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A relevância do artigo deve-se ao crescimento estável da indústria de compósitos. Devido às suas altas características físicas e mecânicas, os materiais compósitos (MC) desempenham um papel vital em muitas áreas da tecnologia, como indústria aeroespacial, aviação, indústria automotiva, engenharia e instrumentação e a indústria médica. Ao criar os materiais com as características mecânicas e térmicas necessárias, são frequentemente usados vários aditivos e enchimentos que afetam a resistência e a elasticidade das amostras obtidas. Neste artigo, estudamos o efeito de inclusões esféricas em resina epóxi nas propriedades mecânicas do material. Uma estrutura composta de resina epóxi ED-20 com inclusões na forma de partículas esféricas de vidro PBS-50 foi considerada. O tamanho característico das partículas foi de cerca de 50 μm. No âmbito deste estudo, foram produzidos lotes de amostras com o volume característico de inclusões de 5%, 10%, 15% e 20%. Cada lote consistia em 6 amostras do mesmo tipo. Para verificar a distribuição do volume de partículas e estudar as inclusões, a microestrutura da seção delgada da amostra e o pó foram estudadas separadamente. Usando métodos de modelagem do processo, as amostras foram submetidas ao teste de flexão de três pontos. Com base nos resultados de testes mecânicos, foram obtidos o módulo de elasticidade, a resistência à tração e as deformações finais. Como parte do estudo dos materiais, foram realizados os cálculos numéricos usando o software Digimat (MSC Software) para modelar a estrutura e obter propriedades efetivas do material. Também foram realizados os cálculos de tensões usando o método dos elementos finitos em Ansys Workbench. O cálculo foi realizado para o conteúdo volumétrico de inclusões da ordem de 5%, 10%, 15% e 20% e na ausência de inclusões. Os resultados numéricos obtidos foram comparados com o estudo experimental. Com base nos cálculos numéricos, foi obtida a dependência da porcentagem de inclusões na resistência à tração e no módulo de elasticidade. The relevance of the article is due to the stable growth of the composite industry. Due to its high physical and mechanical characteristics, composite materials (CM) play a vital role in many areas of technology, such as aerospace, aviation, automotive, engineering and instrumentation, and the medical industry. When creating materials with the required mechanical and thermal characteristics, various additives and fillers are often used that affect the strength and elasticity of the samples obtained. In this paper, we study the influence of spherical inclusions in epoxy on the mechanical properties of the material. A composite structure of ED-20 epoxy with inclusions in the form of spherical particles of PBS-50 glass was considered. The characteristic particle size was about 50 μm. Within the framework of this study, batches of samples with a specific volumetric inclusion content of 5%, 10%, 15%, and 20% were produced. Each batch consisted of 6 samples of the same type. To check the distribution of particle volume and inclusion studies, the microstructure of the thin section of the sample and separately the powder were studied. Using methods of modeling the process, the samples were tested for 3-point bending. Based on the results of mechanical tests, the elastic module, strength limit, and ultimate strains were obtained. As part of the study of materials, numerical calculations were performed using Digimat software (MSC Software) to model the structure and obtain effective material properties, as well as strength analysis using the finite element method in Ansys Workbench. The calculation was carried out for the volumetric content of inclusions of 5%, 10%, 15%, and 20% order and in the absence of inclusions. The obtained numerical results were compared with an experimental study. Based on the numerical calculations, the dependence of the percentage of inclusions on the strength limit and elastic module was obtained. [ABSTRACT FROM AUTHOR]

As of now, many investigations are performed in order to develop methods of correlation with the help of relevant algorithms. This is especially helpfull for plotting vectors of displacements in order to estimate deformation of various materials, as well as to determine correspondence between sections of two images through calculation of the cross-correlating functions and to ensure seeking of the extremum. The aim of this study was to develop relevant method to estimate mechanism of fracture of materials in accordance with the data of analysis of a photographic image in respect of the parameter of the image intensity. In addition, this method is to be used with the help of the multivariate analysis (multi-factor analysis) of the interrelationship between image intensity, surface roughness, and possibility to determination the geometrical parameters of the deformation area/deformation volume under different conditions of operation. Digital method of processing of photographs/video frames has been used in order to investigate microstructure and surface of materials in respect of criterion of the image intensity in the course of mechanical tests in accordance with deformations. Quantitative parameters of the image intensity were compared to the structure of material, as well as to the surface roughness before and after destruction of samples. The images used were obtained during mechanical testing of aluminium samples. To ensure the validity of the test results, six specimens of the same type were tested. A stress-strain diagram was drawn up for each specimen. Stress-strain diagrams from the mechanical tests were compared with those from the photo analysis using the method described above. The results correlate well with each other, but unlike the experiment, where the strain is measured only at the strain gauge location, the photo analysis provides a complete picture of the strain distribution over the entire specimen area. In addition, a multivariate analysis has been carried out to evaluate the geometric dimensions and shapes of the structure elements. [ABSTRACT FROM AUTHOR]

The scientific paper presents a technique for calculating a thick-walled axially symmetrical construction consisting of a steel rod (reinforcing component) and an external thick-walled shell made of carbon fiber. The construction is loaded with linear load distributed along its length, associated with the operating external pressure, and inertial forces. The technique is based on a one-dimensional model of a composite rod of variable cross-section, roughly taking into account transverse deformations, which is necessary when analyzing a thickwalled construction operating under pressure. In the proposed approach, the geometry of the product is divided into sections and approximated by fragments in the form of truncated cones and, in the particular case, in the form of cylinders. As a result of calculations, the distribution of normal tensile/compression stresses in the shell and in the reinforcing rod, as well as tangential stresses at the boundary of their contact, are determined. As a result of test calculations, a fairly good consistency of the considered one-dimensional model with refined finiteelement modeling is shown. It has been established that the concentration of shear stresses is realised due to the presence of substantially inhomogeneous deformations in the areas of sharp changes in geometry, a reduction in the radius of the shell (the appearance of edge effects), and in the area of a sharp increase in the radius of the bevel of the shell where external pressure is in place. [ABSTRACT FROM AUTHOR]