@article{ziccarelli_kanvinde_deierlein_2023, title={Calibrating an adaptive cohesive zone model to simulate ductile crack propagation in structural steel under cyclic loading}, volume={11}, ISSN={["1460-2695"]}, url={https://doi.org/10.1111/ffe.14183}, DOI={10.1111/ffe.14183}, abstractNote={AbstractA procedure is outlined for calibrating a finite element model to simulate ductile cracking that employs a continuum damage criterion for ductile fracture initiation, termed the Stress Weighted Ductile Fracture Model, with an Adaptive Cohesive Zone method to simulate crack propagation. The proposed procedure is implemented and validated with data from 44 coupon‐scale tests of an A913 structural steel. The fracture model calibration is performed in two stages to determine parameters to evaluate: (1) the continuum damage mechanics criterion and (2) ductile crack initiation and propagation. Sensitivity of the calibration to parameter uncertainty is evaluated using synthetic data, followed by calibration and validation against experimental test data. The results indicate that the computational model can accurately simulate the overall response of experimental specimens, as well as other key aspects of observed behavior, including crack tunneling and crack face closure. Guidelines are provided for practical calibration of the model components.}, journal={FATIGUE & FRACTURE OF ENGINEERING MATERIALS & STRUCTURES}, author={Ziccarelli, Andy and Kanvinde, Amit and Deierlein, Gregory}, year={2023}, month={Nov} }
 @article{ziccarelli_kanvinde_deierlein_2023, title={Cyclic adaptive cohesive zone model to simulate ductile crack propagation in steel structures due to ultra-low cycle fatigue}, volume={2}, ISSN={["1460-2695"]}, DOI={10.1111/ffe.13964}, abstractNote={AbstractMicromechanics‐based continuum damage criteria have previously been developed to simulate the initiation of ductile fracture in structural steels under conditions with large‐scale plasticity where conventional fracture mechanics indices are invalid. Such models have been combined with methods to simulate ductile crack growth for monotonic loading. In this study, a micromechanics‐based adaptive cohesive zone model for simulating ductile crack propagation under monotonic loading is extended to handle cyclic loading. The proposed model adaptively modifies the cohesive traction–separation relationship for crack opening and closure, as the loading reverses between tension and compression. The approach is implemented into the finite element analysis platform WARP3D, and results of simulations that use the model are compared with data from coupon‐scale tests. The results demonstrate that the proposed model can accurately simulate the effect of crack propagation on specimen response, as well as other key aspects of observed behavior, including crack face closure and crack tunneling.}, journal={FATIGUE & FRACTURE OF ENGINEERING MATERIALS & STRUCTURES}, author={Ziccarelli, Andy and Kanvinde, Amit and Deierlein, Gregory}, year={2023}, month={Feb} }
 @article{vajari_neuner_arunachala_ziccarelli_deierlein_linder_2022, title={A thermodynamically consistent finite strain phase field approach to ductile fracture considering multi-axial stress states}, volume={400}, ISSN={["1879-2138"]}, url={https://doi.org/10.1016/j.cma.2022.115467}, DOI={10.1016/j.cma.2022.115467}, abstractNote={Phase field models for ductile fracture have gained significant attention in the last two decades due to their ability in implicitly tracking the nucleation and propagation of cracks. However, most crack phase field formulations for elastoplastic solids focus only on the effects of plastic deformation , and do not consider the different multi-axial stress states that may arise in practical designs. In this work, a thermodynamically consistent phase field approach coupled with finite strain plasticity, considering multi-axial stress states is presented. In order to account for the coupling between plasticity and stress states, the Stress-Weighted Ductile Fracture Model (SWDFM) is utilized. The SWDFM represents a criterion for predicting ductile crack initiation under both monotonic and cyclic loadings based on histories of an internal plastic variable, stress triaxiality , and the Lode angle parameter. The excellent performance of the SWDFM for predicting ductile crack initiation motivates for its incorporation into a phase field approach for predicting both crack initiation and propagation through degradation of the fracture toughness . Moreover, based on the second law of thermodynamics , exact requirements are imposed on the rate at which the fracture toughness can evolve. A novel function for degrading the plastic yield surface during the evolution of damage is introduced. This function, in line with experimental observations, leads to an accumulation of plastic deformation in damaged regions of a solid, and avoids numerical instabilities arising from concentrations of large plastic deformations in severely damaged regions. For validating the proposed model, results of computational simulations are compared to data from selected tests considering different multi-axial stress states. Comparisons of the numerical results with data from laboratory experiments demonstrate the capabilities of the proposed framework.}, journal={COMPUTER METHODS IN APPLIED MECHANICS AND ENGINEERING}, author={Vajari, Sina Abrari and Neuner, Matthias and Arunachala, Prajwal Kammardi and Ziccarelli, Andy and Deierlein, Gregory and Linder, Christian}, year={2022}, month={Oct} }