Structure analysis of helically wrapped composite pressure vessels
Wojciech Błażejewski, Ewa Juskowiak, Joanna Mażulis, Radosław Rybczyński
Quarterly No. 3, 2013 pages 193-197
DOI:
keywords: high-pressure composite vessels, filament winding method, winding architecture, mosaic-shaped patterns, mosaic patterns, diamond patterns, diamond-shaped patterns, triangular repeating mosaic, triangular-shaped mosaic patterns, matrix method, structures of winding composites, interweaving, tow undulations, crossovers, CNG, CH2
abstract This paper investigates the structures of composite overwrapped pressure vessels (COPV) intended for use as storage tanks for compressed gas fuels in automobiles and other vehicles. The objective of this work was to establish the use of mosaic patterns arising during winding in the helical layers. In the authors' opinion, the optimal mosaic pattern considering the behavior of reinforcement tows under loading is the one designated as Nr1 in the matrix method. It exhibits the lowest number of crossovers, as well as their most orderly array - linear. Crossovers are considered as local distortion of a composite structure, which has a negative effect on the development of damage in the material. This statement is the result of previous studies performed by the authors, as well as papers by other researchers. In total, 9 different type 3 and type 4 vessels produced by filament winding were studied. The studies encompassed an analysis of the mosaic patterns in selected helical layers only. This work contains neither information on the thickness, sequence or winding angle in the helical layers, nor on the number of longitudinal or circumferential layers. The work presents non-standard methods for the assessment and designation of mosaic patterns. The mosaic patterns in the helical layers were designated in accordance to the matrix method. The patterns were compared to the Nr1 patterns, which are optimal because of the lowest number of crossovers. The results of the study point to a lack of good engineering practices in the usage of specific mosaic patterns in responsible high-pressure constructions. In the opinion of the authors, the only rationale for the use of specific mosaic patterns now in use by the industry is the visual effect and attractive, rhombic character of the pattern. Each vessel had a unique composite layer template . Among the analyzed vessels, only one Nr1 mosaic pattern was found. It was used in the layer laid down at the angle of 14°.