Study on evolution mechanism of uniaxial fatigue damage of fiber woven reinforced laminated composites

Abstract

The fiber woven reinforced flexible composite film has been widely concerned in the fields of adjacent space aerostats, high air balls, etc due to its excellent properties such as high strength, good toughness, light weight and good foldability. However, the temperature difference which is too large between day and night around the high-altitude environment causes the flexible composite film to undergo stress fatigue damage with the alternating change of the bearing pressure, which induces to form the damage microcrack and cause the air leakage damage of the flexible composite film, consequently, the damage seriously affects the normal service life of the aerostat and the airbag. Here, a typical Vectran fiber reinforced plain woven flexible composite film was taken as an example. The uniaxial warp stress fatigue damage evolution model of fiber reinforced plain weave flexible composites was constructed by using flexible film mechanics theory and progressive damage accumulation principle. And the uniaxial stress fatigue damage test and the SEM test of the damage mode were performed to identify the parameters of the uniaxial stress fatigue damage evolution model. It was found that the uniaxial warp-induced stress fatigue damage of flexible fiber reinforced plain woven composites was closely related to the properties, structure and stress state of the main load-bearing fiber bundles, and the damage mode was mainly represented by fiber bundle control, which synchronously induced the damage evolution of internal matrix and functional film layer. The fatigue test data of warp uniaxial fatigue damage under different fatigue loads showed good double logarithmic linear variation law, which could provide theoretical references for the structure optimization design and service life analysis of the fatigue damage mechanism.