Estimation of Acoustic Source Positioning Error Determined by One-Dimensional Linear Location Technique

The one-dimensional (1D) linear location technique has been considered as one of the methods for determining the position of acoustic emission (AE) sources in metallic objects. However, this approach does not take into account the heterogeneity of materials and that leads to poor accuracy of AE sources localization. To estimate the positioning error of the linear location technique which is typically used to determine the AE source location a new approach based on the combination of experimental and simulation methods is proposed. This approach for error estimation contains a finite element model construction of the AE signals localization. The model consists of transmitting and receiving transducers mounted on the test object, the frequency response of which selected close to the characteristics of acoustic emission transducers applied in the preliminary experiments. The application of the approach in current research showed that a reduced positioning error on a flat steel plate reaches 15%. The proposed technique can be used to optimize the number of preliminary tests required to calculate the reduced error of the 1D linear location technique applied for the AE sources localization during the inspection of the structure.

Computational Analysis of the Forces Distribution in a Metal Frame Structure Taking into Account Plastic Deformations of the Material

Постановка задачи. С целью снижения материалоемкости строительных конструкций нормативные документы рекомендуют учитывать пластические свойства стали в прочностных расчетах. Это требует развития соответствующих методов расчета с применением современного программного обеспечения. Результаты. Усовершенствована методика расчета плоского стального рамного каркаса на статическую нагрузку на основе принципа предельного равновесия с применением программно-вычислительного комплекса «ЛИРА». Исследован поэтапный характер разрушения конструкции при воздействии сверхнормативных нагрузок. Выводы. Показано, что применение пошагового метода нагружения позволяет моделировать поведение конструкции в ходе увеличения нагрузки. Проведенные исследования позволяют давать верхнюю оценку максимально возможной нагрузки, возникающей в исключительных условиях эксплуатации. Statement of the problem. In order to reduce the material consumption of building structures, in regulatory documents it is recommend that the plastic properties of steel in strength calculations are taken into account. This requires the development of appropriate calculation methods by means of modern software. Results. The method of calculating a flat steel frame structure for static load based on the principle of limiting equilibrium using the design-computational complex LIRA has been improved. The gradual nature of structural failure under the influence of excessive loads is studied. Conclusions. It is shown that the application of the step-by-step loading method makes it possible to model the behavior of the structure during an increase in load. The studies allow us to provide an upper estimation of the maximum possible load that occurs under exceptional operating conditions.

FEATURES OF CALCULATING THE DEFLECTION OF ROUND PLATES

A method for calculating the deflection of a round flat steel plate bearing an ax isymmetric load is considered. For practical calculations, dimensionless coefficients of deflection in the center of the plate, deflection at a certain distance from the center of the plate, the stress coefficient and the accompanying function, which depends on the deflection of the plate and the pressure force on it, are used.

CALCULATION OF THE DEFLECTION OF A PINCHED ROUND PLATE

A method for calculating the deflection of a round flat steel plate pinched along the edge, bearing an axisymmetric load, is considered. For practical calculations, dimensionless coeffi cients of deflection in the center and in the area of fixing a round flat plate pinched along the edge are applied, the stress coefficient and the accompanying function, which depends on the deflection of the plate and the pressure force on it, are taken into account

Nonlinear problems of structural mechanics. Methods of optimal design of structures

The textbook discusses methods of optimal design of structures, including methods for minimizing the functions of one and several variables; methods for solving linear and nonlinear programming problems; examples of optimal design of flat steel frames with elements made of rolled and composite I-beams. It is intended for students studying in the specialty 08.05.01 "Construction of unique buildings and structures", undergraduates studying in the training program 08.04.01.24 "Modern technologies of design and construction of buildings and structures", studying the discipline "Nonlinear problems of structural mechanics", as well as for postgraduates of the direction 08.06.01 " Engineering and construction technologies. Construction of buildings and structures", studying the discipline "Construction Mechanics".