Numerical study of defects in glass reinforced composite transducer shells

Fatigue in composite shells of flextensional transducers can be investigated experimentally but in service results transposition is uncertain. This study can also be carried out numerically. However, a simple model rarely allows to describe the fracture in fatigue of an existing structure. The approach that is suggested here aims (starting from a modal analysis of a damaged structure in situ and according to results of a numerical computation by finite elements) at identifying the type of flaw in a qualitative and quantitative way. This paper first presents the finite element used to deal with this problem. Second the approach is validated on a shell example. Finally an experiment on a simple G.R.P. plate is used to compare numerical and experimental results to validate the approach.