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The advantages of carbon nanotubes (CNTs) in fortifying the glass fiber reinforced polymeric (GFRP) composites are discussed in this paper. Bolted steel straps are utilized at the edges of composite plate to establish clamped conditions in the test setup. To minimize uncertainties caused by bolt attachments, a genetic algorithm-based model updating approach has been implemented by introducing artificial linear springs at the margins to achieve a better balance between theory and reality. The accuracy of the plate's results (natural frequencies and mode shapes) is verified, and the mechanical properties of randomly dispersed CNTs are incorporated in the formulations of folded plates. Remarkably, the motion equations are brought forward by the first order shear deformation theory (FSDT). Thereafter, two-directional generalized differential quadrature (2D-GDQ) technique is employed to determine natural frequencies from available motion, continuity, and boundary equations. The results of the folded plate are validated first by an experimental modal testing and finally some effective parameters such as folding angle, CNT weight ratio, boundary condition and flange-shape length are examined. [ABSTRACT FROM AUTHOR]

The present study investigates the flexural failure properties of a hybrid laminate beam subjected to three-point bending. A symmetrically laminated hybrid beam is constructed using high-strain and inexpensive glass fibre on the top layers and low-strain and expensive carbon fiber on the middle layers. Classical lamination plate theory is used to find the stress and strain distribution that occurs due to the bending moment on the compressive side. The theoretical failure limits of the laminated hybrid beam are analyzed considering the targeted span-to-depth ratios, volume fractions of the fibers and hybrid ratios using the Tsai-Wu failure criterion and Matlab codes. Using the graph of failure index versus hybrid ratios, the minimum thickness of carbon fiber needed for the delay of failure and cost efficiency of the laminated hybrid beam is identified by applying the linear interpolation method. The numerical results indicate that the failure index increases with the increasing loading span and decreases when the volume fraction of fiber increases. In particular, the placement of glass fiber on the top layer of the laminated hybrid beam might have contributed to obtaining higher strains and curvatures before the catastrophic failure properties of carbon fiber. The flexural stiffness of the laminates is found to increase when the hybrid ratio increases. Overall, it is noted that the theoretical analysis is one method that is less time-consuming and cost-effective than other alternative approaches, such as finite element methods and experimental tests to estimate the minimum thickness of high-stiffness and the expensive material needed to maintain the strength and stiffness of the hybrid composite structures over long periods. [ABSTRACT FROM AUTHOR]

In this study, the axial compressive stresses of hollow circular composite tubes were investigated. For this purpose, hollow circular composite tubes with various inner diameters (Ø12 and Ø13 millimeters), a height of 80 millimeters, and an outer diameter kept constant at Ø17 millimeters were fabricated using a fiber winding process. In the production of hollow circular tubes, epoxy was used as resin, and glass fiber, carbon fiber, and Kevlar fiber were used as reinforcement materials. Experimental investigations were carried out for three different reinforcement materials, two thin-wall thicknesses, and five orientation angles. Axial compression tests were performed to research the influences of reinforcement materials, thin-wall thickness, and orientation angles on the compressive stresses. The axial compressive strength of the samples was observed experimentally by applying the load in the vertical direction. The reinforcement material, orientation angle, and thin-walled thickness had an important influence on the axial compressive stress. The glass/epoxy reinforcement material was found to have the highest axial compressive strength at 204 Mpa. When the orientation angle increased from 45° to 88°, the axial compressive stress increased by 2.27 times in glass/epoxy, 2.36 times in carbon/epoxy, and 2.37 times in Kevlar/epoxy specimens, respectively. In addition, by increasing the specimen wall thickness by 0.5 millimeters, the axial compressive stress at an 88° orientation angle increased by 9.67 % glass/epoxy, 11.85 % carbon/epoxy, and 7.14 % Kevlar/epoxy specimens. [ABSTRACT FROM AUTHOR]

Owing to the importance of fibre architectures in the design of textile composite materials, understanding their effect on the failure mechanisms of these composites have taken more considerations. In this regards, non-crimp preform and 2/2 twill fabric have been manufactured from glass fibre by using pin-board and power loom machines respectively, and subsequently composites laminates from both preforms are manufactured via vacuum assisted resin infusion method. In addition, quasi-static tensile and compressive strength tests have been conducted for the composite laminates that have same volume fraction. Damage failure mechanisms that occurred in compressive strength in both composites have been examined by using scanning electronic machine (SEM). Findings show that the mechanical properties are primly determined by fibre architectures and the presence of fibre crimp can further weaken tensile and compressive strength values. It was noticed that the tensile strength of non-crimp composite was 610 MPa whereas that of twill fabrics composite laminates it was found to be 350 MPa and 440 MPa in warp and weft directions respectively. Moreover, in case of twill fabric composites, fibre crimp has a considerable effect on the mode and characteristics of damage in the compressive loading; this leads to fibre fracture and kinks that primarily happened in the intersection point of warp and weft yarns. Results also showed improved ductility, strain to failure and absorbing energy in the twill fabric composites compared to non-crimp composites under in-plane shear strength test. [ABSTRACT FROM AUTHOR]

