Determination of fracture mechanics parameters structural components with surface crack under thermomechanical loads

Equipment that is exposed to severe operational pressure and thermal cycling, like coke drums, usually suffer fatigue. As a result, equipment of this sort develop defects such as cracking in the circumferential welds. Operating companies are faced with the challenges of deciding what is the best way to prevent these defects, as well as determining how long they could operate if a defect is discovered. This paper discusses a methodology for fracture mechanics testing of coke drum welds, and calculations of the critical crack size. Representative samples are taken from production materials, and are welded employing production welding procedures. The material of construction is 1.25Cr-0.5Mo low alloy steel conforming to ASME SA-387 Gr 11 Class 2 in the normalized and tempered condition (N&T). Samples from three welding procedures (WPS) are tested: one for production, one for a repair with heat treatment, and one for repair without heat treatment. The position and orientation of test specimen are chosen based on previous surveys and operational experience on similar vessels that exhibited cracks during service. Fracture mechanics toughness testing is performed. Crack finite element analysis (FEA) model is used to determine the path-independed JI-integral driving force. Methodology for the determination of critical crack size is developed.

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Interaction of a Crack in the Plasma-Sprayed Ceramic Coating with the Metal Substrate

Materials Science Forum ◽

10.4028/www.scientific.net/msf.482.223 ◽

2005 ◽

Vol 482 ◽

pp. 223-226

Author(s):

Luboš Náhlík ◽

Zdeněk Knésl ◽

F. Kroupa

Keyword(s):

Fracture Toughness ◽

Fracture Mechanics ◽

Surface Crack ◽

Ceramic Coating ◽

Ceramic Coatings ◽

Metal Substrate ◽

High Density ◽

Initial Surface ◽

Young’S Moduli ◽

Plasma Sprayed

Plasma-sprayed ceramic coatings contain a high density of intrasplat microcracks which are responsible for small Young’s moduli and low fracture toughness. The extension of an initial surface crack in the direction to the interface, where the crack is repelled by the metal substrate with higher Young’s modulus, is studied using the methods of fracture mechanics. It is shown that high tensile stresses induced by the crack in the interface can lead to a local decohesion along the interface so that the crack can deviate into the interface.

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Fracture Mechanics Approach into the Crack Growth of Si3N4 under Ball-on-Plate Contact. (Surface Crack Growth Behavior in the Center of the Contact Area).

TRANSACTIONS OF THE JAPAN SOCIETY OF MECHANICAL ENGINEERS Series A ◽

10.1299/kikaia.65.2113 ◽

1999 ◽

Vol 65 (638) ◽

pp. 2113-2119 ◽

Cited By ~ 1

Author(s):

Katsuyuki KIDA ◽

Keiji OGURA

Keyword(s):

Fracture Mechanics ◽

Crack Growth ◽

Contact Area ◽

Contact Surface ◽

Surface Crack ◽

Growth Behavior ◽

Crack Growth Behavior ◽

Surface Crack Growth

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THE CONTENT ASPECT OF THE IMAGE “I” IN THE STRUCTURE OF TEACHERS’ PERSONAL IDENTITY AT DIFFERENT STAGES OF PROFESSIONAL DEVELOPMENT

Pedagogical Review ◽

10.23951/2307-6127-2020-6-230-242 ◽

2020 ◽

pp. 230-242

Author(s):

Ольга Владимировна Савельева ◽

Александр Витальевич Гычев ◽

Юлия Валерьевна Овчинникова

Keyword(s):

Professional Development ◽

Identity Formation ◽

Personal Identity ◽

Point Of View ◽

Educational Institutions ◽

Structural Components ◽

Developmental Impairment ◽

Social Components ◽

The City

В меняющихся социально-экономических условиях происходит нарушение развития личностной идентичности педагогов, что приводит к искажению (деформации) ее структурных компонентов. В связи с этим необходим научный поиск путей преодоления кризиса идентичности и построение программ развития подсистем личностной (индивидуальной) и социальной (профессиональной) идентичности педагогов, адекватных изменившимся условиям. В работе изучены уровни дифференцированности идентичности, рефлексивности, особенности эмоционально-оценочного тона идентификационных характеристик, соотношение личностных и социальных компонент в самоопределении идентичности. Выборку исследования составили 132 педагога образовательных учреждений г. Киселёвска Кемеровской области в возрасте 24–63 лет с педагогическим стажем от 1 года до 35 лет. Все педагоги разделены на шесть групп в соответствии с периодизацией профессионального становления В. А. Дмитриевского. Для всех испытуемых характерна негармоничность элементов идентичности, преобладание социальных компонент (учебно-профессиональные и семейно-клановые характеристики) в структуре самоописаний, средний уровень рефлексивности и низкий уровень самопринятия. Полученные данные интерпретируются с точки зрения теорий профессионального становления и формирования идентичности. In the changing socio-economic conditions there is a developmental impairment of teachers’ personal identity, which leads to a distortion (deformation) of its structural components. The relevance of the study is due to the need for a scientific search for ways to overcome the identity crisis and build programs for the development of subsystems of personal (individual) and social (professional) teachers’ identity that are adequate to changing conditions. The aim of the study was to investigate the levels of differentiation, reflexivity, features of the emotional-evaluative tone of identification characteristics, the ratio of personal and social components in self-determination of identity. Research sample consists of 132 teachers of educational institutions of the city of Kiselevsk, Kemerovo region, aged 24 to 63 years, with pedagogical experience from 1 year to 35 years. All teachers were divided into 6 groups in accordance with the periodization of the professional development of V. A. Dmitrievsky. All subjects were characterized by the the inharmony of elements of identity, the predominance of social components (educational, professional and family-clan characteristics) in the structure of self-descriptions, the average level of reflectivity and a low level of self-acceptance. The received data were interpreted from the point of view of theories of professional formation and identity formation.

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