Large deformations and failure of clamped circular steel plates under uniform impulsive loads using various phenomenological damage models

Abstract

Paper presents numerical models based on a detailed characterization of various uncoupled damage models in a finite element analysis (FEA) setup to assess their results and comparative performance in simulation of structural response and failure of clamped circular plates subjected to a wide range of uniform impulse loading. The significance of numerical modeling of ductile fracture in simulating the various observed modes of failure in steel structures under intense blast loading has also been presented along with an overview of various phenomenological damage models in the published domain. Numerical schemes presented in the paper are founded on a detailed and well-defined material model using mechanical uniaxial tension tests (UTT) and its inverse FEA simulations. Elaborate UTT experiments have been conducted to establish the mechanical strength and ductile fracture characteristics of a particular grade of mild steel for its usage in the calibration of the discussed damage models. Relative performance of various simple as well as complex phenomenological damage models in simulating/ predicting the experimentally observed structural response and different failure modes of fully clamped circular steel plates over a broad range of uniform impulsive loads has also been presented. Published results based on extensive experimental works by various authors on response of thin walled clamped circular plates under transversely applied uniform air blast loads, manifesting in plastic deformations of large magnitude, inception of thinning and tearing under various ductile fracture modes, have been utilized in the validation of the numerical model and procedure. Based on the evaluated performance of the discussed numerical models, a hybrid damage model adopted within the FEA setup has been proposed, demonstrating a very good correlation of numerical predictions with experiments. The validated FEA setup incorporating the calibrated hybrid damage model has further been gainfully utilized towards critical insights in the evolution of plastic deformations, progression of damage and their correlation with experimentally observed failure modes over a wide range of loading, involving varying stress states and tri-axiality.