Mechanical Characteristics Of Composite Materials Research Articles

Mechanical Characterization of Hybrid Bagasse/Eggshell/E-glass Fiber-based Polyester Composite

Currently, numerous researchers, scientists, and industrialists are drawn towards utilizing natural fillers rather than synthetic ones because of their environmentally-friendly characteristics, lower density per unit volume and favorable mechanical attributes. Several studies have demonstrated that using organic filler in polyester matrix composites, instead of disposing of them in landfills, has various advantages. The current study focuses on the investigation of the mechanical characteristics of composite material made from a combination of bagasse, eggshell, and e-glass fibers exhibit characteristics such as strength under tension, strength under bending, resistance to indentation, and mass per unit volume. Different weight percentages of eggshell/bagasse were used to make the material using the hand lay-up technique (3wt%, 6wt%, 9wt%, and 12wt%), with 19wt% of glass fiber mixed in the resin. The use of inorganic fillers like calcium carbonate, a non-renewable mineral that may be expensive and environmentally hazardous to extract and process, is being reduced in favor of organic fillers like eggshell and bagasse, which are inexpensive and readily available. Specimens were generated by interposing fiber waste amidst chopped strand glass fiber mats, with variations in the bagasse, eggshell and polyester content, while keeping the amount of E-glass fiber constant. Afterward, the specimens were trimmed to the appropriate dimensions and subjected to analysis with a universal apparatus. The research showed that enhancing the quantity of bagasse/eggshell fiber within the hybrid composite resulted in an enhancement of its mechanical characteristics. The best reinforcement effect was observed in a hybrid composite with 6% bagasse/eggshell fiber.

A Review of Delamination Damage of Composite Materials

The theoretical and practical achievements in the field of the theory of strength and reliability of composite materials are discussed in a review conducted on the scientific research conducted on the effect of delamination on the reliability and quality of composites. The methodological aspects of the stability of the mechanical characteristics of composite materials under the combined action of cyclic and impact loads are examined, as are the manufacturing and processing technologies. The reasons for delamination, such as technological, manufacturing and application, free edge, joints and loads, are revealed. The influence of delamination on the bearing capacity of structural elements made of composite materials is analyzed. The mechanism of delamination growth is outlined, and the criteria and processes are defined, such as the growth of delamination cracks in a multidirectional laminated plate from a straight edge, edge delamination during plate bending, delamination in plates in the field of residual stresses, etc. The importance of taking into account the visco-plastic effect at the top of the edge crack of delamination of composite materials is emphasized. The concept of critical delamination behavior is characterized, and the issues of delamination stability are described.

Utilization of Plastic Waste in Road Paver Blocks as a Construction Material

India is confronted with the substantial issue of plastic debris due to the absence of an efficient waste management infrastructure. Recycled plastic has the potential to enhance various construction materials, such as roofing tiles, paving blocks, and insulation. The aforementioned materials possess notable attributes such as high strength, low weight, and exceptional resistance to extreme temperatures and humidity. The objective of this study is to ascertain feasible alternatives for manufacturing road paver blocks utilizing plastic waste (Polyethene terephthalate (PET)), and M-sand (stone dust). Three variations of a discarded plastic cube measuring 150 mm × 150 mm × 150 mm were prepared for the experiment. The experimental findings indicated that a ratio of 1:4 was determined to be the most effective in achieving the desired level of compressive strength. I-section road and brick paver blocks were produced as an alternative to the traditional concrete ones. Compressive strength tests were performed on I-sections and brick paver blocks, revealing that the 1:4 mix ratio exhibited the highest average compressive strength for both materials. The findings indicated that including plastic waste positively impacted the compressive strength of the I-sections and brick paver blocks. Additionally, the quality grading of these materials was evaluated using an ultrasonic pulse velocity test. The ultrasonic pulse velocity test results demonstrated a high-quality grading for the I-sections and brick paver blocks. Scanning electron microscopy (SEM) tests assessed the microstructural behavior and performance. The results of this study demonstrate that incorporating plastic waste in combination with M-sand can effectively improve the mechanical characteristics of composite materials, rendering them viable for use in construction-related purposes.

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.

