Mechanical Properties Of Composite Materials Research Articles

Experimental study on bio fiber reinforced composites

Biofibers are an economical, environmentally friendly, and lightweight alternative to traditional materials. Different types of fibers have different properties, and each plays a key role in composites. Screw Pine (Pandanus Odoratissimus) is abundant and strong. This research made and tested NaOH- and Acetic Acid-treated random fiber composites. This research shows the mechanical properties of Pandanus Odoratissimus composite. The stem of the screw pine plant, Pandanus Odoratissimus, contained several interesting fibers (PO fibers). This research will investigate the effect of fibre concentration and alkali treatments on the mechanical properties of unsaturated polyester matrix composites. Similarly, soaking times will vary for alkali treatments. Individual PO fibres exhibit modifications in their cross-sectional area and water absorption prior to and after treatment with NaOH solution and acetic acid for varying durations of time. These modifications are observable prior to and after treatment. As a result of extended therapy, the cross-sectional area of PO fibres gradually decreases. Compared to other fibre types, PO fibres that were submerged in water for the longest period of time exhibited the most structural degradation. There is a considerable effect on the improvement of polyester composites' tensile strength and tensile modulus when PO fibre is soaked in different concentrations of NaOH and acetic acid for roughly 90 min. This influence is significant. This investigation will also shed light on how the composition of polyolefin (PO) fibres influences the mechanical properties of composite materials. Maximum tensile strength of a composite material is proportional to the fraction of fibres present in the material. After calculating tensile, compressive, shear, and other stresses, materials (components) are manufactured.

Study of the Phase Composition, Structure and Mechanical Properties of Synthetic Composites Produced by High-Temperature Vacuum Sintering of SHS-Fabricated CrNi-TiN Powders

This work studies the phase composition, structure and mechanical properties of composite materials obtained by high-temperature vacuum sintering of SHS-fabricated CrNi–TiN powders synthesized in semi-industrial-scale production conditions. It was found that changes in the synthesis conditions have no effect on the phase composition and structure of the final products. Additionally, a small increase in the average size of ceramic TiN particles was observed. Compacted rectangular samples were obtained by high-temperature vacuum sintering of fine-ground CrNi–TiN SHS products. A minimum sintering temperature was found at which specimens with a density of 95% of the theoretical one could be obtained. The structure of sintered composites inherits the metal-matrix structure of a part of SHS products. It was shown that CrNi–TiN composite materials are superior to NiTi–TiB2 composites in terms of hardness as well as binding strength for three-point bending at temperatures up to 550 °C.

Mechanical and Thermophysical Properties of Epoxy Nanocomposites with Titanium Dioxide Nanoparticles

The introduction of nanoparticles and their homogeneous distribution in the polymer matrix, as well as their size, can have a significant effect on the mechanical properties of composite materials. In this work, we studied the mechanical characteristics of TiO2/epoxy nanocomposites with different contents and sizes of nanoparticles. The preparation of nanocomposites was carried out by a stepwise curing (at 90 and 160 °C) of ED-20 dianic epoxy resin in the presence of an aromatic hardener with the addition of titanium (IV) dioxide nanoparticles preliminarily synthesized by the plasma-chemical method. Ultrasonic dispersion was used to achieve a uniform distribution of nanoparticles in the polymer matrix. The chemical and phase composition, the structure of the as-synthesized TiO2 nanoparticles, and the resulting epoxy nanocomposites were characterized by elemental analysis, X-ray diffraction, transmission and scanning electron microscopy, and infrared spectroscopy. The mechanical properties of the nanocomposites were determined by the static tensile test, and the impact toughness was determined by the Charpy method. The glass transition temperature and thermal stability of the TiO2/epoxy nanocomposites were studied by thermal analysis methods. The formation of an interfacial layer between the TiO2 nanoparticles and an epoxy matrix has been shown for the first time by spectral methods. It is shown that the mode of curing and ultrasonic dispersion used, as well as varying the content and dispersity of the TiO2 nanoparticles, make it possible to obtain epoxy nanocomposites with simultaneously improved deformation-strength characteristics and impact strength values.

COMPUTER MODELING OF PROPERTIES OF A COMPOSITE MATERIAL WITH POROUS FILLERS

The article is devoted to forecasting of heat-shielding and mechanical properties of composite materials based on porous fillers.Analytical dependencies for determining the thermal conductivity coefficient of materials of homogeneous and heterogeneous structure are given. Based on the finite element method, there has been developed a method for numerical determination of the thermal conductivity coefficient of composite materials with a variotropic structure.The results of computer studies are in line with the dependences obtained on analytical models. The expediency of using multilayer composite materials based on porous fillers in load-bearing and enclosing structures of shell and plate types has been shown.

