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Title: Improvement of analytical dynamic models using vibration test data.
Author: Guo, Shijun.
Awarding Body: University of Herfordshire
Current Institution: University of Hertfordshire
Date of Award: 1993
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Generally speaking, difficulties encountered during the improvement of an Analytical Dynamic Model (ADM) using vibration test data come from both the Spatial Coordinate Incompatibility (SCI) and especially the Modal Coordinate Incompatibility (MCI) between the ADM and the test data. Efforts were therefore made in this project to cope with these two problems by extending some of the existing methods and also by developing new methods with consideration of their feasibility, efficiency and accuracy. A general description of this part of the project and the literature survey of this study area are presented in part 1 of the thesis. In part 2, in order to solve the SCI problem, a new extended Complete Modal Expansion (CME) and a Branch Modal Expansion (BME) method were proposed especially for the case when using a branch mode method to produce the ADM. Application of these two methods and the existing physical expansion method were demonstrated in a beam example in this part and were also used in some of the examples later in this project. In part 3, efforts were made to extend the existing Direct Matrix Updating (DMU) and the Direct Parameter Identification (DPI) methods for solving the MCI problem using a direct approach. Firstly a new Direct Modal Extension (DME) method was proposed and compared with the DMU method when they were used to improve a reduced-size ADM. Secondly, in order to overcome the main limitation of the existing DPI methods in their practical use, an extended Corrected Modal Constraint (CMC) method was proposed. In part 4, in order to achieve the feasibility and accuracy of ADM improvement, efforts were then made in the study of the indirect approach. Firstly a procedure using a new Orthogonality Sensitivity Method (OSM) working together with a model reduction method was proposed. Secondly, a new Energy Error Estimation (EEE) method was also presented. The original contribution of the EEE method is that the poorly modelled stiffness and mass elements of an ADM can be identified and corrected accurately and effectively. Applications of these new proposed methods were demonstrated by taking beam examples. Further application of the EEE method was examined in a full-scale aircraft tail plane example. A general discussion, conclusion and recommendation for further study of these methods are presented in the fmal part 5. Based on the study of this project, it is concluded that the feasibility and accuracy of the direct methods described in part 3 of this thesis are at a low level for practical use. Therefore, the main efforts and contributions in this project were made in the study of the indirect methods described in part 4 of this thesis. It is concluded that both of the new proposed OSM and EEE methods provide feasible tools for ADM improvement and possess a high level of accuracy.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Aircraft & aircraft components