Influence of fiber areal density on mechanical behavior of basalt fiber/epoxy composites under varying loading rates: An experimental and statistical approach

AbstractThe stress–strain characteristics and failure behavior of composites are strain rate dependent and affected by the fiber areal density. To elucidate the combined influence of areal density and strain rate on the strength of basalt fiber‐reinforced polymer composites (BFRP), an experimental study was conducted on BFRP laminates of two different fiber areal densities, that is, 380 GSM and 200 GSM, having distinct stacking sequence under three different loading rates. Failure modes, failure strength, and Weibull parameters were used to characterize the experimental outcomes. The experiment was carried out to investigate the mechanical responses and associated failure modes at strain rates ranging from quasi‐static 0.1 mm/min to a high strain rate of 10 mm/min. It has been demonstrated that there is a substantial correlation between the fiber areal density, loading rate, and stacking order of BFRP laminates and the increase in maximum flexural strength and interlaminar shear strength. For an increase in the fiber areal density from 200 GSM to 380 GSM flexural strength is increased by 18%–30%, while ILSS strength is increased by 30%–52%. Based on the finding, the asymmetric type‐2 laminate exhibits better properties than the symmetric and asymmetric type‐1 laminates due to the presence of more (0°/90°) laminae at the tensile side of the laminate. Inferring the mechanical characteristics of composite materials and their relationship to strain rate from experimental data required a statistical technique. The statistical analysis and experimental findings demonstrate that the shape parameter and linear coefficient are not reliant on the strain rate.

An Alternative Electro-Mechanical Finite Formulation for Functionally Graded Graphene-Reinforced Composite Beams with Macro-Fiber Composite Actuator.

With its extraordinary physical properties, graphene is regarded as one of the most attractive reinforcements to enhance the mechanical characteristics of composite materials. However, the existing models in the literature might meet severe challenges in the interlaminar-stress prediction of thick, functionally graded, graphene-reinforced-composite (FG-GRC)-laminated beams that have been integrated with piezoelectric macro-fiber-composite (MFC) actuators under electro-mechanical loadings. If the transverse shear deformations cannot be accurately described, then the mechanical performance of the FG-GRC-laminated beams with MFC actuators will be significantly impacted by the electro-mechanical coupling effect and the sudden change of the material characteristics at the interfaces. Therefore, a new electro-mechanical coupled-beam model with only four independent displacement variables is proposed in this paper. Employing the Hu–Washizu (HW) variational principle, the precision of the transverse shear stresses in regard to the electro-mechanical coupling effect can be improved. Moreover, the second-order derivatives of the in-plane displacement parameters have been removed from the transverse-shear-stress components, which can greatly simplify the finite-element implementation. Thus, based on the proposed electro-mechanical coupled model, a simple C0-type finite-element formulation is developed for the interlaminar shear-stress analysis of thick FG-GRC-laminated beams with MFC actuators. The 3D elasticity solutions and the results obtained from other models are used to assess the performance of the proposed finite-element formulation. Additionally, comprehensive parametric studies are performed on the influences of the graphene volume fraction, distribution pattern, electro-mechanical loading, boundary conditions, lamination scheme and geometrical parameters of the beams on the deformations and stresses of the FG-GRC-laminated beams with MFC actuators.

Mathematical Apparatus for the Synthesis of Composite Materials with Specified Properties

The meaning of the creation and functioning of the system is defined as the achievement of extreme values of goals that unite the individual elements of the system into a single whole. Based on this, the main system attributes of composite materials are indicated. It is assumed that the systemic effect is generated by the systemic properties of quality criteria. The implementation of the technical task is initially determined at the stage of cognitive modeling with the establishment of intensive and extensive properties with the allocation of control parameters. Based on the cognitive map, hierarchical structures of quality criteria are determined, and in accordance with the selected quality criteria, the corresponding structural schemes of the system (for each selected scale level). Further, the system's quality criteria are formalized, and mathematical models are developed in accordance with each of the criteria. The main purpose of using system analysis is to apply the general principles of decomposition of the system into individual elements and establish connections between them, in determining the research goal and stages to achieve this goal (based on solving single-criterion optimization problems using the found optimal values). The formalization of the multicriteria problem and its solution are made based on the required operational values, the type of kinetic processes of the formation of the physical and mechanical characteristics of the material (determine its structure and properties). The problem of materials synthesis is reduced to the choice of the order and type of the differential equation; parametric identification within the chosen model; comparison of experimental and model kinetic processes at a given accuracy; adjusting the model (if necessary). Therefore, it is important to interpolate the kinetic processes of the formation of the main physical and mechanical characteristics of composite materials. The technological process is considered as a complex system consisting of elements of various levels of detail: from atomic to a separate process. Decomposition of the technological process consists in dividing it into basic operations (elements): preparation of materials, mixing of components, molding of a semi-finished product, heat treatment and additional operations. The effectiveness of this approach was confirmed in the development of chemically resistant sulfur composites, epoxy composites for radiation protection, etc. The initial prerequisite was the required operational values of the material and the type of kinetic processes. The results of effective use of interpolation models (including splines) of compressive strength, heat release, and shrinkage of composite epoxy materials are presented.

