Layers Of Composite Material Research Articles

Laser forming of glass laminate aluminium reinforced epoxy (GLARE): On the role of mechanical, physical and chemical interactions in the multi-layers material

The present work concerns the laser forming of Fiber-Metal Laminates (FMLs) by a high power diode laser source. FMLs are made of different layers of metal and composite material. The wide difference in the thermo-mechanical and physical properties of the different layers within FMLs makes them extremely problematic to be reprocessed. In particular, the economic shaping of FMLs in complex shapes is practically impossible, limiting greatly their field of application. Therefore, this manuscript explores the possibility of using laser forming to reprocess FMLs and obtain final components with precisely controlled bending radii. For this purpose, the effect of the laser operating parameters, namely laser power, scanning speed and number of passes, on the final shapes of FMLs was investigated. Secondly, further tests were also performed to obtain other complex shapes on FMLs from multiple laser scanning paths, side by side and equidistant on the substrates. An analysis of the failure of the substrates during the shaping process was also performed, with particular emphasis on deformation mechanisms, interfacial delamination and thermal alteration of the layers. The experimental results showed the good viability of laser reprocessing to shape FMLs, thus opening up new possible applications of this class of materials in aeronautical and aerospace applications.

The averaged model of layered elastic-creeping composite materials

Composite materials consisting of several phases are widely used in modern construction. The mechanical characteristics of elastic-creeping layered composite materials are considered in the article. Each of the constituent phases has the properties of elasticity, viscosity or creep. Numerous experiments have shown that the properties of structurally heterogeneous materials can differ significantly from those of the individual components making up the composition. Besides, rapidly changing coefficients of differential equations describing such composite materials greatly complicate the solution of boundary value problems even with the help of computer calculation methods. Therefore, the homogenization method is used to solve such problems. Creep kernels are given by the sum of a finite number of decreasing exponential functions. The use of creep kernels of this type is experimentally justified. In this paper, it is shown that an effective (averaged) model for a composite material with the indicated properties is a homogenized medium that is described by a creep kernel, also represented by a sum of exponential functions. An algorithm for the rapid and accurate calculation of averaged creep kernels of a homogenized material is proposed.

Preparation and Properties of Laminated Bionic High-strength Composites of B 4 C Ceramic/Al

Based on the laminar composite structure, the hardness distribution pattern and crack arrest property of Rapana venosa shell, bionic layered composite materials were prepared via hot-pressing sintering by using B4C/5083Al system and pure 5083Al as materials. The microstructure and mechanical properties were investigated by scanning electron microscope (SEM) and universal tester. The results show that on the macroscopic level, the bionic layered composite material has a multi-layered structure which is composed of layer of B4C/5083Al and flexible layer of 5083Al. The bionic composites exhibit and hard” distribution characteristic of hardness. On the microscopic level, the layer of B4C/5083Al consists of B4C and 5083Al matrix, and B4C is staggered and interlinked in 5083Al matrix with combination of soft and hard properties. The bionic layered composites own higher compressive strength and impact toughness, and the layered overlapping structure can reset the direction of crack in the next layer, which lead the crack deflection phenomena and high impact resistance.

Influence of High Energy Impact on the Structural-Phase State and Tribological Properties of the Surface Layer of Metal-Ceramic Composite Materials

The structural-phase state of the 50 vol % TiC/50 vol % (Ni‒Cr) surface layer of a metal-ceramic composite subjected to pulsed electron irradiation in plasma of inert gases with different atomic masses is experimentally investigated and the obtained results are presented. The regularities of the influence of the atomic mass of a plasma-forming inert gas on the characteristic features of the heterogeneous structure of the nanostructured surface layer of a metal-ceramic composite and the thickness of the surface layer with modified structure are presented and discussed. It is demonstrated that, in the case of the pulsed electron irradiation of a metal-ceramic alloy, the formation of a nanostructured surface layer significantly increases the surface-layer wear resistance and reduces the friction coefficient over the irradiated surface. An increase in the wear resistance of the surface layer and a decrease in the friction coefficient along the irradiated surface occur in accordance with an increase in the atomic mass of the plasma-forming gas under pulsed electron irradiation.

Investigation of the Behavior of Hardening Masonry Exposed to Variable Stresses.

This paper analyzes the behavior of masonry under variable loads during execution (construction stage). It specifies the creep coefficient for calcium silicate brick masonry, presenting the research data of masonry deformation under variable and constant long-term loads. The interaction of separate layers of composite material in masonry is introduced and the formulae for determining long-term deformations are offered. The research results of masonry’s compressive strength and deformation properties under variable and constant long-term loads are presented. These are then compared to calculated ones. According to the presented comparison, the calculated long-term deformations coincide quite well with those determined experimentally.

