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Acoustically actuated magnetoelectric (ME) antennas based on resonant magnetoelectric coupling within ferromagnetic/piezoelectric ME laminated composites have recently been considered as a promising solution for antenna miniaturization. However, its radiation performance has been theoretically overestimated, since the negative effects on performances due to the magnetization saturation and the nonlinear mechanical behavior that occur from high-field driving have not been paid enough attention. This work presents a unique equivalent-circuit-based numerical method to analyze the near-field resonance radiation performances of ME antennas driven by high electric fields. In this method, we establish an equivalent circuit of the converse magnetoelectric effect for a ME laminated composite to describe the operating principle of acoustically actuated electromagnetic radiation. The equivalent parameters related to resonance characteristics are determined by fitting the circuit model to the data from frequency response measurements of the near-field magnetic flux density. The validity of the model is verified by comparing the theoretical predictions with the experimental results, in the view of the volume fraction dependence of the mechanical resonance-related radiation characteristics of the fabricated ME composites. Based on the proposed model, the influence of driving voltage amplitude on near-field radiation performances is further analyzed by experimental fitting to the model, and the potential limiting factors of ME antennas are discussed according to the driving-amplitude dependence of parameters obtained from the fit. This work provides an effective and engineering-friendly approach to predict the evolution of ME antenna performances, leading a way to improve the performance limit for resonant magnetoelectric coupling. [ABSTRACT FROM AUTHOR]

This study presents photothermal imaging results of subsurface material defects within fiber metal laminates utilizing the virtual wave concept. Therefore, we theoretically analyze the propagation of the virtual wave signal in a hybrid composite laminate via the method of images. For provoking local material damage, the hybrid composite sample is subjected to a defined impact loading. The results obtained from photothermal defect imaging, utilizing rectangular laser pulse excitation, are compared with results obtained from 3D x-ray computed tomography. To sum up, we demonstrate a fast, non-invasive, and easily interpretable reconstruction of defects within macroscopic hybrid composite laminates based on the virtual wave concept. [ABSTRACT FROM AUTHOR]

Purpose: To investigate the influence of immediate dentin sealing (IDS) vs delayed dentin sealing (DDS) on the marginal gaps of machinable monolithic zirconia vs pressable lithium disilicate laminate veneers.Materials and Methods: A total of 40 maxillary lateral incisors were used and received butt-joint laminate veneer preparation. The samples were divided into two groups (n = 20 each) according to ceramic material: pressable lithium disilicate ceramic (PLD) was used in the first group, and machinable monolithic zirconia (MMZ) was used in the second. Each group was then divided into two subgroups according to the bonding protocol: IDS was employed in one, and DDS in the other (n = 10 each). The marginal gap widths were measured using digital microscopy and statistically analyzed.Results: The smallest marginal gaps were observed in MMZ-DDS (57.2 ± 8.4 μm), followed by PLD-DDS (62.4 ± 2.7 μm) and MMZ-IDS (63.5 ± 1.9 μm). The largest marginal gaps were observed in PLD-IDS (81.5 ± 6.3 μm). Two-way ANOVA revealed that the bonding technique (P < .001) and ceramic material (P < .001) both showed significant differences.Conclusions: MMZ produced better marginal accuracy than PLD. IDS seems to have a predisposition to significantly wider marginal gaps than DDS, but these gaps are within the clinically acceptable range. The marginal accuracy of ceramic veneers appears to be related to the bonding technique as well as the material of construction. [ABSTRACT FROM AUTHOR]

Graphene oxide (GO) sheets are widely used as building blocks in flexible electronic devices, structural materials, and energy storage technology owing to physicochemical flexibility and remarkable mechanical properties. GO exists as lamellar structures in these applications and, thus, it urges to enhance interface interaction to prevent interfacial failure. This study explores the adhesion of GO with and without intercalated water utilizing steered molecular dynamics (SMD) simulations. We find the interfacial adhesion energy (γ) depends on the synergistic effect of the types of functional groups, the degree of oxidation (c), and water content (wt). The intercalated monolayer water confined within GO flakes can improve the γ by more than 50% whereas the interlayer spacing is enlarged. The enhancement of adhesion is from the cooperative hydrogen bonding bridges between confined water and functional group on GO. Furthermore, the optimal water content wt = 20% and oxidation degree c = 20% are obtained. Our findings provide an experimentally available way to improve interlayer adhesion through molecular intercalation, which opens the possibility of high-performance laminate nanomaterial-based films for versatile applications. [ABSTRACT FROM AUTHOR]

The magnetoelectric (ME) response of laminated composites consisting of BaFe12O19 and Pb(Zr,Ti)O3 ceramics is systematically investigated. A butterfly-shaped curve of a magnetoelectric coefficient emerges in both three-layer and multilayer composites. We show that the appearance of a 7 ppm residual strain in the BaFe12O19 layer after magnetization is the main reason for this special curve. We also observe the self-biasing effect of the composites and a maximum ME response from 0.6 to 5 mV/(Oe cm) in laminated composites with magnetic and ferroelectric layers of different thicknesses that can be measured at a zero-bias magnetic field. The repeatable and stable maximum and minimum values of the magnetoelectric coefficient can be obtained under periodically applied biasing magnetic fields, which is important for a practical device application. An electric-field control of ferromagnetism, evidenced by a 17%–19% enhancement in the magnetization of the BaFe12O19 layer after Pb(Zr,Ti)O3 is polarized, is observed in the composites, implying potential applications in memory devices for the composites. Our work indicates that both magnetic field-controlled polarization and electric-field-controlled magnetization exist in BaFe12O19/Pb(Zr,Ti)O3 laminated composites. [ABSTRACT FROM AUTHOR]

This study explores the impact of incorporating Halloysite Nanotubes (HNTs) nanoparticles on the low-velocity impact (LVI) behavior of carbon fiber (CF) laminate epoxy nanocomposites. The objective of this investigation was to observe the effects of different nanotube loadings (0.5 wt.% and 0.7 wt.%) on CF composites and assess their impact resistance. To achieve this, the CF was subjected to Electrophoretic Deposition (EPD) process to introduce the HNTs. Vacuum-assisted Resin Transfer Molding (VaRTM) was employed to fabricate the CF-reinforced epoxy-based laminated nanocomposites with incorporated HNTs. LVI tests were conducted following the ASTM-D-7136 standard, utilizing impact energies of 10 J and 15 J. Subsequently, the damaged areas within the composites were examined using optical microscopy (OM) and scanning electron microscope (SEM). The findings of this investigation revealed a significant enhancement in impact damage resistance with the addition of HNTs. The highest damage resistance and minimal energy absorption were observed at a loading of 0.7 wt.% HNTs. The results reveal that incorporating 0.7 wt.% HNTs substantially reduces delamination damage, influenced by absorbed impact energy. As well it composite underscores enhanced interlaminar bonding through 0.5 wt.% and 0.7 wt.% HNTs modification. Hence, we confidently assert that the addition of HNTs nanoparticles to CF/epoxy composites has considerably influenced the impact response of the nanocomposites. [ABSTRACT FROM AUTHOR]

