Application of non-prior base analysis in diagnosing the boundary loose of cantilever beam

The boundary loose of cantilever beam is one of the factors that affect the structural safety. By ADAMS calculation and experiment, it is proved that the nature frequency of cantilever beam will change subtly when the constraint force on the boundary of a cantilever beam is changed. The Discrete Fourier Transform (DFT) method adopts prior base strategy . The frequency interval and leakage error exist in DFT and it is difficult to use DFT to diagnose the boundary loose of cantilever beam. A non-prior base method is suggested to diagnose the boundary loose of cantilever beam. In non-prior base method, the basis functions for diagnosis aren´t set in advance, and the real frequency of a measured signal is determined by searching the maximum of inner product. A corresponding experiment is carried out to prove the research work. The experiment result shows that the nor-prior method diagnoses out the boundary loose of cantilever beam by identifying the minor changes in the natural frequency of cantilever beam.