A. M. Rajendran¹, D. J. Grove²

CMES-Computer Modeling in Engineering & Sciences, Vol.3, No.3, pp. 367-380, 2002, DOI:10.3970/cmes.2002.003.367

Abstract This paper presents detailed computational analyses investigating the ability of constitutive relationships to describe the response of a 99.5% pure alumina (AD995) subjected to a wide range of stress/strain loading states. Using a shock-wave-propagation-based finite element code, one and two-dimensional simulations were performed for the following shock and impact configurations: plate-on-plate impact; rod-on-rod impact; single-density plate-on-rod impact; graded-density plate-on-rod impact; and rod penetration into a thick plate. The detailed analyses presented in this paper include a model constant sensitivity study through comparisons of computed wave profiles with experimental measurements. More >

Liming Xiong¹, Youping Chen¹

CMES-Computer Modeling in Engineering & Sciences, Vol.24, No.2&3, pp. 203-214, 2008, DOI:10.3970/cmes.2008.024.203

Abstract This paper presents the application of an atomistic field theory (AFT) in modeling and simulation of boron- , boron/nitrogen and silicon/nitrogen-doped nanocrystalline silicon carbide (B-, BN-, SiN-SiC). Intergranular glassy films (IGFs) and nano-sized pores have been obtained in triple junctions of the grains in nanocrystalline SiC (nc-SiC). Residual tensile stress in the SiC grains and compressive stress in the grain boundaries (GBs) are observed. Under uniaxial tension, the constitutive responses of nanocrystalline SiC were reproduced from the simulations. It is found that the mechanical properties of nanocrystalline SiC are strongly dependent on the compositions of GBs. Although there are more… More >

Aurora Costales¹, C. J. F. Solano², E. Francisco¹, A. Martín Pendás¹

CMC-Computers, Materials & Continua, Vol.38, No.2, pp. 105-128, 2013, DOI:10.3970/cmc.2013.038.105

Abstract An extension of our previously reported periodic cluster model (J. Phys. Chem. C 2008, 112, 6667-6676 ) to nanorings and nanobelts is presented. This new scheme allows for accurately calculating reasonably large nanostructures while preserving a very small number of optimization parameters. The model has been applied to a number of AlN semiconducting structures using ab initio pair potentials. Attention has been paid to the variation of the B1-B4 phase transition pressure as the the size of the structures is varied. More >

R. R. Valisetty¹, A.M. Dongare², A.M. Rajendran³, R. R. Namburu¹

CMC-Computers, Materials & Continua, Vol.36, No.3, pp. 231-255, 2013, DOI:10.3970/cmc.2013.036.231

Abstract Materials used in soldier protective structures, such as armor, vehicles and civil infrastructures, are being improved for performance in extreme dynamic environments. Nanocrystalline metals show significant promise in the design of these structures with superior strengths attributed to the dislocation-based and grain-boundary-based processes as compared to their polycrystalline counterparts. An optimization of these materials, however, requires a fundamental understanding of damage evolution at the atomic level. Accordingly, atomistic molecular dynamics simulations are performed using an embedded-atom method (EAM) potential on three nano-crystalline aluminum atom systems, one a Voronoi-based nano-crystalline system with an average grain size of 10 nm, and the… More >

A. M. Dongare^1,2, A. M. Rajendran³, B. LaMattina⁴, M. A. Zikry¹, D. W. Brenner¹

CMC-Computers, Materials & Continua, Vol.24, No.1, pp. 43-60, 2011, DOI:10.3970/cmc.2011.024.043

Abstract Large-scale molecular dynamics (MD) simulations are used to investigate the effects of microstructure and loading conditions on the dynamic failure behavior of nanocrystalline Cu. The nucleation, growth, and coalescence of voids is investigated for the nanocrystalline metal with average grain sizes ranging from 6 nm to 12 nm (inverse Hall-Petch regime) for conditions of uniaxial expansion at constant strain rates ranging from 4x107 s - 1 to 1010 s - 1. MD simulations suggest that the evolution of voids can be described in two stages: The first stage corresponds to the nucleation of voids and the fast linear initial growth… More >

P. B. Wang¹, Z. H. Yao^1,2, T. Lei¹

CMC-Computers, Materials & Continua, Vol.3, No.2, pp. 65-76, 2006, DOI:10.3970/cmc.2006.003.065

Abstract The fast multipole method (FMM) is applied to the dual boundary element method (DBEM) for the analysis of finite solids with large numbers of microcracks. The application of FMM significantly enhances the run-time and memory storage efficiency. Combining multipole expansions with local expansions, computational complexity and memory requirement are both reduced to O(N), where N is the number of DOFs (degrees of freedom). This numerical scheme is used to compute the effective in-plane bulk modulus of 2D solids with thousands of randomly distributed microcracks. The results prove that the IDD method, the differential method, and the method proposed by Feng… More >