Assessing the safety and reliability of type-3 high-pressure composite tanks: a comprehensive analysis of failure metrics.

Pressure tanks play a pivotal role in various industrial applications, serving as vessels for the storage of gases under different pressures and environmental conditions. The burgeoning interest in hydrogen gas as a clean energy source has necessitated a comprehensive assessment of pressure tank structural integrity, particularly under high-pressure demands exceeding 700 bar. In this study, we systematically investigate the influence of different aluminum alloys, including AL6061, AL7075, and AL7178, reinforced with various fiber/epoxy composite materials. Our primary objective is to identify the optimal combination of liner and composite materials, along with the number of composite layers and fiber winding orientations that minimize distortion energy within the tank's liner and composite layers while maximizing safety factors. Our results indicate that distortion energy decreases as the fiber angle increases from zero to 75°, with the ideal fiber orientation angle shifting with the number of composite layers. The lowest distortion energy levels in the liner were achieved in composite tanks comprising 60 laminates of reinforcing composite material, wound at an orientation angle of [±55°/90°]. Across various internal pressure levels, pressure tanks reinforced with boron/epoxy composite material consistently outperformed other fiber materials. In terms of aluminum liner materials, AL6061 exhibited a remarkable 10.5% reduction in distortion energy on average when compared to AL7075. Safety indices revealed that pressure tanks reinforced with aramid/epoxy composite material provided the highest level of reliability, particularly when applying the maximum principal stress criterion. Carbon/epoxy and graphite/epoxy composites followed closely. In contrast, glass/epoxy and Kevlar/epoxy composites did not meet the stringent safety requirements for high-pressure storage tanks. These findings offer invaluable guidance for designing high-pressure composite tanks, ensuring their structural integrity and safety when storing hydrogen gas at elevated pressures, and exemplify the importance of materials and design considerations for such critical applications. [ABSTRACT FROM AUTHOR]