In defense and military applications, the growing use of radar technology necessitated the development of effective stealth solutions for military equipment like drones and fighter jets. This paper explored a new approach that glass fiber mat coated with various concentrations of grapheme embedded polyvinylidene fluoride (PVDF) nanofibers using electrospinning technique and stacked the Graphene/PVDF/Glass fiber mat layers by epoxy resin and hardener to form the glass fiber laminate composite by hand layup technique to enhance the electromagnetic wave absorption. These research findings demonstrated that composite materials were more successful than metals at absorbing electromagnetic waves. The tailored composite showed above 80% increase in electromagnetic absorption over conventional metal in the X-band (8–12 GHz), although having a minimum thickness of 3 mm. According to X-ray diffraction, PVDF/Graphene nanofibers had improved electroactive β-phase behavior when compared to pure PVDF nanofibers. The PVDF/graphene nanofibers which have an average diameter of 80–160 nm, were seen using scanning electron microscopy. The tailored composites also had simple configuration and mechanical characteristics that were improved when compared to plain glass fiber laminate composite. In comparison to all other configurations, experimental findings showed that the composite with 0.5 wt% Gp/PVDF had a wide band absorption of above 90% in all the frequencies. This innovative method of fabrication of the tailored Gp/PVDF nanofibers coated glass fiber laminate composite provided a promising strategy in the manufacture of military equipment and stealth fighters. [ABSTRACT FROM AUTHOR]

A systematic evaluation of the interlayer crack resistance in the modes I and II loadings of a glass fiber epoxy laminated composite by experimental and computational methods using the cohesive zone model was carried out. The local properties (the ultimate stress σC, the maximum displacement δmax, and the specific work of fracture γF) of the cohesive zone were determined experimentally by the methods of separation and shear of the layer contact zone; the critical intensities of elastic energy release (GIC and GIIC) were found by the method of linear elastic fracture mechanics. Based on the experimental data obtained, the critical length of the cohesive zone was calculated by the Barenblatt micromechanical theory. A numerical evaluation of the crack resistance of a laminated composite under conditions of static loading in the modes I and II was carried out using 3D finite-element models of a double-cantilever beam and end-notched flexure specimens with an implemented cohesive zone obeying the exponential law. The optimal number of interface elements in the finite-element mesh was determined for the cohesive zone calculated based on experimental data, which ensured a sufficient accuracy of numerical calculating the ultimate load of the onset of crack growth and the stress distribution along the length of the cohesive zone with a minimum number of calculations. The approach proposed and the results obtained showed a good agreement between the calculated and experimentally determined characteristics of standard specimens of glass fiber epoxy composite and can be used to calculate the interlayer strength and crack resistance of structural members with a complex geometry made of layered polymer composites. [ABSTRACT FROM AUTHOR]

An evaluation of the interlaminar fracture toughness of polyamide/glass fiber laminates with various layups is reported. Due to large differences in thermal expansion coefficients of fiber and binder the laminates with layups where single layers are swapped exhibit high warping. A technique for avoiding this is proposed, allowing evaluating interlaminar fracture toughness of various angle interfaces. Two different layups for evaluating the Mode I and II interlaminar fracture toughness are tested. The differences of delamination behavior of a number of different-angle fiber interfaces are shown and analyzed. The applicability of the proposed testing technique is discussed. [ABSTRACT FROM AUTHOR]

The fiber-metal composites made of aluminum sheets and glass fibers reinforced with a polyester resin as the matrix were studied. The composites were prepared by hand lay-up method. Some aspects of manufacturing affecting the composite behavior were considered. In particular, the influences of the arrangement of layers and their number on the mechanical and physical properties of composites with ten different compositions were investigated. In addition two different densities of glass fibers were considered. The tensile modulus, tensile and impact strengths were determined following ASTM D3039 and ASTM D6110 standards. The results obtained show that the arrangement of the laminate layers influences Young's modulus and the tensile strength of the composite. The impact test results of the laminated structure reinforced with glass fibers illustrate a significant increase in the impact strength owing to adding the glass fibers compared to the control specimens. The simulations of tests using ABAQUS-based FEA were performed. [ABSTRACT FROM AUTHOR]

Degradation of polymer composites is a significant problem in many engineering aspects. Due to the interaction of various degradation factors during the exploitation of composites, a synergistic effect of destruction is observed. The article describes the phenomena occurring in glass fiber reinforced polyester laminates under the influence of ultraviolet radiation (UV) in an aquatic environment. The laminates were exposed to UV-A, UV-B and UV-C radiation for 1000 h in free-air and underwater conditions. During the test, the materials were immersed at stable depth of 1 mm and 10 mm, respectively. The three-point bending tests performed on the samples after being exposed to UV showed an increase in the flexural strength of the composites. Simultaneously, degradation of the outer surface layer was observed. The degradation removed the thin resin film from the surface which resulted in a direct exposure of the reinforcing fibers to the environment. The transformations taking place in the deeper layers of the composite increased the mechanical strength due to the additional cross-linking reactions excited by the energy arising from the radiation. Moreover, the formation of polymer structures from free styrene remaining after the technological process and the occurrence of free radical reactions as a result of the cage effect was also observed. [ABSTRACT FROM AUTHOR]

