Properties Of Laminates Research Articles

Synergistic mechanism of strengthening and toughening of tissue regulation response to Mg/Al composite laminates by hard plate accumulative roll bonding

The significance of light alloy in realizing the national strategy of energy saving and emission reduction and promoting the upgrading of the manufacturing industry is self-evident. Mg/Al composite laminates combine the lightweight of magnesium alloy and the plasticity and corrosion resistance of aluminum alloy. Traditional accumulative roll bonding technology relies on the advantage of introducing large deformation. Although high strength is obtained, it is often accompanied by a large loss of ductility, and there is a problem that it is difficult to balance strength and ductility. To solve this problem and optimize the process conditions, a new hard-plate accumulative roll bonding process is proposed in this paper, which is used to prepare high-performance Mg/Al composite plates, and the influence of forming temperature on the microstructure and mechanical properties of Mg matrix is studied. The results show that when the forming temperature is 350 °C, the properties of composite laminates are the best, the tensile strength can reach 243 MPa, the elongation is 14.7 %, and there are a lot of tearing edges and dimples on the fracture surface. At the same time, complete recrystallization can be realized at this temperature, and the opening of non-base slip can coordinate deformation stress, promote the dislocation slip, and reduce the dislocation density, SEM images show that there are no defects such as delamination at the interface, and a firm metallurgical bonding is achieved. It provides a new approach to the forming and manufacturing of high-quality lightweight heterogeneous composite laminates.

Identification of different lithofacies laminations in oil shale and their mechanical properties

Lamination can greatly enhance the anisotropy and heterogeneity of shale and plays a significant role in influencing hydraulic fracturing. The structure and mechanical difference of different lithofacies lamination are the basis to reveal the fracture propagation mechanism. In this paper, research focused on three continental oil shale with different lithofacies in Qikou sag, Bohai Bay basin, including Quartz-Feldspar dominated shale, Carbonate dominated shale and mixed-mineral shale. Scanning electron microscopy and mineral analysis are used to identify quartz-feldspar lamination and mixture lamination in Quartz-Feldspar dominated shales, as well as carbonate lamination and mixture lamination in Carbonate dominated shales. The distinct laminations with different characteristics were precisely located using FIB, which served as the guiding tool for the indentation experiment. The micromechanical properties of laminations with different lithofacies in oil shale samples are examined using the nanoindentation technique, highlighting their distinct differences. The findings demonstrate that the micromechanical properties of quartz-feldspar lamination in Quartz-Feldspar dominated shales exhibit superior strength, while the mechanical difference between laminations in Quartz-Feldspar dominated shales are significantly larger. The quartz-feldspar lamination exhibits the highest resistance when subjected to indentation force. The mechanical properties of mixture lamination in Quartz-Feldspar dominated shales and Carbonate dominated shales are comparable due to their similar mineral composition. Moreover, in conjunction with macroscopic rock mechanics experiments, it has been verified that the lamination structure facilitates the initiation and propagation of macroscopic fractures under stress loading.

Mechanical properties of vinyl ester hybrid composite laminates reinforced with screw pine and glass fiber

<abstract> <p>The screw pine and E-glass fibers were hybridized in the vinyl ester resin matrix to prepare the hybrid composite laminates in the present communication. Hybrid composite laminates at the constant volume fraction of 35.12% has been fabricated using the hot press compression molding in two forms, namely dispersed and skin-core, to evaluate the mechanical properties. Mechanical properties of composite laminates were studied based on the various volume fraction of glass fiber content (0, 3.32, 8.15, 12.44 and 16.53 vol.%). The scanning electron microscopy (HITACHI S-3000N) was used to study the fracture surface of composite laminates. The results of hybrid composite laminates were compared with a neat resin sample and screw pine fiber (35.12 vol.%) alone composite. The results revealed that the mechanical properties of both the type of composite laminates increased as glass fiber addition was increased. The SPF18.59/GF16.53 hybrid composite laminate exhibits the highest level of mechanical properties because of the concentration and higher elongation percentage of glass fibers. Moreover, the skin-core type composites perform better than those of the dispersed type hybrid composites. Because of the stretching nature of screw pine fibers, they elongate when the load is transferred from glass fibers to screw pine fibers, resulting in an increase in mechanical properties. The property values were predicted using a theoretical model, and it was found that the two were in good agreement.</p> </abstract>

