@article{BoyceKramerBosiljevacetal., author = {Boyce, Brad L. and Kramer, Sharlotte L. B. and Bosiljevac, T. R. and Corona, Edmundo and Moore, J. A. and Elkhodary, Khalil and Simha, C. Hari Manoj and Williams, Bruce W. and Cerrone, Albert R. and Nonn, Aida and Hochhalter, Jacob D. and Bomarito, Geoffrey F. and Warner, James E. and Carter, Bruce J. and Warner, Derek H. and Ingraffea, Anthony R. and Zhang, T. and Fang, X. and Lua, Jim and Chiaruttini, Vincent and Maziere, Matthieu and Feld-Payet, Sylvia and Yastrebov, Vladislav A. and Besson, Jacques and Chaboche, Jean Louis and Lian, J. and Di, Y. and Wu, Bei and Novokshanov, Denis and Vajragupta, Napat and Kucharczyk, Pawel and Brinnel, Viktoria and Doebereiner, Benedikt and Muenstermann, Sebastian and Neilsen, Michael K. and Dion, Kristin and Karlson, Kyle N. and Foulk, James Wesley and Brown, Arthur A. and Veilleux, Michael G. and Bignell, John L. and Sanborn, Scott E. and Jones, Chris A. and Mattie, Patrick D. and Pack, Keunhwan and Wierzbicki, Tomasz and Chi, Sheng-Wei and Lin, S.-P. and Mahdavi, Ashkan and Predan, Jozef and Zadravec, Janko and Gross, Andrew J. and Ravi-Chandar, KRISHNASWAMY and Xue, Liang}, title = {The second Sandia Fracture Challenge: predictions of ductile failure under quasi-static and moderate-rate dynamic loading}, series = {International journal of fracture}, journal = {International journal of fracture}, number = {198, 1-2}, publisher = {Springer}, doi = {10.1007/s10704-016-0089-7}, pages = {5 -- 100}, abstract = {Ductile failure of structural metals is relevant to a wide range of engineering scenarios. Computational methods are employed to anticipate the critical conditions of failure, yet they sometimes provide inaccurate and misleading predictions. Challenge scenarios, such as the one presented in the current work, provide an opportunity to assess the blind, quantitative predictive ability of simulation methods against a previously unseen failure problem. Rather than evaluate the predictions of a single simulation approach, the Sandia Fracture Challenge relies on numerous volunteer teams with expertise in computational mechanics to apply a broad range of computational methods, numerical algorithms, and constitutive models to the challenge. This exercise is intended to evaluate the state of health of technologies available for failure prediction. In the first Sandia Fracture Challenge, a wide range of issues were raised in ductile failure modeling, including a lack of consistency in failure models, the importance of shear calibration data, and difficulties in quantifying the uncertainty of prediction [see Boyce et al. (Int J Fract 186:5-68, 2014) for details of these observations]. This second Sandia Fracture Challenge investigated the ductile rupture of a Ti-6Al-4V sheet under both quasi-static and modest-rate dynamic loading (failure in 0.1 s). Like the previous challenge, the sheet had an unusual arrangement of notches and holes that added geometric complexity and fostered a competition between tensile- and shear-dominated failure modes. The teams were asked to predict the fracture path and quantitative far-field failure metrics such as the peak force and displacement to cause crack initiation. Fourteen teams contributed blind predictions, and the experimental outcomes were quantified in three independent test labs. Additional shortcomings were revealed in this second challenge such as inconsistency in the application of appropriate boundary conditions, need for a thermomechanical treatment of the heat generation in the dynamic loading condition, and further difficulties in model calibration based on limited real-world engineering data. As with the prior challenge, this work not only documents the 'state-of-the-art' in computational failure prediction of ductile tearing scenarios, but also provides a detailed dataset for non-blind assessment of alternative methods.}, language = {en} } @article{RajaramanKeimPondicherryetal., author = {Rajaraman, Dhanraj and Keim, Vincent and Pondicherry, Kannaki and Nonn, Aida and Hertele, Stijn and Fauconnier, Dieter}, title = {Stress state characterization of ductile materials during scratch abrasion}, series = {Wear}, volume = {476}, journal = {Wear}, number = {15}, publisher = {Elsevier}, doi = {10.1016/j.wear.2021.203712}, abstract = {Abrasive wear limits the lifetime of many machine components. Most empirical models relate the abrasive wear resistance to material hardness. In reality, however, other material properties are also influencing as scratch abrasion damage follows from a highly complex stress trajectory upon scratching. Numerical (finite element) simulation of scratch abrasion requires the use of a material damage model, which translates this stress trajectory into material degradation and removal. Most damage models include the first two stress invariants. However, fully incorporating the complex stress trajectories that occur during scratch abrasion may require damage models with dependence of the third deviatoric parameter (Lode angle). This paper serves as an a-priori study to evaluate the stress states that may occur during scratch abrasion. Three mechanisms (ploughing, wedging, cutting) are considered. Hereto, the results of an extensive parametric study using elastic-plastic finite element simulations of a scratch indentation process are discussed. Complex, non-proportional variations in stress state values are observed to occur during scratch abrasion. Distinct stress state trajectories are identified for the three abovementioned mechanisms. These variations are critically discussed to motivate a selection of suitable damage models for rigorous finite element analysis of the wear processes associated with scratch abrasion.}, language = {en} } @article{XueKeimParedesetal., author = {Xue, Lufeng and Keim, Vincent and Paredes, Marcelo and Nonn, Aida and Wierzbicki, Tomasz}, title = {Anisotropic effects on crack propagation in pressurized line pipes under running ductile fracture scenarios}, series = {Engineering fracture mechanics}, volume = {249}, journal = {Engineering fracture mechanics}, publisher = {Elsevier}, doi = {10.1016/j.engfracmech.2021.107748}, abstract = {The current analyses present results of running ductile fracture propagation in high strength X100 line pipe steels under the influence of anisotropy. Mechanical anisotropy is commonly available in pipe products as a result of the manufacturing process, especially, those subjected to hot/cold-worked deformation. The outcomes of the present analyses show that its effect on the behavior of running ductile fracture in cracked pipes undergoing depressurization is meaningful. For instance, the Crack-Tip Opening Angle (CTOA) not only exhibits a strong dependence to the pipe's diameter size, but also to the material's anisotropy nature when compared to a hypothetical isotropic material. Moreover, laboratory scale tests such as those performed on Battelle Drop Weight Tear (BDWT) samples provide useful information about initiation of ductile crack propagation when the anisotropy features are taken into account in the material description.}, language = {en} }