Bio-inspired helicoidal carbon fiber reinforced polymer composite (CFRPC) laminates stacked with Bouligand configurations are considered to own great potential in engineering fields. The optimization design of helicoidal layups with single-form and combination-form of linear and nonlinear helicoidal arrangements is carried out using ABAQUS and Isight. Two single-objective optimizations and one multi-objective optimization of maximum fundamental frequency and the difference among the first four adjacent vibration frequencies of helicoidal CFRPC laminated plates are performed and the nonlinear free vibration characteristics of optimal ones are investigated for the first time. Numerical studies are carried out for 16-ply symmetrical rectangular helicoidal laminated plates under two different boundary conditions compared with quasi-isotropic counterparts. The results show that the combination-form helicoidal layup sequences can improve the linear vibration characteristics of CFRPC laminated plates. The plates stacked with the combination form of nonlinear Fibonacci and linear patterns are expected to provide better vibration characteristics. [ABSTRACT FROM AUTHOR]

Piezoelectric quasicrystals have attracted the tremendous attention of researchers for their unique properties. In this paper, the semi-analysis solutions of the functionally graded multilayered two-dimensional decagonal piezoelectric quasicrystal plates are investigated for mixed boundary-value problems. Based on the quasicrystal linear elastic theory, the state-space method is employed to derive the state equations composed of partial differential along the thickness direction. The differential quadrature method is utilized to discretize state variables to satisfy the mixed boundary conditions in the horizontal plane. Different from the conventional propagator matrix, a new propagator relationship is proposed to study numerical instability caused by extensive discrete points. Comprehensive numerical results are shown for the sandwich quasicrystal plate with four different stacking sequences. The numerical results reveal the effect of the functional gradient index factors, and boundary conditions on the electric potential, electric displacements, stresses, and displacements under the mechanical/electric loadings. [ABSTRACT FROM AUTHOR]

Composite laminates are prone to occur delamination. Currently, there is still lacking research on the temperature effect on mode II delamination of laminates, especially the multidirectional ones. Systematically experimental and numerical studies are conducted here. Delamination tests are performed at four temperatures (−50 °C, 23 °C, 80 °C and 130 °C) on aerospace-grade T800/epoxy multidirectional laminates using an end-notched flexure set-up. Pre-cracked and non pre-cracked fracture toughness, and R-curves are measured. The non pre-cracked fracture toughness is affected by temperature. Their values at −50 °C, 23 °C and 80 °C are relatively close to each other while the value at 130 °C is 34.14% lower than that at 23 °C. The pre-cracked fracture toughness exhibits negligible dependence on temperature and is significantly higher than the non pre-cracked one. R-curve phenomena are observed in specimens evaluated at different temperatures, which exhibit a good linear increase with the increase in delamination length. The R-curves measured at −50 °C∼80 °C are similar while significantly higher than that at 130 °C. In addition, the bridging stress is lower when the temperature is between −50 °C and 23 °C, compared to those at high temperatures of 80 °C and 130 °C. Numerical framework for simulating the mode II delamination growth behavior is established based on the cohesive zone model. Predicted results show that the reasonable interfacial strength of cohesive elements first increases and then decreases with the increase in temperature. Temperature effect on the damage area around crack tip is also revealed. [ABSTRACT FROM AUTHOR]

Thermoplastic carbon fiber-reinforced plastics (CFRPs) are increasingly utilized in the aerospace industry owing to their beneficial properties and enhanced formability relative to thermoset CFRPs. Despite the extensive use of these materials, studies focusing on compression after impact (CAI) tests with impact energies exceeding 20 J for thermoplastic CFRPs remain scarce. This study examines CAI tests on quasi-isotropic laminates of thermoplastic CFRP, subjected to a low-velocity impact energy of 27.04 J. For comparison, quasi-isotropic laminates of thermoset CFRP were subjected to a low-velocity impact energy of 36.5 J. These tests reveal that the CAI strength of both materials is comparable, notwithstanding the lower fiber volume fraction in the thermoplastic CFRP. Further, this research incorporates a finite element (FE) analysis to investigate the damage mechanisms in thermoplastic CFRP. The FE model, integrating interlaminar damage observed during the impact tests, accurately predicted the relationship between compressive stress and strain, correlating closely with the experimental outcomes. It was observed that both interlaminar and intralaminar damage propagation were constrained until the point of maximum compressive stress. Prior to reaching this maximum, a region of elevated compressive stress in the fiber direction was noted in the 0° layer near the non-impacted side. These findings indicate that the compressive stress in the fiber direction in the 0° layer adjacent to the non-impacted side is pivotal in dictating the final failure, which determines the CAI strength of thermoplastic CFRP laminates. [ABSTRACT FROM AUTHOR]

To solve the problem of the wall panel of high‐performance shelters protecting against the oblique penetration of projectiles, ballistic experiments were carried out with ultra‐high molecular weight polyethylene (UHMWPE) laminates subjected to normal penetration by high‐velocity projectiles, and the deformation and failure characteristics of UHMWPE laminates were analyzed. The numerical model of the resistance of UHMWPE laminates against penetration of projectiles was established by using the finite element program LS‐DYNA. The validity of the numerical model was verified by the experimental results of damage morphology and the depth of depression of the target plate and the deformation of the warhead. On this basis, the ricochet angle and failure mode of the UHMWPE target plate against projectile penetration were studied numerically, and the impact of the angle of incidence on the residual kinetic energy and normal penetration displacement of the bullet, as well as the damage morphology of the UHMWPE target plate, was revealed by using simulation. The results showed that the ricochet angle of the bullet obliquely penetrating into the UHMWPE target plate was in the range of 45° to 50°; at the initial stage of projectile penetration, the shear fracture failure of the fiber layer mainly occurred at the striking face of the UHMWPE target plate. Under the impact of the warhead deformation, with the reduction of the residual velocity of the bullet, the failure mode gradually changed to the tensile and interlaminar cohesion failure of the fiber layer near the back face; When the angle of incidence was greater than the ricochet angle, the residual kinetic energy of the projectile increased slowly with the increase of the angle of incidence of the bullet and then went up approximately linearly; the normal displacement of the bullet obliquely penetrating into the UHMWPE target plate decreased slowly after reaching the peak, and the peak value of the normal penetration displacement decreased gradually with the increase of the angle of incidence, and the time to peak of the displacement shortened gradually. The damage area of the bulge on the back surface of the UHMWPE target plate after penetration decreased gradually with the increase of the angle of incidence. The research results can provide a theoretical reference for the application of UHMWPE laminates in the design of military bulletproof shelters and armor. [ABSTRACT FROM AUTHOR]