Study on the Influence of Modified Thermoplastic Adhesive on the Properties of Metamaterial Composite Laminates

Study on the Influence of Modified Thermoplastic Adhesive on the Properties of Metamaterial Composite Laminates

An Analysis of Tensile and Compressive Properties of Carbon Fiber High-Entropy Alloy Composite Laminates

An Analysis of Tensile and Compressive Properties of Carbon Fiber High-Entropy Alloy Composite Laminates

GO-tagged PEI sizing agent imparts self-healing and excellent mechanical properties to carbon fiber reinforced epoxy laminates.

Carbon fiber-reinforced epoxy (CFRE) laminates have attracted significant attention as a structural material specifically in the aerospace industry. In recent times, various strategies have been developed to modify the carbon fiber (CF) surface as the interface between the epoxy matrix and CFs plays a pivotal role in determining the overall performance of CFRE laminates. In the present work, graphene oxide (GO) was used to tag a polyetherimide (PEI, termed BA) containing exchangeable bonds and was employed as a sizing agent to improve the interfacial adhesion between CFs and epoxy. This unique GO-tagged-BA sizing agent termed BAGO significantly enhanced the mechanical properties of CFRE laminates by promoting stronger interactions between CFs and the epoxy matrix. The successful synthesis of BAGO was verified by Fourier-transform infrared spectroscopy. Additionally, the partial reduction of GO owing to this tagging with BA was further confirmed by X-ray diffraction and Raman spectroscopy, and the thermal stability of this unique sizing agent was evaluated using thermogravimetric analysis. The amount of GO in BAGO was optimized as 0.25 wt% of BA termed 0.25-BAGO. The 0.25-BAGO sizing agent resulted in a significant increase in surface roughness, from 15 nm to 140 nm, and surface energy, from 13.2 to 34.7 mN m-1 of CF. The laminates prepared from 0.25-BAGO exhibited a remarkable 40% increase in flexural strength (FS) and a 35% increase in interlaminar shear strength (ILSS) due to interfacial strengthening between epoxy and CFs. In addition, these laminates exhibited a self-healing efficiency of 51% in ILSS due to the presence of dynamic disulfide bonds in BAGO. Interestingly, the laminates with 0.25-BAGO exhibited enhanced Joule heating and enhanced deicing, though the EMI shielding efficiency slightly declined.

Effects of seawater and acidic environment on mechanical properties of iron powder-loaded glass-epoxy composite laminates: Experimental and analytical investigation

This study assesses the impact of seawater and acidity on a glass epoxy composite filled with pure iron powder. Plates with varying iron content (15%, 20%, and 25%) were created using contact molding, with 30% glass fiber content. After dividing the plates into samples, a three-point bending examination was conducted following ISO14125 standards. The samples were immersed in saltwater (Group A), an acidic solution (Group B), or kept dry for comparison (Group C). Each subgroup had 15 specimens (5 for each iron %), immersed for over 60 days before undergoing bending tests. Results showed a significant decline in flexural strength, with a maximum reduction of 29.7% in Group A and 37.9% in Group B, while Young's modulus decreased up to 34.8% in Group A and 45.6% in Group B. The two-way ANOVA approach confirmed these findings, and microscopic examinations and FTIR analysis after immersion elucidated physical alterations and chemical reactions. Despite certain advantages, such as specific applications, the composite's limitations in corrosion resistance, durability, and production cost may restrict its relevance in various industrial and real-world applications. Consideration of these factors is essential before choosing this material for a specific project.

INVERSE ANALYSIS OF THE AMPLITUDE-DEPENDENT DAMPING PROPERTIES OF EPOXY/GLASS FIBER LAMINATES

In this paper, we present the experimental results obtained and corresponding inverse analysis employed to determine the amplitude-dependent damping properties of laminates made of glass fiber reinforced plastic (GFRP). Free damped vibration tests of cantilever beams with different symmetric stacking sequences were performed. Logarithmic decrement analysis was used to evaluate the effective amplitude-dependent loss factor of the samples. Inverse analysis was used to find the single-ply dynamic properties based on the laminated beam theory and the complex moduli approach. It was found that the loss factors of GFRP laminates almost linearly depend on the maximum strain amplitude. The maximum value of the loss factor of unidirectional ply was realized in the transverse direction to the fibers and reached ~ 0.023 for strain amplitudes up to 0.1% in the frequency range of 20-60 Hz.

