Research Papers - Department of Civil Engineering
Permanent URI for this collectionhttps://rda.sliit.lk/handle/123456789/598
Browse
2 results
Search Results
Publication Embargo Atomistic and continuum modelling of stress field at an inhomogeneity in graphene(Elsevier, 2018-12-15) Dewapriya, M. A. N; Rajapakse, R. K. N. DThe influence of an atomic inhomogeneity on the resulting stress field of a nanoscopic matrix material can be remarkably different from the corresponding continuum descriptions due to the significance of surface energy and the discrete nature of matter at the nanoscale. In this work, we conducted a comprehensive molecular dynamics study to investigate the stress field at an atomic inhomogeneity, in the form of an elliptical hole or a circular hexagonal boron-nitride inclusion, in graphene. The results show that stress concentration factor at an inhomogeneity is higher than the corresponding classical continuum solution. We estimated the surface elastic constants for a modified continuum framework using the molecular dynamics results. Comparison between the atomic simulations and the modified continuum model reveals the limitations of such continuum-based models for the two-dimensional materials. Molecular dynamics results imply that the underlying atomic structure softens the effect of inhomogeneity compared to a continuum description thus causing an amplification of the stress filed. The molecular dynamics and modified continuum solutions for stress concentration are presented in simplified forms and design charts to facilitate preliminary design of graphene-based hybrid materials.Publication Embargo Atomistic and continuum modelling of temperature-dependent fracture of graphene(springer, 2014-06-01) Dewapriya, M. A. N; Rajapakse, R. K. N. D; Phani, A.SThis paper presents a comprehensive molecular dynamics study on the effects of nanocracks (a row of vacancies) on the fracture strength of graphene sheets at various temperatures. Comparison of the strength given by molecular dynamics simulations with Griffith’s criterion and quantized fracture mechanics theory demonstrates that quantized fracture mechanics is more accurate compared to Griffith’s criterion. A numerical model based on kinetic analysis and quantized fracture mechanics theory is proposed. The model is computationally very efficient and it quite accurately predicts the fracture strength of graphene with defects at various temperatures. Critical stress intensity factors in mode I fracture reduce as temperature increases. Molecular dynamics simulations are used to calculate the critical values of J integral (JIC) of armchair graphene at various crack lengths. Results show that JIC depends on the crack length. This length dependency of JIC can be used to explain the deviation of the strength from Griffith’s criterion. The paper provides an in-depth understanding of fracture of graphene, and the findings are important in the design of graphene based nanomechanical systems and composite materials