Modal Analysis Based Structural Damage Localisation Under Varying Operating Conditions

A variation in the operating condition of a structural health monitored system can have a very bad influence on the performance of modal based techniques. The modal parameter changes caused by, for instance, uncontrolled temperature fluctuations can easily mask small changes in these parameters that are caused by structural defects. In this contribution, a method is proposed for compensating the effect of unknown global variations in the natural frequencies of a test structure: e.g. uniform coatings and/or uniform (environmental) temperature changes. Unlike other methods, the compensated results are used for localising as well as detecting structural damage.