Effects of Composite Material Layers on the Mechanical Properties for Partial Foot Prosthetic Socket

In this work, nine types of laminated composite materials used for experimental study to investigate the tensile and fatigue properties of partial foot prosthetic socket which fabricated by using vacuum pressure system . The composite material matrix were Lamination 80:20and reinforced with nine types of laminations (perlon, n-glass, fiber glass and carbon) by variation of thickness according to lamination. Results show that the mechanical properties were improved by increasing the two layers of carbon fiber, fiber glass and n-glass layers instead of zero layer with six layers of perlon lead to the increased in(yield strength σy, ultimate tensile strength σult and modules of elasticity E with (71% ,76% and 58%) respectively for carbon fiber, (20% , 19% and 40%) for fiber glass and ( 22% , 5.5% and 29% ) for n-glass. Results show that (3perlon+2carbon fiber+3perlon) gives the best value of mechanical properties and has higher Endurance limit stresses (σe) which increase lifetime for the patient . It is recommend to use this type of lamination for the layup partial foot prosthetic socket because it meets the demand lamination layers for acceptable mechanical properties and its minimizing the cost of socket lamination to suitable costing value.

LABORATORY STUDY OF POLYMERIZATION DEPTH OF COMPOSITE MATERIALS

With the advent of modern improved restorative materials, the process of teeth restoration has become even more complex, but it provides an impeccable anatomical, functional and aesthetic result. In the new generation of composites there is a number of advantages, namely, increased mechanical strength, increased abrasion resistance, hardness, colour stability. All these allows restoring the anatomical shape of teeth and functional characteristics even with a significant degree of damage. However, after restoration, complications are often associated with polymerization of stress and shrinkage of composite materials, inconsistency between the coefficients of volume expansion of materials and hard tissues of teeth, etc.
 Recently, due to the improvement of materials, the appearance of highly filled composites, it has become possible to apply the first layer of reinforced rarefaction of composite with a thickness of up to 4 mm. However, when the thickness of a layer of any composite material increases, there must be a question about the degree, quality and depth of the polymerization that initiates the light flux of the photopolymerizer. Therefore, the choice of materials and technology for restoration of the teeth should be reasonable and optimal.
 The aim of this work was to study the polymerization depth of composite materials under different modes of light exposure in laboratory conditions.
 Materials and methods. In the course of a laboratory research the ISO 4049 method was used, the depth of polymerization of liquid and composite materials, and total number of 120 samples were studied. Samples were made up in a special shape with a diameter of 4 mm hole and exposed to light flux of 1000 mW/cm2 of LED photopolymerizer in two modes: “soft start” and constant high intensity. Then a sample of photoconductive material was extracted from the form, a layer of material that was not hardened was separated, the length of the hardened specimen was measured, divided by 2 and the value for the polymerization depth of the material under study was obtained.
 Results of the research and their discussion. Statistically significant maximum indices of the polymerization depth were obtained with the use of composite materials for solidification of the light flux of a photoconductive photoconductor of constant high intensity. Light flux in the “soft start” mode leads to a systematic decrease in the level of polymerization depth. But if we compare the polymerization depth of samples of nanocomposite material in case of one-stage hardening with the adhesive system, they were close enough to such relatively rarefying composites in both modes of light exposure.
 Conclusions. The results obtained in the study indicate the expediency, in case of need, to increase the thickness of the layer of rarefied composite materials for the application of their solidification of the light flux of constant high intensity. Concerning the simultaneous hardening of nanocomposite material and the adhesive system, it can be assumed from the results of the study that some of the properties of this material, thus obtained, correspond to the corresponding characteristics of the rarefied composites.

Finite Element Simulation of Aluminium/GFRP Fibre Metal Laminate under Tensile Loading

The response of a fibre metal laminate (FML) model to the tensile loading is predicted through a computational approach. The FML consisted with layers of aluminum alloy and embedded with one layer of composite material, Glass fibre Reinforced Plastic (GFRP). The glass fibre and aluminium alloy 2024-0 was laminated by using thermoset epoxy. A compression moulding technique was used in the process of a FML fabrication. The aluminium has been roughen by a metal sanding method which to improve the bonding between the fibre and metal layer. The main objective of this paper is to determine the failure behaviour of the FML under the tensile loading. The responses on the FML under the tensile loading were numerically performed. The FML was modelled and analysed by using Abaqus/CAE 6.13 version. Based on the experimental and FE data of the tensile, the ultimate tensile stress is 120 MPa where delamination and fibre breakage happened. A numerical model was developed and agreed well with the experimental results. The laminate has an inelastic respond to increase the tensile loads which due to the plasticity of the aluminium layers.