Effect of CNT film interleaves on the flexural properties and strength after impact of CFRP composites

Abstract Carbon nanotubes (CNTs), with their high strength, modulus, and large aspect ratio, have emerged as a frontrunner in nano-reinforcements. In this study, CNT films (CNTFs) were inserted between carbon fiber-reinforced polymer (CFRP) prepregs and were cured together to form interleaved composite laminates. The influence of CNTF interleaves on the flexural and interlaminar properties of fiber-reinforced polymer (FRP) laminates is investigated. Three different types of FRP specimens were tested, namely, 0CNTs-CFRP, 2CNTs-CFRP, and 4CNTs-CFRP. The surface and internal damage characteristics and mechanism of CNTF were analyzed using scanning electron microscopy and computed tomography testing methods. The results showed that the flexural strength of 0° CNTs-CFRP beams increased by 3.79 and 14.34% for 2CNTs-CFRP and 4CNTs-CFRP, respectively, while the flexural modulus increased by 7.33 and 13.76%, respectively. It was also found that the damage area and overall deformation after impact with the energy of 5 J was reduced in the CNTF interleaved composite beams. This work has confirmed that the mechanical properties of FRP laminates can be improved by conveniently inserting CNTF during stacking prepregs in the manufacturing process. However, there is a reduction in the flexure after impact properties of the CNTF-CFRP composites, suggesting that the interface between CNTF and FRP layers should be optimized for high residual strength.

Effects of manufacturing parameters on mechanical interface properties of thin wood veneer laminates

This study explores fast manufacturing techniques for thin wood laminates made from European beech veneers and 1-component polyurethane adhesive. Manufacturing factors such as pressure and pressing time are investigated following well-established standards developed for fibre-reinforced materials (ASTM D5528 and ASTM D7905). Mode I and Mode II interlaminar fracture properties are calculated to quantify the effects of the different manufacturing techniques on the bond quality. It is found that pressing time and pressure can be minimised to 10 minutes and 0.1 MPa from 75 min and 1.0 MPa as suggested by the adhesive manufacturer, without reducing critical Mode I strain energy release rates of around 500 to 600 J/m2. However, the standard deviation of these properties increases with decreasing pressure and pressing time. Furthermore, the results show that while ASTM D5528 for Mode I testing can be used with thin wood veneer laminates, the ASTM D7905 for Mode II fracture testing is not directly applicable to these materials.

Experimental Study on the Optimization of the Autoclave Curing Cycle for the Enhancement of the Mechanical Properties of Prepreg Carbon-Epoxy Laminates.

In this study, the influence of the technological parameters of autoclave curing on the resulting mechanical properties of laminates was investigated. The main criterion for optimizing the curing was to extend the processing window with a lower prepreg viscosity. At the same time, the issue of setting the pressure level before the heat ramp to the final cure temperature was also addressed. An experimental method of measuring the indentation viscosity of the prepreg was used to determine the viscosity profile. Despite the experimental nature of the method, the reliability of this method for rapid approximate identification of the processing window of the prepreg was verified by the results of the study. Several laminates with the same ply orientation were produced using the selected cure cycles, from which test specimens were cut with a water jet and inspected by confocal microscopy. The mechanical properties of tension and flexure were measured within the individual curing cycles using tests according to ISO standards. The data reported demonstrate that the experimental method of optimizing the curing parameters has successfully increased the selected mechanical properties. The resulting mechanical properties of the laminates were enhanced by up to 20% compared to the non-optimized cure cycle. The influence of the type of cure cycle on the resulting thickness of the cured laminate was evaluated in this study.

