DURABILITY ASSESSMENT OF PZT-TRANSDUCERS FOR GUIDED WAVE BASED SHM SYSTEMS USING TENSILE STATIC AND FATIGUE TESTS

摘要

Structural Health Monitoring (SHM) systems are used within various industries for different application scenarios. Military aviation industry focuses on application scenarios to satisfy the future needs of autonomous health diagnostic and prognostic capabilities. Numerous investigations in the area of damage detection have shown that Guided Wave based SHM techniques offer a great potential to fulfil the diagnostic requirements for these systems. In service applications generate great demands concerning reliability and durability of system components which have to be considered for certification. Aerospace structures are exposed to harsh operational conditions (environmental and structural loading effects) affecting the diagnostic capabilities of individual system components as well as the performance of the diagnostics algorithms. These effects have to be considered for application of SHM systems enabling reliable damage detection performance. Guided Wave based SHM techniques typically use lightweight PZT-Transducers which are permanently applied to the monitored component to assess its structural condition. This paper presents results of durability tests performed using co-bonded PZT-Transducers on composite panels under tensile static and fatigue loading. Different measurement techniques (e.g. measurement of electric charge vs. applied strain) are used to determine sensitive failure indicators of PZT-Transducers. Additionally, the effect of degrading PZT-Transducers on signal generation and Guided Wave sensing is evaluated to assess the diagnostic capabilities of this SHM method. These results are used to verify the applicability of PZT-Transducers for Guided Wave based SHM for aerospace structures considering operational loading conditions.