• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 추계학술대회논문집
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• pp.865-868
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• 2006

In this paper, a dynamic behavior(natural frequency) of a cracked simply supported pipe conveying fluid is presented. In addition, an analysis of the flutter and buckling instability of a cracked pipe conveying fluid due to the coupled mode (modes combined) is presented. Based on the Euler-Bernouli beam theory, the equation of motion can be constructed by using the Lagrange's equation. The crack section is represented by a local flexibility matrix connecting two undamaged beam segments. The stiffness of the spring depends on the crack severity and the geometry of the cracked section. The crack is assumed to be in the first mode of fracture and to be always opened during the vibrations. This study will contribute to the safety test and stability estimation of structures of a cracked pipe conveying fluid.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2007년도 정기 학술대회 논문집
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• pp.99-104
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• 2007

In this paper a dynamic behavior(natural frequency) of a cracked cantilever beam with tip mass and follower force is presented. In addition. an analysis of the flutter and buckling instability of a cracked cantilever beam subjected to a follower compressive load is presented. Based on the Euler-Bernouli beam theory, the equation of motion can be constructed by using the Lagrange's equation. The vibration analysis on such cracked beam is conducted to identify the critical follower force for flutter ins stability based on the variation of the first two resonant frequencies of the beam. Besides. the effect of the crack's intensity and location on the flutter follower force is studied. The crack section is represented by a local flexibility matrix connecting two undamaged beam segments. The crack is assumed to be in the first mode of fracture and to be always opened during the vibrations.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 추계학술대회논문집
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• pp.713-716
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• 2004

In this paper a dynamic behavior of a double-cracked cnatilver beam with a tip mass and the moving mass is presented. Based on the Euler-Bernoulli beam theory, the equation of motion is derived by using Lagrange's equation. The influences of the moving mass, a tip mass and double cracks have been studied on the dynamic behavior of a cantilever beam system by numerical method. The cracks section are represented by the local flexibility matrix connecting two undamaged beam segments. ,Therefore, the cracks are modelled as a rotational spring. Totally, as a tip mass is increased, the natural frequency of cantilever beam is decreased. The position of the crack is located in front of the cantilever beam, the frequencies of a double-cracked cantilever beam presents minimum frequency.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 추계학술대회논문집
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• pp.600-603
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• 2005

In this paper we studied about the effect of the double cracks on the dynamic behavior of a simply supported beam. The equation of motion is derived by using Lagrange's equation and analyzed by numerical method. The simply supported beam is modeled by the Euler-Bernoulli beam theory. The crack section is represented by a local flexibility matrix connecting three undamaged beam segments. The influences of the crack depth and position of each crack on the vibration mode and the natural frequencies of a simply supported beam are analytically clarified. The theoretical results are also validated by a comparison with experimental measurements.

• Structural Engineering and Mechanics
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• 제58권1호
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• pp.103-119
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• 2016

Multi-storey frame structures are frequently exposed to static and dynamic forces. Therefore analyses of static (buckling) and dynamic stability come into prominence for these structures. In this study, the effects of number of storey, static and dynamic load parameters, crack depth and crack location on the in-plane static and dynamic stability of cracked multi-storey frame structures subjected to periodic loading have been investigated numerically by using the Finite Element Method. A crack element based on the Euler beam theory is developed by using the principles of fracture mechanics. The equation of motion for the cracked multi-storey frame subjected to periodic loading is achieved by Lagrange's equation. The results obtained from the stability analysis are presented in three dimensional graphs and tables.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 춘계학술대회논문집
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• pp.254-257
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• 2006

In this paper a dynamic behavior(natural frequency) of a cracked cantilever and simply supported pipe conveying fluid is presented. In addition, an analysis of the flutter and buckling instability of a cracked pipe conveying fluid subjected to a follower compressive load is presented. Based on the Euler-Bernouli beam theory, the equation of motion can be constructed by using the Lagrange's equation. The crack section is represented by a local flexibility matrix connecting two undamaged beam segments. The crack is assumed to be in the first mode of fracture and to be always opened during the vibrations.

• Advances in nano research
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• 제16권5호
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• pp.489-500
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• 2024

This paper studies the free vibration analysis of the piezo-magneto-thermo-elastic FG nanobeam submerged in a fluid environment. The problem governed by the partial differential equations is determined by refined higher-order State Space Strain Gradient Theory (SSSGT). Hamilton's principle is applied to discretize the differential equation and transform it into a coupled Euler-Lagrange equation. Furthermore, the equations are solved analytically using Navier's solution technique to form stiffness, damping, and mass matrices. Also, the effects of nonlocal ceramic and metal parts over various parameters such as temperature, Magnetic potential and electric voltage on the free vibration are interpreted graphically. A comparison with existing published findings is performed to showcase the precision of the results.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2006년도 정기 학술대회 논문집
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• pp.703-708
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• 2006

In this paper a dynamic behavior(natural frequency) of a cracked simply supported pipe conveying fluid is presented. In addition, an analysis of the buckling instability of a cracked pipe conveying fluid subjected to a follower compressive load is presented. Based on the Euler-Bernouli beam theory, the equation of motion can be constructed by using the Lagrange's equation. The crack section is represented by a local flexibility matrix connecting two undamaged beam segments. TI1e crack is assumed to be in the first mode of fracture and to be always opened during the vibrations.

• 한국항행학회논문지
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• 제19권6호
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• pp.544-551
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• 2015

본 논문에서는 첨단 운전자 보조 시스템 (ADAS; advanced driver assistance system) 용 이동객체검출 (MOD; moving object detection)을 위한 광학흐름추정기 (OFE; optical flow estimator) 의 하드웨어 구조 설계 결과를 제시하였다. 광학흐름추정 알고리즘은 차량 환경에서 높은 정확도를 나타내는 광역 최적화 (global optimization) 기반 Brox 알고리즘을 적용하였다. Brox 알고리즘의 에너지 범함수 (energy functional)를 최소화 하는 과정에서 생성되는 Euler-Lagrange 방정식을 풀기 위해 하드웨어 구현에 용이한 Cholesky factorization이 적용되었으며, 메모리 접근율 (memory access rate)를 줄이기 위해 시프트 레지스터 뱅크 (shift register bank)를 도입하였다. 하드웨어 구현은 Verilog-HDL을 사용하였으며, FPGA 기반 설계 및 검증이 수행되었다. 제안된 광학흐름추정기는 40.4K개의 logic slice 및 155개의 DSP48s, 11,290 Kbit의 block memory로 구현되었다.

• Steel and Composite Structures
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• 제49권3호
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• pp.325-335
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• 2023

The missile is affected by both spinning and axial motion during its movement, which will have a very adverse impact on the stability and reliability of the missile. This paper regards missiles as cylindrical shell structures with spinning and axial motion. In this article, the forced vibration of carbon nanotube-reinforced composites (CNTRCs) cylindrical shells with spinning motion and axial motion is investigated, in which the clamped-clamped and simply-simply supported boundary conditions are considered. The displacement field is described by the first-order shear theory, and the vibration equation is deduced by using the Euler-Lagrange equation, after dimensionless processing, the dimensionless equation of motion is obtained. The correctness of this paper is verified by comparing with the results of the existing literature, in which the simply-simply supported ends are taken into account. In the end, the effects of different parameters such as spinning velocity, axial velocity, carbon nanotube volume fraction, length thickness ratio and load position on the resonance behavior of cylindrical shells are given. It can be found that these parameters can significantly change the resonance of axially moving and rotating moving CNTRCs cylindrical shells.