Sensitivity Analysis of OFDR-Based Distributed Sensing for Flaws Detection in Representative Coupon from Filament Wound Motor Vessel

摘要

Traditionally, metallic vessels have to comply with specific regulation rules (Pressure Equipment Directive from the European Parliament) involving periodic re-qualifications. However, for high pressure composite vessels, standards, and particularly non-destructive techniques, have to be developed, tested and validated. In this new frame, a research project has been set up for VECEP program (VEga launcher Consolidation and Evolution Preparation Programme) aiming at funding developments to set-up new control/monitoring techniques applicable to composite vessels, for both future regulatory and inspection needs. To reach the market, these techniques have also to be cost-effective in comparison with traditional ones. To monitor such vessels behavior and finalize the sensor system to the detection of structural defects, CIRA and AVIO have conducted R&D activities based on high resolution distributed strain profiles sensitivity analysis along single mode optical fibers. To elaborate this method, preliminary tests were carried out for testing different bonding agents and different surface finishing, on a set of representative coupon from composite overwrapped pressure vessels under bending incremental solicitation until reaching ultimate load. Additionally, their sensitivity, analyzed during the test, provided additional valuable data about structure integrity. A mechanical criterion based on OFDR (Optical Frequency Domain Reflectometry) differential strain profiles analysis was preliminarily implemented in order to evidence structural anomalies during the test.