GLARE laminates are multi-layered metal-composite materials created from bonding sheets of metallic alloys with carbon or glass fibre layers. The application of hybrid-conventional machining processes such as ultrasonic-assisted drilling (UAD) is becoming of great interest to the aerospace industry due to its capability in reducing the cutting forces and tool wear which are directly responsible for drilling-induced delamination. There is rich literature on the conventional drilling (CD) of GLARE, but no work reported using UAD process. This study will fill this gap and investigate the UAD of GLARE laminates using an indigenously developed UAD system. The influence of spindle speed and feed rate on thrust force and surface roughness metrics (Ra and Rz) were investigated under CD and UAD regimes. The quality of the borehole and damage mechanisms in the laminate constituents was examined using scanning electron microscopy (SEM). The contribution of the drilling parameters on the measured outputs was further evaluated using the analysis of variance (ANOVA) statistical analysis. It was found that UAD resulted in a significant reduction in thrust force by up to 65% while surface roughness metrics Ra and Rz were unaffected by the type of drilling process used. SEM analysis showed irregular and fuzzier surfaces in glass fibre layers in holes machined using UAD due to the longitudinal vibration of the tool. [ABSTRACT FROM AUTHOR]

The incorporation of inorganic nanoparticles with thermosetting epoxy polymer is an emerging field of research over the past few years. It is well analyzed that epoxy matrix is brittle in nature that shows rapid crack initiation and rapid propagation without increasing applied stress value. Therefore, researchers are showing their interest in nanoparticles embedded epoxy composites to improve their fracture resistance (brittleness and toughness). In this investigation, the dispersion of TiO2 nanoparticles at different weight fractions (0-2 %) with glass fiber reinforced epoxy composites is performed to enhance structural and thermo-mechanical properties. The TiO2 nanoparticles are prepared by sol-gel method and structural analysis of TiO2 nanoparticles shows greater interfacial bond with epoxy matrix and glass fibers due to fine dispersion of nanoparticles. From obtained results, a significant enhancement in their tensile strength (38.56 %), flexural strength (30.52 %), inter-laminar shear stress (25.22 %), impact strength (327.10 %), micro-hardness (48.53 %) and fracture energy (40.19 %) with a minimal detrimental effect on toughness was revealed for GFRP-T1.0 compare to GFRP-T0.0 composite laminates. The stiffness and rigidity also improved up to 52.72 % and 34.13 % respectively for GFRP-T1.5 compare to GFRP-T0.0 composite laminates. The effects of nanoparticles contents and clustering size on thermal stability and glass transition temperature of developed composites are observed by thermo-gravimetric analysis. The surface morphology of TiO2 nanoparticles is characterized by transmission electron microscope (TEM) while the dispersion of nanoparticles and failure of developed composites were analyzed by scanning electron microscopy (SEM). [ABSTRACT FROM AUTHOR]

Laminated composites with complex structures, such as L, C, or T-shaped geometries, are used at junction parts in the automotive and aerospace industries. Due to delamination failure in the curved or angled region, these structures are relatively weak in the through-thickness direction when subjected to complex loading. To overcome the issue of weak delamination resistance, this study is aimed at investigating the effect of various reinforcements on the strength properties and delamination resistance of glass/epoxy curved laminates under a four-point bending test. Experimental research was carried out on glass/epoxy curved laminates strengthened by combining three different types and geometries of reinforcement. These included chopped short fibers and glass fiber patches between each ply at the corner region of curvature, and stitching of aramid filament at the corner region of 90-degree bending. A 4 mm pitch interval was observed to enhance curved beam strength, interlaminar tensile strength and delamination resistance. The obtained findings show that glass/epoxy curved laminates reinforced with chopped kenaf short fiber, 45° glass fiber and a single stitch at the corner show greater enhancement in curved beam strength by 52.7, 34.3, and 5.6%, respectively, compared to the baseline sample. Similarly, interlaminar tensile strength improved by 69.3, 40, and 78.5% compared to the baseline sample. On the other hand, curved laminates needled with a single stitch at the corner show higher delamination resistance than other reinforcements. The experimental results correlate well with the damage morphology indicated in SEM fractographic images. [ABSTRACT FROM AUTHOR]

As material age, the durability, strength, and other mechanical properties are impacted. The lifespan of a material generally decreases when exposed to weathering conditions such as wind, temperature, humidity, and light. It is important to have knowledge of how materials age and how the material properties are affected. Regarding materials´ fire behaviour and the effect of ageing on these properties, the knowledge is limited. The research questions of the current work are: Are the fire properties of composite materials affected by ageing? And if so, how is it affected? The study is on material at Technology Readiness Level 9 (TRL). In this study, three composite fibre laminates developed for marine applications were exposed to accelerated ageing. Two different ageing conditions were selected, thermal ageing with an increased temperature of 90°C and moisture ageing in a moderately increased temperature of 40°C and a relative humidity of 90%. Samples were collected after one, two and four weeks of ageing. The reaction-to-fire properties after ageing was evaluated using the ISO 5660–1 cone calorimeter and the EN ISO 5659–2 smoke chamber with FTIR gas analysis. The test results showed that the fire behaviour was affected. Two of the composite laminates, both phenolic/basalt composites, showed a deteriorated fire behaviour from the thermal ageing and the third composite laminate, a PFA/glass fibre composite, showed an improved fire behaviour both for thermal and moisture ageing. The smoke toxicity was affected by the accelerated ageing, especially for the PFA/glass fibre composite that showed a higher production of CO and HCN, both for the thermal aged and the moisture aged samples. [ABSTRACT FROM AUTHOR]

