Центральноукраїнський науковий вісник. Технічні науки. Випуск 5. Частина 1. - 2022
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Item Метрологічне забезпечення контролю технічних характеристик будівельних матеріалів і виробів(ЦНТУ, 2022) Пашинський, В. А.; Пашинський, М. В.; Дарієнко, В. В.; Pashynskyi, V.; Pashynskyi, М.; Darienko, V.На основі теорії похибок та методу лінеаризації функцій випадкових величин отримані робочі формули для оцінювання імовірних похибок експериментального визначення середньої густини, вологості, водопоглинання та міцності при стиску будівельних матеріалів на зразках правильної геометричної форми. Отримані формули дозволяють обґрунтовано вибрати засоби вимірювань з урахуванням необхідної точності визначення технічних характеристик. The problem of assessing the possible relative errors of the technical characteristics of building materials when testing samples of the correct geometric shape has been solved. The work is based on the theory of errors and on the method of linearization of functions of random variables. The technical characteristics of the materials are determined by the equations of indirect measurements through the input parameters, directly measured during the tests with known level of accuracy. Linearization of the equations of indirect measurement allowed to obtain dependences for determining the standard and probable relative errors of determining the average density, humidity, water absorption and compressive strength of building materials. Samples of the correct geometric shape of the following types are considered: cube, parallelepiped, circular cylinder. The input values of the obtained formulas are the size and weight of the samples, as well as the destructive force during compression. The accuracy of direct measurement of these values is determined by the values of division of the corresponding measuring instruments. The obtained formulas give possible relative errors of indirect measurements of the analyzed technical characteristics corresponding to the given two-way security level. The use of the obtained formulas allows you to reasonably choose the means for measuring the input parameters that provide the necessary accuracy of the results of determining the technical characteristics with the maximum ease of performing the measurements. The method for assessing the accuracy and the choice of measuring instruments for measuring the size and mass of samples is illustrated by an example of determining the average density of a mortar based on the results of testing cubic samples of different sizes. The results of the study can be used in the experimental determination of the analyzed technical characteristics of building materials of other types, as well as extended to assess the accuracy of other technical characteristics, which are determined by indirect methods.Item Підвищення ефективності конструкції кованого дворогого гака(ЦНТУ, 2022) Портнов, Г. Д.; Тихий, А. А.; Дарієнко, В. В.; Пукалов, В. В.; Portnov, G.; Tykhyi, А.; Dariienko, V.; Pukalov, V.Запропоноване вдосконалення вантажних дворогих гаків ГОСТ 6628-73, яке теоретично дозволяє зменшити масу на 7% при збереженні експлуатаційних властивостей. Проведено аналіз впливу форми кованого дворогого гака на його ефективність. Побудована модель для вивчення напружено – деформованого стану кранового гака в умовах максимального навантаження, придатна до утворення конфігурацій номерів гака. Визначені найменш навантажені елементи моделі за допомогою візуалізації розподілених напружень. An improvement of standard cargo two-horned hooks is proposed, which theoretically allows to reduce the weight by 7% while maintaining performance. The analysis of influence of the form of the forged two-horned hook on its efficiency is carried out. The model for studying the stress - strain state of the crane hook under conditions of maximum load, suitable for the formation of configurations of hook numbers. The modeling of solid objects is carried out, which allows to analyze the structures made according to the scheme of the curved beam with an accuracy greater than that allowed by the theoretical calculation. The least loaded elements of the model are determined by visualization of distributed stresses. Comparison of world standards of two-horned hooks shows a significant difference in material efficiency with the same classes and groups of classification. To study the stress - strain state of the crane hook under conditions of maximum load in the program SolidWorks built a model suitable for the formation of hook configurations. The stress-strain state of the models was determined for two load variants. The load on both hooks of the hook is distributed evenly and the load is suspended on one horn. Experience in the operation of standardized hooks has determined the ergonomics of the surfaces of products in contact with the rafter equipment. The geometric ratios of the cross-sectional dimensions of the hooks, as well as the threaded part can be considered determined theoretically and experimentally as optimal. It is reasonable to remove part of the material of the middle part of the hook. The strength criterion was the coefficient of safety margin. It is acceptable to reduce the value of K of the newly developed model by 5% of the K model of the hook. Making a hole in the model changes the ratio of the stiffness of its elements, which leads to a change in the load pattern. The process of choosing the shape of the hole is iterative. The stress distribution in the elements of the model at different load variants with the indication of the minimum value of the safety factor K is presented. When developing design documentation for a two-horned hook with holes should take into account the ratio of the parameters of the holes with the characteristic size of the throat.