach is successfully demonstrated through comparisons between experimentally-measured and computed force-time histories for impact of carbon fiber-reinforce plastic (CFRP) plates. Parametric studies are also conducted by varying Mesh results obtained are correlated with the results in the published literature.

Hygrothermal Effects on Dynamic Instability of Hybrid Composite Plates

The dynamic characteristics of hybrid composite plates under an arbitrary periodic load in hygrothermal environments are investigated. The material properties of the plate are assumed to be dependent on the temperature and moisture. The governing equations of motion of the Mathieu-type are established based on the Galerkin method with reduced eigenfunction transforms. The periodic stress is taken to be a combination of the pulsating axial and bending stress in the example problems. Based on Bolotin’s method, the dynamic instability behaviors of hybrid composite plates are determined. The effects of layer thickness ratio, fiber volume fraction, temperature rise, moisture concentration and dynamic load on the instability regions of hybrid composite plates are studied, along with the dynamic instability index discussed. The results reveal that the layer thickness ratio and hygrothermal conditions have a significant impact on the dynamic instability of hybrid composite plates.

Investigation of the mechanical properties and failure modes of hybrid natural fiber composites for potential bone fracture fixation plates

The purpose of this study is to investigate the mechanical feasibility of a hybrid Glass/Flax/Epoxy composite material for bone fracture fixation such as fracture plates. These hybrid composite plates have a sandwich structure in which the outer layers are made of Glass/Epoxy and the core from Flax/Epoxy. This configuration resulted in a unique structure compared to prior composites proposed for similar clinical applications. In order to evaluate the mechanical properties of this hybrid composite, uniaxial tension, compression, three-point bending and Rockwell Hardness tests were conducted. In addition, water absorption tests were performed to investigate the rate of water absorption for the specimens. This study confirms that the proposed hybrid composite plates are significantly more flexible axially compared to conventional metallic plates. Furthermore, they have considerably higher ultimate strength in tension, compression and flexion. Such high strength will ensure good stability of bone-implant construct at the fracture site, immobilize adjacent bone fragments and carry clinical-type forces experienced during daily normal activities. Moreover, this sandwich structure with stronger and stiffer face sheets and more flexible core can result in a higher stiffness and strength in bending compared to tension and compression. These qualities make the proposed hybrid composite an ideal candidate for the design of an optimized fracture fixation system with much closer mechanical properties to human cortical bone.

Shear strengthening of reinforced concrete beams with Hybrid Composite Plates (HCP) technique: Experimental research and analytical model

This paper presents a study on the efficiency of Hybrid Composite Plates (HCPs) in enhancing the shear strength and stiffness of reinforced concrete (RC) beams. HCP is a thin plate of Strain Hardening Cementitious Composite (SHCC) reinforced with Carbon Fiber Reinforced Polymer (CFRP) laminates applied to the sides of reinforced concrete beams according to the Near Surface Mounted technique (NSM). Due to the excellent bond conditions between SHCC and CFRP laminates, these reinforcements provide the necessary tensile strength capacity to the HCP. To examine the efficiency of HCPs as a shear strengthening technique, a total of 17 RC beams are tested. Seven of these beams have a rectangular cross-section and ten have a T cross-section. The influence of the percentage and inclination of the CFRP laminates on the shear strengthening effectiveness of HCPs is investigated. Two different processes for applying the HCPs to the beams’ concrete substrate are examined: (1) using epoxy adhesive; and (2) using mechanical anchors in addition to the epoxy adhesive. It is demonstrated that when only epoxy adhesive is used, the shear strengthening contribution of the HCPs is limited by the tensile strength of the concrete substrate of the strengthened beams. When mechanical anchors are applied in addition to the epoxy adhesive, the shear strengthening potential of HCPs is fully mobilized. An analytical model is proposed to predict the shear strength of RC beams strengthened with HCPs. It is demonstrated that the analytical model predicts with good accuracy the shear strength of RC beams strengthened with HCPs.

Thermomechanical buckling of hybrid cross-ply laminated rectangular plates

A thermomechanical buckling analysis is presented for simply supported rectangular symmetric cross-ply laminated composite plates that are integrated with surface-mounted piezoelectric actuators and are subjected to the combined action of in-plane compressive edge loads, two types of thermal loads, and constant applied actuator voltage. The formulation of equations is based on the classical laminated plate theory and the von-Karman non-linear kinematic relations. The analysis uses an exact method to obtain closed-form solutions for the buckling load. The effects of applied actuator voltage, thermal and mechanical loads, plate geometry, and lay-up configuration of the laminated plates are investigated. The novelty of the present work is to obtain closed-form solutions for electro-thermomechanical buckling of hybrid composite plates, and to cover non-uniform temperature distribution loading. The results for various states are verified with known data in the literature.