In the present work, the response of composite hybrid laminates made of carbon and glass fibers in different stacking configurations was tested under low-velocity impact loads. Experimental drop impact tests were conducted on three different stacking sequences and three rising impact energy levels. The results from the tests were assumed for the development and validation of a numerical impact model reproducing for each stacking sequence and all the impact energy levels, the laminates impact response. The validated model investigated the occurred damage mechanisms, their distribution in the panel thickness and their extension on the plane of the laminate. Depending on the stacking sequence and the impact energy level, the energy absorption capacity was related to the dominant damage mechanism. The percentage contribution of interlaminar and intralaminar damages was presented and conclusions were drawn about the influence of stacking sequences on energy absorption and damage characteristics. [ABSTRACT FROM AUTHOR]

The reduction of weight elements is considered as a major objective of several manufacturing companies. This objective will help in growing application sections of the used fiber composites for important structural elements. Modern fiber metal laminate (FML) having lightweight properties is established to be used instead of other substances in different applications including those related to the aerospace industrial sector. Fiber metal laminate is being deemed as an alternative significant substance that is being extensively explored due to its operation, unlike other current materials. There are different profitable FML such as GLARE (glass-reinforced aluminum laminate), established on elevated intensity ARALL glass fibers (aramid-reinforced aluminum laminate), built on fibers of aramid, in addition to CARALL (carbon-reinforced aluminum laminate), centered on fibers of carbon. This paper analyzes important information that contributes to the mechanical characteristics of FMLs under tensile, flexure, impact, etc. conditions. [ABSTRACT FROM AUTHOR]

The development of autonomous finishing operations in manufacturing process has the potential to decrease the costs and increase the quality of the operations. In this context, robotic manipulators have been introduced in sanding and polishing applications. Inspired by the recent development in machine learning and robotics, this paper is focused on designing a system capable of estimating the surface roughness using only a force torque sensor integrated with a robotic manipulator that performs the sanding of fiberglass panels. We present an investigation into the usage of convolution neural networks on the force-torque data to produce a quantitative estimation of surface roughness. To validate the results obtained a profilometer is used to gather pre- and post-operation data. The establishment of a relationship between measured force data and post-operation surface roughness will be used to develop a prediction of the surface quality for sanding operation using robotic manipulators. This project intents to act as proof-of-concept that traditional robotic sensors, can be used beyond their original scope, minimize the complexity of robotic systems integrated into manufacturing processes. [ABSTRACT FROM AUTHOR]

Fiber-reinforced composites have a wide range of industrial applications owing to their light weight, high modulus, and good specific strength. Trimming using a mechanical punching tool is the fastest way to post process fiber-reinforced composites. However, quantitative analyses of the defects and process parameters are required to analyze the damage mechanisms and achieve high-quality cut surfaces. In this study, we quantitively investigated the defects on the sheared edge of woven glass epoxy laminates subjected to mechanical punching and explored the correlations between these defects and key process parameters, including punch-die clearance, weave alignment angle, and laminate thickness. The results demonstrate the necessity of considering glass fiber burr length and the dimensions of the cracked area simultaneously to evaluate the quality of the sheared surface. This study provides qualitative data on the interfacial damage mechanisms that occur during mechanical punching, which will help to tailor the process parameters of mechanical punching for fiber-reinforced polymers to obtain smooth cut surfaces. [ABSTRACT FROM AUTHOR]

Modeling and Methods: This work is devoted to the numerical dynamic bending characterization of delaminated multi-walled carbon nanotubes (MWCNTs) reinforced epoxy/glass fiber-based hybrid composite plate based on finite element method with displacement fields derived from classical laminated plate theory (CLPT). Verification: The accuracy and performance of the developed method were confirmed by a validation study with reference solutions available in the literature. Results: Various parametric studies were carried out to study the influence of MWCNTs content, delamination location, delamination interface, ply orientation, and end condition on the dynamic bending characteristics of the intact and delaminated hybrid laminated composite plate. Conclusion: The weight fraction of MWCNTs, delamination location, and clamping condition significantly influences the natural frequency. The natural frequencies also depended upon the ply configuration and delamination interface irrespective of the MWCNT loadings. However, anomalous trends were observed as far as the influence of end conditions is concerned. [ABSTRACT FROM AUTHOR]

In this paper, the influence of E-glass fiber volume fraction and laying angle on the damping and strength of composite laminates was comprehensively analyzed. By increasing the fiber laying angle and reducing the glass fiber volume fraction, the damping capacity of the composite laminate was increased, but the tensile strength of the laminate was reduced; By reducing the fiber laying angle and increasing the glass fiber volume fraction, the tensile strength of the composite laminate was increased, but the damping characteristics of the laminate was reduced. In addition, in the damping experiment of composite laminates, in order to avoid the influence of external damping sources, the vacuum non-contact damping test method was adopted in this paper, and the influence of air damping on the damping experiment results of composite laminates was comparatively analyzed. The results of comparative experiments showed that air damping had a very obvious influence on the damping of composite laminates, especially when the damping of composite laminates was small, the influence of air damping would be greater. [ABSTRACT FROM AUTHOR]

