بكارگيري روش امپدانس الكترومكانيكي در تشخيص عيب سازه‌ها‌ي كامپوزيت

Application of Electromechanical Impedence in Structural Health Monitoring

پايش سلامت سازه به روش امپدانس الكترومكانيكي با به كارگيري مواد پيزوالكتريك به صورت حسگر و عملگر، روشي قدرتمند براي ارزيابي بلادرنگ سلامت سازه مي‌باشد.. در اين روش، وصله پيزوالكتريك بر روي سطح سازه چسبانده مي‌شود و از آن به عنوان محرك در توليد انرژي مكانيكي اعمالي به سازه و نيز به عنوان حسگر براي دريافت پاسخ ديناميكي سازه به وسيله اندازه گيري امپدانس الكتريكي پيزو، استفاده مي‌شود. همچنين به دليل اينكه وزن و اندازه پيزو در مقابل سازه‌اي كه به آن متصل شده بسيار كم مي‌باشد، لذا وزن و اندازه پيزو قابل چشم پوشي بوده و روي مشخصات ديناميكي سازه اثر چنداني نمي‌گذارد. از جمله موارد كاربرد اين روش، پايش سلامت كامپوزيت‌ها مي‌باشد. . در اين مقاله به رفتار خستگي تير‌هاي كامپوزيتي شيشه‌-‌اپوكسي به روش امپدانس الكترومكانيكي پرداخته شده است.

Structural health monitoring by electromechanical impedance method that uses piezoelectric materials as sensors and actuators, is a powerful way to assess the structural health in real time. Also, due to using high frequencies in this way, the possibility of identifying small damage in the early stage of planning is possible. In this method, the piezoelectric patch is bonded on the structure surface and is used as actuators to produce mechanical energy applied to the structure and used as sensor to receive dynamic response of structure by measuring electrical impedance of piezoelectric. Also, because the size and weight of piezoelectric patch in compare to the size and weight of base structure is very low, it is negligible and does not impact on the dynamic characteristics of the structure. Most of composite structures are considered as laminates. In these products, lamina with different stacking is placed and matrix is infused to fix lamina that would increase quality and mechanical properties of final product. Today, composites are widely used in various industries including compressed gas storage tanks which fatigue is a common phenomenon in this tank because of their charge and discharge. In this thesis glass-epoxy composite beams are studied using electromechanical impedance and Timoshenko beam theory analytical solution is verified with experimental results. Then composite beam behavior in fatigue loading is studied using electromechanical impedance method. Composite beams are fabricated by using 7 glass-epoxy UD Plies in the VIP method.