TY - JOUR
T1 - Nonlocal modeling in high-velocity impact failure of 6061-T6 aluminum
AU - Ahad, F. R.
AU - Enakoutsa, K.
AU - Solanki, Kiran
AU - Bammann, D. J.
N1 - Funding Information:
The study was supported by the US Department of Transportation, Office of the Secretary, Grant No. DTOS59-08-G-00103. Dr. Lee Binderman from LSTC Inc. is gratefully thanked for his insightful discussions on the use of the nonlocal concept in LS-DYNA FE code. KNS would like to acknowledge support from the School for Engineering of Matter, Transport, and Energy (SEMTE) at Arizona State University.
PY - 2014/4
Y1 - 2014/4
N2 - In this paper, we present numerical simulations with local and nonlocal models under dynamic loading conditions. We show that for finite element (FE) computations of high-velocity, impact problems with softening material models will result in spurious post-bifurcation mesh dependency solutions. To alleviate numerical instabilities associated within the post-bifurcation regime, a characteristic length scale was added to the constitutive relations and calibrated through a series of different notch specimen tests. This work aims to assess the practical elevance of the modified model to yield mesh independent results in the numerical simulations of high-velocity impact problems. To this end, we consider the problem of a rigid projectile moving at a range of velocities between 89 and 107 m/s, colliding against a 6061-T6 Aluminum disk. A material model embedded with a characteristic length scale in the manner proposed by Pijaudier-Cabot and Bazant (1987), but in the context of concrete damage, was utilized to describe the damage response of the disk. The numerical result shows that the addition of a characteristic length scale to the constitutive model does eliminate the pathological mesh dependency and shows excellent agreements between numerical and experimental results. Furthermore, the application of a nonlocal model for higher strain rate behavior shows the ability of the model to address intense localized deformations, irreversible flow, softening, and final failure. Finally, we show that the length scale introduced in the model can be calibrated using a series of tensile notch specimen tests.
AB - In this paper, we present numerical simulations with local and nonlocal models under dynamic loading conditions. We show that for finite element (FE) computations of high-velocity, impact problems with softening material models will result in spurious post-bifurcation mesh dependency solutions. To alleviate numerical instabilities associated within the post-bifurcation regime, a characteristic length scale was added to the constitutive relations and calibrated through a series of different notch specimen tests. This work aims to assess the practical elevance of the modified model to yield mesh independent results in the numerical simulations of high-velocity impact problems. To this end, we consider the problem of a rigid projectile moving at a range of velocities between 89 and 107 m/s, colliding against a 6061-T6 Aluminum disk. A material model embedded with a characteristic length scale in the manner proposed by Pijaudier-Cabot and Bazant (1987), but in the context of concrete damage, was utilized to describe the damage response of the disk. The numerical result shows that the addition of a characteristic length scale to the constitutive model does eliminate the pathological mesh dependency and shows excellent agreements between numerical and experimental results. Furthermore, the application of a nonlocal model for higher strain rate behavior shows the ability of the model to address intense localized deformations, irreversible flow, softening, and final failure. Finally, we show that the length scale introduced in the model can be calibrated using a series of tensile notch specimen tests.
KW - BCJ model
KW - Damage delocalization
KW - Dynamic failure
KW - Mesh dependence
KW - Nonlocal modeling
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U2 - 10.1016/j.ijplas.2013.10.001
DO - 10.1016/j.ijplas.2013.10.001
M3 - Article
AN - SCOPUS:84894090107
SN - 0749-6419
VL - 55
SP - 108
EP - 132
JO - International Journal of Plasticity
JF - International Journal of Plasticity
ER -