Elastic–Plastic Collapse of Short Length Tube under Lateral Crushing between Two Rigid Plates Considering Initial Ovality

External accidental damage to industrial or buried pipes often results in excessive deformation of cross-section. Cross-section deformation may destroy the integrity of pipeline system. The deformation level could be predicted based on the energy dissipated by plastic flow. This study presents a numerical analysis of elastic–plastic collapse of circular and elliptic rings under compression of two flat plates. Aluminium rings of width 1.5 mm are manufactured by CNC milling. The ellipticity is incorporated by the machined elliptical geometric profile of constant uniform thickness without introducing additional residual stress. The FEA based on isotropic hardening model is established and compared against the experimental result and they agree very well. The effect of eccentricity, orientation, thickness and hardening property is parametrically analyzed in ABAQUS. The load-displacement curves and absorbed energy’s dependence on ovality and thickness are discussed. The collapse mechanism is clearly indicated by the active yielding region analysis from FEA. When hardening is small one top plastic hinge is separated into two moving hinges and this separation is not observed for larger hardening. This paper serves as a reference for assessment of plastic failure due to excessive deformation and energy absorption capacity of pipelines under lateral impact.