Some problems of reliability of structural health monitoring

Analysis of stress state and strength of piezoelectrical transducer (PET) in-built to structural component which loaded by static or cyclic load is done. All results and conclusions are applicable for thin PET of rectangular shape. The data of the fatigue test of reinforced Al-alloy panel and FEA results were used. The general statistical estimation of fatigue test data was made. The high probability of PET destruction at the cyclic load of typical level is shown for considered conditions. The detailed FEA of in-built PET stress state is performed, and in this base the development of brittle PET destruction at monotonically increasing load was predicted as equi-fragmental crushing (EFC) and its properties were described. The EFC process was adapted to PET destruction at cyclic load and used for construction of likelihood estimation (LHE) of the fatigue strength of PET. Using LHE model, the estimation of parameters of the normal distribution of the fatigue strength was obtained. The general comparison of in-built PET strength and PET at pure tension is given.