Reduced model and nonlinear analysis of localized instabilities of residually stressed cylinders under axial stretch

TL;DR

This paper develops a one-dimensional model for analyzing localized necking and bulging in residually stressed cylinders under axial stretch, combining nonlinear elasticity theory with numerical methods to identify bifurcation points and material optimization.

Contribution

It introduces a novel dimensional reduction approach and numerical framework for studying localized instabilities in residually stressed cylinders under different loading conditions.

Findings

Identified critical bifurcation values for localized necking and bulging.

Quantified radius change during localized deformation.

Optimized material properties for stability analysis.

Abstract

In this paper we present a dimensional reduction to obtain a one-dimensional model to analyze localized necking or bulging in a residually stressed circular cylindrical solid. The nonlinear theory of elasticity is first specialized to obtain the equations governing the homogeneous deformation. Then, to analyze the non-homogeneous part, we include higher order correction terms of the axisymmetric displacement components leading to a three-dimensional form of the total potential energy functional. Details of the reduction to the one-dimensional form are given. We focus on a residually stressed Gent material and use numerical methods to solve the governing equations. Two loading conditions are considered. In the first, the residual stress is maintained constant, while the axial stretch is used as the loading parameter. In the second, we keep the pre-stretch constant and monotonically increase the residual stress until bifurcation occurs. We specify initial conditions, find the critical values for localized bifurcation and compute the change in radius during localized necking or bulging growth. Finally, we optimize material properties and use the one-dimensional model to simulate necking or bulging until the Maxwell values of stretch are reached.