A Vibration Technique for Non-Destructive Testing of Fibre Composite Structures

A vibration technique for non-destructively evaluating the integrity of structures is described and applied to components fabricated from fibre reinforced plastics. The method uses measurements of changes in the lower structural natural frequencies, which can be made at a single point in the structure, in conjunction with a dynamic analysis of the system to detect, locate and roughly to quantify damage. The mathematical model of the structure need not be sophisticated and only one analysis is required for each type of structure to be tested. It is shown to be possible to detect and locate a variety of types of damage in structures which are representative of the use of fibre reinforced materials in the aerospace industry. An indication of the severity of damage is also obtained.