tailieunhanh - Abstract of doctor thesis in Mechanical engineering and Engineering mechanics: Crack detection in bars, beams by measurement of frequency response function

The aims of this study are to develop and apply the method of using frequency response functions to diagnose cracks in elastic bar and beams structure. The contents of the study includes: building models of cracked elastic bar and 3 beams structure; studying the changes of oscillation parameters, mainly frequency response functions due to cracks. | MINISTRY OF EDUTATION VIETNAM ACADEMY OF SCIENCE AND TRAINING AND TECHNOLOGY GRADUATE UNIVERSITY OF SCIENCE AND TECHNOLOGY ----------------------------- LE KHANH TOAN CRACK DETECTION IN BARS BEAMS BY MEASUREMENT OF FREQUENCY RESPONSE FUNCTION Specialization Engineering Mechanics Code 9 52 01 01 ABSTRACT OF DOCTOR THESIS IN MECHANICAL ENGINEERING AND ENGINEERING MECHANICS HANOI - 2019 The thesis has been completed at Graduate University of Science and Technology - Vietnam Academy of Science and Technology Supervisions 1 . Nguyen Tien Khiem 2 . Nguyen Viet Khoa Reviewer 1 Reviewer 2 Reviewer 3 Thesis is defended at Graduate University of Science and Technology - Vietnam Academy of Science and Technology at on date month 2019 Hardcopy of the thesis be found at - Library of Graduate University of Science and Technology - Vietnam National Library INTRODUCTION 1. Significance of the study Damage in structures especially cracks can cause the construction to collapse if not detected in time. This is proved by the results of studies of accidents that have occurred in important projects such as offshore rigs. However it is difficult to determine the position and the extent of a crack in a structure because the crack usually stays in the structures that the naked eye cannot detect. Therefore to diagnose cracks people often use non-destructive testing methods. One of these methods which is comprehensive and applicable to complex construction is based on measuring the oscillation parameters of a building to determine the position and extent of the damage in construction. The oscillation parameters commonly used in structural failure diagnosis are specific frequencies and patterns of oscillations or frequency response functions. These parameters are characteristics which are quite comprehensive for the technical condition of a building without depending on external stimuli. However identifying these characteristics from measurement data often understood as