Study On Probability Damage Reliability Based On Identification Modal Parameters

For the three layer steel frame model, it is firstly studied on the finite element modal analysis method, and made use of analysis based on several modal identification methods by the DASP collection and analysis system in this paper. In these methods, they are admittance circle methods of complex modal in the frequency domain, others are eigenvalue realization method and stochastic subspace identification method in the time domain. The results of modal parameter identification based on the three methods are contrasted with finite element method. It is shown that the finite element analysis result is the same as the three experiment methods, and presented that the result of modal analysis is accurate and efficient.The stochastic subspace identification method is used as parameter identification for the identification based on the frequency fingerprint method in the time domain in this paper. The identification method based on stabilization diagram is used of being ensure the dynamic parameters and getting the difference order of the modal parameters. According to the stabilization diagram and the identification modal frequency, the frequency fingerprint is got by stochastic collection. According to the judgement method of W test of normality, the frequency fingerprint is proved that it obeys the general normal distribution. Based on the foundation ideal of critical domain, the identification of frequency fingerprint is estimated in the difference confidence level and the simple normal general domain is ensured.Based on the simple normal general critical domain, the structure damage is simulated by the adding quality method. Meanwhile the most unfavorable processing condition is searched by the Modal Assurance Criterion (MAC). The working condition is deemed to base operation condition, which is combined with the most unfavorable processing condition, the criterion domain of the frequency fingerprint is got by the parameter estimation based double normal general distribution in the difference confidence level.The conception of statistical damage domain is presented by the conception of damage degree and the theory of estimated critical domain. For the base operation condition and the most unfavorable processing condition. Combined with estimated parameters based on the double normal general distribution, the domain of damage degree is estimated in the most unfavorable processing condition. According to the theory of reliability of damage, the formulae of reliability of damage based on frequency fingerprint is deduced by the basis theory of the reliability. Finally, the corresponding failure probability is ensured for the difference order frequency in the most unfavorable processing condition.