Refined constitutive, bridging, and contact laws for including effects of the impact-induced temperature rise in impact responses of composite plates with embedded SMA wires

In the present research, effects of the impact-induced temperature rise on the phase transformation of shape memory alloy (SMA) wires embedded in composite plates and consequently, impact responses of the hybrid plates are investigated, for the first time. In the available approaches, effects of the temperature rise have been studied only for single SMA wires under uniaxial tensile loads whereas the stress and martensite volume fraction vary along the SMA wires embedded in a hybrid composite plate under transverse impact. The impact-induced heat of the SMA wires is determined based on proposing a refined free energy function that includes the latent heat of the phase transformation. Furthermore, Brinson's constitutive law of the superelastic SMAs and Hertz contact law are revised based on the refined phase version of the free energy function and a proper bridging law wherein, distributions of the SMA phases are considered to be both localized and time-dependent. Results of the employed bridging law are more accurate than those of the common homogenization techniques wherein, stresses of the wires cannot be easily distinguished from those of the mixture. The resulting governing equations are solved by the finite element method and the refined nonlinear constitutive laws are solved through a return-mapping Newton-Raphson procedure, within each time step. Results reveal that incorporation of the realistic heat generation phenomenon leads to remarkably higher local stresses; a fact that has to be considered in the design stage.

Microstructures and mechanical properties of 2024Al/Gr/SiC hybrid composites fabricated by vacuum hot pressing

The 2024Al/Gr/SiC hybrid composite plates with 5%–10% SiC particles (volume fraction) and 3%–6% flaky graphite (Gr) (volume fraction) were fabricated by vacuum hot pressing and hot extrusion processing. The effects of SiC and Gr on the microstructures and mechanical properties of the composites aged at 160, 175 and 190 °C were studied by optical microscopy, scanning electron microscopy (SEM), and hardness and tensile tests. The results indicate that the SiC particles have a more obvious effect on accelerating the aging response as compared with the Gr. Both the tensile strength and elongation are reduced by the Gr and SiC particles added into the matrix, while the Gr has a more negative influence on the elongation than the SiC particles. The tensile strength (σb), yield stress (σs) and elongation (δ) of the 2024Al/3Gr/10SiC composite aged at 165 °C for 8 h are 387 MPa, 280.3 MPa and 5.7%, respectively. The hybrid composites are characterized by ductile fracture, which is associated with the ductile fracture of the matrix and the tearing of the interface between the matrix and the particles.

Impact behavior of hybrid composite plates dependent on curing and different stacking sequences

Abstract In this study, the drop weight impact response of cured hybrid composite plates has been investigated. Experiments were conducted on two groups of hybrid composite plates. The first group was based on upper and lower surfaces that are made of carbon (c) with the inner plates of glass (g), while for the second group the upper and lower surfaces were examined which are made of glass (g) with the inner plates of carbon (c). The orientation angle of the plates was 0, 15, 30 and 45° and the collision energy was 12 J. Contact forces were obtained and compared for the plates with respect to the different sequence and orientation angles. Peak forces increased for all the sequences and orientation angles. However, the (g-c-c-g) stacking sequence showed a larger sensitivity to an orientation angle change. The deflections decreased for the (c-g-g-c) stacking sequence when the orientation angle increased.

Parametric Studies of Shape Memory Alloy Hybrid Composite Laminates Under Low-Velocity Impact

AbstractIn the paper, the influence of shape memory alloy (SMA) by varying the parameters such as volume fraction, orientation, and temperature on the hybrid-SMA composite laminate subjected to low-velocity impact is studied. A theoretical model for the composite laminated plate bonded with SMA reinforced layers is presented. The constitutive relation of the SMA layer is obtained by using the method of micromechanics. The governing relations obtained can be used for theoretical predications of thermomechanical properties of SMA plies in this paper. The analytical expressions for the hybrid SMA composite plate are derived based on Tanaka's constitutive equation and linear phase transformation kinetics presented by Liang and Rogers.The laminated plate theory, first-order shear deformation theory and minimal potential energy principle is utilized to solve the governing equations of the hybrid composite plate and calculate the absorbed energies including tensile, shear and bending.An orthogonal array and analysis of variance is employed to investigate the influence of the mentioned parameters on the energy absorption of the hybrid laminated plate. The results showed that the effects of the phase transformation temperature are more significant than the effects of the volume fraction and orientation of SMA on structural energy absorption.

Shear Strengthening of Reinforced Concrete T-Beams with Hybrid Composite Plate

AbstractThis paper aims to evaluate the effectiveness of hybrid composite plates (HCPs) technique for the shear strengthening of the reinforced concrete (RC) T cross-section beams. HCP consists of a thin plate of strain hardening cementitious composite (SHCC) reinforced with carbon fiber reinforced polymer (CFRP) laminates. Two HCPs with different CFRP laminates percentage (ρfw=0.08% and ρfw=0.14%) were adopted for the shear strengthening of the beams. The HCPs were bonded to substrate in two different ways. In the first case, the HCPs were bonded using epoxy adhesive, whereas in the second case they were bonded using epoxy adhesive and fixed by mechanical anchors. The effectiveness of this technique was limited by the tensile strength of the concrete cover of the strengthened beams. Therefore, in the second case, mechanical anchors prevented a premature debonding of the HCPs and a certain concrete confinement was applied in the zone of the beam to be strengthened, resulting in favorable effects in terms ...