Recently, the design of low cost, lightweight, and flexible electromagnetic interference (EMI) shielding fabrics mitigation is a great issue, and are required for a variety of defense, wireless power transfer (WPT), and medical applications. Hybrid alternate layer of Carbon fiber CF/Glass fiber GF and an internal layer of (carbon/glass) weaving technique with addition titanium dioxide TiO2 and Cobalt Co Nano-particle laminate epoxy films that simultaneously exhibit a good electrical conductivity, and a high level of EMI shielding in the 'E, F, I, and J' band frequency. In this paper, we propose a coupling mechanism with an alternate-layer shielding structure by presenting a process for scalable composition of laminate epoxy hybrid composites with high content of CF/GF/Co–TiO2, and report on the EMI shielding effectiveness (SE) and electrical properties of hybrid laminate composites. An experimental stand was built to evaluate the total transmitted efficiency and SE of the proposed laminate composite. The experimental results show that the alternate layers of shielding laminate could effectively enhance the EMI SE and transmit power of the order under the working environment with poor coupling through improving the stability of the system. We expect that the design directions prophesy by our model provide the basis for future works in which higher levels of EMI shielding efficiency may be accomplished using alternative fabrication techniques. [ABSTRACT FROM AUTHOR]

The delamination produced during drilling CFRP will affect its structural strength seriously. Delamination is closely related to the thrust force during drilling, which is closely related to the tool, so it is particularly important to choose the tools with appropriate geometric structure. Many scholars used tools with different geometric structure to drill CFRP, and then conducted the drilling damage analyses and drilling mechanism researches. It finally came to a conclusion that a drill with a special structure had certain advantages compared with a common twist drill in the drilling process. A new type of plane rake–faced twist drill was used to drill the CFRP laminate with a thin-woven glass fiber surface layer. Experimental results showed that the plane rake–faced twist drill along cutting edge had a constant reference rake angle value, which caused the plane rake–faced twist drill generated smaller thrust force and less drilling damage than the common twist drill. As the reference rake angle of the plane rake–faced twist drill increased, the thrust force and drilling damage decreased. It was revealed the inhibition of the thin-woven glass fiber surface layer on the drilling damage at entrance and exit. Finally, it was proposed that when the plane rake–faced twist drill was used to drill CFRP laminate with a thin-woven glass fiber surface, 46° reference rake angle should be selected. [ABSTRACT FROM AUTHOR]

Al laminates are widely used in various applications due to their light weight, corrosion resistance, and good electrical conductivity. In this work, aluminum laminates were reinforced with glass fibers and a boron nitride (BN) epoxy resin. Different concentrations of BN (0, 0.3, 0.6, 0.9, and 1.2 wt.%) were incorporated into the epoxy matrix. The laminates were prepared using a vacuum infusion process (VIP) technique. The addition of BN significantly improved the thermal conductivity of the composites. To further improve the interfacial adhesion between the aluminum alloy sheets and the composite layers, plasma surface treatment was applied to the 6061-T6 aluminum alloy sheets. Plasma surface treatment is a well-known technique that can modify the surface properties of materials, including roughness, wettability, and chemical functionality. By introducing surface roughness and functional groups, plasma treatment can improve adhesion between dissimilar materials. After plasma treatment, the surface morphology and composition of the aluminum alloy sheets were analyzed using X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy with energy dispersive spectrometry (SEM-EDS). XPS provides information about the chemical composition and bonding state of the surface, while SEM-EDS provides a detailed view of the surface morphology and elemental distribution. Surface roughness and wettability were measured using a surface roughness tester and a contact angle goniometer. The Al/GF/BN/EP laminates were prepared using a thermoforming technique. Mechanical properties including peel, interlaminar shear, tensile, and flexural strength were evaluated. The laminates prepared by plasma surface treatment showed improved mechanical properties with increasing BN concentration up to 0.9 wt.%. This improvement can be attributed to the synergistic mechanism of mechanical and chemical bonding between the metal layer and the composite layer, which is facilitated by the increased surface roughness and the presence of functional groups (C–N and C=N). [ABSTRACT FROM AUTHOR]

Currently, hybridization of natural-synthetic fibers within a polymeric matrix has received wide attention owing to its promising properties. This study investigated the mechanical properties of interply and intraply hybrid jute (J)-glass (G) fiber/epoxy composites. The mechanical properties (i.e., tensile, flexural, and impact) of the pure jute, pure glass, and their hybrid composites were evaluated. The prepared composite samples consisted of five plies of woven fabrics. Interply hybrid composites comprised three layering sequences: G3JG, GJGJG, and 2GJ2G. Intraply hybrid composites of similar co-woven plies were fabricated by either the alternative replacement of a single glass yarn with a single jute yarn (G1J1) or two jute yarns (G1J2). The results showed that increasing the glass fraction in the interply hybrid composites improved their tensile properties. The two intraply hybrid composites provided almost similar tensile moduli, while the tensile strength of the G1J1 samples was approximately 41% higher than that of the G1J2 counterparts. The maximum flexural properties were provided by 2GJ2G composites, followed by GJGJG, and they were interestingly higher than those of pure glass composites. The G1J1 intraply hybrid composites offered a higher flexural strength and a lower flexural modulus than those provided by the pure glass composites. Compared to the pure glass composites, the impact strengths of the 2GJ2G and GJGJG samples decreased by 4% and 16%, respectively. In summary, the GJGJG hybrid composites exhibited the highest specific tensile, flexural, and impact properties compared to the other hybrid composites. [ABSTRACT FROM AUTHOR]

