• 제목/요약/키워드: Composite Structures

검색결과 4,815건 처리시간 0.024초

특정두께를 갖는 이방성복합재 구조의 전자파 응답특성 연구 (A Study on Electromagnetic Absorption Characteristics of the Anisotropic Composite Structure with Specific Thickness)

  • 정헌달;김덕주;이윤상
    • 한국군사과학기술학회지
    • /
    • 제1권1호
    • /
    • pp.114-127
    • /
    • 1998
  • A user friendly computer code(EMCOMST; Electro-Magnetic response for COMposite STructures) was developed which provides with computations of the response characteristics such as reflectance and transmittance to the incident wave angles, frequencies, composite thicknesses, ply orientations, and types of backplate as the linearly polarized transverse electro-magnetic wave is emitted to the advanced composite structures. In this investigation were reviewed the electromagnetic characteristics of the continuous orthotropic fiber-reinforced organic matrix composites with or without ferrite fillers, which are actively applied to low-weight and high-strength aircraft structures. Also were calculated the response of the three layered compound structures which have appropriately stacked above-mentioned materials as transmitting layer, absorbing layer, reflection layer, respectively under the specific thickness constraints for mechanical strength design requirements. For the composite structures presented in this study, minimum reflectance value less than -5㏈ can be obtained in the frequency range of 4 to 12 ㎓. In addition, analysis of structures attached isotropic radar absorbing materials(RAM) is facilitated by putting the material properties in the material input card entries adequately.

  • PDF

Cyclic tests on bolted steel and composite double-sided beam-to-column joints

  • Dubina, Dan;Ciutina, Adrian Liviu;Stratan, Aurel
    • Steel and Composite Structures
    • /
    • 제2권2호
    • /
    • pp.147-160
    • /
    • 2002
  • This paper summarises results of the research performed at the Department of Steel Structures and Structural Mechanics from the "Politehnica" University of Timisoara, Romania, in order to evaluate the performance of beam-to-column extended end plate connections for steel and composite joints. It comprises laboratory tests on steel and composite joints, and numerical modelling of joints, based on tests. Tested joints are double-sided, with structural elements realised of welded steel sections. The columns are of cruciform cross-section, while the beams are of I section. Both monotonic and cyclic loading, symmetrically and antisymmetrically, has been applied. On the basis of tested joints, a refined computer model has been calibrated using a special connection element of the computer code DRAIN 2DX. In this way, a static/dynamic structural analysis of framed structures with real characteristics of the beam to column joints is possible.

복합신소재 도로구조물의 변환단면이 고유진동수에 미치는 영향 (The Effects of Different Cross Section on Natural Frequency of the Advanced Composite Materials Road Structures)

  • 한봉구
    • 한국도로학회논문집
    • /
    • 제15권3호
    • /
    • pp.23-29
    • /
    • 2013
  • PURPOSES: This paper aims to give a guideline and the way to apply the advanced composite materials theory to the road structures with different cross sections to the practicing engineers. METHODS: To simple but exact method of calculating natural frequencies corresponding to the modes of vibration of road structures with different cross sections and arbitrary boundary conditions. The effect of the $D_{22}$ stiffness on the natural frequency is rigorously investigated. RESULTS: Simple method of vibration analysis for calculating the natural frequency of the different cross sections is presented. CONCLUSIONS: Simple method of vibration analysis for calculating the natural frequency of the different cross sections is presented. This method is a simple but exact method of calculating natural frequencies of the road structures with different cross sections. This method is extended to be applied to two dimensional problems including composite laminated road structures.

Experimental studies on impact damage location in composite aerospace structures using genetic algorithms and neural networks

  • Mahzan, Shahruddin;Staszewski, Wieslaw J.;Worden, Keith
    • Smart Structures and Systems
    • /
    • 제6권2호
    • /
    • pp.147-165
    • /
    • 2010
  • Impact damage detection in composite structures has gained a considerable interest in many engineering areas. The capability to detect damage at the early stages reduces any risk of catastrophic failure. This paper compares two advanced signal processing methods for impact location in composite aircraft structures. The first method is based on a modified triangulation procedure and Genetic Algorithms whereas the second technique applies Artificial Neural Networks. A series of impacts is performed experimentally on a composite aircraft wing-box structure instrumented with low-profile, bonded piezoceramic sensors. The strain data are used for learning in the Neural Network approach. The triangulation procedure utilises the same data to establish impact velocities for various angles of strain wave propagation. The study demonstrates that both approaches are capable of good impact location estimates in this complex structure.