EXPERIMENTAL STUDY ON MODAL STRAIN ANALYSIS OF RECTANGULAR THIN PLATES WITH HOLES

摘要

The relationship between strain mode and displacement mode of a vibrating structure is presented. A method of experimental modal strain analysis by using this relationship is introduced and an approach for parameter identification is also described. An experiment on a vibrating cantilever plate with small holes is performed. The displacement modes and strain modes of the same cantilever plate are obtained, respectively. It is found that it is difficult to detect the influence of such small holes on displacement mode, but obvious changes of strain mode due to the stress concentration induced by the small holes are detected. Therefore, the strain mode is more sensitive to local changes of structure, such as, local cracks, small holes or grooves, etc. This indicates that modal strain analysis can be used in detection of structural damage and therefore it is hopeful to be used in machine life monitoring.