Natural fiber‐reinforced composites exhibit excellent mechanical properties. However, achieving a balance between excellent mechanical properties and optimal acoustic performance remains a challenge. In this study, four composite laminates with different stacking orders were fabricated using polyester fiber mats (WFs) and palm sheaths (WPs) through a hot‐press process. Moreover, the effects of different stacking orders on the mechanical and acoustic properties of the composite were investigated. The results revealed that the incorporation of polyester fiber felts and the modification of the layup sequence of WP and polyester fiber felts significantly improved the mechanical and acoustic properties of the composites. Scanning electron microscopy images revealed a strong bonding between palm fibers and polyester fibers at the epoxy resin interface. Compared with pure palm fiber composites, the alternately stacked palm fibers and polyester fibers (WP/WP/WF/WP/WF) exhibited the highest mechanical properties, with a significant enhancement of 142.67% and 16.90% in flexural and tensile strengths, respectively. Additionally, the peak absorption coefficient of polyester fiber felts, positioned in the surface layer of the composite material, within the 2580–3400 Hz frequency band significantly increased from 0.07 to 0.44. Therefore, this study indicates that modifying the stacking order improves the mechanical and acoustic properties of the composites, making them suitable for use in acoustic engineering materials for buildings and decorative panels for furniture, including perforated panels and acoustic screens. Highlights: The fabric‐like textured structure significantly enhanced the overall performance of the composites.The stacking order significantly influenced the overall properties of the composite.Alternately stacked polyester fiber felts and palm fibers exhibited excellent mechanical performance.The polyester fiber felts positioned on the surface layer of the composites exhibited superior mechanical performance.A laminate with "green" attributes and good acoustic properties was fabricated. [ABSTRACT FROM AUTHOR]

The finite element model of a 7.62 mm armor‐piercing incendiary bomb penetrating lightweight composite target is established. The structure of the target plate is composed of boron carbide ceramic/carbon fiber laminate/aramid fiber laminate/damping material. The reasonable distribution position of damping material is explored by designing the material structure and geometric parameters. Genetic algorithm is used to optimize the structure of the lightweight composite target plate, and the feasibility of the optimization results is verified through experiments. The results show that under the same surface density, the energy absorption value of the target plate with a certain thickness of back layer damping is 1.36% higher than that of the target plate without damping. And the damping material on the back layer can act as a buffer layer to reduce blunt trauma caused by bullets to the human body. The surface density of the optimized lightweight composite target plate is reduced by 21.6% under the same protection capability. This work provides a theoretical foundation for the impact resistance design and optimization of lightweight composite target plates. Highlights: Impact resistance performance of lightweight composite target plate is investigated.The impacting analytical model of the structure is established.The validity of the optimized impacting analytical model is verified by numerical simulation. [ABSTRACT FROM AUTHOR]

Elium® Acrylic/Glass Fiber thermoplastic laminate composites are liable to develop irreversible local defects under quasi‐static loading. To reinforce the damaged material, repair is a cost‐effective mechanical alternative. The present study investigates the tensile behavior of an Elium® glass‐fiber‐based acrylic laminate composite panel, repaired by vacuum bonding with Elium® repair resin and double overlap of external patches (DP). The results obtained for all repaired laminate composites E190/GF_D(10, 20, 30)R with diameters 10, 20, and 30 mm showed an improvement in the mechanical properties of the repaired panels, compared with the drilled and pristine samples. Average load recovery rates were significant for E190/GF_D10R (7.9%, 3.55%, 13%) E190/GF_D20R (23%, 18%, 3.32%), E190/GF_D30R (7.2%, 9.36%, 32.37%) at strain rates of 0.001, 0.01, and 0.05 s−1 respectively. Finite element (FE) models for the virgin, drilled, and repaired composite, performed by coupling the Hashin criteria with the cohesive zone model (CZM), provided a relevant prediction of intra‐ and interlaminar failures of these woven laminated composites. Highlights: The effect of vacuum bonding repair with Elium E351 EOT resin was studied.Symmetrical repair of acrylic laminate drilled by fiberglass patches.Tensile strength of the repaired laminates was investigated.Intra‐ and interlaminar damage was predicted by finite elements modeling. [ABSTRACT FROM AUTHOR]

This study proposes a process for the preparation of composite laminates using the shear thickening fluid (STF) impregnated aramid fabric and presents some fabric panel configuration strategies. Firstly, this study prepared two kinds of STF using 20 nm and 500 nm silica particles. Then, the STF‐impregnated Kevlar fabrics were laminated and hot‐pressed to form the fabric panels. After that, the ballistic performance of the fabric panels was evaluated by firing the 9 mm steel core projectile using a gas gun. The ballistic tests showed that the ballistic performance of the hybridized configuration panels using STF‐20 treated fabrics as the front panels and STF‐500 treated fabrics as the backing panels was superior, with a reduction of 36.1%–37.6% in the number of perforated layers (4.7–5 layers) compared to a single STF‐treated panel. This study provides a new idea and method for applying STF in protective equipment. Highlights: Shear thickening fluid (STF) and aramid fabric are better combined by hot pressing lamination process;The ballistic properties of fabric panels are significantly improved by hybrid configuration;The ballistic performance enhancement mechanism of composite bulletproof plate was revealed. [ABSTRACT FROM AUTHOR]

