Correct estimation of load bearing capabilities and prediction of failure has an important role in design and quality control of filament wound (FW) composite fiber reinforced plastic (CFRP) structures such as composite overlapped pressure vessels, filament wound pipes and other. Such structures are widely used in aerospace, military and gas industries and must provide safe operation.
There is a limited number of studies and methods that are used today for assessment of load bearing capabilities of FW CFRP structures. The present research is intended to review the state-of-the-art practices and assist in development of a new approach for evaluation of structural integrity of filament wound structures at loads below those normally applied during proof testing and improve operational safety of CFRP pressure equipment.
During the present research , we have tested and analyzed NOL ring, a parallel filament wound hoop test specimens, for identification of characteristic stages of damage accumulation and development using experimentally measured characteristics of acoustic emission (AE), strain and displacement. A correlation between fracture loads and different parameters of AE was observed. It was shown also that acoustic emission technology can detect effectively matrix micro-cracking, fiber brakeage and other damage mechanisms related to CFRP damage. The results of the tests of NOL rings and full-scale products test showed similarity in fracture properties including stages of damage accumulation and developing that were confirmed experimentally by acoustic emission and strain measurements.