Enhanced Reverse-Engineering Method for Accurately Predicting Lamina Properties in Laminated Composites via Combined Static and Dynamic Finite Element Simulations

This study aims to ascertain the material characteristics that are intrinsic to the prepreg layer within a laminated composite structure. The elastic modulus of the lamina, a primary determinant of composite structural behavior, is the focal point of this analysis. This parameter has been assessed by employing reverse-engineering techniques on a composite composed of sequentially stacked prepregs. The investigation entailed simulating the behavior of the composite under static loads and conducting modal analyses to reflect both static and dynamic conditions. The findings indicate that the elastic modulus values derived from combined tensile and modal analysis simulations exhibit superior accuracy compared to those obtained through tensile simulation alone. Specifically, the maximum prediction error for E1 (the tensile-direction elastic modulus of one lamina sheet) decreased from 1.17% to 0.28%, and that of E2 (the transverse-direction elastic modulus of one lamina sheet) decreased from 12.01% to 7.30%. Further simulations incorporating fabrication error variances underscored the critical nature of precise E2 analysis. The proposed methodology evidenced a more accurate assessment of E2, underscoring its potential to enhance the reverse-engineering process in composite material design.

Significantly improve the strength and ductility of AZ31 Mg alloy by introducing pure Ti

In this work, we introduced pure Ti into AZ31 Mg alloy by extrusion process followed by annealing at 350 °C for 1 h to significantly improve the mechanical properties of AZ31 laminate, with a yield strength of 243 MPa, an ultimate tensile strength of 338 MPa and a uniform elongation of 17.7%. Microstructural characterizations showed that there was slight diffusion of elements (Al, Zn, and Mn) across the layer interface, and the interface between the constituent layers maintained semi-coherent. Moreover, significant microstructure heterogeneities appeared across the hetero-interface, where the Mg layer possessed large equiaxed grains with lower dislocation density, while the Ti layer formed ultrafine grains (UFG) and unrecrystallized block grains with extensive dislocation cells and dislocation walls. Combining the digital image correlation (DIC) technique and in-situ electron backscatter diffraction (EBSD), it was found that the microstructural heterogeneities induced significant strain gradients near the layer interface during plastic deformation, which needed to be accommodated by geometrically necessary dislocations (GNDs). This resulted in hetero-deformation-induced (HDI) strengthening and HDI strain hardening to strengthen and toughen the AZ31 laminated composite. Additionally, the introduction of the Ti layer effectively hindered the propagation of the cracks and consequently improved the ductility of the laminate.

On the mechanical behavior of carbon fiber/epoxy laminates exposed in thermal cycling environments

Carbon fiber reinforced polymer (CFRP) composites are commonly used for reflectors of artificial satellites operating in low earth orbit (LEO). The decay of the modulus of the CFRP composite varies under different thermal cycling environments, which can lead to a reduction in the accuracy of the reflector panels, affecting the transmission of signals. This paper investigates the impact of different thermal cycling conditions on the mechanical behavior of carbon fiber/epoxy laminated composites experimentally. Three kinds of thermal cycling conditions involving continuous temperature changes are employed to explore the influence of temperature range on the residual tensile and in-plane shear moduli of the laminates. Test results indicate that the upper temperature limit and the temperature span of the thermal cycling conditions jointly affect the mechanical properties of CFRP composite laminates, but the responses of the residual tensile and in-plane shear moduli are different under the variation of each temperature parameter alone. The residual tensile and in-plane shear moduli of the laminates under thermal cycling decrease with an expansion of the temperature span having the same upper limit. If the temperature span remains constant, an increase in the upper temperature limit leads to an increase in the residual tensile modulus, but a decrease in the residual in-plane shear modulus. The main damages causing the decay of residual tensile and in-plane shear moduli of unidirectional laminates were investigated by scanning electron microscopy (SEM) technology. Observations of the microscopic fracture of the material show that the post-curing reaction factor predominantly influences the residual tensile modulus of unidirectional laminates, while the fiber/matrix interface damage factor dominates the residual in-plane shear modulus of the unidirectional laminates. Furthermore, an increase in the fiber tensile modulus decreases both residual tensile and residual in-plane shear moduli. Notably, the residual in-plane shear modulus exhibits greater sensitivity to thermal cycling compared to the residual tensile modulus. The findings reported in this paper would provide valuable insights and guidance for the design and application of carbon fiber/epoxy composites subjected to thermal cycling conditions.