This research conducts a comprehensive experimental and numerical analysis of carbon fiber composite laminates under low‐velocity impact conditions. Split Hopkinson Pressure Bar (SHPB) was employed to conduct impact testing on laminates with two layup sequences (03/+45/−45s and 03/903s) under impacts ranging from 2 to 6 J. For assessing damage in laminates, a comprehensive progressive damage model and a simplified model were developed. The primary distinction between these models lies in the fact that the former incorporates the strengthening effect of compression on the delamination behavior, while the latter does not. Both models produce a good agreement with experimental results in terms of force–time, force–displacement curves, and absorbed energies. However, notable differences were noted in the predicted internal damage; the simplified model was underpredicted in terms of damage size and distribution compared to the comprehensive progressive damage model. Highlights: Impact tests were conducted on 03/+45/−45s and 03/903s composites.In order to simulate damage caused by impacts in laminates, an energy‐based damage model was created, and cohesive elements were utilized to model interlaminar delamination.The strengthening effect of compression was explored.Distinct damage criteria were established for two cases.Damage detection of composites by x‐rays. [ABSTRACT FROM AUTHOR]

Self‐resistance electric (SRE) heating for the curing of carbon fiber reinforced plastic (CFRP) offers the benefits of saving energy consumption and reducing investment in equipment. In this work, the investigation was carried out to illustrate the effect of carbon nanotubes (CNTs) addition (0.5, 1.0, and 1.5 wt%) on the thermoset curing and mechanical properties of carbon fiber‐reinforced epoxy laminates fabricated by SRE heating method. The results show that adding CNTs can improve the temperature uniformity and interlayer‐resin flow during the SRE heating process and have a limited influence on the curing degree of CFRP composites. The tensile strength in the longitudinal direction of the composites increased with the increase of CNT addition. Meanwhile, the flexural strength and interlaminar shear strength had the maximum value with the CNTs content of 0.5 wt% and decreased significantly at the CNTs content of 1.5 wt%. It concludes that the appropriate content of CNTs addition has the potential to improve the thermoset curing performance and mechanical properties of the CFRP laminate composites fabricated by SRE heating. Highlights: This study focuses on the effect of CNT addition on SRE heating for CFRP.The addition of CNTs improved the temperature uniformity during SRE heating.The addition of CNTs can reduce the voids of SRE‐cured CFRP composites.Threshold value of CNTs affected the mechanical performance of SRE‐cured CFRP. [ABSTRACT FROM AUTHOR]

The snap-through behaviors and nonlinear vibrations are investigated for a bistable composite laminated cantilever shell subjected to transversal foundation excitation based on experimental and theoretical approaches. An improved experimental specimen is designed in order to satisfy the cantilever support boundary condition, which is composed of an asymmetric region and a symmetric region. The symmetric region of the experimental specimen is entirely clamped, which is rigidly connected to an electromagnetic shaker, while the asymmetric region remains free of constraint. Different motion paths are realized for the bistable cantilever shell by changing the input signal levels of the electromagnetic shaker, and the displacement responses of the shell are collected by the laser displacement sensors. The numerical simulation is conducted based on the established theoretical model of the bistable composite laminated cantilever shell, and an off-axis three-dimensional dynamic snap-through domain is obtained. The numerical solutions are in good agreement with the experimental results. The nonlinear stiffness characteristics, dynamic snap-through domain, and chaos and bifurcation behaviors of the shell are quantitatively analyzed. Due to the asymmetry of the boundary condition and the shell, the upper stable-state of the shell exhibits an obvious soft spring stiffness characteristic, and the lower stable-state shows a linear stiffness characteristic of the shell. [ABSTRACT FROM AUTHOR]

A meshfree orthotropic laminated shell model for geometrically nonlinear static and dynamic analysis based on the reproducing kernel particle method (RKPM) and the Mindlin-Reissner shell theory is proposed for the first time, suitable for dealing with the finite deformation of composite shell structures of arbitrary geometry in engineering. The Mindlin-Reissner shell theory is adopted to describe the geometric configuration of the laminated shells via a single-layer particle. Then, the Galerkin weak form governing equations are established explicitly and discretized using RKPM and linear transformation in the thickness direction. Furthermore, a laminate stacking sequence that can eliminate the coupling terms of linear and angular acceleration is proposed for simplification. For considering the orthotropic materials, the stress–strain transformation between local and material coordinates is introduced. A stiffened laminated shell model is also presented for simulating complex composited structures. The accuracy and convergence of the proposed laminated shell model are verified through several static and dynamic benchmarks, demonstrating the ability of the presented model to solve the nonlinear response of composite structures. [ABSTRACT FROM AUTHOR]

In the current work, for the first time, bending and vibration information of the axisymmetric thick annular nanoplate made of laminated composite layers is studied. The structure is placed on Winkler-Pasternak substrate with elastic and tortional coefficients. Initial stress as an external load is also considered in the composite structure. For modeling the mechanical deformation in layer-wise composite materials, zigzag theory that its functions themselves are continues in the interface of layers is presented. By coupled quasi-3D new refined theory (Q3D-NRT) and nonlocal strain gradient theory are used for obtaining the nonclassical governing equations a general boundary condition of the current composite nanoplate. Also, for obtaining the static and dynamic equations of the current nanostructure, Hamilton's, and Minimum total potential energy principles are used, respectively. Via differential quadrature method with weighting factors and nth-order derivative, the nonclassical governing equations with the aid of size-dependent boundary conditions are solved. By comparing the current results with the outputs of previous reports, the accuracy of the results is shown. [ABSTRACT FROM AUTHOR]

The main purpose of this study was to observe the degree of the improvement on the film adhesive joining performance of Poly(phenylene sulfide)/Carbon Fiber (PPS/CF) thermoplastic composite laminates when their surfaces were treated by atmospheric plasma technique. For this purpose, plasma treated surfaces were compared with untreated and the traditional grit-blasted surfaces. Treated surfaces were characterized by various techniques including contact angle, surface energy, surface roughness, Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) analyses. Then, joining performance of the PPS/CF composite samples bonded by an epoxy-based film adhesive was determined by using three different mechanical tests; single-lap shear strength, mode-I interlaminar fracture toughness energy, and drop-weight impact toughness. Grit-blasting surface treatment increased surface roughness of the specimens enormously (7 times more), leading to mechanical interlocking as the dominant bonding mechanism. Contrarily, plasma surface treatment resulted in formation of chemically reactive sites, thus dominant bonding mechanisms in the film adhesive joining were certain polar interactions and chemical bonding. Mechanical tests pointed out that compared to grit-blasting, plasma surface treatment resulted in considerably higher joint performance regarding interlaminar shear strength (35% more), interlaminar fracture toughness (67% more) and impact toughness (28% more), with the cohesive failure mode. Accordingly, it could be stated that traditional grit-blasting could be replaced with plasma surface treatment applied before film adhesive joining of PPS/CF composite parts in aircraft industry. [ABSTRACT FROM AUTHOR]

