The Experts below are selected from a list of 4545 Experts worldwide ranked by ideXlab platform

D J Ewins - One of the best experts on this subject based on the ideXlab platform.

  • ground vibration tests of a Helicopter Structure using oma techniques
    Mechanical Systems and Signal Processing, 2013
    Co-Authors: N Ameri, Chiara Grappasonni, Giuliano Coppotelli, D J Ewins
    Abstract:

    Abstract This paper is focused on an assessment of the state-of-the-art of operational modal analysis (OMA) methodologies in estimating modal parameters from output responses on Helicopter Structures. For this purpose, a ground vibration test was performed on a real Helicopter airframe. In the following stages, several OMA techniques were applied to the measured data and compared with the results from typical input–output approach. The results presented are part of a more general research activity carried out in the Group of Aeronautical Research and Technology in Europe (GARTEUR) Action Group 19, Helicopter technical activity, whose overall objective is the improvement of the structural dynamic finite element models using in-flight test data. The Structure considered is a medium-size Helicopter, a time-expired Lynx Mk7 (XZ649) airframe. In order to have a comprehensive analysis, the behaviour of both frequency- and time-domain-based OMA techniques are considered for the modal parameter estimates. An accuracy index and the reliability of the OMA methods with respect to the standard EMA procedures, together with the evaluation of the influence of the experimental setup on the estimate of the modal parameters, will be presented in the paper.

N Ameri - One of the best experts on this subject based on the ideXlab platform.

  • ground vibration tests of a Helicopter Structure using oma techniques
    Mechanical Systems and Signal Processing, 2013
    Co-Authors: N Ameri, Chiara Grappasonni, Giuliano Coppotelli, D J Ewins
    Abstract:

    Abstract This paper is focused on an assessment of the state-of-the-art of operational modal analysis (OMA) methodologies in estimating modal parameters from output responses on Helicopter Structures. For this purpose, a ground vibration test was performed on a real Helicopter airframe. In the following stages, several OMA techniques were applied to the measured data and compared with the results from typical input–output approach. The results presented are part of a more general research activity carried out in the Group of Aeronautical Research and Technology in Europe (GARTEUR) Action Group 19, Helicopter technical activity, whose overall objective is the improvement of the structural dynamic finite element models using in-flight test data. The Structure considered is a medium-size Helicopter, a time-expired Lynx Mk7 (XZ649) airframe. In order to have a comprehensive analysis, the behaviour of both frequency- and time-domain-based OMA techniques are considered for the modal parameter estimates. An accuracy index and the reliability of the OMA methods with respect to the standard EMA procedures, together with the evaluation of the influence of the experimental setup on the estimate of the modal parameters, will be presented in the paper.

Chiara Grappasonni - One of the best experts on this subject based on the ideXlab platform.

  • ground vibration tests of a Helicopter Structure using oma techniques
    Mechanical Systems and Signal Processing, 2013
    Co-Authors: N Ameri, Chiara Grappasonni, Giuliano Coppotelli, D J Ewins
    Abstract:

    Abstract This paper is focused on an assessment of the state-of-the-art of operational modal analysis (OMA) methodologies in estimating modal parameters from output responses on Helicopter Structures. For this purpose, a ground vibration test was performed on a real Helicopter airframe. In the following stages, several OMA techniques were applied to the measured data and compared with the results from typical input–output approach. The results presented are part of a more general research activity carried out in the Group of Aeronautical Research and Technology in Europe (GARTEUR) Action Group 19, Helicopter technical activity, whose overall objective is the improvement of the structural dynamic finite element models using in-flight test data. The Structure considered is a medium-size Helicopter, a time-expired Lynx Mk7 (XZ649) airframe. In order to have a comprehensive analysis, the behaviour of both frequency- and time-domain-based OMA techniques are considered for the modal parameter estimates. An accuracy index and the reliability of the OMA methods with respect to the standard EMA procedures, together with the evaluation of the influence of the experimental setup on the estimate of the modal parameters, will be presented in the paper.

Giuliano Coppotelli - One of the best experts on this subject based on the ideXlab platform.

  • ground vibration tests of a Helicopter Structure using oma techniques
    Mechanical Systems and Signal Processing, 2013
    Co-Authors: N Ameri, Chiara Grappasonni, Giuliano Coppotelli, D J Ewins
    Abstract:

    Abstract This paper is focused on an assessment of the state-of-the-art of operational modal analysis (OMA) methodologies in estimating modal parameters from output responses on Helicopter Structures. For this purpose, a ground vibration test was performed on a real Helicopter airframe. In the following stages, several OMA techniques were applied to the measured data and compared with the results from typical input–output approach. The results presented are part of a more general research activity carried out in the Group of Aeronautical Research and Technology in Europe (GARTEUR) Action Group 19, Helicopter technical activity, whose overall objective is the improvement of the structural dynamic finite element models using in-flight test data. The Structure considered is a medium-size Helicopter, a time-expired Lynx Mk7 (XZ649) airframe. In order to have a comprehensive analysis, the behaviour of both frequency- and time-domain-based OMA techniques are considered for the modal parameter estimates. An accuracy index and the reliability of the OMA methods with respect to the standard EMA procedures, together with the evaluation of the influence of the experimental setup on the estimate of the modal parameters, will be presented in the paper.

Chiu W - One of the best experts on this subject based on the ideXlab platform.

  • Battle damage repair of a Helicopter composite frame-to-skin junction - A sole external repair approach
    Elsevier Ltd (United Kingdom), 2010
    Co-Authors: Wang J, Stankiewicz M, Ake A., Zhou Z., Chiu W
    Abstract:

    Research was conducted to examine the effectiveness of a rapid repair to a Helicopter composite frame-to-skin junction subjected to battlefield damage. The repair design consists of a laminate patch and aluminium angle bracket adhesively bonded and riveted, respectively, to the Helicopter external surface. The assessment involved a relative comparison of three models, representing pristine, damaged and repaired configurations. Computational analyses were conducted to examine the stiffness and buckling onset load of the overall Structure and the strengths of individual components (laminates, adhesive bondlines and rivets) under three typical load conditions, namely in-plane shear, axial compression and transverse compression. The results showed that the damage would cause significant stiffness and strength reduction. The repair could sufficiently restore the stiffness and static strength for the load cases considered. However, for the specimen without support from its adjacent Helicopter Structure, it is predicted that the failure mode under the transverse compression loading would be via buckling under a relatively low load. A compression test was conducted to further validate the repair design. The result agreed well with the prediction. It showed that compared with an un-repaired damaged specimen, the external repair increased the strength by 83%. The equivalent far field failure strain exceeded 3300 μe which is considered satisfactory for a rapid field battle damage repair (BDR)