Analysis of the use of composite materials for further application in the support of mine workings

Purpose. To analyze composite materials and prospects of their use for roof support in coal mines. Research methodology. To achieve this purpose, we used analytical data on the market of composite materials, the volume of their production capacity, and cost indicators. Data on the physical and mechanical properties of composite materials and their quantitative indicators were used. Research results. The areas of application of composite materials in industry are analyzed and summarized. The analysis shows that composite materials are used in many areas of industry: medicine, construction, defense, etc. A comparative analysis of the physical and mechanical properties of carbon fiber-reinforced plasticand steel shows that this composite material has identical (and sometimes even better) properties than metal materials. The study concluded that it is better to use carbon fiber as a support material for mine workings in coal mines. The advantages and disadvantages of carbon fiber-reinforced plasticas a roofing material for coal mine workings are evaluated. It is clarified that the current limiting factor is the cost of carbon fiber-reinforced plastic, but over time, their price will decrease and their demand will increase. It is concluded that the use of this composite material in the elements of mine support can increase the pace of their implementation, reduce the labor intensity of the work performed and improve the working conditions of miners while lightening the structure. Scientific novelty. The physical and mechanical properties of composite materials have been analytically determined and it has been substantiated that carbon fiber-reinforced plasticsupports can be used in the support of preparatory workings in coal mines. Practical value. The obtained results prove that the support made of carbon fiber-reinforced plasticwill facilitate the design of the support, which, together with the acceleration of the shift operation, will contribute to the development of underground coal mining.

A multiscale finite element model for prediction of tensile strength of concrete

Concrete is a highly heterogeneous composite material on the microscopic length scale (10 −6 m) to the mesoscopic length scale (10 −1 m). The heterogeneous structure of concrete influences its macro mechanical properties. The multiscale approach is an effective method to analyze the mechanical properties of composite material and support the design of material. In this paper, a 3D multiscale model for prediction of tensile strength of concrete is presented. The microstructure of H ydrated C ement P aste (HCP) is generated by the HYMOSTURC and exported to the Abaqus by using Python program. The local background grid method is used to directly generate the meso-scale models of mortar and concrete. An uncoupled multiscale method is applied to transfer parameters from a smaller scale to a larger scale model. In the case of scale overlapping, parameter transfer is carried out through a simplified uncoupled averaging method. Finally, the multiscale model is verified by flexural test of mortar and splitting tensile test of concrete. • A multiscale model for concrete is constructed. • The mechanical properties of material in the larger scale model are obtained from the smaller scale model. • The multiscale model is verified by experiments. • The multiscale model can predict tensile strength of concrete based on its composition.

Free Vibration Analysis of Composite Cylindrical Shell Reinforced with Silicon Nano-Particles: Analytical and FEM Approach

Previous research presented the effect of nanomaterials on the mechanical properties of composite materials with various volume fraction effects; in addition, their research presented the effect of nanomaterials on the same mechanical characteristics for a composite plate structure, such as vibration and thermal buckling behavior. Therefore, since the use of shell structures is for large applications, it is necessary to investigate the modification of the vibration characteristics of its design with the effect of nanomaterials and study the influence of other reinforced nanoparticle types on its features. Therefore, in this work, silicon nanoparticles were selected to investigate their effect on the vibration behavior of a shell structure. As a result, this work included studying the vibration behavior by testing the shell structure with a vibration test machine. In addition, after manufacturing the composite material shell with various silicon volume fractions, the mechanical properties were evaluated. In addition, the finite element technique with the Ansys program was used to assess and compare the vibration behavior of the shell structure using the numerical technique. The comparison of the results gave an acceptable percentage error not exceeding 10.93%. Finally, the results evaluated showed that the modification with silicon nanomaterials gave very good results since the nanomaterials improved about 65% of the shell's mechanical properties and vibration characteristics.