Improving the quality of fiber-reinforced composite laminates using out-of-autoclave techniques has been a challenge for a long time. The recent trends toward the replacement of autoclave processes with out-of-autoclave processes for thermoplastic composites still lack a compressive recipe. This study first develops an understanding of the integrated effect of the automated fiber placement (AFP) lay-up process parameters (compaction force and lay-up velocity) and the type of post-processing: i) autoclave and ii) vacuum bag only (VBO) processing with two vacuum hold times, 2 and 24 h. The void content results highlight the potential of the VBO process to replace the autoclave with an improved void content of VBO with 24 vacuum hold times. Then, this result has been correlated with the morphology of voids after the AFP lay-up as isolated or connected via air permeability characterization. This study reveals that the high air permeability to effective porosity ratio of samples after AFP lay-up which is achievable with low compaction force facilitates the air removal mechanism during the VBO process with sufficient vacuum hold times. [ABSTRACT FROM AUTHOR]

The present study investigates the effect of internal defects on the composite laminated (CL) plates comprised of two distinct graphite-epoxy materials (AS4/3501-6 and T300/5208). The centrally damaged laminates stacked in two distinct lamination sequences are exposed in thermally varying environments. The CL plates are considered to experience damage in two different combinations of damage parameters. The improved first-order shear deformation theory (IFSDT) based finite element (FE) model is employed to estimate the thermal buckling of CL plates comprised of multiple fiber orientation angles and constrained to C-S-C-S and S-C-S-C boundary restrictions. The implementation of a Radial basis function network (RBFN) surrogate model has demonstrated its potential as a feasible substitute for the computationally demanding Monte-Carlo simulations (MCS) in the context of stochastic exploration. The present investigation scrutinizes the probabilistic properties of diverse materials and their associated damage characteristics. Subsequently, the RBFN-based surrogate model is employed to evaluate the likelihood of failure. [ABSTRACT FROM AUTHOR]

The nonlinear buckling response of laminated composite cylindrical shells reinforced with graphene nanoplatelets (GNPs) is studied in this paper. The functionally graded (FG) shell reinforced by GNPs is analytically studied under external pressure and uniform temperature rise loadings. It is also assumed that the GNP-reinforced laminated composite shell is in contact with an elastic foundation. Various types of profiles are employed for the GNP distribution patterns in the shell thickness including 10 nanocomposite layers. The nonlinear strain-displacement relations of the shallow cylindrical panel are established utilizing the third-order shear deformation shell theory. Governing equilibrium equations of the laminated GNP-reinforced composite shell are formulated employing the principle of virtual displacement. The coupled system of nonlinear differential equations is solved analytically for the hinged–hinged and fixed–fixed boundaries of the shell using a perturbation-based technique. Correctness of presented formulations and obtained solutions is proved by comparisons with results from previous studies for an isotropic cylindrical shell. Novel numerical results reveal that the material properties, geometrical characteristics and load parameters significantly affect on the buckling behavior of laminated composite cylindrical shells. [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]

Bolted joints are widely used in aircraft structures. Proper design and accurate strength assessment of these joints are of great importance in aircraft design. In this paper, to investigate the mechanical behavior of single lap shear joints of carbon fiber reinforce plastic, four types of fastener of numerical model methods are developed. Based on the same principle of lap joint, different double bolt, and single‐lap joint structures with three distinct width‐diameter ratios (w/D) are designed and manufactured. Each specimen is loaded under tension until complete failure. The experimental results are used not only to verify the fastener models, but also to investigate the failure transformation induced from the composite load bypass and the bolt‐hole load bearing. It is found that the increase of w/D, the failure model could transfer from the net cross section damage caused by load bypass to the bolt hole failure caused by load bearing. By comparison, the numerical results show that the Cbush+RBE3 model has high adaptability and good fidelity in elastic stage without increasing the model scale in terms of the level of details. To improve the accuracy in nonlinear stage, hole geometry details need to be considered. Additionally, single bolt is created to reveal the nonlinear deformation affected by laminate thickness. Three/four/five row of bolt models are used to show the bolt load distribution characteristics. Finally, the influences of the element size and the bolt modeling methods on the bolt load distribution are analyzed, respectively. [ABSTRACT FROM AUTHOR]

Three‐dimensional (3D) orthogonal woven composites can overcome the drawback of weak interlaminar strengths in traditional laminated composites and exhibit excellent resistance to out‐of‐plane impact, however, the significant difference in properties in the in‐plane orthogonal direction will limit the potential range of application thereof. Predicting elastic properties and exploring methods of adjustment are therefore of paramount importance. Using computed tomography (CT) scanning to obtain detailed parameter models, a corresponding dual‐scale model of microscopic representative volume element (RVE) and mesoscopic RVE was established, and the accuracy of the model was experimentally validated, which can predict the elastic properties of materials. In addition, the influences of the yarn fiber volume fraction and weaving distance on elastic properties were evaluated using the elastic modulus visualization method, and a formula integrating these two factors is provided for adjustment of the in‐plane orthogonal Young's modulus. Highlights: Experimentally validated microscale and mesoscale RVE models were established.The influences of factors on elastic properties were visualized.The relationship between Young's modulus and influencing factors was derived.A reliable strategy for adjusting the in‐plane Young's modulus was proposed. [ABSTRACT FROM AUTHOR]

In this study, micro‐drilling tests were carried out on composite laminates reinforced with hybrid (aramid‐carbon) and carbon fibers. Thrust force, hole quality, tool wear, and temperature parameters were measured and assessed following each drilling test. The quality of holes includes circularity, overcut, hole damage factor (HDF), and taper ratio. Micro‐drilling was performed on a CNC milling machine using 0.6 mm drill diameter, 7500 rpm, and 0.5 mm/min feed parameters. The plates are 3.05 mm (carbon fiber) and 3.45 mm (hybrid) thick. According to the results, the maximum thrust force (29.8 N) was measured in the hybrid composite due to the high fracture toughness of the aramid. In addition, it was determined that the thrust force and drill wear were related. The increase in thrust force during drilling caused an increase in drill wear values. While the average wear of the drill in carbon composite was 0.013 mm, the average wear of the drill in hybrid composite was 0.021 mm. Thrust force and tool temperatures were found to have a similar trend. The highest tool temperature was measured as 86.7°C in the hybrid composite. Hole quality results showed that drilling in carbon composite was more successful than in hybrid composite. Holes drilled in carbon composite have lower values for overcut (0.017 mm), HDF (1.028), and taper ratio (0.008). It has been understood that hole quality depends on thrust force and damage formation. Highlights: Carbon and hybrid (carbon‐aramid) composites were produced with a vacuum infusion process (VIP).Micro‐drilling of composites was investigated focusing on thrust force, tool temperature, and hole quality.Hybrid composites exhibited greater thrust forces due to their higher toughness compared to carbon composites.Hybrid composites showed higher maximum tool temperatures compared to carbon composites.The carbon composites exhibited better hole quality compared to the hybrid composites. [ABSTRACT FROM AUTHOR]

