Modeling The Microrelief Structure of Ti6Al4V Titanium Alloy Surface After Exposure to Femtosecond Laser Pulses

A method of mathematical modeling of the ordered surface relief of titanium alloy Ti6Al4V after femtosecond laser treatment is proposed, which allowed obtaining the informative signs of the self-organized surface irregularities, taking into account the stochastic and cyclic nature of this process. An algorithm has been developed, and a package of computer programs has been created based on the proposed mathematical model. These methods make it possible to analyze the zone-spatial two-dimensional structure of the cyclic relief of the modified surface. They are also the basis for creating the specialized software for the automated profilometric diagnostic systems

Analysis of surface relief evolution of polycrystalline aluminum alloy under static deformation

The peculiarities of using the surface as a damage sensor of the A2024 aluminum alloy under significant plastic strains are analyzed. Physical and mechanical regularities in the spatial self-organization of the structural and mechanical defects are found, and their relationship with the pore formation and deformation processes inside the material is established. It is proved that the surface relief formation can be used as the engineering parameter of the A2024 aluminum alloy damage under static deformation

Recognition and definition of parameters of separated dimples of ductile tearing and their conglomerates

Запропоновано метод кількісного аналізу параметрів ямок в’язкого відриву та їх конгломератів на фрактографічному зображенні. Обчислено поля розподілу коефіцієнта кореляції аналізованих ділянок зображення із розпізнаванням ділянок «ямка-фон». Оцінено особливості застосування розробленого методу сегментації для ямок різної фізичної природи.The method of quantitative analysis of parameters of dimples of ductile tearing and their conglomerates in a fractographic image is proposed. Fields of distribution of the correlation coefficient of the analyzed image areas are calculated with the recognition of “dimple-background” areas

The analysis of influence of a nozzle form of the Bernoulli gripping devices on its energy efficiency

This article presents the advantages of using Bernoulli gripping devices in the transport and loading systems of the automated production. It provides the modeling of air flow dynamics in a nozzle and in a radial interval between the interacting surfaces of Bernoulli gripper and object of transportation. For this purpose we use averaging on RANS equation of dynamics of viscous gas, SST-model of turbulence and γ-model of laminar and turbulent transition. As a result of the study, this paper offers options of constructive improvement of a nozzle form and conditions for the analysis of energy efficiency of Bernoulli gripper. The theoretical contribution of this paper is that, as a result of numerical modeling in the program Ansys-CFX environment, the influence of the nozzle form in the Bernoulli gripping devices’ on its carrying power, account characteristics, and energy efficiency has been determined

Experimental research of partial regular microreliefs formed on rotary body face surfaces

The basic regularities in the influence of processing parameters on the geometrical characteristics of the partially regular microreliefs, formed on the rotary body face surface, are established. Combinations of partially regular microreliefs are formed by using a contemporary CNC milling machine, and an advanced programing method, based on previously developed mathematical models. Full factorial experimental design is carried out, which consist of three factors, varied on three levels. Regression stochastic models in coded and natural form, which give the relations between the width of the grooves and the deforming force, feed rate and the pitch of the axial grooves, are derived as a result. Response surfaces and contour plots are built in order to facilitate the results analysis. Based on the dependencies of the derived regression stochastic models, it is found that the greatest impact on the width of the grooves has the magnitude of the deforming force,followed by the feed rate. Also, it is found that the axial pitch between adjacent toolpaths has the least impact on the width of the grooves. As a result of the full-factorial experiment, the average geometric parameters of the microrelief grooves were obtained on their basis. When used, these values will provide for the required value of the relative burnishing area of the surface with regular microreliefs, and, accordingly, the specified operational properties

Fatigue and brittle fracture of carbon steel of gas and oil pipelines

The areas of low frequency and corrosion fatigue for basic metal and welding joints of oil and gas pipelines have been determined on the basis of corrosion-fatigue test results. The most dangerous diapasons of the operation loadings were also determined. The present work also proposes the methodical approaches to the survivability prediction

Defectiveness of external and internal surfaces of the main oil and gas pipelines after long-term operation

Damage by pitting corrosion of the surface areas of the local oil and gas pipelines was identified and numeri-cally analysed in this paper. Having used the methods of optical and scanning electron microscopy, the basic laws of structural and mechanical degradation were established. Based on the data of fractographic control, the shape of defects and substantiated morphological characteristics were examined. It was established that certain informative signs of the defects correspond to certain stages of operation. Having used methods of fractodiagnostics, the main reasons for the performance defects of main oil and gas pipelines were established, and the mechanisms of degradation as well as frac-ture of the materials they are made from were described. According to the findings, the cause of the decrease in the reli-ability of the main oil and gas pipeline networks is general and localised corrosion as well as technological defects in the pipeline metal. These studies are essential for the establishment of the complex of mechanical and corrosion-mechanical properties, particularly sensitive to degradation in the steel used for the pipe wall after a lengthy use of a pipe

Автоматизований аналіз множинного розтріскування нанопокриву за інтегральними параметрами

Ідентифіковано та кількісно проаналізовано мережі тріщин у цирконієвому нано- покриві на основі оброблення цифрових зображень. Поведінку дефектів оцінено за результатами діагностування окремих етапів деформаційного процесу. Встановлено, що окремим стадіям руйнування покриву відповідають свої інтегральні параметри зображення. На основі послідовної обробки даних поверхневого множинного розтріскування виявлено основні закономірності коалесценції окремих дефектів та фрагментації покриву. Встановлено, що множинні дефекти в матеріалі частково збільшують його деформаційні властивості, спричиняючи "поглинання" енергії пружно-пластичних деформацій прилеглих ділянок. Подано теоретичні передумови і експериментальні результати.Проведена идентификация и количественный анализ сетки трещин в циркониевом нанопокрытии на основе обработки цифровых изображений поверхности. Поведение дефектов оценивали по результатам диагностики отдельных этапов деформационного процесса. Установлено, что отдельным стадиям разрушения покрытия соответствуют определенные интегральные параметры изображения. На основании последовательной обработки данных множественного поверхностного растрескивания выявлены основные закономерности коалесценции отдельных дефектов и фрагментации покрытия. Установлено, что множественные дефекты в материале увеличивают его деформационные свойства, вызывая "поглощение" энергии упруго-пластических деформаций прилегающих участков. Представлены теоретические предпосылки и экспериментальные результаты.Identification of the quantitative analysis of crack network in the zirconium nanocoating based on the digital imaging surface processing are described. The behavior of the defects was assessed by the results of diagnostics of individual stages of the deformation process. The basic laws of coalescence of individual defects and fragmentation of the coating was analysed on the base on the serial processing of multiple cracking of the surface. The presence of multiple defects in the material increases its deformation properties, causing the energy "absorption" of elastic-plastic deformation of the surrounding areas. Theoretical background and experimental results are presented