Modeling of mechanical characteristics of composite materials applied for protection of information and control complexes of aircraft

In modern conditions of electronic warfare, effective protection of information and control complexes of aircraft (AC) from the destructive effects of external interference is impossible without the use of innovative solutions in the field of creating new composite materials (CM) with radio-absorbing properties. This scientific area is inextricably linked with the issues of predicting the properties of these materials. A wide variety of design solutions to protect aircraft “electronics”, as well as a wide range of electromagnetic and mechanical effects, require the creation of functional materials for specific operating conditions. Thus, the developers of functional materials must have an effective tool to predict the properties of the CM being created. Solutions can be based on mathematical models that allow predicting the properties of CM and subsequently optimizing their composition. The article discusses the identification and verification of mathematical models of the mechanical characteristics of CMs based on BASF polyurethane with the addition of both untreated and processed ferric iron oxide as a filler, with subsequent optimization of the characteristics and determination of the corresponding CM composition with radio-absorbing properties. Experimental studies have been carried out, which confirm the adequacy of the developed mathematical models.

Determining the mechanical characteristics of composite materials reinforced with woven preforms

Reduction of the complexity of production of articles from composite materials is largely ensured by the use of reinforcing semi-finished products in which fibers pre-form a framework. Among all the variety of reinforcing systems, woven sleeves (preforms) occupy a special place. The high degree of deformability in a nonimpregnated condition makes it possible to lay this reinforcement on any surface without folds and cuts that provide preservation of strand continuity. This advantage of woven sleeves is accompanied by a change in local reinforcement angles and, consequently, the variable nature of physical and mechanical characteristics of the curved part surface. A method for calculating physical and mechanical characteristics of the composite based on preforms at any point of the part depending on the pattern of laying strands on a curved surface has been developed. The possibility of application of the rod model of the composite to describe physical and mechanical characteristics of the composite material with a woven reinforcement was analyzed. The model essence consists in that the composite is modeled by a diamond-shaped rod system. The rhombus sides serve as fibers and the diagonals as the binder. To verify the theoretical results and substantiate practical recommendations, a series of experimental studies were performed based on the formation of material specimens from two types of woven sleeves with different reinforcement angles. The experimental study program included tensile, bending, and compression tests. A fairly good convergence of theoretical and experimental data was obtained. For example, a square of the correlation coefficient was not less than 0.95 for the modulus of elasticity, not less than 0.8 for the Poisson's ratio, and not less than 0.9 for tensile and compressive strengths. This is the rationale for using the rod model to describe the considered class of composites. The use of the developed procedure will make it possible to increase the perfection of the considered class of designs and obtain rational parameters of the process of their manufacture.

FORECASTING CHARACTERISTICS OF COMPOSITE STRENGTH ON THE BASIS OF PREFORMS IN ELEMENTS OF BUILDING STRUCTURES

Currently, wicker composite structures for various purposes are widely used in many industries. The use of such preforms allows to provide the possibility of automation of production, high speed and efficiency of the process of manufacturing polymeric composite materials and structures based on them. Knowledge of their properties allows you to optimize the production of structures with the necessary parameters during design. In the article the model of composite material on the basis of wicker reinforcement was further developed. For the practical implementation of this model, it is sufficient to test material samples with three different angles between the harnesses, for example, ± 30º, ± 45º and ± 60º. A mathematical description of the model is given. The model made it possible to predict the physical and mechanical characteristics of the composite material when it is laid out on curved surfaces. At the same time some fictitious limits of durability of a composite are defined. This is due to the fact that each value of the angle between the harnesses corresponds to its physical and mechanical characteristics of the unidirectional composite material. In this case, the ultimate strength curves necessarily pass through the points corresponding to the experimental data. The article shows that the possible deviations of the strength limits in the range of angles between the harnesses will lie within the range of characteristics obtained by testing. The article shows that in the realized interval of angles between the harnesses, almost any polynomial criterion of strength will accurately describe the strength of the composite reinforced with a braided sleeve. The obtained parameters, in contrast to the existing ones, allow to predict the strength characteristics of the composite on the basis of braided sleeves depending on the positioning and location of the material on the forming surface. The obtained results are the basis for solving the problems of calculating the strength of building structures from composite materials based on wicker preforms.