Effect of ultraviolet radiation on the low‐velocity impact and compression after impact performances of aerospace composite laminates

AbstractThe low‐velocity impact (LVI) characteristics and compression after impact (CAI) properties of aircraft composite laminates under the influence of ultraviolet (UV) radiation were studied. Firstly, 0, 30, 60, 90 days of UV radiation experiments were carried out on the specimens to analyze the characteristics of the surface topography. Secondly, LVI experiments, the impact energies of 10, 17, and 25 J, were carried out on specimens to analyze the impact response laws and the characteristics of the impact instantaneous deformation. Finally, through CAI experiments and scanning electron microscope (SEM) techniques to clarify the influence mechanism of UV radiation on the residual compressive strength of specimens. The results showed that with the increase of UV radiation time, the shrinkage and erosion phenomena of the surface matrix and the exposure degree of the surface fibers were gradually increased, and the surface fibers were completely exposed after 90 days of radiation. At the same impact energy, with longer radiation time, the peak force gradually decreased (from 8673.86 to 7851.68 N at 17 J), the absorbed impact energy (from 9.48 to 11.13 J at 17 J) and maximum displacement (from 4.1 to 4.73 mm at 17 J) increased, the depth of pit on the impact surface decreased (from 0.213 to 0.14 mm at 17 J), and the internal damage projection area increased (from 906.68 to 1158.66 mm2 at 17 J). The compression damage of the specimens not exposed to/ exposed to UV radiation was mainly fiber cracking/interlayer delamination, respectively.Highlights Ultraviolet (UV) radiation makes the matrix of surface shrink, the fibers exposure increase. The Stage II has obvious oscillation phenomenon in four stages of the low‐velocity impact process. With prolonged UV radiation, the projected area of internal damage expands. The residual compressive load increases with the increase of UV radiation time.

Experimental and simulation analysis of the effect of GNPs on the mechanical and interfacial properties of CF/PEEK-Ti fiber metal laminates

In this study, graphene nanoplatelets (GNPs) were used to improve the interfacial and mechanical properties of carbon fibre-reinforced polyetheretherketone-based titanium alloy laminates (CF/PEEK-Ti) and molecular dynamics (MD) simulations were used to investigate the mechanism by which GNPs improve CF/PEEK-Ti, collectively known as fibre reinforced metal laminates (FMLs). In addition, surface anodising of titanium (Ti) sheets was used further to enhance the interfacial bonding properties of the FMLs. The experimental results showed that the flexural and shear strengths of the anodised FMLs were increased by 77.7% and 29.5%, respectively, compared with those of the Ti plates without surface anodisation. Based on this, different levels (0–1.5 wt.%) of GNPs were added to the FMLs matrix, and test results showed that FMLs containing 0.5 wt.% GNPs had the best flexural and shear strengths, 108.9% and 130.8% higher than untreated FMLs without GNPs. In addition, an in-depth microscopic analysis was carried out to understand the enhancement mechanism of GNPs on FMLs. Finally, MD simulations were used to analyze the role and mechanism of GNPs in this system. The results show that the addition of GNPs can increase the interfacial energy of FMLs. In other words, the interfacial mechanical properties of FMLs are improved. The effect of the dispersion of GNPs on the interfacial properties of FMLs was also investigated. The polyetheretherketone (PEEK) matrix could be significantly improved by well-dispersed GNPs. These findings provide insight into designing high-performing composites for various engineering applications.

Coupling four-parameters bond-based peridynamic and finite elements for damage analysis of composite structures

The difficulty in inferring the failure region is the main obstacle for applying coupling algorithms for progressive damage analysis of composite structures. This paper presents a new finite element and peridynamic (PD) coupling framework, in which an adaptive transformation technique is implemented for failure analysis of laminated structures. Since the mechanical properties of a multi-layer laminate can be characterized by single-layer finite elements, this coupling model (CM) exhibits great potential in balancing numerical accuracy and computational efficiency. During the damage evolution process, the single-layer finite element is adaptively transformated into multi-layer PD material points according to the transformation criterion as the load increases, and then the damage begins to nucleate and evolve in the PD subregions. Compared with other coupling models, the PD subregions adaptively appear in the potential failure sites, and its area is much smaller than other finite element subregions. Thus, the theoretical advantages of coupling algorithms in modeling multi-layer structures can be fully utilized, and the computational efficiency of numerical models will be greatly improved. The accuracy of the developed coupling model is demonstrated by the stretching example of composite laminates, and the damage examples of laminates with a cutout further demonstrates the strong capability of the proposed coupling model in capturing the failure characteristics.