Experimental and simulation studies of the response of bonded‐repaired and scarf‐repaired carbon fiber‐reinforced polymer laminates under the low‐velocity impact (LVI) were carried out. The center‐ and eccentric‐repaired laminates were prepared for experiments. The experimental results verify the validity of the finite element model in terms of the force response and different modes of damage. The effect of impact energy and the variation of repair position on the impact response of the laminate was investigated based on the benchmark model. The bonded repaired laminates have higher peak impact forces and lower energy absorption than the scarf‐repaired laminates; the damage of the bonded repaired laminate is mainly intralaminar damage and delamination damage of the patch; the adhesive of the scarf repair is prone to failure, leading to poor impact resistance. The relative positions of the impact point and the patch determine the impact response of a laminate repaired at different locations. The impact point at the edge of the patch has a detrimental effect on the repaired laminate. The impact point vertical position near the bottom hole edge of the parent plate in the scarf‐repaired case harms the impact resistance of the laminate. Highlights: The low‐velocity impact response of bonded versus scarf‐repaired laminates was compared.Bonding repairs provide superior impact resistance to damaged laminates than scarf repairs.The risk of adhesive failure in scarf repair is significantly higher than in bonded repair.The relative position of the damage (repair) to the impact point critically influences the impact response.Impacts near the edge of the initial damage hole can cause severe damage to scarf‐repaired laminates. [ABSTRACT FROM AUTHOR]

Through evolutionary processes, helicoidal structures have been proven to exhibit exceptional load‐carrying capacity and impact resistance performance. To date, extensive experimental and numerical studies have been carried out on their impact behaviors, while few relevant analytical studies have been reported even though it is urgently needed for the preliminary assessment of structure design and optimization. In this work, based on the first shear deformation theory (FSDT) and the improved linearized Hertzian contact method, an analytical model for low velocity impact (LVI) performances of helicoidal laminates with arbitrary layups is developed. Therein, the post‐impact damage is taken into account according to continuum damage mechanics (CDM). Comparisons of load‐carrying capacity and energy‐absorbed performance between the proposed model prediction and the existing experimental data\numerical results have been made for verification. Besides, LVI behaviors of conventional laminates with unidirectional distribution andcross‐ply arrangement are discussed. Moreover, the role of rotation angle, impact velocity and the plate dimension on helicoidal laminates' LVI performances are analyzed quantitatively. There is evidence that helical layouts are better able to absorb energy and delay the in‐plane damage. Highlights: The LVI responses of bio‐inspired single‐helicoidal (SH) and double‐helicoidal (DH) composite laminate are studied.An effective model to predict the LVI responses considered the post‐impact damage is developed.A comparison of the LVI performance of single‐helicoidal structures with various lay‐up schemes is carried out.DH structure has better low velocity impact resistance than SH structure when the rotation angle shares the same. [ABSTRACT FROM AUTHOR]

This article presents the uncertainty of the part performance due to the estimated ply orientations of a carbon fiber laminate inspected using ultrasound inspection. Recent developments to quantify the orientation using ultrasound inspection is accurate to within ±2° for each lamina. The research presented in the current work statistically analyzes the impact this uncertainty in measurement has on the resulting expected failure envelope using two different analytical methods: (1) Monte‐Carlo (MC) simulation approach extending classical laminate theory and (2) Closed form approach of Mean Value First Order Second Moment method based on derivatives of failure envelope as a function of lamina orientation. The results are validated against a commercial finite element‐based MC simulation approach. The Tsai‐Wu failure criteria is implemented to determine the first ply failure stresses by applying a variety of planer loads to form the failure envelope for a given layup sequence of a carbon fiber reinforced polymer laminate. In this article, using stochastic simulations, the failure envelope is no longer deterministic but is stochastic in nature and converts the reporting from a deterministic factor of safety concept to a probability of failure for a given loading state. The analysis is visualized and quantified using the cumulative‐density‐function (CDF), which demonstrates the similarity between the stochastic results and the classical deterministic approach. To demonstrate a possible end use of the presented statistical analysis, a study of a woven composite laminate is presented where the ply orientation is estimated using ultrasound and the resulting CDF of failure is presented. Highlights: Statistical analysis (Monte‐Carlo, mean value, first order, second moment) on the ply orientation variability via ultrasound inspection.Statistical analysis of classical laminate theory and FE based Tsai‐Wu failure model is developed and compared.Tsai‐Wu failure envelope is quantified and visualized using cumulative density function. [ABSTRACT FROM AUTHOR]

A mesoscopic representative volume element (RVE) model of carbon fiber reinforced polymers (CFRP) laminate with 15 plies was established based on the principle of fiber random disturbance. The RVE model was validated by comparing the elastic parameters calculated by the RVE model, Chamis model, and Bridge model. Wet stress and thermal stress were coupled using a sequential method. Macroscopic and microscopic subroutines were developed to calculate the stress–strain field of CFRP laminate and RVE model. A multiscale numerical simulation of three‐point bending of moisture‐saturated CFRP laminate was conducted. Failure process and failure modes of CFRP laminate were discussed based on the multiscale simulation and SEM observations. The results show that the RVE model and the multiscale simulation strategy presented in this work can predict the coupled hygrothermal stress and the strength degradation due to moisture absorption very well. The maximum error between the simulated and experimental averaged force of the moisture‐saturated CFRP laminate subjected to three‐point bending is about 3.4%. Multiscale simulation demonstrated that uneven distribution of fibers can result in the fiber/matrix interfaces bearing a larger transverse stress in the fiber's dense distribution area. It is the main reason that results in fiber/matrix interface failure of CFRP laminates working in hygrothermal environments. Highlights: A RVE model of CFRP laminate was presented using fibers random disturbance.Coupled hygrothermal stress of single fiber and surrounded matrix was obtained.A multiscale simulation of the strength change of the CFRP plate due to wet‐thermal stress was conducted.Failure modes of CFRP laminate are discussed based on the multiscale simulation. [ABSTRACT FROM AUTHOR]

