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Composite material high-pressure storage vessel has been increasingly applied in the hydrogen storage industry. This study aims to establish parametric analysis of fiber wound composite vessel and investigate the stress distribution, failure mechanism as well as the burst strength. Based on the maximum strain criterion and Tsai-Wu failure criterion, the burst strength of the vessel and the failure mechanism of the cylinder segment were evaluated and studied. The stresses of the cylinder were much higher than those of the dome. The cylindrical part of the vessel is its weakest area. Matrix failure initiated at the spiral wound layer, then the accumulation of matrix failure resulted in the stiffness becoming degraded and hence fiber failure happened on the hoop wound layers. The fiber failure leaded to the ultimate failure of the vessel. The wound scheme of the outer layers also plays an important role on the load-bearing ability of the vessel. The burst strength of vessel with case-A wound was 122 MPa, while it was 91 MPa for case-B wound, about 25.4% decrease. The numerical results were compared with the burst mode studied in experiments on composite vessels and a good agreement was obtained. This study provides a theoretical foundation for safe design and utilization of composite material high-pressure vessel in the fields of hydrogen storage.

A meso-structure model of fiber-bar composites reinforced by three-dimensional weaving (FBCR3DW) is proposed. Optical microscopy images of the preform structure revealed that the fibers along the circumference of the yarn cross-weave were twisted randomly due to alternating yarn winding on either side of the fiber bars during the manufacturing process. Sections of the cross-woven yarn were divided into five regions based on the twist characteristics. Stochastic function theory was used to describe the twist characteristics and to calculate the compliance tensor for each twisted yarn region. The twist characteristics and compliance tensor of each region were then introduced into a finite element model to calculate the elastic properties of the twisted yarn and FBCR3DW; unidirectional tensile stress-strain curves were generated based on the Tsai-Wu failure criterion. Several FBCR3DW specimens with randomly twisted yarns inside the weave structure were used in experimental tests. Our numerical results were in good agreement with the experimental values. Yarn distortion had a significant effect on the elastic properties and axial tensile strength of the yarn; specifically, the influence of yarn distortion on the transverse elastic modulus and transverse shear modulus of FBCR3DW was severe, whereas only a slight effect occurred with regard to the other elastic Appl Compos Mater constants and unidirectional tensile properties. Thus, the proposed method provides an effective reference for modeling fiber composites with a weave structure.

Laminate composites contain holes as a means of connection in industrial applications. A better understanding of the mechanical properties of open-hole components is necessary. Herein, progressive damage postbuckling analysis models are proposed for investigation of tensile damage and compressive buckling behaviors of open-hole laminate composites. The progressive damage model is based on failure criteria provided by the continuum damage mechanics model; virtual crack closure technology was employed to calculate the energy release rate for crack delamination in compressive postbuckling analysis. The models were utilized to analyze variations in the tensile and compressive mechanical properties, failure process, and buckling evolution of open-hole laminate composites using finite element analysis. The tensile failure patterns and failure processes of plies with different open-hole laminate composite angles were obtained and analyzed. Buckling characteristics, as well as the progression of buckling onset, buckling propagation, crack delamination, unstable delamination, and global buckling, were investigated. The influence of delamination crack length and crack distribution on the buckling properties of open-hole laminate composites are discussed in detail. Additionally, unstable and stable buckling characteristics were examined. The numerical results were in good agreement with theoretical and experimental results; damage initiated at the edge of a hole propagated to two sides with the onset of matrix damage, followed by fiber damage. The fiber damage of a 0°-ply led ultimately to laminate failure. The laminate with a symmetrical crack distribution showed stable buckling, whereas a short, nonsymmetrical distribution of cracks usually led to unstable buckling and delamination.