Influence of Relative Humidity on Electrical Properties of Textile Laminates

The aim of this paper is to determine the influence of relative humidity on the comfort and electrical resistance properties of textile laminates in order to predict possible changes in footwear protection levels. Four textile laminates of different structure and fibre nature were selected for the study. It was determined that water vapour absorption of textile laminates strongly depends on the humidity of the storage environment. The absorption ability of laminates increases about 1.8 – 3 times as relative humidity increases from 65 % up to 95 %. The degree of increase depends on the textile laminate structure and the nature of the materials layers. The electrical properties of protective footwear can be influenced by the structure, thickness, relative humidity, and voltage of textile laminates. For textile laminates composed of natural and synthetic fibres and polymer foam as insulators, the resistivity increases with the thickness of the synthetic fibre and polymer layer. At low voltage (U = 100 V), the textile laminates tested became insulating materials, as the electrical resistivity exceeded the threshold values for antistatic materials in all relative humidity ranges. At high voltage (U = 500 V) the electrical resistivity of textile the laminates drops dramatically when the relative air humidity increases and the level of protection of the laminates depend on the amount of moisture absorbed and the nature of the layer materials. The laminates possessed insulating properties in environments of up to 65 % relative humidity. In a high humidity of the environment, the insulating properties of textile laminates turned to antistatic, except for laminate without a polymeric membrane, which became conductive.

Structural characteristics of continental carbonate-rich shale and shale oil movability: A case study of the Paleogene Shahejie Formation shale in Jiyang Depression, Bohai Bay Basin, China

Based on rock mineral and geochemical analysis, microscopic observation, physical property measurement, and thin laminae separation test, etc., the characteristics of typical laminae of the Paleogene Shahejie Formation carbonate-rich shale in the Jiyang Depression were analyzed, and the organic matter abundance, reservoir properties, and oil-bearing properties of different laminae were compared. Typical shale storage-seepage structures were classified, and the mobility of oil in different types of shale storage-seepage structure was compared. The results show that the repeated superposition of mud laminae and calcite laminae are the main layer structure of carbonate-rich shales. The calcite laminae are divided into micritic calcite laminae, sparry calcite laminae and fibrous calcite vein. The mud-rich laminae are the main contributor to the organic matter abundance and porosity of shale, with the best hydrocarbon generation potential, reservoir capacity, and oil-bearing property. The micritic calcite laminae also have relatively good hydrocarbon generation potential, reservoir capacity and oil-bearing property. The sparry calcite laminae and fibrous calcite vein have good permeability and conductivity. Four types of shale storage-seepage structure are developed in the carbonate-rich shale, and the mobility of oil in each type of storage-seepage structure is in descending order: sparry calcite laminae enriched shale storage-seepage structure, mixed calcite laminae enriched shale storage-seepage structure, fibrous calcite vein enriched shale storage-seepage structure, and micritic calcite laminae enriched shale storage-seepage structure. The exploration targets of carbonate-rich shale in the Jiyang Depression Shahejie Formation are different in terms of storage-seepage structure at different thermal evolution stages.

Rock Plate Impact Experiment Based on ANSYS Workbench

The study of the physical properties of laminate mainly focuses on the static strength and elastic modulus. Its impact resistance has not attracted enough attention. However, the impact resistance of the multi-layer board used in climbing walls is particularly important to protect the safety of climbers. Using the display dynamics solver ANSYS Workbench and referring to the test method in EN 12572-1-2007, a finite element model of the rock slab impact test was established. The maximum stress and strain of each part during impact were solved, and the vulnerability point of the structure was analyzed. By changing the impact height and solving the influence on the rock slab under each test condition, the results show that the maximum stress of the slab changes nonlinearly. The numerical simulation results provide reference data and new development modes for the development of test methods and testing equipment in the next step of improving national standards.