Physical and mechanical characteristics of a composite material made of birch wood hydrolyzed in the presence of hydrogen peroxide

The results of research of physical and mechanical characteristics of the plate composite material obtained from birch wood after its processing by the method of explosive autohydrolysis are shown. Before barothermal treatment, the wood was impregnated with an aqueous solution of hydrogen peroxide. The composite material is made from hydrolyzed wood pulp by hot pressing without adding binders. It was found that the properties of the composite material depend on the amount of hydrogen peroxide and the rigidity of the barothermal treatment conditions. Each of the modes of barothermal treatment corresponds to a certain value of the amount of hydrogen peroxide, when using which the density of the material reaches the maximum value. The dependence of the bending strength of a composite material obtained using different amounts of hydrogen peroxide is characterized by the presence of an extremum point. At this point, the strength value is the maximum. Further increase in the amount of hydrogen peroxide is accompanied by a deterioration in strength characteristics. It is suggested that the effect is a consequence of the dominance of destructive processes over the processes of intermolecular crosslinking when using a large amount of hydrogen peroxide.

Calculation and experimental research of mechanical characteristics of composite materials

Research and use of composite materials for scientific experiments, engineering activities, as well as industrial purposes has expanded significantly, since the development of technologies for the production of composite materials has made it possible to create and research new types of their physical and chemical properties, reinforcement schemes and fiber lengths, etc. This paper presents the results of computational and experimental studies of the elastic and damping properties of a composite material. The studies were carried out on samples of laminated fiberglass, the dimensions of which are 160 × 16 × 4 mm, cut in three directions, in the direction of the warp, weft and at an angle of 45 degrees, five samples were cut in each direction. To study the mechanical properties of the obtained cantilever samples, the electrodynamic shaker was used. The study of damping properties was carried out by the Oberst method based on the experiment of the frequency response characteristics of cantilever samples. The determination of Young's moduli of laminated fiberglass samples was carried out by the dynamic method, and also the theory of vibrations of continuous systems was used. The experimental data obtained are compared with the results of numerical solutions performed by the finite element method (FEM). Geometric and finite element models were constructed and the natural frequencies and vibration modes of the samples were determined. Frequency and phase response characteristics are given. To reduce the error according to the results of the experiment, statistical processing was carried out. The values of the mathematical expectation and the standard deviation of the mechanical loss coefficient are calculated. The estimation of the measurement error was made on the assumption of the normal distribution of the error.

Study of the Mechanical Characteristics of Composite Materials of the ZrB2–Si System

A dense composite material in the ZrB2–Si system (1400°C, air atmosphere) was obtained. The structure, phase composition, and basic physical properties (density, porosity, elastic modulus, critical stress intensity factor, Vickers hardness) of heat-resistant materials were studied.

Effect of Position and Content of a Basalt Filler on the Mechanical Characteristics of Composite Materials Based on an Ice Matrix

The effect of position of basalt filler layers on the bending strength and resistance to falling weight impact is investigated for ice-based composite materials (CMI). Zones of optimal reinforcement are revealed for laboratory CMI samples. The obtained bending strength values are five times higher than those for unreinforced ice.

Analytical Description of the Kinetic Processes of Forming the Properties of Composites

Effective methods are proposed for approximating the kinetic processes of formation of physical and mechanical characteristics of composite materials for solving problems of both single-criterion and multi-criteria optimization of their structure and properties. The approximation of kinetic processes on a given interval with the definition of partial intervals of the maximum length approximation is considered in detail. An approximation algorithm on cubic splines is given. To determine the transfer functions of composites, as dynamic systems with many inputs and outputs, it is recommended to use Laguerre polynomials. The possibility of a cognitive approach is also not excluded with the direct selection of the form of the approximating function.

Физико-механические характеристики композиционных материалов, получаемых из древесины березы, гидролизованной в присутствии органических кислот

Физико-механические характеристики композиционных материалов, получаемых из древесины березы, гидролизованной в присутствии органических кислот

Anomalous concentration dependence of the thermal conductivity of refractory sintered binary nano-composites TiN-ALN and ZrC-ZrB2

