Pure Model Experiment For The Composite Structure And The Modification Of FEM Model

Due to its excellent high strength, resistance to erosions, high damping ratio anddesign flexibility, composite materials have been increasingly widely applied inmodern structural field, especially new forms of ship and aircraft structures.Compared with commonly used steel, one important characteristic of compositematerial is its dispersity. Its mechanical properties, such as elastic modulus, mass,strength and damping, are of some uncertainties. Therefore, in the FEM analysis ofcomposite structures, a key factor is to ensure the accuracy of the FEM model. Onlyby doing this can researchers guarantee a accurate result from the FEM analysis. Themodification of FEM model is to modify the FEM model based on experimentalresults such as frequencies of the structures. One strategy is to select severalparameters of the model and alter them according to certain optimization principals tomake the frequencies of the model approximate the data derived from experiments,thus ensuring the FEM model is a better description of the physical model.This article adopts random excitation-based model parameters identification andphase resonance-based pure model test to carry out the model analysis of thecomposite panel applied in engineering structures, which identify the preliminarymodes, including natural frequencies and mode shapes. Different from commonmodel identification, pure model method adjusts the frequency of the excitationaround the natural frequencies to make the structure to vibrate in the shape ofvibration mode, and the so-called pure modes are derived from the experiment. Byobtaining the model parameters through physical measurements, pure mode method is a more explicit physical identification method. The experiment in this article showsthat pure mode method can obtain a more accurate mode parameters.Based on the result of the pure model experiment, this article establishes theFEM model with Patran/MSC software and selects the plate of the panel, elasticmodulus and density of the composite materials as optimization parameters to modifythe model. Taking the preliminary overall frequencies and mode result as restrains, thearticle uses a first-order numerical method to modify the FEM model and the naturalfrequencies and vibration modes of modified model matches the data from experimentbetter. Using the modified FEM model, this article carries out quasi-static analysis,buckling analysis, mode analysis and transient response analysis.