Silica-Fiber-Reinforced Composites for Microelectronic Applications: Effects of Curing Routes

For curing of fiber-reinforced epoxy composites, an alternative to thermal heating is the use of microwave energy, which cures quickly and consumes less energy. Employing thermal curing (TC) and microwave (MC) curing methods, we present a comparative study on the functional characteristics of fiber-reinforced composite for microelectronics. The composite prepregs, prepared from commercial silica fiber fabric/epoxy resin, were separately cured via thermal and microwave energy under curing conditions (temperature/time). The dielectric, structural, morphological, thermal, and mechanical properties of composite materials were investigated. Microwave cured composite showed a 1% lower dielectric constant, 21.5% lower dielectric loss factor, and 2.6% lower weight loss, than thermally cured one. Furthermore, the dynamic mechanical analysis (DMA) revealed a 20% increase in the storage and loss modulus along with a 15.5% increase in the glass transition temperature (Tg) of microwave-cured compared to thermally cured composite. The fourier transformation infrared spectroscopy (FTIR) showed similar spectra of both the composites; however, the microwave-cured composite exhibited higher tensile (15.4%), and compression strength (4.3%) than the thermally cured composite. These results illustrate that microwave-cured silica-fiber-reinforced composite exhibit superior electrical performance, thermal stability, and mechanical properties compared to thermally cured silica fiber/epoxy composite in a shorter time and the expense of less energy.

Experimental Study of Curing Temperature Effect on Mechanical Performance of Carbon Fiber Composites with Application to Filament Winding Pressure Vessel Design.

During the forming process of carbon fiber composite pressure vessels, the parameters of the curing and forming processes become one of the critical factors affecting the production cost and forming quality. The curing temperature of 4251 A4/B2 epoxy resin is measured in this research, and the effect of curing temperature on the mechanical properties of composite materials for winding is studied, which is finally verified in the test of pressure vessels. First, the actual curing temperature of the epoxy resin is tested and analyzed using differential scanning calorimetry (DSC). Second, under two different curing regimes, the tensile and flexural properties are tested by making pure epoxy resin matrix test pieces, Naval Ordnance Laboratory (NOL) rings, and carbon fiber composite unidirectional plates that affect the overall performance of composite pressure vessels. At the same time, the test results provide reliable process parameters for numerical simulation and manufacturing of pressure vessels. Finally, the filament-wound 35 MPa type III pressure vessel is cured and carried out using a hydraulic burst test. The results show the resin matrix has good fluidity and excellent interface bonding with carbon fiber when the curing temperature is 112 °C. Compared with the results in curing temperature of 100 °C, the tensile strength of the NOL ring reaches 2260.8 MPa, up by 22%. In the 90° direction, the tensile and flexural strengths of the unidirectional plates increase by 68.86% and 37.42%, respectively. In the 0° direction, the tensile and flexural strengths of the unidirectional plates increase by 5.82% and 1.16%, respectively. The pressure vessel bursting form is reasonable and meets the CGH2R standard. The bursting pressure of the vessel is up to 104.4 MPa, which verifies the rationality of the curing regime used in the curing process of the pressure vessel. Based on the results of this paper, the curing temperature affects the fluidity of the epoxy resin, which in turn affects the interfacial bonding properties of the composite, and the forming quality of the wound components and the pressure vessel, ultimately. When using 4251A4/B2 epoxy resin for wet winding pressure vessels, the choice of a 112 °C curing temperature will help improve the vessel's overall performance. This work could provide reliable experience and insight into the curing process analysis of pressure vessel manufacturing.

Monitoring of Engineered Stones Used in Artwork Reproductions: Mechanical Characterization by Laser Vibrometry

Many museums have been producing reproductions for several years to replace artworks weakened by outdoor exhibition. Among these, in order to imitate the original aesthetic, the French consortium Réunion des Musées Nationaux–Grand Palais has chosen to work from large-format marble sculpture molds to complex composite materials based on resins comprising mineral fillers. However, similar to the original works of art, these reproductions age and deteriorate due to constant outdoor exposure. For this reason, current research focuses on the preventive conservation and monitoring of the structural health of these reconstructed objects. The goal of this paper was to study the resin/mineral powder composite materials used to produce cultural heritage reproductions of sculptures. This work is oriented toward a comparison of the mechanical properties of composite materials used in the replacement of cultural heritage sculptures (for instance, in the Garden of the Palace of Versailles or the Rodin Museum). The objectives were to first characterize the physical and mechanical properties of these materials in order to identify the most suitable material for cultural heritage reproduction, and secondly, to propose a method with minimal contact that obtained equivalent information as analyses performed with conventional ultrasonic techniques. These nondestructive evaluation techniques could be used for laboratory and in situ analyses. Samples of different polymer/mineral powder filler compositions were analyzed by compressional, shear and surface waves, generated by a 1 MHz center frequency ultrasonic transducer. Firstly, the measurements made it possible to evaluate the velocities of the bulk acoustic waves and extract the Young’s modulus of each tested material. Secondly, in order to have minimal contact with the analyzed structure, a laser interferometry system was used to detect waves at the surface and follow their propagation. The results clearly showed the possibility of using this technique to extract mechanical characteristics of composite materials, allowing for selection of material for the reproduction of large-format statues. For different types of polymer resins, the ability of ultrasonic analysis to track the impact of rock powder (marble or slate) on the mechanical properties of these synthetic materials was clearly observed, proving that this technique holds promise for monitoring the structural health of large-format artwork.