Studies of the Microstructure and Physical and Mechanical Properties of Layered Metal Composite Materials Based on a Molybdenum Matrix

A method of producing layered metal composite materials (layered MCM) based on a molybdenum matrix is examined; the microstructure and physical and mechanical properties of the produced layered MCM are investigated. Molybdenum foil with a thickness of 0.25 mm and metal composite powder based on a molybdenum matrix doped with silicon and boron are used as layers. The metal composite powder based on a molybdenum matrix is synthesized by a high-energy mechanochemical method. The layered metal composite material is produced by compacting the molybdenum foil and the metal composite powder by means of spark plasma sintering (SPS). Investigation of the microstructure of layered MCM samples after thermal treatment demonstrates that the material preserves the layered structure after a prolonged exposure to elevated temperatures. Preservation of a layered structure upon high-temperature treatment indicates a high thermal stability of the obtained composite material. The performed physical and mechanical tests allow us to make conclusions on a complete consolidation of the metal composite materials by means of spark plasma sintering. The layered MCM based on a molybdenum matrix are to be used in a production of assemblies and parts of for aeronautic and space flight vehicles.

Hollow porous bowl-shaped lithium-rich cathode material for lithium-ion batteries with exceptional rate capability and stability

Although lithium-rich layered composite cathode materials can meet the requirements of high discharge capacities and energy densities of lithium-ion batteries (LIBs), the drawbacks of encountering structural reconstruction, sharp voltage decay during cycling as well as low packing density still exist, which retard their further commercial development. This paper presents a novel approach to construct hollow porous bowl-shaped Li1.2Mn0.54Ni0.13Co0.13O2 (denoted as HPB-LMNCO) particles, which involves bowl-shaped carbonaceous particles as the predominant template and polyvinylpyrrolidone as an assistant soft template. One crucial step during the synthetic process is the controlled growth of metal ions with specific molar ratios in the bowl-shaped carbonaceous particles, and the key control parameter is the heating rate to ensure the prepared particles own the desired hollow porous bowl-shaped morphology. Of particular note is the desirable architecture which not only inherits the merits of hollow structures but also facilitates the tight particles packing. Owing to these advantages, utilizing this HPB-LMNCO as a cathode material manifests impressive rate capability and exceptional cycling stability at high rates with capacity retention of above 82% over 100 cycles. These results reveal that structural design of cathode materials play a pivotal role in developing high-performance LIBs.

Pharmacology of BMN 250 administered via intracerebroventricular infusion once every 2 weeks for twenty-six weeks or longer in a canine model of mucopolysaccharidosis type IIIB

An analytical method for determination of dimensions of longitudinal crack in monolithic beams, based on frequency measurements, has been extended to model L and inverted T cracks. Such cracks including longitudinal crack arise in beams made of layered isotropic or composite materials. A new formulation for modelling cracks in bi-material beams is presented. Longitudinal crack segment sizes, for L and inverted T cracks, varying from 2.7% to 13.6% of length of Euler-Bernoulli beams are considered. Both forward and inverse problems have been examined. In the forward problems, the analytical results are compared with finite element (FE) solutions. In the inverse problems, the accuracy of prediction of crack dimensions is verified using FE results as input for virtual testing. The analytical results show good agreement with the actual crack dimensions. Further, experimental studies have been done to verify the accuracy of the analytical method for prediction of dimensions of three types of crack in isotropic and bi-material beams. The results show that the proposed formulation is reliable and can be employed for crack detection in slender beam like structures in practice.

Preparation and characterization of graphene oxide and it application as a reinforcement in polypropylene composites

In this article, graphene oxide (GO) is modified using Phosphorous acid via the strong –P = O in the study reported in the paper. And the chemical structure was characterized by Fourier Transform infrared spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X‐ray diffraction. And polypropylene (PP) composites are prepared by melt compounding method, and functionalized graphene oxide (FGO) is in situ thermally reduced during the processing. The thermal stability, mechanical and flame properties, and morphology for the char layer of composite materials were separately investigated using TG (Thermogravimetric analysis), tensile and charpy impact tests and SEM (scanning electron microscope). The results of SEM and TEM indicate that FGO nanosheets are homogeneously dispersed in polymer matrix with intercalation and exfoliation microstructure. The FGO/PP nanocomposite exhibits higher thermal stability and flame retardant property than those of the GO counterpart and pure PP. During the thermal decomposition, The –P = O introduced to improve the flame effect and the yield of the carbon residue was increase. The heat release rate and the escape of volatile degradation products are reduced in the FGO‐based nanocomposites. POLYM. COMPOS., 40:723–729, 2019. © 2018 Society of Plastics Engineers