The low-velocity impact behavior of thick and thin unidirectional E-glass fiber-reinforced laminated composite plates with three different stacking sequences subjected to three different impact energies have been investigated. The test specimens were produced by the Vacuum Assisted Resin Injection (VARI) method in a laboratory environment. The thick specimens contained 50 layers of unidirectional E-glass fibers and the thin ones — 16 layers of unidirectional E-glass fibers. The low-velocity impact tests were carried out using a CEAST Fractovis drop-weight impact test device. The contact force–time and energy–time graphics were plotted and the experimental results were interpreted in detail. [ABSTRACT FROM AUTHOR]

Global economic development and efforts to enhance overall quality of life yielded growth in the construction and building sector, increasing not only the demand for materials but also waste generation. Its efficient management should take full advantage of the exceptional properties of building materials. The presented work is the first reported study on possibly using waste rigid polyurethane (PUR) foam, commonly applied as thermal insulation, as particle-shaped low-density filler for manufacturing hybrid epoxy-basalt composites. It investigated the potential management of waste PUR foam by applying it as a functional filler to hybridize epoxy-basalt composites. Herein, 1, 2, 5, and 10 wt% PUR powder were introduced into the thermoset-based composites prepared using the vacuum bag method. A comprehensive analysis of mechanical and thermomechanical properties correlated with changes in the composite structure revealed the beneficial aspects of the waste filler addition associated with increased heat deflection temperature and mechanical damping ability. Introducing micrometric domains of the waste filler changed the composites' fracture character. It enabled maintaining the impact strength of composites containing up to 5 wt% of PUR powder at the level of unfilled epoxy resin. However, despite that, the incorporation of PUR powder unfavorably affected tensile and flexural performance, yielding a significant drop in moduli and strength. [ABSTRACT FROM AUTHOR]

Fiber-metal laminates (FMLs) are rapidly advancing materials that combine the characteristics of resin-based composites and metals. These properties can be further enhanced by incorporating nanoscale particles, resulting in a variant known as FMLs-Nano. This study explores the mechanical properties of FMLs with the incorporation of Graphene Oxide (GO) and investigates for the first time the influence of GO on bonding strength, aiming to improve the laminate's performance during the forming operation by eliminating delamination defects. The goal is to expand the potential applications of FMLs-Nano and enable the production of intricate components. To evaluate the influence of GO, we conducted tests on several mechanical aspects, including tensile strength, flexural performance, and lap shear strength. These tests involved using different GO fractions in the laminate. Microscopy was employed to examine damage patterns and understand failure behavior. Additionally, deep drawing experiments were performed and compared with conventional FMLs to evaluate the GO influence on delamination failure. The results indicate that FML-GO exhibits superior tensile performance compared to conventional FMLs, with FML-GO tensile strength and Young's modulus improved by 11.7% and 13.5%, respectively. Moreover, flexural and interface shear strength showed remarkable improvements, with an increase of 134% and 150% compared to conventional FMLs. These improvements were verified through mechanical testing and further confirmed by scanning electron microscope observations. Additionally, deep drawing experiments demonstrated significant improvement as delamination of the FML layers was successfully eliminated during the forming process. [ABSTRACT FROM AUTHOR]

The modal testing and numerical results on free vibration behavior of completely free woven fiber glass/epoxy-laminated composite shallow shell panels are presented in this investigation. The finite element numerical model is established by a doubly curved shell model on the basic of first-order shear deformation theory (FSDT). Vibration study of the composite shell panels is carried out using a quadratic eight-noded isoparametric element. The modal testing experiments are carried out using FFT analyzer with PULSE software to determine natural frequencies of woven fabric glass/epoxy composite cylindrical shell panels under free–free boundary condition. The first four natural frequencies of completely free woven fabric glass/epoxy laminated cylindrical shell panels are obtained for different curvature ratios, sequences of lamination and number of laminate layers. The modal test values illustrate an excellent concurrence with the numerical values and will serve as bench mark for future investigators in the present area. [ABSTRACT FROM AUTHOR]

