• 한국정밀공학회지
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• 제27권1호
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• pp.41-48
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• 2010

Non-contacting, laser-based resonant ultrasound spectroscopy (L-RUS) was applied to characterize the microstructure of a material. L-RUS is widely used by virtue of its many features. Firstly, L-RUS can be used to measure mechanical damping which related to the microstructural variations (grain boundary, grain size, precipitation, defects, dislocations etc). Secondly, L-RUS technology can be applied to various areas, such as the noncontact and nondestructive quality test for precision components as well as noncontact and nondestructive materials characterization. In addition, L-RUS technology can measure the whole field resonant frequency at once. In this paper, we evaluated material characteristics such as resonant frequency, nonlinear propagation characteristic through the development of Laser-Based Resonant Ultrasound spectroscopy (Laser-RUS) System for the detection of Micro Crack in Materials.

• 한국자동차공학회논문집
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• 제12권5호
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• pp.108-117
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• 2004

In this paper, a measuring NDT(nondestructive testing) system using RUS(Resonant Ultrasound Spectroscopy) was built for nondestructive evaluation of the flaw in a ceramic Ferrule. The principle of RUS is that the mechanical resonant frequency of the materials depends on density, and the coefficient of elasticity. The RUS system is the measuring which is to exite specimen and to inspect the difference of natural frequency pattern between acceptable specimen and specimen which has some defects. RUS system is configured of spectrum analyzer, power amplifier, PZT sensor and support frame. For defect evaluation by the RUS, we performed to measure natural frequency of Ferrule, both acceptable and cracked. In the case of Ferrule, the resonant frequency of cracked-Ferrule existed to higher frequency band than acceptable-Ferrule.

• 비파괴검사학회지
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• 제25권2호
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• pp.127-132
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• 2005

광학기기용 렌즈는 결함이 없는 높은 형상정밀도가 요구되어지는 제품으로써 본 논문에서는 공명초음파 분광법을 이용하여 결함을 검출하는 시험을 하였다. RUS는 시험편을 가진 시켜 양품시험편과 결함을 갖는 시험편 사이의 공진주파수 차를 검사하는 측정시스템이다 RUS를 이용한 비파괴 평가를 위하여 우리는 구면렌즈와 비구면 렌즈의 공진주파수를 측정하였다. 그 결과, 우리는 측정된 공진주파수에 의해 구면렌즈의 연마 가공정도를 알 수 있었으며, 결함을 갖는 비구면 렌즈의 특성평가를 할 수 있었다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2004년도 추계학술대회 논문집
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• pp.1491-1495
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• 2004

In this paper, resonant ultrasound spectroscopy(RUS) was used to determine the natural frequency of a spherical and a aspherical lens. The objective of the paper is to evaluate defect and shape error by using nondestructive evaluation method with Resonant Ultrasound Spectroscopy(RUS). The principle of RUS is that the mechanical resonant frequency of the materials depends on density, and the coefficient of elasticity. We evaluated existence of flaws through comparison with resonant frequency of a spherical and a aspherical lens. The spherical glass lenses were made of BK-7 glass, one's diameter in 2mm and 5mm. The polished spherical glass lenses had no deflection or a deflection below 2.0${\mu}{\textrm}{m}$. Also, The aspherical lens were made of same material and ones diameter in 7mm and thickness in 3.4mm. In the experiment, we were performed to investigate relationship between frequency measuring parameter($\beta$) and mass of each specimens. The difference between resonant frequency and mode of aspherical glass lens which has no defect was distinguished from aspherical glass lens which has some defects.

• 한국자동차공학회논문집
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• 제12권6호
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• pp.143-150
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• 2004

In this paper, resonant ultrasound spectroscopy(RUS) was used to determine the natural frequency of a ceramic ferrule and a ball lens. The ceramic ferrules are cylinderical shape with $\phi$ 2.56mm diameter and l0mm in length. Crack lengths of these ferrules are 10.40$\mu$m, 21.18$\mu$m and 32.35$\mu$m. The spherical ball lens was made of BK-7 glass, one's diameter in 2mm and 5mm. RUS system is consisted of spectrum analyzer, power amplifier, PZT sensor and support frame. The principle of RUS is that the mechanical resonant frequency of the materials depends on density and the coefficient of elasticity. Rus system is based on that given resonant frequency of the materials can be represented by the function of density and the coefficient of elasticity, and it is applied to excite specimen and to inspect the difference of natural frequency pattern between acceptable specimen and defective ones. Defect evaluation by RUS are performed to investigate the natural frequency measure of ferrule and ball lens.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2009년도 추계학술대회 논문집
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• pp.309-310
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• 2009

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2008년도 추계학술대회 논문집
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• pp.393-394
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• 2008

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2008년도 추계학술대회 논문집
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• pp.391-392
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• 2008

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.1345-1348
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• 2003

The Ferrule for the Optical Communication Connector is the product to set the optical ares of an optical fiber very precisely. Therefore, it is required high expectations such as high dimensional precision and new including flaws. Up to new the optical instrument has been used for the defeat and shape inspection of the ferrule, but in the paper we examined the detectable defeat and expectation by using Resonant Ultrasound Spectroscopy(RUS). The RUS is the measurement which is to excite specimen and to inspect the difference at natural frequency pattern between acceptable specimen and specimen which has some defeats. We analyzed the difference of natural frequency pattern in the experiment using Spectrum Analyzer. And we compared the results in the experiment with those in the simulation from the explicit finite elements code, Nastran.

• 비파괴검사학회지
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• 제19권3호
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• pp.180-188
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• 1999

SiC 입자강화 2124Al 금속복합재료의 강화재 부피분율에 따른 탄성 stiffness를 초음파 공명 스펙트로스코피(resonant ultrasound spectroscopy: RUS) 방법을 이용하여 측정하였다. RUS 방법은 한 개의 소형 시편으로 9개의 독립변수를 가진 사방정계(orthorhombic) 탄성계수를 간단한 실험으로 측정 가능함을 보여주었다. SiC 강화재 부피분율 변화에 따른 탄성계수를 측정하였는데 이 경우 초기 추정 탄성계수를 구하기 위해서 부피 분율에 따른 미세조직 사진으로부터 강화재의 형상(aspect ratio)과 방향을 고려한 유효 aspect ratio 개념을 도입하였고. Mori-Tanaka 이론식에 의한 계산결과를 이용하였다. 이로부터 계산된 공진주파수와 RUS의 측정 공진주파수 사이를 최소화함으로 정확한 탄성계수를 측정하였다. 측정된 stiffnesses로부터 공학적 탄성계수인 Young's modulus를 계산하였으며, 계산된 Young's modulus와 압출방향으로 인장 시험한 Young's modulus를 비교분석 하였다. SiC 입자의 부피분율이 증가함에 따라 탄성계수가 증가함을 나타내었고, 탄성 stiffness의 거동은 강화재가 많이 첨가될수록 횡등방성(transversely isotropic)이 강하게 나타났으며 이것은 압출공정에 의해 강화재 입자의 방향성 재배열에 기인한다. 한편 일정크기 시편에 있어서 기본 공진주파수가 강화재 부피분율에 따라 고주파수 영역으로 이동하는 현상이 관찰되었으며, 이로 부터 비파괴적으로 강화재 부피분율을 예측할 수 있는 가능성을 제시하였다.