Fracture toughness of woven glass and carbon reinforced hybrid and non‐hybrid composite plates

The fracture toughness and strength of materials are adversely affected by the cracks in the materials, which can be induced during manufacturing, assembly, and usage. In this study, the effect of crack length and crack location on the fracture toughness of woven glass and carbon reinforced hybrid and non‐hybrid composite plates were investigated experimentally and numerically. For this purpose, glass/epoxy (G8), and carbon/epoxy (C8) non‐hybrid composite plates and glass‐carbon/epoxy (G2C4G2), and carbon‐glass/epoxy (C2G4C2) hybrid composite plates were produced by using hand lay‐up method. The fracture toughness of hybrid and non‐hybrid composite plates having three different crack locations as single edge crack (SEC), center crack (CC), and double edge crack (DEC) with different crack lengths were obtained by determining failure loads under tensile loading. The ANSYS finite element package program was used in order to determine the fracture toughness of hybrid and non‐hybrid composites by means of J‐Integral methods. The results showed that the highest and the lowest fracture toughness values were obtained in the specimens with SEC and CC, respectively. POLYM. COMPOS., 39:783–793, 2018. © 2016 Society of Plastics Engineers

Hybrid Kenaf Fibre Composite Plates for Potential Application in Shear Strengthening of Reinforced Concrete Structure

This paper presents the finding of an experimental study on kenaf fibre hybrid composite plates for potential application in shear strengthening of RC beam. In the experimental programme, hybrid composite plates had been fabricated using kenaf and carbon fibres with five different mixes i.e., 47% kenaf with 0% carbon; 45% kenaf with 2.5% carbon; 47% kenaf with 5% carbon; 45% kenaf with 7.5% carbon and 45% kenaf with 10% carbon. The physical and mechanical properties of the fabricated hybrid composite plates were then experimentally investigated. Results showed that carbon contents had an influence to enhance the tensile strength of the plates. Hybrid composite plate with 10% carbon content had shown 130% higher tensile strength as compared to that of plate without carbon fibre. The carbon content also had enhanced the modulus of elasticity of plates. Higher percentage of carbon had shown higher tensile strength and modulus of elasticity of hybrid composite plates. All fabricated plates had linear elastic properties under tension. The density of plates increased with the increasing of carbon content in composite plates. The research findings indicated that the developed hybrid composite kenaf could be used for shear strengthening of reinforced concrete beam.

Shear strengthening of reinforced concrete beams with hybrid composite plates

The effectiveness of hybrid composite plates for the shear strengthening of the reinforced concrete beams was assessed by executing an experimental program. Hybrid composite plate is a thin plate of strain hardening cementitious composite reinforced with carbon fiber–reinforced polymer laminates. Due to the excellent bond conditions between strain hardening cementitious composite and carbon fiber–reinforced polymer laminates, these reinforcements provide the necessary tensile strength capacity to the hybrid composite plate. Two hybrid composite plates with different inclination of carbon fiber–reinforced polymer laminates (45° and 90°) were adopted for the shear strengthening of reinforced concrete beams by bonding these hybrid composite plates to the lateral faces of the beams with an epoxy adhesive. The results showed that these hybrid composite plates have assured a significant increase in terms of load carrying capacity, mainly those with inclined laminates. The shear strengthening contribution of the hybrid composite plates was limited by the tensile strength of the concrete of the strengthened beams since their failure mode was governed by the detachment of the hybrid composite plates that included part of the concrete cover. Advanced finite element method-based numerical simulations were performed using a constitutive model, whose predictive performance was demonstrated by simulating the experimental tests carried out. Using this computer program, a parametric study was executed to evaluate the shear strengthening efficiency of the arrangement and percentage of carbon fiber–reinforced polymer laminates in hybrid composite plates, as well as the influence of using mechanical anchors to avoid premature detachment of the hybrid composite plates.

Fabrication and Testing of Hybrid Composite plates for Stealth Aircraft using Microwave Oscillator

The objective of this project is to implement the absorption properties of carbon nanotubes and natural fiber together in the stealth technology. It is carried out by designing two Aluminium plates each one with different natural fiber and to test it using a microwave oscillator. The two types of natural fiber that are used are Coconut fiber (Coir) and Banana fiber. The fabrication part involves two types, one with resin and the other without resin. The tests were carried out by keeping the Aluminium plate with Coconut fiber with and without resin under microwave oscillator and were examined by passing the voltage at a specified frequency and the amount of power they absorb by power meter. The same tests were carried out for Aluminium plate with Banana fiber with and without resin. The results were compared with the powers that were absorbed by both the fibres with resin and also without resin. The plate with coir fiber bonded with resin has 100% absorbing capacity whereas the banana fiber has 83% and combination of both coir and banana fiber has 73% absorption capacity. Thus the absorption capacity of coir was greater than that of the banana fiber irrespective of the fiber combined with the plate (either with resin or by inserting).