Samid Khan

Type‐V composite pressure vessels (CPVs) for hydrogen storage face challenges in balancing high structural strength, lightweight construction, and permeation‐barrier performance. In this study, hybrid 4 carbon and 3 polyethylene (4C3PE) laminates alternating reinforced with graphene nanoplatelets (GNP) are prepared. A comparative multi‐scale analysis was conducted for Type‐V laminate architectures, integrating analytical hoop‐stress, finite element analysis (FEA) simulations, and ASTM D3039 tensile experiment analysis to develop a reliable design framework. Experimental characterization of the 4C3PE laminate revealed that a 2 wt.% GNP loading provides an allowable ultimate tensile strength of 648 MPa, with uniform dispersion of GNPs of an average agglomerate size (0.42 ± 0.11 μm), and a low void content below 1.5%. The carbon fiber‐polyethylene interlayers function as compliant barriers, reducing interlaminar shear stresses and preventing microcrack propagation. Structural scaling studies indicate that the 4C3PE architecture with unidirectional (0/0/0) _s stacking sequences is unsafe under 70 MPa pressure for configurations under 12C11PE. The 16C15PE laminate, as the optimal design, achieves a balanced Factor of Safety of 3.11 by maintaining circumferential stresses at 208.605 MPa within allowable limits, despite the weight penalties associated with thicker laminates. Microstructural observations suggest that GNP‐assisted crack deflection, PE‐mediated delamination suppression, and the formation of tortuous diffusion pathways may reduce potential hydrogen‐permeation routes. The study establishes a framework for screening materials in laminated architectures, with the 16C15PE laminate and 2 wt.% GNP as a promising candidate for linerless Type‐V vessels. This groundwork will facilitate future tests on pressure‐cycling and hydrogen permeability for full‐scale vessel production.

Hydrogen storage in lightweight composite pressure vessels demands materials with excellent thermal stability, reliable dimensional properties, and consistent curing behavior. In this study, carbon fiber reinforced epoxy laminates based on 4 carbon fiber layers with epoxy bisphenol A diglycidyl ether and hardener Diethylenetriamine as (4C-DGEBA/DETA) and other with our novel schema of 4 carbon fibers and 3 polyethylene films hot pressed with identical epoxy system as (4C3PE–DGEBA/DETA) analyzed and compared by using thermogravimetric analysis (TGA), Dynamic-mechanical analysis (DMA), and differential scanning calorimetry (DSC). TGA identified the degradation onset and differences in thermal stability between the two systems, while DMA provided insights into temperature-dependent viscoelastic behavior, including stiffness retention and damping characteristics. DSC used to evaluate curing characteristics and glass transition temperatures, revealing links between resin chemistry and thermal performance. The comparison showed that the modified 4C3PE–DGEBA/DETA system exhibited superior thermal resistance and dimensional stability compared to the baseline 4C-DGEBA/DETA composite. These results also improve the understanding of composite behavior in liner-less (Type-V) hydrogen storage pressure vessels and guide material selection and design improvements, supported by SEM surface morphology analysis for a novel 4C3PE laminate geometry.

Hemispherical end caps cover cylindrical pressure vessels mid‐surfaces for oil and gas, subsea vacuum enclosures, and automobile, and aerospace hydrogen carriers globally. This review discusses the importance of composite overwrapped cylindrical pressure vessel design characteristics like external pressures. The analysis of composite material properties and their resistive behavior on the cylindrical section is used to ensure accurate, safe, and effective pressure vessel operation at high pressures. Composite materials are popular for lightweight and end‐use performance in pressure vessel carriers for diverse applications. Current fibers include carbon, glass, and carbon/glass hybrid composite pressure vessels that employ less heavy material. Composite overwrapped pressure vessels (COPV) need accurate lamina sequence, laminate thickness, and fiber winding angles. Mandrel (liner) material, is also examined and suggested for metallic composite high‐pressure vessels (MC‐HPVs) including metal liners or circular rings circumferentially to decrease buckling and reinforce (Type‐III) COPV shells. The focus is on designing cylindrical components to prevent buckling in space rockets and automobiles under high‐pressure conditions, using stiffeners and holes for various stress scenarios. Genetic algorithm (GA) optimizes worst defects in composite cylinder shape on buckling, circular cutting holes on the shell for optimum stacking sequence lamination of fiber over the liner, and snap‐through reactions to support against buckling factors under pressure. The importance of autofrettage pressure and vibration on composite cylinder buckling was also analyzed. Liner‐less (Type‐V) composite pressure vessels represent the future of lightweight high‐performance pressure vessels, yet (Type IV) composite cylinders with plastic liners are light and strong and have numerous uses.Highlights: Buckling of cylindrical shells with mandrel material (liner) transition.

Low‐thickness/diameter cylindrical storage pressure vessels with composite overwrapping fail at diverse internal and external pressure circumstances, causing several faults that must be included and minimized to retain effectiveness and working capability. The bursting effect is caused by hoop (internal) stresses and can be reduced by composite lamination alignment and internal pressure resistance. Pressure vessel bursting faults vary with internal tensions and can induce fiber reinforced polymer fracture and composite cylinder failure under many failure criteria. Micro‐mechanical nondestructive testing uses independent failure criteria associated to modes like Tsai‐Wu, Tsai‐Hill, Azzi‐Tsai, Hoffman, and Chamis. Micro‐cracking of composite layers generates delamination in composite pressure vessels, causing porosity. Pressure vessel micro‐cracking was assessed using classical laminate theory. Composite material strain‐rate failures in mobile applications like hydrogen storage cars with composite pressure vessels are examined due to their widespread use. Finally, Polar, Helical, and Hoop winding sequences are consistently focused to optimize the design and analyze the parameters for the overall impact of different failure aspects as bursting behavior in cylindrical composite pressure vessels. Type‐IV composite pressure vessels have the best results due to their lightest weight but complexity of winding over the polar head geodesic and non‐geodesic curvatures overwrapped carbon include all these internal composite and liner geometry faults and optimize them to reduce failure issues to fix composite overwrapped pressure vessels (COPV's) design. Liner‐less composite pressure vessels (Type‐V) need more design and production study for high‐pressure and temperature applications.Highlights: Failure deals with the internal and external pressures exerted on composite pressure vessels. Failures like bursting of the pressure vessel, due to like micro‐cracking, delamination's and strain‐rate failures of composites. Failures detection through NDT inspection for polymer composite materials for composite pressure vessels. (COPV) perfect lamina sequence, liner materials and fiber winding angles must be considered for designing state of the art liner‐less Type‐V pressure vessels. Independent Failure criteria like (Tsai‐Wu & Hashin).