Abstract
Abstract The cylindrical filament wound composite overwrapped pressure vessels (COPV) with metal liner has been widely used in spaceflight due to their high strength and low weight. After the autofrettage process, the plastic deformation of the metal liner is constrained by composite winding layers, which introduce depressions to the metal liner that causes local buckling. To predict the local buckling of the inner liner with depressions of the pressure vessel after the autofrettage process, a local buckling analysis method for the metal liner of COPV was developed in this article. The finite element method is used to calculate the overall stress distribution in the pressure vessel before and after the autofrettage process, and the influence of local depressions on the buckling is evaluated. The axial buckling of the pressure vessel under external pressure is analyzed. The control equation of the metal liner with depressions is developed, considering the changes in the pressure and the bending moment of the liner depressions and its vicinity during the loading and unloading process. Taking the cylindrical COPV (38 L) with aluminum alloy liner as an example, the effects of liner thickness, liner radius, the thickness-to-diameter ratio, autofrettage pressure, and the length of straight section on the autofrettage process are discussed. The results show that the thickness of the inner liner has the most significant influence on the buckling of the liner, followed by the length of the straight section and the radius of the inner liner, while the autofrettage pressure has the least influence.
Highlights
As a core component of the space reentry vehicle, pressure vessels occupy the largest proportion of weight and volume in the propulsion system, which is the most significant part of the carrier structures [1,2]
To make full use of the high strength of composites and the plasticity of the metal material [12], the wound layer should bear most of the load under the working pressure, while the inner liner only acts as a seal
The thin-walled liner structure is adopted, and the autofrettage process that exceeds its working pressure is applied to the pressure vessel before it is put into use [13,14]
Summary
Buckling analysis of thin-walled metal liner of COPVs 541 liner-less COPV, and so on. According to the buckling analysis on the metal line of COPV with the initial depression, Phoenix and Kezirian [31] believed that the elastic support of the composite material winding layer on the liner limits the deformation of the liner. If a three-dimensional finite element model for the buckling analysis of Figure 1: Damaged morphology of COPV with metal liner caused by local buckling in the axial direction. The stress distributions of pressure vessels before and after autofrettage are calculated by FEA to obtain the in-plane tension and interface pressure of the metal liner; Secondly, an analytical model of the effect of depression on the interface pressure and residual bending moment of the liner is established to calculate the change in the depression profile before and after the autofrettage to determine whether the metal liner will be locally buckled. The effect of the changes of dimensional parameters on local buckling of cylindrical COPV with initial depressions is further discussed, such as the autofrettage pressure, liner thickness, radius, and thickness-to-diameter ratio
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