Use of resistive ladder sensors for crack monitoring during Full Scale Fatigue Test

The paper presents an application of resistive ladder sensors (or resistive crack gages) for health monitoring of an aircraft structure. An experiment was conducted during a Full Scale Fatigue Test (FSFT) of PZL 130 ORLIK TC II turbo-prop military trainer. The sensor can be successively used to detect and quantify fatigue cracks. It is a parametric transducer, similar to foil strain gages. Differences in shape of the measuring grid can be noticed. Principle of operation, sensor´s characteristics as well as block diagram of measurement system is presented in the article. Also examples, both laboratory and FSFT data are delivered to prove surface crack detection capabilities. Simultaneously with new data collection, some investigation is carried out, connected with customize hardware elaboration, signal processing and structure-sensor integration method, what is briefly described.