History Memorable Monitoring System for Composites using Electrical Impedance Changes

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Carbon Fiber Reinforced Polymer (CFRP) laminates are applied to many aerospace structures. Several processing methods of the CFRP laminates have been adopted to fabricate the CFRP structures. Cure monitoring of composite structures is crucial for quality control and improvement of mechanical properties of structures. After curing, strain monitoring of the CFRP structures is very important to confirm integrities of processing, as well as vibration monitoring and applied stress monitoring to know the condition of the external loading. Since the delamination is invisible or difficult to detect by visually, the delamination causes low reliability for primary structures. To improve the low reliability, smart systems of delamination identifications in-service are desired. A structural health monitoring system to monitor the delaminations is one of the desired approaches. Matrix cracking simply causes fuel leak when a lot of matrix cracking occurs in a CFRP fuel tank. These damages of matrix … More cracking and delaminations are significant for aerospace applications. Recently, an electrical impedance change method is employed to detect the internal damages of CFRP laminates. The electrical resistance change method does not require expensive instruments. Since the method adopts a reinforcement carbon fiber itself as a sensor, this method does not cause reduction of strength, and it is applicable to existing CFRP structures.In the present research, therefore, the electrical impedance change method is adopted for sensors of cure monitoring, strain monitoring, matrix crack monitoring and delamination monitoring. These successful results enable us to monitor a lot of information of the CFRP laminates by means of the electrical resistance and capacitance changes in many applications. Not only the individual successful results, a new united concept of the electrical resistance change method is proposed here. Object-oriented programming system is adopted for analyses of composites. Class "composites" is designed here to represent composite materials and history of the target composite component. All of the curing applied strain and damage information monitored using the electrical impedance change method is input in the memory of the "composite" class. By means of the electrical impedance change method, we can obtain the personal resume of the composite components. Less