This study investigates the effect of damage interference resulting from impact loads on the mechanical response and impact fatigue life of E‐glass/epoxy composite laminate shells. The analysis involves single impacts at different points to evaluate the impact strength's dependency on boundary conditions. Notably, there is a gradual reduction in both maximum impact force and absorbed energy beyond 10 mm from the centre, towards unconstrained edges, accompanied by an increase in displacement. Specifically, at a distance of 30 mm, the maximum force and absorbed energy register a decrease of 9.4% and 7.9%, respectively, while the displacement rises by 14.5%. The findings reveal that the damage severity decreases as the impact point is closer to the unconstrained edge of the specimen, which can be attributed to a stiffness reduction, which can reach up to 22%. Symmetrically induced pre‐damages exhibit no discernible effect on the subsequent impact response. It is observed that beyond 10 mm from the shell's centre, the number of impacts required to reach puncture increases by 10.5% and 21.1% for distances of 20 and 30 mm, respectively. Furthermore, it is also found that alternating impacts between symmetrical points show no inclination towards a preferential point for puncture. Highlights: The single impact strength's dependents on the boundary conditions.Reduction in both maximum impact force and absorbed energy near the unconstrained edges.Damage severity decreases as the impact point is closer to the unconstrained edges.Symmetrically induced pre‐damages have no discernible effect on the subsequent impact response.Alternating impacts between symmetrical points show no inclination towards a preferential point for puncture. [ABSTRACT FROM AUTHOR]

Composite structures are vulnerable to delamination under out‐of‐plane loading due to the absence of reinforcing fibers in the thickness direction. This paper introduced the interlaminar basalt fiber veil technique to improve the interlaminar fracture toughness of basalt fiber‐reinforced thermoplastic composite laminates. The reinforcement effect of the basalt fiber veil on GIC of composite laminates was investigated by a double cantilever beam (DCB) test. The toughening effect, damage morphology, and the basalt fiber veil toughening mechanism were analyzed by mechanical response, optical photos, and scanning electron microscopy (SEM). It was found that the basalt fiber veil could significantly inhibit the propagation of interlaminar cracks. Compared to the unreinforced specimen, the maximum load of basalt fiber veil‐reinforced laminate was increased by 73%, the average platform load was increased by 72.7% and the GIC was increased by 157%. Highlights: Improvement of GIC of basalt fiber‐reinforced thermoplastic laminates by basalt fiber veil.The toughening mechanism for the basalt fiber veil.The GIC of the fiber veil‐reinforced laminate was 157% higher than the unreinforced laminate. [ABSTRACT FROM AUTHOR]

A RVE finite element model was developed, and the effective mechanical properties were predicted by analyzing the fine structure of Z‐pin reinforced composite laminates. A new damage criterion based on strain description is adopted, a progressive damage analysis model is established and progressive damage analysis is carried out, which provides a reference for further research on Z‐pin reinforced composites. By applying both longitudinal tensile and in‐plane shear loads to the RVE, the material strength prediction was carried out the damage evolution process was emphasized, and the stress–strain curves of the material as well as the damage modes and damage levels in different regions were finally predicted. From the damage evolution process, it can be seen that the damage in the fiber direction and the damage in the transverse direction appear the earliest and have the highest percentage of failure. Highlights: The RVE model was developed and its effective mechanical properties were predicted.A new damage criterion is introduced, a UMAT subroutine is written, and a progressive damage model is developed.Material strength predictions were made for the RVE and the damage evolution process was emphasized. [ABSTRACT FROM AUTHOR]

Mantis shrimps deliver one of the fastest strikes with their powerful dactyl clubs. The kinematic energy derived by a saddle storing and releasing mechanical energy with large deformation. As an exoskeleton, the toughness of saddles can achieve a remarkable value ≈15.28 ± 2.32 MJ m−3, which exceeds most bulk natural materials. The excellent toughness of saddles is mainly attributed to the synergy of the helical mineralized fiber architectures and interlaminar fibrils. The interlaminar fibrils connect adjacent mineralized fiber layers closely, enhancing the toughness through viscoelastic deformation during sliding and separating of adjacent layers. They further cooperate with rigid interlacing fiber structure induced by helical structure to transform little normal strain to large shear strain utilizing incompressibility of soft fibrils further to enhance strain energy for toughening. Inspired by unique laminated saddles, the laminate composites are designed with basalt fabrics achieving remarkable fracture toughness to solve the problem of delamination in traditional laminate composites with poor interlaminar toughness. The Mode I and Mode II interlaminar fracture toughness of bio‐inspired laminate composites respectively increase by 44% and 118% reaching 906.8 and 1394.6 J m−2, which provides an innovative bionic strategy for designing new generation structural engineering materials with excellent mechanical properties. [ABSTRACT FROM AUTHOR]

In order to investigate the durability of fiber-reinforced polymer composites in hygrothermal environments, hygrothermal accelerate aging tests, for 360 days at 70 °C, RH70%; 70 °C, RH85%; 85 °C, RH70%; and 85 °C, RH85% and natural storage for 2 years in Guangzhou, China, were carried out for composite laminates. Then, the moisture absorption and interlaminar shear strength were measured. The hygrothermal damage mechanism of the composite was studied by Fourier transform infrared (FTIR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and field emission scanning electron microscopy (FSEM). A dual stress storage life prediction model and the equivalent relationship between natural storage and hygrothermal acceleration were established. The results show that the order of moisture absorption rates, moisture absorption contents, and the severity effect order on the interlaminar shear strength is RH85%; 85 °C > 70 °C; RH85% > 85 °C; RH70% > 70 °C; and RH70%. The time to achieve an effective moisture absorption balance is opposite to this. The moisture absorption rate meets Fick's law before the effective moisture absorption balance, and then shows a linear trend. The interlayer shear strength still decreases exponentially with aging, which is mainly caused by the resin plasticization and interface weakening. Hygrothermal accelerated aging for 13.4831 days at 85 °C; RH85% is equivalent to that for one-year actual storage in Guangzhou. According to the failure criterion of shear strength decreasing to 77%, the storage life of T700/epoxy in Guangzhou is 14.4661 years. [ABSTRACT FROM AUTHOR]

