Advanced Search
Displaying 11391-11400 on page 1140 of 15662. Per Page  

Articles / Online

  • Real time ultrasonic imaging of aerospace composites
  • Abstract Ultrasonic inspection techniques have a proven record of applications during manufacturing and maintenance of metallic and composite aircraft structures. Traditional ultrasonic inspection techniques use a point-by-point scanning method to acquire a full-field image. This scanning method is slow and inadequate in satisfying modern manufacturing and maintenance time line requirements. The next generation of ultrasonic inspection eliminates the need for point-by-point scanning using an imaging array that is capable of displaying thousands of points to create a full-field image in real-time.
    In this study, a next generation dual-channel ultrasonic imaging system is used for real-time three-dimensional evaluation of small composite aerospace…
  • More
  •   Views:408       Downloads:335        Download PDF
  • Post-traumatic recovery mechanism on the ankle articulation
  • Abstract The mechanism which is going to be made following the technical data presented in this work, represents a major step in the post-traumatic rehabilitation on the ankle articulation. The machine's support is a metallic confection of welded rectangular pipe, metallic profiles and sheet, which assures the appliance of the component parts and contains the sitting basis of the mechanism on the floor. The plaque is the element which directly sustains the person using the mechanism, and which has an oscillating movement in a vertical plane on the circumference. The plaque is turning-proof around the vertical axis of the 1st axel,…
  • More
  •   Views:381       Downloads:350        Download PDF
  • Dynamic analysis of asymmetrically laminated composite frames
  • Abstract Based on elastic wave theory, Pao[1] and his colleagues recently proposed a novel frequency domain matrix method, i.e. the Method of Reverberation-Ray Matrix (MRRM) for solving the transient response of truss-type structures. The theory has been shown accurately coincided with experimental data of a model truss for the early responses.
    Fiber reinforced laminated composites have advantages such as high specific strength, high specific stiffness, corrosion resistance etc.. The dynamic as well as the static behavior of laminated composites is largely dependent upon fiber orientation and ply-stacking sequence. Due to inhomogeneity and anisotropy of the material, these structures are vulnerableto highly…
  • More
  •   Views:380       Downloads:304        Download PDF
  • Measuring displacement of a bridge using multi-channel image processing techniques
  • Abstract Measuring the displacement of a flexible bridge is difficult particularly on a long span bridge. In this study, real-time displacement measurement of a long span bridge was carried out using digital image processing techniques which require a target recognition algorithm, projection of the captured image, and calculation of the actual displacement using target geometry and the number of pixels moved. To measure the displacement of a bridge from a distant location which can be regarded as a fixed reference point, a novel image processing method has been devised. By measuring the same target with two independent cameras placed in a…
  • More
  •   Views:401       Downloads:303        Download PDF
  • On the stability of the upper airways system
  • Abstract Simple models for the upper faryngeal obstruction, describing the sleep apnea syndrome are proposed. Stability is discussed, of two and three individualized elements, with and without elastic connections, interacting with the steady flow. Considering the flow as the controlling parameter, critical steady state flows are located and their post-critical behavior is discussed for various models. It is pointed out that the non-linear constitutive elastic laws are necessary contrary to the linear ones introduced by Fodil [1998]. Finally the three element model will be presented and studied with non-linear constitutive relations and side connections. Applications of the theory will be performed…
  • More
  •   Views:396       Downloads:296        Download PDF
  • The winding road from QNDE to SHM and beyond
  • Abstract A significant limitation of NDE became apparent in the sixties with the advent of fracture mechanics as a major consideration for the determination of structural safety. Fracture mechanics requires quantitative information that has to be obtained from non-destructive testing procedures. The 1970's mark the start of research and development to achieve quantitative capability, and adding the Q to NDE. Since that time significant advances have been made of the methods of quantitative non-destructive evaluation that are the basis of the diagnostics part of structural health management, including sensor development, new techniques such as laser-based ultrasonics, acoustic and x-ray imaging, thermal…
  • More
  •   Views:403       Downloads:319        Download PDF
  • Buckling driven delamination in uniaxially compressed composite panels
  • Abstract A geometrically nonlinear plate model has been developed analytically in order to investigate the buckling behaviour of laminated composite panels containing a centrally located delaminated patch. The panels examined are rectangular and under uniaxial compression. Trigonometric out-of-plane displacement functions are employed in the Rayleigh--Ritz procedure where minimum energy principles are applied to solve for the mechanical behaviour of the plates. The in-plane deformations are determined via von K\'arm\'an's compatibility equation by applying restrained edges at the boundary of the delaminated region. Different delamination configurations are investigated with the critical buckling loads and eigenvectors being determined using linear analysis and the…
  • More
  •   Views:432       Downloads:294        Download PDF
  • A path iterative method for laser-controlled crack propagation and its convergence
  • Abstract Laser controlled separation of brittle materials like glass is a promising non-conven\discretionary {-}{}{}tional cutting method. It is an application of the crack propagation driven by thermal stresses induced by laser irradiation. In order to induce and control a crack propagating accurately along predetermined asymmetric trajectory in a brittle plate, an iterative method for effective laser scanning path was presented, and the effect of control parameters on the convergence was investigated. The iterative formulation for laser scanning path was based on PID control theory, which was composed of deviation of the crack from predetermined trajectory and its integral and differential. To…
  • More
  •   Views:406       Downloads:299        Download PDF
  • Stay cable vehicle live load effects analysis based on structural health monitoring data
  • Abstract Stay cables are some of the most critical structural components of a bridge. However, stay cables readily suffer from corrosion damage and stress corrosion damage. Thus, health monitoring of stay cables is important for ensuring the integrity and safety of a bridge. Glass Fibre Reinforced Polymer Optical Fibre Bragg Grating (GFRP-OFBG) cable, a kind of fibre Bragg grating optical sensing technology-based smart stay cables, is proposed in this study. The fabrication procedure of the smart stay cable was developed and the self-sensing property of the smart stay cable was calibrated. The application of the smart stay cables on the Tianjin…
  • More
  •   Views:400       Downloads:311        Download PDF
Displaying 11391-11400 on page 1140 of 15662. Per Page