An abnormal concentration dependence of the thermal conductivity of nanocomposites Titanium Nitride-Aluminum Nitride and zirconium carbide-zirconium diboride has been experimentally established from the volume fraction of components. An explanation of the nature of the anomalous dependence and a technique for an approximate estimation of the dependence of the thermal conductivity of a nanocomposite on the volume fraction of components are proposed. Oxygen-free refractory compounds - covalent and metal-like active investigated in the development of new ceramic materials used for achieving higher physical and mechanical characteristics as well as for use in extreme conditions in mechanical engineering, nuclear engineering, aviation, special equipment. The development of technology is constantly stimulates the creation of new materials, which must manifest a complex of properties rarely show by one substance, such decisions cannot find the formation of composite (hetero) materials. In the case of eutectic systems with diffusive non-interacting refractory components, used for the synthesis of composite ceramic materials in a highly thermodynamic state, the possibility of co-building a new group of ceramics with interphase boundary (of eutectics “coarse conglomerate”) with anomalous concentration dependences of the physical and mechanical characteristics of composite materials (flexural strength and modulus of elasticity, super plasticity – elongation more than 500%, tensile, strength and fracture toughness) and thermal properties (thermal conductivity and thermal diffusivity) [1-3].

The Classification of Methods of Defining of Calculated Mechanical and Physical Characteristics of Composite Materials

A short description with the analysis of the choice of the equivalent characteristics of the material with the further classification of the casting method is represented in this article. The choice and definition of elastic characteristics of composite materials depend on a number of factors: they are the geometry of the estimated element of the construction, the stress-strained state and the mathematical model of this state, the calculation method, the final precision of the solution. The technical methods of calculation of such elements as rods, shells and plates are analytically connected with the resolving equation set-up. One of the most widely used approaches to the solution of practical tasks is to transform heterogeneous materials to homogeneous ones, either isotropic or orthotropic. The most common variants of the choice of physical and mechanical characteristics of the composite material are discussed in this article. One limitation is introduced, that is the work in the elastic strain range and the fulfillment of the conditions of the strain compatibility of the reinforced matrix. These limitations are in accordance with the security of the work of the constructions. A high-quality formulae analysis depending on the final task is given in the article. The given formulae analysis for defining the effectiveness of physical and mathematical characteristics of composite rods, plates and shells enables to make calculations for more complicated tasks. A structural scheme of methods of defining of characteristics of composite materials is given.

Mechanical properties of new functional composite materials based on polymeric binders

Composite materials which include components (binding and fillers) that provide technological and operational characteristics were investigated. As a fillers AlN, Al(OH)3, SiO2, CaSi03 powders are used. Binder – dimethylsiloxane rubber SKTN A + PMS silicone oil in 4:1 proportion. Studied composite materials are designed for dielectric coatings materials creation, which have a high thermal conductivity and do not support combustion (through the use of fillers with flame retardant properties). The results of experimental studies of the mechanical characteristics of composite materials based on siloxane binder and fillers in the form of fine powders AlN, Al(OH)3, SiO2, CaSi03 are presented. The values of strength, coefficient of elasticity, relative elongation in tensile tests, modulus of elasticity in compression tests, Shore hardness are measured.

Property Modelling and Durability of Composite Materials

Composite materials are considered as complex systems with corresponding system attributes. The necessity of studying the properties and structure of composite materials as a whole as systems connected by relationships that generate integrative qualities is pointed out. When synthesizing a composite, it is proposed to use the principle of simulability: a complex system is represented by a finite set of models reflecting a certain facet of its essence. This makes it possible to investigate a certain property or group of properties of a building material using one or several simplified (narrowly-oriented) models. Identification of new properties and entities is done on the basis of building up a set of simplified models (the reflection of a complex system as a whole is provided by the interaction of simplified models). Using the principle of purposefulness makes it possible to describe the quality of the material by some functionality for an integrated system. Internal causal relationships, the existence and function of the composite material (system) are based on the principle described physicality (any system regardless of the inherent physical laws of nature, possibly unique); no other laws are required to describe the operation of the system. The study of material properties is made on the basis of parametric identification of kinetic processes of formation of physical and mechanical characteristics of composite materials. For special purpose building materials, a number of particular criteria (properties) are determined, and their description is formalized using the principal component method (reducing the dimensionality of problems in assessing the quality of a material with simultaneous determination of a set of independent partial criteria). The results of the practical application of the method for evaluating the quality of composite materials with special properties are presented. Among the priority criteria were: strength, density and porosity of the material. Their dependences on the coded volume fractions of aggregate and filler were obtained by methods of mathematical experiment planning. It is shown that for most properties one can confine oneself to second-order differential models; each of the properties of the composite is considered as one of the particular criteria. Appendices are given to the development of composite materials for various purposes. Using the methods of control theory, an analytical description of the durability of the composite material is given; parametric identification is reduced to the determination of time constants in a second-order differential model, taking into account their dependencies on the prescription and technological parameters. Assessment of durability of a radiation protective composite taking into account dependences of the main properties on the prescription and technological parameters received on the basis of the generalized model is made.