A Time Domain Method On Two Dimensional Distributed Dynamic Load Identification

The technique of dynamic load identification can be used to identify unknown force in the case of modal parameters and dynamic response to be measured before. This dissertation mainly discusses distributed dynamic load identification in time domain using orthogonal polynomial.At first, this paper discusses the orthogonality and astringency of the two-dimensional orthogonal polynomial which is produced based on the Chebyshev orthogonal multinomial and pointed out that such expansion way is a general approach which can be extended to higher dimensional polynomials. The main thought of this method is that use orthogonal polynomial to fit the dynamic load function, establishes the relation between polynomial progression coefficient and dynamic responses, work out the coefficient of the polynomial with the information of the response on the measuring point and the character of the system itself, thereby completes the dynamic load identification.Then, we try to identify the continuous distributed dynamic load which is act on beam system using both two-dimensional and Chebyshev polynomial, the simulation results shows that dynamic load identification using two-dimensional polynomial is theoretically feasible, Further, by utilizing discrete calculation of the Duhamel convolution, the identification model of the distributed dynamic load acts on the continuous beam system is advanced as well as various forms of time domain dynamic load which act on rectangular plate system. Computer simulation indicates that this method has no special require to the position of measuring point, with a certain anti - interference performance.Finally, combine with FEM software MSC.Patran&Nastran, dynamic load identification based on the finite element model is discussed. Design a one boundary fixed plate and a simple fixed-frequency distributed dynamic load identification test is carried on, the result shows that this identifying method is correct theoretically, effective and feasible in engineering practice.