http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
횡방향 전단하중을 받는 단일방향 복합재료의 미시역학적 거동연구
최흥섭,Choi, Heung-Soap,Achenbach, J.D. 대한기계학회 1997 大韓機械學會論文集A Vol.21 No.11
Effects of fiber-matrix interphases on the micro-and macro-mechanical behaviors of unidirectionally fiber-reinforced composites subjected to transverse shear loading at remote distance have been studied. The interphases between fibers and matrix have been modeled by the spring-layer which accounts for continuity of tractions, but allows radial and circumferential displacement jumps across the interphase that are linearly related to the normal and tangential tractions. Numerical calculations for basic cells of the composites have been carried out using the boundary element method. For an undamaged composite the micro-level stresses at the matrix side of the interphase and effective shear stiffness have been computed as functions of fiber volume ratio $V_f$ and interphase stiffness k. Results are presented for various interphase stiffnesses from the perfect bonding to the case of total debonding. For a square array composite the results show that for a high interphase stiffness k>10, an increase of $V_f$ increases the effective transverse shear modulus G over bar of the composite. For a relatively low interphase stiffness k<1, it is shwon that an increase of $V_f$ slightly decreases the effective transverse shear modulus. For the perfect bonding case, G over bar for a hexagonal array composite is slightly larger than that for a square array composite. Also for a damaged composite partially debonded at the interphase, local stress fields and effective shear modulus are calculated and a decrease in G over bar has been observed.
Detection of Second-Layer Corrosion in Aging Aircraft Fuselage
Kim, Noh-Yu,Achenbach, J.D. The Korean Society for Nondestructive Testing 2006 한국비파괴검사학회지 Vol.26 No.6
A Digital X-ray imaging system using Compton backscattering has been developed to obtain a cross-sectional profile and mass loss of corroded lap-splices of aging aircraft from density variation. A slit-type camera was designed to focus on a small scattering volume inside the material, from which the backscattered photons are collected by a collimated scintillator detector for interpretation of material characteristics. The cross section of the lap-joint is scanned by moving the scattering volume through the thickness direction of the specimen. The mass loss of each layer has been estimated from a Compton backscatter A-scan to obtain the thickness of each layer including the aluminum sheet, the corrosion layer and the sealant. Quantitative information such as location and width of planar corrosion in the lap splices of fuselages is obtained by deconvolution using a nonlinear least-square error minimization method(BFGS method): A simple reconstruction model is also introduced to overcome distortion of the Compton backscatter data due to attenuation effects attributed to beam hardening and quantum noise.
조윤호(Younho Cho),신봉재(Bongjae Sheen),J. D. Achenbach,이준현(Joon-Hyun Lee) 대한기계학회 2010 대한기계학회 춘추학술대회 Vol.2010 No.11
There has been a great concern about the on-line structural health monitoring in plate-like structures using guided wave tomography method. Most studies on guided wave tomography have only dealt with defect position. They cannot give information of defect size. In this paper, we studied tomography algorithm to detect a defect size using reflection of guided wave. The work presented here introduces a Reconstruction Algorithm for the Probabilistic Inspection of Damage (RAPID) which is used to construct tomographic images of defect position and size. Through this study, a feasibility of quantitative defect imaging based on the guided waves tomography is explored.