A Modified Phase-Field Damage Model for Metal Plasticity at Finite Strains: Numerical Development and Experimental Validation

Abstract

Steel structures are designed to operate in an elastic domain, but sometimes plastic strains induce damage and fracture. Besides experimental investigation, a phase-field damage model (PFDM) emerged as a cutting-edge simulation technique for predicting damage evolution. In this paper, a von Mises metal plasticity model is modified and a coupling with PFDM is improved to simulate ductile behavior of metallic materials with or without constant stress plateau after yielding occurs. The proposed improvements are: (1) new coupling variable activated after the critical equivalent plastic strain is reached; (2) two-stage yield function consisting of perfect plasticity and extended Simo-type hardening functions. The uniaxial tension tests are conducted for verification purposes and identifying the material parameters. The staggered iterative scheme, multiplicative decomposition of the deformation gradient, and logarithmic natural strain measure are employed for the implementation into finite element method (FEM) software. The coupling is verified by the ‘one element’ example. The excellent qualitative and quantitative overlapping of the force-displacement response of experimental and simulation results is recorded. The practical significances of the proposed PFDM are a better insight into the simulation of damage evolution in steel structures, and an easy extension of existing the von Mises plasticity model coupled to damage phase-field.

Analysis of Damage and Failure in Anisotropic Ductile Metals Based on Biaxial Experiments with the H-Specimen

“…Uncertainties in manufactured parts may cause remarkable problems in automotive or aeronautical applications and, therefore, accurate prediction of their performances is very important. As a consequence, detailed analysis of irreversible deformations as well as damage and fracture behavior of these optimized metals and alloys is one of the main issues in engineering [3] allowing proposition of accurate and practically applicable constitutive models [4,5]. These theoretical frameworks and corresponding numerical programs must be based on experiments taking into account different loading directions with respect to the principal axes of anisotropy and a wide range of multi-axial loading conditions causing different stress states to be able to identify material parameters and to validate the constitutive theories for various engineering applications [6].…”

A Comparison Study of Fatigue Behavior of S355J2+N, S690QL and X37CrMoV5-1 Steel

“…Mild-strength S355J2+N steel, high-strength S690QL steel, and hot work tool steel grade X37CrMoV5-1 steel were used for this experimental study. A comparison of the chemical composition (in terms of weight %) of these steels [35][36][37][38] was obtained using spark emission spectrometry and is shown in Table 1. The S355J2+N and S690QL steels are suitable for welding; however, due to the higher amount of alloy elements, the weldability of high-strength steels is often less than that of mild-strength steel.…”

Advances in Design by Metallic Materials: Synthesis, Characterization, Simulation and Applications

“…The collection includes papers regarding the most multifaced aspects of metals as synthesis [1][2][3], treatments [2][3][4], experimental characterization [4][5][6][7], material models [7][8][9] and engineering applications [10][11][12] providing a clear cross-section of the wide variety of topics and research arguments under investigation in the scientific community now.…”

“…However, surface hardening and wear continues to represent a relevant aspect to take care on in the use of metals, as demonstrated in [6] where metal matrix composites are experimentally investigated or in [8] where numerical models are developed in a way that predicts the final effect of hardening treatments. Numerical models, sometimes powered by finite elements, are also present in other contributions with the scope to predict plasticity [9] or failures [10] or, even, to support design actions with the scope to optimize the use of metal structures [11]. Finally, the last paper in the list [12] is maybe able to provide a synthesis in the proposed concept, regarding the opportunity of metallic materials, often considered as belonging to a quite old past, in an epoch where a large assortment of new materials is emerging, as in the case of polymer composites.…”