How to achieve both toughness and enhanced electromagnetic interference shielding effectiveness (EMI SE) of carbon fibers (CFs) reinforced rigid polyurethane (RPU) composites is a significative challenge at present. In this work, a ring-shaped zinc coating was deposited on the short CFs by electrodeposition technique. It is expected to improve the interfacial properties between the fibers and the resin matrix as well as enhance the EMI shielding properties of the composites by changing the surface morphology and roughness of the fibers. Results showed that the surface free energy of the ring-shaped zinc modified carbon fibers (RS-CFs) increased from 49.0 mJ/m2 to 53.2 mJ/m2, indicating that the surface roughness and wettability of the CFs were effectively improved. In comparison with the pristine short carbon fibers/rigid polyurethane (CFs/RPU) composites, tensile strength and tensile toughness of RS-CFs modified composites were increased by 27.1% and 121.4%, respectively. In addition, the bending and impact strengths of RS-CFs reinforced RPU composites were also improved. Notably, the electrical conductivity of RS-CFs/RPU composites reached 1.2×10−5 S/m, which was much higher than that of CFs/RPU composites at 1.4×10−10 S/m. Moreover, the EMI SE of the modified composites reached 22 dB, which was 152.9% higher than that of CFs/RPU composites. The enhanced electrical conductivity and EMI shielding properties of the composites could be attributed to the synergistic effect of the porous structure in the RPU matrix and the CFs modified by the metal coating. [ABSTRACT FROM AUTHOR]

We study multiple transverse cracking of symmetric laminates in the framework of the variational approach to fracture. Considering the Griffith model, we assume that several cracks can appear instantaneously through the whole thickness of the core layer, separating the bar in n elastic segments. We show that the energy minimization implies the bifurcation from solutions with uniform crack spacing to non uniformly spaced solutions, a phenomenon ignored in the literature for perfect systems. The stability of uniformly spaced solutions crucially depends on the concavity of the elastic compliance of each elastic segment as a function of the segment length. We compute this function and its derivatives numerically with domain-derivative techniques for a large set of geometric and material parameters. Our results indicate that the change of concavity and the related instability is a robust qualitative property that becomes quantitatively relevant in the case of laminates with thin and soft outer layers. [ABSTRACT FROM AUTHOR]

In this article, Grewia Optiva fiber (GOF) has been reinforced with epoxy and hybrid (epoxy-Lannea Coromandelica gum) resins. The biocomposite has been fabricated with 5, 10, and 15 weight% of continuous and discontinuous GOFs. The effect of fiber surface treatment has been examined on the mechanical properties of GOF. Additionally, the mechanical properties along with physicochemical, morphological, and thermal characterization have been determined for GOF reinforced composites. The results have revealed that GOF treated with 5% NaOH has shown superior tensile strength. Also, the increase in fiber content has increased the water absorption, and it has been maximum for 15 wt% GOF reinforced hybrid resin composites. Further, the stress-strain behaviors under tensile and flexural load have confirmed that 15 wt% continuous GOF reinforcement with epoxy resin has shown maximum tensile strength and flexural strength. In Charpy impact test, 15 wt% GOF reinforcement with hybrid resin has shown the best results compared to their counterparts. The spectroscopy has confirmed the interaction between resins and GOF. The morphological analysis has confirmed the porous structure and inter-connected open cavities with unique hollow and multiscale structures of GOF. The fractured surface of composites under tensile and flexural loading has confirmed the fiber-matrix debonding, fiber breaking, and microcracking. Also, no gaps or pull outs confirming the good interfacial adhesion between fiber and matrix. The thermal analyses have shown the low thermal stability of composites and the lower values of glass transition temperature for composites in comparison to pure resins. Further, this work can expose a fresh way to implement locally accessible eco-friendly natural fiber and resins to produce high-performance biocomposites. The utilization of agricultural by-product as a sustainable green composite can resolve the problem of disposal of these materials and maintain an eco-friendly environment. These composites could be suitable for buildings, automotive parts, sound barriers, marine parts, etc. [ABSTRACT FROM AUTHOR]

Fiber metal laminates (FMLs) are a super hybrid material that provides the combined advantages of metals and composites and offers significant potential as an ultralight structural material in the aerospace industry. Consequently, there has been increased research attention on FML mass production processes. The recent developments in FML component production and FML sheet preparation are the main topics of this review. First, a general overview of the development history, fabrication process, and properties of FMLs and their production process is presented in this paper. With a focus on combined die forming, such as stamping and hydroforming, which is the most promising method for the mass manufacture of complex curve-shaped FML components, several other forming technologies are also discussed in depth. Afterward, the FMLs' forming limitations and challenges, which have been observed in previous research, are also mentioned thoroughly. The defect and deformation modes that can develop during the forming processes of FMLs are addressed. Furthermore, considering all the relevant factors, the future scope of study and development has also been evaluated. [ABSTRACT FROM AUTHOR]

The optimal design of multilayer substrates containing the cutout under compressive loads is fundamental to achieving maximum buckling resistance compared to structural weight, especially in aerospace structures. In this study, buckling and post-buckling behavior of composite laminated plates with orthogonal and symmetrical lay-up containing cutouts with different diameters have been investigated experimentally, semi-analytically, and numerically. Based on the first-order shear deformation theory, a finite strip method is developed to study the buckling of the composite laminates with cutout semi-analytically. A finite element method was used for numerical analysis. The required mechanical properties were obtained from standard tests. The current study results show that the size of the cutout diameter doesn't have a considerable effect on the elastic rigidity of the plate. Still, the buckling load decreases significantly by increasing the cutout diameter. Also, the plate's buckling load and elastic rigidity are increased considerably by increasing the number of composite layers. The thickness of the plate has more effect on the buckling load than the diameter of the cutout. The present study shows a good correlation between the results of buckling behavior derived from semi-analytical and finite element methods with experimental results. [ABSTRACT FROM AUTHOR]