Preparation and Properties of Graft-Modified Bagasse Cellulose/Polylactic Acid Composites

ABSTRACT Fiber reinforcement is the most common method for modifying polylactic acid (PLA). However, poor compatibility between fibers and PLA, especially at high cellulose contents, can promote cellulose agglomeration in the continuous phase, which damages the mechanical properties of composite materials. To address these issues, bagasse cellulose (BC) was used as a substrate and bifunctional glycidyl methacrylate (GMA) was used as a reactive monomer for graft modification. GMA-modified BC (BC-GMA)/PLA composite materials with different particle sizes were prepared using a blending grafting method, and the influence of the type and content of BC-GMA on the mechanical properties of the composite materials was explored. During the grafting modification of BC, a longer reaction time was found to result in smaller BC particles and a higher degree of grafting. For BC-GMA, the degree of grafting reached 27.02% with a maximum thermal decomposition temperature of 359.31°C. Furthermore, the BC-GMA/PLA composite material had a greater relative crystallinity of PLA, indicating that BC-GMA was evenly dispersed in the continuous phase. This study demonstrates that grafting modification can successfully achieve high cellulose loading in composite materials and thus reduce the production costs of PLA-based packaging materials.

Interlaminar properties of carbon nanotubes modified carbon fibre fabric reinforced polyimide composites

Carbon fibre reinforced polymers are widely used in industrial applications due to their excellent properties. However, the weak matrix-dominated interlaminar properties limit its further application. With their unique properties, carbon nanotubes (CNTs) have great potential to improve the mechanical properties of composite materials. In this paper, carbon nanotube-modified carbon fibre/polyimide (CF/CNTs/PI) multi-scale composites were prepared by introducing amino-functionalized multi-walled CNTs into a PI resin matrix using an ultrasonic dispersion method. The interlaminar properties of the prepared composites were comprehensively evaluated by double cantilever beam (DCB), end-notched flexure (ENF), and short seam shear (SBS) tests. It is shown that the addition of 0.5wt.% CNTs increased the Mode I and Mode II interlaminar fracture toughness of the material by 50.21% and 61.74%, respectively, and the interlaminar shear strength (ILSS) by 42.85%. The CNTs bridging the crack tip and enhancing the fibre/matrix interface bonding ability were the dominating mechanisms for the improvement of interlaminar properties.

Semi-empirical formulas on notch stress field and SIF of orthotropic V-shaped thin plate with initial crack under tensile-bending loads

For orthotropic materials, the solution of notch stress field and stress intensity factor (SIF) is not only related to crack opening angle, crack depth, notch length, geometric parameters, but also obviously influenced by material characteristics and constitutive relation. On the basis of isotropic notch stress field and SIF theoretical formula, a series of multi-parameter models of orthotropic materials were constructed and fitted. The effects of notch depth, crack length, the ratio of notch depth to plate width, opening angle and mechanical properties of composite materials on geometric correction coefficient YI are systematically analyzed. On this basis, a semi-empirical formula of YI is put forward by combining stress field analysis and multi-parameter fitting. The semi-empirical formula is further verified with finite element method, traditional formula and various composite materials. The numerical results show that the simple formula proposed in this paper has higher prediction accuracy. Finally, the proposed formula is extended to the solution of notch stress field and geometric correction coefficient for V-notch-cracked plate under bending load, tension-bending complex loads.

Nano-additives and their effects on the microwave absorptions and mechanical properties of the composite materials

The review addresses the effect of various carbon and iron-based percentage nano- additives on both electromagnetic (EM) wave and mechanical properties of composite materials. It also assessed the influence of particle and fiber size along with the manufacturing process, on mechanical properties (tensile strength and flexural strength), fracture behaviors (fracture toughness) and electromagnetic properties (reflection loss). Reviewing the selection of nanomaterials for a particular frequency band and application, as well as their impacts on bulk materials in relation to loading, were overviewed. As per this review, adding those iron and carbon-based additives influence positively for both electromagnetic and mechanical properties. Furthermore, review organized natural based fiber and filler-based composites along with fillers for the production of green strong radar materials. The review also showed, how highest and smaller percentage of iron-based fillers affected for microwave absorption and mechanical properties. Mainly, the optimized use of nano particles percentage for both mechanical and electromagnetic wave to produce strong radar materials were overlooked. Finally, these papers give a quick hint on how these nano particles manufacturing methods and particle size affect the mechanical properties and micro wave absorption of composite materials.