Synthesis and properties of a new halogen-free flame retardant for polyethylene

PurposeThis paper aims to study a new halogen-free flame retardant that was prepared and characterised.Design/methodology/approachThe phenyl phosphinic arid di-4-[1-(4-pheny phodphonic acid monophenyl ester-yl)-methyl-ethyl] phenyester dimelaminium (PDEPDM) was synthesised using phenylphosphonic dichloride, melamine, bisphenol A, triethylamine and dichloromethane via solvent-based reaction, that was added into the polyethylene to test flame performance. The chemical structures of PDEPDM were characterised by 1H nuclear magnetic resonance spectroscopy, mass spectrometry and Fourier transform infrared spectrometer. The thermal stability, mechanical and flame properties, and morphology for the char layer of composite materials were separately investigated using thermogravimetric analysis, tensile and charpy impact tests, limiting oxygen index (LOI) and UL-94 HB flammability standard and scanning electron microscope.FindingsThe results showed that the PDEPDM had been prepared successfully. When the intumescent fame retardant was added into the PE, the LOI of composite material was improved.Research limitations/implicationsThe PDEPDM can be prepared successfully and can improve the flame resistance of composite material.Practical implicationsThe PDEPDM has excellent flame-retardant properties and produce no toxic fumes when burnt in case of fire.Originality/valueUnder the optimal conditions, when the 32 per cent (Wt.%) PDEPDM was added into the PE, the LOI was 29.8, tensile strength and impact strength were 10.06 MPa and 16.77 kJ/m2.

Analysis of S0/A0 elastic wave mode conversion phenomenon in glass fibre reinforced polymers

In this paper results of experimental analysis of elastic guided wave mode conversion phenomenon in glass fibre reinforced polymers GFRP are presented. Results of research presented in this paper are strictly focused on S0/A0' mode conversion caused by discontinuities in the form of circular teflon insert simulating damage and impact damage. Experimental research is based on non-contact elastic wave sensing with utilisation of scanning laser Doppler vibrometer SLDV and full wave-field measurements. In presented research influence of location of circular teflon insert on S0/A0' mode conversion is investigated. Teflon inserts were located between layers of composite material at different depth. Moreover influence of impact damage with different energy on S0/A0' mode conversion is investigated. Analysis of influence of investigated discontinuities on S0/A0' mode conversion are based on the elastic wave mode filtration in frequency-wavenumber domain. Mode filtration process allows to remove effects of unwanted type of mode propagation in forward or backward direction. Effects of S0/A0' mode conversion are characterise by mode conversion indicator based on amplitude of new mode A0'.

Fracture resistance assessment of endodontically accessed hybrid ceramic crowns repaired with two different protocols

Statement of the Problem: It is frustrating when the patient has recently placed an all ceramic crown and now has symptoms of irreversible pulpitis or necrosis and an endodontic treatment is indicated. Providing endodontic care through all ceramic crowns in situ is a challenge. Endodontic access through the restoration may weaken it and initiate micro cracks that may propagate resulting in failure. The best practice protocol to improve the fracture resistance of endodontically accessed and repaired all ceramic crowns cannot be identified based on the currently available scientific data. In addition, wider variations in repair protocols are worthy of further investigation.Purpose: The aim of this in vitro study was to measure the fracture resistance of endodontically accessed Vita Enamic crowns repaired with two different protocols (direct composite and ceramic plug).Materials and Methods: Fifteen freshly extracted human mandibular molar teeth were used in this study. All teeth were mounted in epoxy resin blocks using a special device (parallelometer). Teeth were randomly divided into three groups of five specimens each according to the type of restoration as follows; Group I: Teeth restored with full coverage CAD/CAM Enamic crowns (control group), Group II: Teeth restored with full coverage CAD/CAM Enamic crowns, endodontically treated and repaired with direct composite, Group III: Teeth restored with full coverage CAD/CAM Enamic crowns, endodontically treated and repaired with CAD/CAM bonded enamic plugs. Teeth were prepared using a special milling machine. Cerec Premium SW 4.4 was used for the fabrication of crowns from hybrid ceramic Enamic blocks. Crowns were cemented using Rely X Ultimate dual-cure resin cement. For groups II and III, an access cavity was made at the center of the occlusal surface using a round-end diamond bur and copious amounts of water spray followed by root canal treatment. A thin layer of flowable composite material was placed at the base of the pulp chamber. For group II; the access cavity was filled with Filtek Supreme nanofilled composite. For group III; the access cavity was scanned then a ceramic plug filling the access cavity was designed using the Cerec Premium software and milled from Vita Enamic blocks. The ceramic plug was then cemented inside the access cavity using Rely X Ultimate resin cement. All the specimens were subjected to thermo mechanical aging in a chewing simulator for 150,000cycles. Fracture resistance was measured using a computer controlled universal testing machine. For each crown, a single static compressive load was applied along the long axis till fracture occurred. The load required to induce failure was recorded in Newton (N).Data were recorded, tabulated and statistically analyzed.Results: The highest mean±SD values were recorded for group I (2027.64±294.24 N) followed by group III (1784.26±72.15 N) while the lowest mean±SD values were recorded for group II (1494.95±46.95 N). The difference between groups was statistically significant as indicated by ANOVA test (p=0.0017 0.05) differences between (group I and group III) and (group II and group III).Conclusions : 1- The endodontically accessed hybrid ceramic crowns repaired with the novel protocol (ceramic plug) recorded high fracture resistance values. 2- The use of ceramic plug is a feasible alternative to the currently used composite repair protocol.

