Search

The main results of research on some nonclassical problems of fracture/failure mechanics are analyzed. These results have been obtained by the author and his followers at the Department of Dynamics and Stability of Continua of the S. P. Timoshenko Institute of Mechanics of the National Academy of Sciences of Ukraine (the NAS of Ukraine) during the last 50 years. The nonclassical problems of fracture/failure mechanics are problems to which the approaches and criteria of classical fracture mechanics are not applicable. A distinguishing feature of the results obtained by the author and his followers is application of three-dimensional theories of stability, dynamics, and statics of solid mechanics to study the nonclassical problems of fracture/failure mechanics. The majority of other researchers have been using various approximate theories of shells, plates, and rods as well as other approaches to studying the nonclassical problems of fracture/failure mechanics. The main scientific results of solving the eight nonclassical problems of fracture\failure mechanics obtained in the framework of the above mentioned approach (three-dimensional theories of solid mechanics) have been presented very briefly, with focus on the statement of problems, the analysis of corresponding experiments, the development of methods for their solution within the framework of approach under consideration, and the discussion of final results. The mathematical aspects of the methods for solving the mentioned problems and their computer-aided implementation have not been discussed in this review, with information on this subject briefly presented as annotation. The following eight nonclassical problems of fracture\failure mechanics (results by the author and his followers) are considered in this review: – first problem is fracture of composites compressed along the reinforcement; – second problem is short-fiber model in stability and fracture of composites under compression; – third problem is end-crush fracture of composites under compression along the reinforcement; – fourth problem is brittle fracture of cracked materials with initial (residual) stresses acting along the cracks; – fifth problem is shredding fracture of composites stretched or compressed along the reinforcement; – sixth problem is fracture of materials under compression along parallel cracks; – seventh problem is brittle fracture of cracked materials under dynamic loads (with contact interaction of the crack faces); – eighth problem is fracture of thin-walled cracked bodies under tension with prebuckling. About 523 monographs and papers published by the author and his followers on the eight nonclassical problems of fracture mechanics have been included in the references to this review. This review consists of three parts. The first part is General Problems; it is published in Prikladnaya Mekhanika (55, No. 2, 2019). The second part is Compressive Failure of Composite Materials; it is published in Prikladnaya Mekhanika (55, No. 3, 2019). The third part is Other Nonclassical Problems of Fracture/Failure Mechanics; it is published in Prikladnaya Mekhanika (55, No. 4, 2019). [ABSTRACT FROM AUTHOR]

The principal results of research on some nonclassical problems of fracture/failure mechanics have been analyzed. These results have been obtained by the author and his followers at the Department of Continuum Dynamics and Stability of the Tymoshenko Institute of Mechanics of the National Academy of Sciences of Ukraine (the NAS of Ukraine) during the last 50 years. The nonclassical problems of fracture/failure mechanics are problems to which the approaches and criteria of classical fracture mechanics are not applicable. A distinguishing feature of the results obtained by the author and his followers is application of three-dimensional theories of stability, dynamics, and statics of solid mechanics to study the nonclassical problems of fracture/failure mechanics. The majority of other researchers have been using various approximate theories of shells, plates, and rods as well as other approaches to studying the nonclassical problems of fracture/failure mechanics. The main scientific results of solving the eight nonclassical problems of fracture\failure mechanics obtained in the framework of the above mentioned approach (three-dimensional theories of solid mechanics) have been presented very briefly, with focus on the statement of problems, the analysis of corresponding experiments, the development of methods for their solution within the framework of approach under consideration, and the discussion of final results. The mathematical aspects of the methods for solving the mentioned problems and their computer-aided implementation have not been discussed in this review, with information on this subject briefly presented as annotation. The following eight nonclassical problems of fracture\failure mechanics (results by the author and his followers) are considered in this review: – first problem is fracture of composites compressed along the reinforcement; – second problem is short-fiber model in stability and fracture of composites under compression; – third problem is end-crush fracture of composites under compression along the reinforcement; – fourth problem is brittle fracture of cracked materials with initial (residual) stresses acting along the cracks; – fifth problem is shredding fracture of composites stretched or compressed along the reinforcement; – sixth problem is fracture of materials under compression along parallel cracks; – seventh problem is brittle fracture of cracked materials under dynamic loads (with contact interaction of the crack faces); – eighth problem is fracture of thin-walled cracked bodies under tension with prebuckling. About 523 monographs and papers published by the author and his followers on the eight nonclassical problems of fracture mechanics have been included in the references to this review. This review consists of three parts. The first part is General Problems; it is published in Prikladnaya Mekhanika (55, No. 2, 2019). The second part is Compressive Failure of Composite Materials. The third part deals with other nonclassical problems of fracture mechanics. [ABSTRACT FROM AUTHOR]

Integrity of the reactor pressure vessel is a critical element in demonstrating the capability of nuclear power plant for operation to at least 80 years. Long-term exploitation of materials at elevated temperatures is manifested in a loss of ductility and a marked shift in the interval from ductile fracture to brittle transition to higher temperatures. Embrittlement of the VVER reactor vessel is associated with many factors that result from prolonged operation. Radiation embrittlement is a key factor that determines the operational long-term of any reactor pressure vessel (RPV). Given that VVERs were intended to operate for 40 years, there are issues that need to be addressed to reduce the uncertainties in regulatory application. Existing approaches in the nuclear power industry of Ukraine to assess the fracture toughness of the irradiated materials of pressure vessel are based on empirical correlations between the parameters of crack resistance and impact strength which leads to a reassessment of the long-term safe operation of RPV. VVER reactors long-term operation require accurate predictions increases in the ductile-brittle transition temperature (ΔTK) of reactor pressure vessel steels of neutron irradiation-induced that are outside the existing database. For example, the neutron dose in RPV will be at least doubled. Associated with this factor are uncertainties regarding flux effects, effects of relatively high nickel content, uncertainties regarding application of fracture mechanics and thermal annealing. In this paper, it is proposed to conduct a research of the metal on fracture toughness, directly obtained from the reactor pressure vessel, in order to study the ΔTK prediction on operating time, irradiation, temperature and number of start/stop cycles when testing sub-sized specimens. To date experimental methods of fracture mechanics allow the directly to determine the properties of materials through the testing of sub-size specimens, which allows to determine long-term of RPV. In NSC KIPT have been developed the equipment, methodology and experience, which allows obtaining additional information in the analysis of the state metal of the equipment, which has been in long-term operation. [ABSTRACT FROM AUTHOR]