Session: Research Posters

Paper Number: 172828

Influence of Vacancy Defects on the Mechanical Properties of Bnnts for Nuclear Radiation Shielding Applications 

Boron Nitride Nanotubes (BNNTs) have garnered significant attention in the realm of advanced materials for nuclear applications due to their exceptional mechanical properties, high thermal stability, and remarkable radiation resistance. Their unique one-dimensional tubular structure, analogous to carbon nanotubes but composed of alternating boron and nitrogen atoms, offers a promising platform for structural reinforcement and radiation shielding in extreme environments. In this study, a comparative analysis of the mechanical properties of pristine and vacancy-defected BNNTs was conducted using classical Molecular Dynamics (MD) simulations to evaluate their suitability in radiation shielding applications within nuclear systems. Pristine BNNTs are known for their high Young’s modulus (approaching 1.2 TPa), excellent tensile strength, and ability to withstand high-energy particle impacts without significant degradation. However, during irradiation in nuclear environments, the creation of point defects such as boron or nitrogen vacancies is inevitable. These defects can alter the local atomic arrangement and bonding environment, leading to degradation in mechanical strength and stability. This study quantifies the extent to which such vacancy defects influence the tensile behavior and failure mechanisms of BNNTs under uniaxial tension, thereby contributing to a deeper understanding of their long-term structural reliability in nuclear settings. BNNT models with different chiralities—zigzag and armchair configurations—were constructed using Visual Molecular Dynamics (VMD), and classical MD simulations were performed using LAMMPS software. The simulations employed the Tersoff potential optimized for B-N interactions to accurately capture interatomic forces. Pristine and defective BNNTs were subjected to uniaxial tensile loading under periodic boundary conditions at room temperature. Point defects were introduced by selectively removing boron or nitrogen atoms from the lattice to simulate realistic radiation-induced damage. Stress-strain responses were recorded for each configuration to evaluate variations in elastic modulus, ultimate tensile strength (UTS), and strain at failure. The simulation results reveal a substantial reduction in mechanical strength due to vacancy defects. Chirality also played a key role; zigzag BNNTs exhibited higher strength retention compared to armchair BNNTs under equivalent defect conditions, suggesting anisotropic mechanical response due to directional bond alignment. Furthermore, defect-induced stress concentrations were observed to initiate bond breakage and crack propagation earlier in defective systems, leading to premature failure. These findings underscore the critical influence of vacancy defects on the structural integrity of BNNTs under mechanical loading and provide valuable insight for designing radiation-resistant nanostructured composites. The comparative analysis supports the continued development of BNNT-reinforced materials for nuclear reactors, space missions, and other high-radiation environments, where mechanical robustness and radiation shielding must co-exist. 

Presenting Author: Ajit Kelkar North Carolina A&T State University

Presenting Author Biography: Dr. Ajit D. Kelkar is a Professor in Mechanical Engineering Department at North Carolina A&T State University. For the past twenty-five years, he has been working in the performance evaluation and modeling of polymeric composites and ceramic matrix composites. He has worked with several federal laboratories in fatigue, impact, and finite element modeling of woven composites including the US Army, US Air force, NASA-Langley Research Center, National Science Foundation, Office of Naval Research, FAA, and Oak Ridge National Laboratory.

Authors:

Issac Lewis North Carolina A&T State University
Sheridan Easterling North Carolina A&T State University
Nachiket Makh North Carolina A&T State University
Mookesh Dhanasar North Carolina A&T State University
Ajit Kelkar North Carolina A&T State University