Gradient design of tubular of the fiber-reinforced composites pressure vessel for diminishing of the edge effect

Highlights: • Gradient structure design. • Influence of tubular structure on edge effect at joint. • Application of fiber reinforced composites. In the composite pressure vessel composed of fiber-reinforced composites tubular and metal head, the discontinuity of the structure at the joint will lead to increase of local stress and the inconsistent of internal and external deformation, which is called edge effect. An analytical procedure is developed to predict the behavior of fiber-reinforced composite circular tubes under axial unilateral loading. The stress and strain fields are solved by using the three-dimensional anisotropic elasticity theory. The results show that gradient structure with axial modulus varying along radius has obvious effect on reducing deformation difference and edge effect of pressure vessel, and the improvement of edge effect increases with the increase of gradient parameter. The numerical simulation is carried out by using finite element method, and the results are in good agreement with the theoretical calculations. The mathematical model established in this paper and the analysis results have some significance for improving the performance of fiber composite pressure vessels.