# Cross-Scale Modeling of CFRP Stacking Sequence in Filament-Wound Composite Pressure Vessels: In-Plane and Inter-Layer Homogenization Analysis

## TL;DR

This paper presents a cross-scale modeling method for filament-wound composite pressure vessels to balance computational efficiency and accuracy.

## Contribution

A novel homogenization method is introduced for cross-scale modeling of CFRP layers in filament-wound vessels.

## Key findings

- The partial homogenization method captures fiber-direction stress distribution in inner layers with 7.56% deviation from detailed models.
- Fatigue life analysis shows only 0.28% variation in liner cycles across stacking sequences, indicating minimal impact from homogenization.
- The proposed framework effectively balances computational efficiency and accuracy for multiscale simulations of composite vessels.

## Abstract

Composite pressure vessels have attracted significant attention in recent years owing to their lightweight characteristics and superior mechanical performance. However, analyzing composite layers remains challenging due to complex filament-winding (FW) pattern structures and the associated high computational costs. This study introduces a homogenization method to achieve cross-scale modeling of carbon fiber-reinforced plastic (CFRP) layers, accounting for both lay-up sequence and in-plane FW diamond-shaped form. The stacking sequence in an FW Type IV composite pressure vessel is numerically investigated through ply modeling and cross-scale homogenization. The composite tank structure, featuring a polyamide PA66 liner, is designed for a working pressure of 70 MPa and comprises 12 helical winding layers and 17 hoop winding layers. An FW cross-undulation representative volume element (RVE) is developed based on actual in-plane mesostructures, suggesting an equivalent laminate RVE effective elastic modulus. Furthermore, six different lay-up sequences are numerically compared using ply models and fully and partially homogenized models. The structural displacements in both radial and axial directions are validated across all modeling approaches. The partial homogenization method successfully captures the detailed fiber-direction stress distribution in the innermost two hoop or helical layers. By applying the Hashin tensile failure criterion, the burst pressure of the composite tank is evaluated, revealing 7.56% deviation between the partial homogenization model and the ply model. Fatigue life analysis of the Type IV composite pressure vessel is conducted using ABAQUS® coupled with FE-SAFE, incorporating an S-N curve for polyamide PA66. The results indicate that the fatigue cycles of the liner exhibit only 0.28% variation across different stacking sequences, demonstrating that homogenization has a negligible impact on liner lifecycle predictions. The proposed cross-scale modeling framework offers an effective approach for multiscale simulation of FW composite pressure vessels, balancing computational efficiency with accuracy.