A numerical model for stress relaxation analysis of sealing systems in nonbonded pipe end fittings

•In this paper, the high temperature stress relaxation experiment of PVDF is carried out, and the experimental results are processed by the L-M method of nonlinear regression to identify the prony parameters used to describe the stress relaxation phenomenon.•This paper discusses the effect of stress relaxation of inner sheath materials on the sealing system sealing performance in flexible pipe end fitting.•This paper changes the prony parameters multiple times and discusses the impact of these changes on the maximum contact pressure of the sealing system, providing certain data for subsequent research.