Curing Residual Strain Monitoring of Carbon Fiber Reinforced Polymer Composite Using Notched Long-Period Fiber Grating

Composite materials are widely used in the aerospace industry and structural engineering owing to their advantageous mechanical properties. The curing monitoring of composite material is important to ensure the quality of the curing process, especially for the characterization of residual strains after manufacturing. In this study, we present a notched long-period fiber grating (NLPFG) with a period of 650 μm and a diameter of 66 μm that can be used in the curing monitoring of composite materials. This NLPFG was embedded into the middle layers of composite materials in order to determine the curing residual stress exhibited by the materials. The experimental results showed that the residual stress was about 107 MPa and the axial residual strain was 1490 με. Therefore, the proposed NLPFG has potential as a strain sensor for composite materials.

Problem of modelling a layered medium taking into account the creep of its materials

Problems for heterogeneous materials arise in many areas of construction. This article deals with elastic-creeping layered composite materials. Relations of the theory of linear heredity of Boltzmann-Volterra are accepted. Creep kernels are given by the sum of a finite number of decreasing exponential functions. Such sum of several exponential functions can be used to approximate the experimental data for the creep and relaxation kernels with a given accuracy. It is obtained that the resulting homogeneous medium is described by a creep kernel, which is also a sum of decreasing exponential functions. Algorithm for the rapid and accurate calculation of averaged creep kernels of a homogenized material is proposed. Some qualitative properties of the received homogenized model are analyzed.

A mesh-free Monte-Carlo method for simulation of three-dimensional transient heat conduction in a composite layered material with temperature dependent thermal properties

A new solution for the three-dimensional transient heat conduction from a homogeneous medium to a non-homogeneous multi-layered composite material with temperature dependent thermal properties using a mesh-free Monte-Carlo method is proposed. The novel contributions include a new algorithm to account for the impact of thermal diffusivities from source to sink in the calculation of the particles’ step length (particles are represented as bundles of energy emitted from each source), and a derivation of the three-dimensional peripheral integration to account for the influence of material properties around the sink on its temperature. Simulations developed using the proposed method are compared against both experimental measurements and results from a finite element simulation.

Structure and Characteristics of the Fracturing of Layered Ni-Al Composites

Layered composite materials with alternating layers of a solid solution of aluminum in nickel and intermetallic Ni-Al compounds are obtained. The evolution of the composite structures depending on the heat-treatment conditions is discussed. The mechanical tests of materials highlight a fracture toughness of up to 23 MPa m1/2, a strength of up to 1800 MPa at room temperature and 150–480 MPa in the range 1000–1150°C.

Analysis of methods for determination of the constants of elasticity unidirectional layer composite materials

Analytical methods for determining the elasticity constants of unidirectional composite materials, such as the rule of a mixture, model of coaxial cylinders, model Kilchinsky and model Vanin are considered. The main assumptions made in the calculations are reduced to the fact that the fibers and the matrix are isotropic elastic materials, which, when loaded, are deformed together, which is ensured by the presence of a rigid connection between them. The calculations of elastic characteristics are presented and a comparative analysis of the chosen approaches is performed on the example of layered composite materials. Recommendations concerning the expediency of using the considered methods are made.