Non-destructive testing due to analysis of natural frequencies of multilayer fibre-reinforced composites

In order to avoid faulty assemblies in a manufacturing process, an early detection of defective components is of high importance. Using a non-destructive testing method, it is possible to verify the quality of every produced part and identify manufacturing and material defects. Especially, errors in fibre-reinforced composites such as delamination are not visibly detectable. One possibility to identify faults in fibre-reinforced materials is to analyse the structural dynamical behaviour of the component. In this study, the structural response of several fibre composite components are obtained by using a laser vibrometer. For this purpose, the structures are excited by a shaker as well as by a loudspeaker. Some of the measured samples contain an artificial defect added during the manufacturing process. By using the modal analysis, the eigenfrequencies are retrieved from the measured frequency response functions. The objective of this study is to identify modes which natural frequencies are effected by the defects.