The aim of this research is to investigate basalt as a natural mineral-based fibre together with a vitrimeric resin as a sustainable alternative to standard composite materials. Vitrimers combine the properties of thermoset and thermoplastic polymers, enabling the repair of specimens and hence prolonging the lifetime of the composite material. The micro-mechanical characteristics between the basalt fibres and the vitrimer resin are reported and shown to match those of a standard Skyflex K51 epoxy resin. Discontinuous (4 mm) basalt fibres were employed to produce aligned discontinuous fibre-reinforced composites (ADFRCs) using the high-performance discontinuous fibre (HiPerDiF) technology. The mechanical characteristics of the laminates were investigated through tensile testing and the fracture zones were analysed under a scanning electron microscope. By normalising the results by their respective fibre volume fraction, it was discovered that the vitrimer–basalt ADFRCs exhibited, on average, a 4% higher strength and a 25% higher stiffness compared to their basalt epoxy counterparts. The repair potential of the vitrimer ADFRC specimens was explored during low-temperature compression repair. Two approaches were tested using double-sided local- and full-patch repair. Both successfully recovered a significant amount of their prime strength. In conclusion, the potential of the sustainable vitrimer–basalt composite is shown by its competitive mechanical performance. Combining this with the manufacturing flexibility, repair potential, and recyclability of the material, the vitrimer–basalt composite seems to be a competitive alternative to standard glass epoxies. [ABSTRACT FROM AUTHOR]

The surface roughness and wettability of wood are critical aspects to consider when producing laminated wood products with adhesive applications. This study aims to investigate the surface roughness and dynamic wettability of Jabon wood in the presence of melamine formaldehyde (MF)-based adhesives. Commercial MF adhesives (MF-0) and modified MF adhesives (MF-1) were applied to Jabon wood, which includes tangential (T), radial (R), and semi-radial (T/R) surfaces. The surface roughness of Jabon wood was assessed using a portable stylus-type profilometer. The low-bond axisymmetric drop shape analysis (LB-ADSA) method was employed to identify the contact angle (θ) of the MF-based adhesives on Jabon wood. The wettability was determined by evaluating the constant contact angle change rate (K value) using the Shi and Gardner (S/G) model. Dynamic mechanical analysis (DMA) was employed to investigate the viscoelastic characteristics of the interphase analysis of the wood and MF-based adhesives. The roughness level (Ra) of the Jabon board ranged from 5.62 to 6.94 µm, with the T/R having a higher level of roughness than the R and T. MF-0 exhibited a higher K value (0.262–0.331) than MF-1 (0.136–0.212), indicating that MF-0 wets the surface of Jabon wood more easily than MF-1. The wood–MF-0 interphase reached a maximum stiffness of 957 N/m at 123.0 °C, while the wood–MF-1 had a maximum stiffness of 2734 N/m at 110.5 °C. In addition, the wood–MF-0 had a maximum storage modulus of 12,650 MPa at a temperature of 128.9 °C, while the wood–MF-1 had a maximum storage modulus of 22,950 MPa at 113.5 °C. [ABSTRACT FROM AUTHOR]

The Diels–Alder equilibrium is a widely known process in chemistry that can be used to provide a thermoset structure with recyclability and reprocessability mechanisms. In this study, a commercial epoxy resin is modified through the integration of functional groups into the network structure to provide superior performance. The present study has demonstrated that it is possible to adapt the curing process to efficiently incorporate these moieties in the final structure of commercial epoxy-based resins. It also evaluates the impact that they have on the final properties of the cured composites. In addition, different approaches have been studied for the incorporation of the functional group, adjusting and adapting the stoichiometry of the system components due to the differences in reactivity caused by the presence of the incorporated reactive groups, with the objective of maintaining comparable ratios of epoxy/amine groups in the formulation. Finally, it has been demonstrated that although the Diels–Alder equilibrium responds under external conditions, such as temperature, different sets of parameters and behaviors are to be expected as the structures are integrated into the thermoset, generating new equilibrium temperatures. In this way, the present research has explored sustainable strategies to enable the recyclability of commercial thermoset systems through crosslinking control and its modification. [ABSTRACT FROM AUTHOR]

The corrosion behavior of a hybrid laminate consisting of laser-structured aluminum EN AW-6082 ∪ carbon fiber-reinforced polymer was investigated. Specimens were corroded in aqueous NaCl electrolyte (0.1 mol/L) over a period of up to 31 days and characterized continuously by means of scanning electron and light microscopy, supplemented by energy dispersive X-ray spectroscopy. Comparative linear sweep voltammetry was employed on the first and seventh day of the corrosion experiment. The influence of different laser morphologies and production process parameters on corrosion behavior was compared. The corrosion reaction mainly arises from the aluminum component and shows distinct differences in long-term corrosion morphology between pure EN AW-6082 and the hybrid laminate. Compared to short-term investigations, a strong influence of galvanic corrosion on the interface is assumed. No distinct influences of different laser structuring and process parameters on the corrosion behavior were detected. Weight measurements suggest a continuous loss of mass attributed to the detachment of corrosion products. [ABSTRACT FROM AUTHOR]

In this study, the frequency and deflection response analysis of basalt, soy, flax and hybrid pineapple and flax hybrid laminated skew plates are done. The conventional hand-layup method is used to fabricate the different bio-composites-based laminated structures. The uniaxial tension test is conducted in the INSTRON 5967 UTM to determine the elastic properties of the bio-composite laminated structure as per ISO 527-5 standards. The hybrid laminate skew plate is modeled using the first-order shear deformation theory (FSDT) and their elastic properties are obtained from the uniaxial tensile test from which the frequency and deflection of the skew laminated plates are calculated. The eight-noded shell elements (S8R5) with each node having five degrees-of-freedom are deputed in the commercial finite element method (FEM) package ABAQUS to beget the numerical solutions. The damping effect is neglected in the analysis. The accuracy of the proposed model is verified with available literature and found to be in good agreement. Later, the effect of different parameters such as boundary conditions, aspect ratio and skew angles on the natural frequency and deflection of the bio-composites hybrid laminated skew plates are investigated. The obtained results inferred the natural frequencies are decreasing with an increasing aspect ratio of skew plates. The skew angles help to increase the natural frequencies of skew plates. The central deflections are lower for high-skew angled laminated plates. [ABSTRACT FROM AUTHOR]