A strategy for toughening phthalonitrile-based resin containing benzoxazine (BA-Ph) with poly (aryl ether nitrile) (PP-PEN) was proposed. Through kinetic analysis, the underlying influence mechanism of PP-PEN with different molecular weight on the polymerization process and cross-linking structure of BA-Ph was explored. In addition, the glass fiber reinforced composite laminates (BA-Ph/PP-PEN/GF) were fabricated by hot pressing. The effect of the molecular weight of PP-PEN on the mechanical and thermal properties of BA-Ph/PP-PEN/GF was verified. The results indicated that the impact strength of the modified composite laminates increased from 77 kJ/m2 to 106 kJ/m2. The bending strength and modulus improved from 484 to 516 MPa and 21 GPa to 25 GPa, respectively. Besides, all the thermal performances of the modified composite laminates had fairly good thermal stability (358 ~ 382 °C). It is believed that the as-prepared phthalonitrile-based composite material with high temperature resistance and toughness is expected to expand the application of high-performance resin based composites. [ABSTRACT FROM AUTHOR]

This paper provides a consolidated review on the characterization of damage mechanisms in laminated composites using acoustic emission (AE) monitoring technique. The overview of challenges encountered during the elimination of noise from AE signals for identifying the initiation and propagation of damages and location of AE source in polymer matrix composite laminates under various loading conditions is reported. However, the transient AE signals can be discretized into different time domains by using wavelet transformation for discriminating damage mechanisms by peak frequency. AE parameters such as energy, rise time, count, amplitude, and frequency are capable to characterize the damage behaviour in laminated composite materials. Various approaches like multivariable analysis of AE parameters, fast fourier transform (FFT), artificial neural networks (ANN), discrete wavelet transform (DWT) were employed to study the behaviour of composite laminates. Moreover, the mechanical strain energy released from the laminates is correlated with acoustic energy played an essential role in damage initiation and propagation during loading. The application of AE is not limited to identifying failure modes; it also includes determining the type, location, and extent of damage in the structures. [ABSTRACT FROM AUTHOR]

In this paper, the modified h-BN coating was coated on the prepreg sheets; then, the carbon fiber/epoxy composite laminates were prepared by compression molding. The through-thickness thermal conductivity, mechanical and thermomechanical properties of the laminates were studied, respectively. The results show that h-BN particles, which are flaky shape with a diameter of about 0.6 μm and thickness of about 70 nm, have been evenly incorporated into the composites, and the thermal stability, through-thickness thermal conductivity, impact strength and glass transition temperature (Tg) of the composites are improved accordingly. When the BN content is 10 m%, the initial thermal degradation temperature (Tinitial) of the prepreg is 370 ℃, which is 10 ℃ higher than that of unmodified prepreg. When the BN content is 7 m%, the thermal conductivity of the laminates reaches 0.9 and 1.0 W·m−1·K−1 at 25 and 100 ℃, respectively, which are 114% and 111% higher than that of pure laminate. When the content of BN is 5 m%, the impact strength of the laminate reaches the highest value of 225 kJ·m−2, which is 15.4% higher than that of pure laminate. BN particles form a dense heat conduction network, thus delaying the thermal degradation of the resin and improving the thermal conductivity. This study provides a facile path to fabricate composite laminates with the integrated structure and function. [ABSTRACT FROM AUTHOR]

Employing the ANSYS Workbench software and a 3D finite-element simulation, a failure analysis of hybrid bonded-bolted vertical T and L joints, with laminated composite adherends, subjected to axial and bending loads is performed. First, the convergence behavior of the joints are examined to select an appropriate and optimized number of elements and then the failure study of each T and L hybrid composite joint for three quasi-static loading cases are performed in three steps, to determine the failure load and failure mode in each case. To demonstrate the validity and precision of the simulations presented, the results obtained are compared with the numerical and experimental data available in the literature. Results indicated that the effectiveness of replacing a bonded joint with a vertical hybrid joint depended on the failure mode. Generally, if the damage mode was delamination of adherend layers or failure of the adhesive layer, this replacement led to significant saving in the cost of raw materials and production and reduced the weight of the joint. [ABSTRACT FROM AUTHOR]

Fibre metal laminates (FMLs) are layered materials based on stacking arrangements of metals and fibre reinforced plastic (FRP) composite laminates. These hybrid fibre metal laminates combine the advantages of both metallic materials and the reinforced hard and strong fibrous materials. A series of low velocity impact and tensile tests were carried out on the fabricated hybrid fibre metal laminates with different orientations and stacking sequences. Aluminium metal, carbon and glass fibres were the layers used for fabricating the hybrid composites and the fabrication was done by varying the position and orientation of the laminates and as well as the stacking sequences. The effect of the different stacking sequence of the metal laminates and the fibre layers on the impact and tensile strengths of the hybrid composites are studied. The stress-strain curve analyses were carried out for tensile properties, while the force-time and energy-time curves were analysed for impact charcteristics of the developed composites. [ABSTRACT FROM AUTHOR]