Research on Properties of Polypropylene/Flake Graphite Molded Composite Materials

PP/FG composite materials were prepared by compressing moulding under high temperature through high-speed mixer, mixing mill and vulcanization machine taking PP as the matrix resin, FG as the thermal conductive filler, and NDZ-201 as the coupling agent. Effects of PP proportion, FG content and particle size on the thermal conductivity and mechanical properties of composite materials were studied. Results showed that PP proportion has little effect on the thermal conductivity of PP/FG composite materials, but it greatly affects the mechanical properties of the composite materials. Overall, the quality ratio of PP230 to K-4038 at 50:50 is more suitable. With the increasing of FG content, the thermal conductivity increases, and a significant critical value appears when the FG content is 50 wt%; The strength of the composite material first decreases and then increases, with an increase in modulus and a decrease in strain. As the FG particle size increases, the thermal conductivity of the composite material increases and the mechanical properties decrease.

Investigation of mechanical properties of composite materials reinforced with carbon fibers

Theoretical and experimental methods for obtaining and investigating effective thermomechanical characteristics - residual stresses and deformation in panels made of nanomodified materials with asymmetrical reinforcement scheme have been developed in this paper. The study of the residual stress-strain state of structural elements made of carbon plastic using the values of thermoelastic characteristics of composite monolayers identified on the basis of the developed methods meade it possible to reveal the possibility of reducing the residual stress-strain state in structures with asymmetric reinforcement schemes.

An overview of recent developments in Al metal matrix nanocomposites for strength-ductility synergy

Researchers worldwide switched their attention from homogeneous structures to heterogeneous structures because they needed composite materials that possess both ultra-high strength and ductility. The goal is to improve the mechanical properties of composite materials by making a new “Harmonic Structure” (H.S.) with a controlled bimodal grain size distribution. A powder metallurgy-based fabrication method has been developed to achieve a controlled microstructure, including a mechanical or a bi-model milling process. Consolidated mechanical milled or bi-model milled powder has been sintered to get the final harmonic structure. The harmonic structure-designed metallic materials are solid and ductile simultaneously because of the microstructure matrix's optimized hierarchical features, which create strain delocalization during plastic deformation. So, unlike traditional homogeneous (homo)-structured materials, HS-designed materials can have synergy effects like synergy strengthening. This study shows how tailoring strain delocalization has changed the strength-ductility synergy. In addition, this study supports future innovations toward a balance between high strength and high ductility.

Dynamic monitoring of epoxy reactions and modulus evaluation by a multispectral approach

The regulation of the polymerization process of moleculars from liquid to solid is crucial for the ultimate mechanical properties of composite materials.

Research of mechanical properties of organic-mineral thermoplastics with mechanically activated fillers

In this article presented the results of a study on improving the mechanical properties of composite materials based on polyethylene. A composition materials filled with a thermoplastic polymer - polyethylene modified with a kaolin-graphite filler is proposed, which will allow obtaining high-quality products based on local raw materials, simplifying the material composition, and expanding their performance due to improved strength and tribotechnical properties. On the basis of the studies carried out, pipes for the branch parts of oil collection tanks were obtained, which were tested under production conditions.

Influence of notch and load direction on impact toughness of fibre reinforced composites produced by 3D printing

Additive production of composites is a relatively new technology, the development of which currently allows the printing of long-fibre reinforced components. The rapid development technology necessarily requires finding a suitable application. Mechanical tests are performed to determine the material characteristics and behaviour of the material under different types of loading for these reasons. Several studies have been published dealing with tensile and bending tests of additive produced composites. The authors have performed a Charpy impact test on the same materials in the past. The influence of printing parameters (infill type, reinforcement type, lamina thickness, infill orientation) and the orientation of the load against the position of the laminas in the composite on the mechanical properties (achieved values of impact toughness) were identified by experimental measurements. The first phase was performed on un-notched specimens. In the second phase, further research and experimental measurements were performed on notched specimens.The aim of the article was to assess the influence of the notch on the mechanical properties of composite materials produced on the basis of 3D printing. The results show the dependence of the laminate layering on the direction of loading. The impact toughness decreased by 35 % on notched specimens in the case of perpendicular direction of loading to laminas layering. In the case of direct loading to laminas layering, notched specimens achieved higher impact toughness than specimens without notch.