The accuracy of the location of acoustic emission (AE) sources in the concentrator zones (central holes 5 mm in diameter) located at a distance of 40 mm from the receiving transducers during tensile tests of steel, aluminum alloy and composite flat specimens with dimensions of 550x50x4 mm was evaluated. Calculated speed dependence of propagation of pulses on the level of their amplitude and the partial energy of the high-frequency components of the spectrum is studied. With the threshold method of signal registration, the error in the location of AE event sources arising in the near zone of the receiving transducers at a distance 𝛥L<0.1 m can significantly exceed 10% relative to the base size (B) of the location area, when B<0.5 m. Moreover, with a decrease in the distance 𝛥L<0.05 m, the level of possible error will increase, reaching 20-30% relative to the basic size of the antenna array, when recording pulses with an amplitude level um<60 dB and a fraction of the energy of high-frequency spectrum components not exceeding 10%.

Рассматривается система комплексной техносферной безопасности, которую предложено создавать на предприятиях, имеющих опасные производственные объекты. Представлены концептуальные направления (задачи) для проведения исследований, в содержании которых вектор приоритета направлен в сторону минимизации (исключения) условий возникновения опасностей, что позволяет перевести рассматриваемую комплексную систему безопасностина новый качественный уровень управления.

Рассматривается методический подход к совершенствованию мероприятий направленных на минимизацию (исключение) рисков в Компании по жизнеобеспечению Московского Региона, за счет проведения работ по комплексному исследованию рисков возникновения опасностей реализуемых на основе связанности между подсистемами безопасности. Представляется иллюстрационный пример с отображением областей (участков) на плоскости, указывающих места для качественного использования финансовых средств Компании направляемых на снижение рисков.

Integrated use of acoustic emission and brittle oxide strain-sensitive coatings at early stages of deformation of damage and fracture zones in the specimens of polymeric composite materials (PCM) may be the most effective method of nondestructive defect detection and strength assessment of modern composite materials. An external load applied to the tested structure forms a crack pattern in brittle tenso-sensitive coatings (TSC), which reflects the actual distribution of the maximum primary stress not only in the zones of stress concentration at the surface but also in the vicinity of the local defects. Proceeding from the resulted crack pat terns and refined characteristics of tenso-sensitivity of the brittle coating we may estimate the distribution of the maximum principal stress (strain). The limitations of the method of brittle coatings are attributed, first, to the location of tenso-sensitive coatings (in the zones that are technologically accessible for deposition) and, second, by the necessity of remote monitoring of the crack formation. To solve the aforementioned shortcomings and automate monitoring of the crack formation in a tenso-sensitive coating, we propose to use the method of brittle coatings in combination with acoustic emission (AE) and video recording. The developed integrated procedure provides a good opportunity to determine zones of the most probable fracture and the rate of specimen degradation during the entire period of structure testing, starting with 10- 15% of the critical load, long before the beginning of the active phase of degradation of the PCM structure. The method ensures an accurate determnination of the area of forthcoming destruction of the sample and provides determination of the field distribution of the main principal strains in the area of TSC cracking and their quantitative assesment.

A method of mathematical processing and algorithm of numerical adjustment of experimental fields of displacements on a specimen surface in the vicinity of the crack tip is proposed taking into account displacement of the body as a rigid unit upon loading and actual position of the crack tip. The initial experimental displacement fields around the tip of the fatigue crack in a compact specimen are determined by the method of digital image correlation. Taking a compact specimen as an example we demonstrate the possibility of successful using of this approach to obtain the distribution of the stress intensity factors and nonsingular Г-stresses along the front of a spatial crack.

The method is based on the assumption that the fracture zone around the crack is the area at the crack top where the stress-strain state (SSS) can not be described by the eigenfunctions of the solution of the elastic problem (Williams solution). To describe SSS beyond the fracture zone we use the aforementioned Williams expansion in which it a significant number of regular members should be taken into account. We proposed to use optical-digital methods to measure SSS parameters in the fracture zone which provide the a great bulk of experimental data in the form of displacement fields of the surface under study directly in a digital form.

Evolution of the parameters of fracture mechanics at different stages of low cycle damage is analyzed. The developed approach is based on processing the results of optical interferometric measurements of the deformation response to a small increment of the crack length. Three consecutive symmetrical notches are used to simulate the process of fatigue crack propagation through the zone of accumulated damage induced by low cycle fatigue. The magnitude of tangential component of the displacement measured at several points on the edge of the notch using speckle-inter-ferometry is an input experimental data. The first four coefficients of the Williams series solution are used to determine the stress intensity factor (SIF) and T-stress values. The values of crack opening, SIF and T-stress for cracks of different lengths are obtained at a fixed number of preliminary loading cycles N c = 0, 100, 1000, 1800, 2500, and 3300. The dependences of the parameters of fracture mechanics for the cracks of fixed length on N c number which illustrate a process of fatigue damage accumulation are constructed.

Разработаны программные средства, позволяющие в среде ANSYS автоматизировать процесс расчета трехмерного поля напряжений у вершины трещины смешанного типа. Приведены результаты расчетов коэффициентов интенсивности напряжений и компонентов несингулярных Г-напряжений для дискового образца с наклонной трещиной в условиях сжатия при варьировании толщины образца и приближенном постоянстве параметра смешанности типов (I + II) нагружения. Отмечено значительное влияние толщины образца на несингулярные /^-напряжения при несущественном изменении /„-напряжений.