2018/03/10 by Mohamed Shaat, Shaat, Mohamed
Engineering · Materials Science · #Applied Physics (physics.app-ph) #Composite Structure Analysis and Optimization #FOS: Physical sciences #Nonlocal and gradient elasticity in micro/nano structures #Numerical methods in engineering #Railway Engineering and Dynamics
paper · pdf · doi:10.48550/arxiv.1803.04829
openalex publication_date 2018/03/10 · openalex created_date 2022/09/16 · openalex updated_date 2026/07/28
In this study effects of surface integrity on the mechanics of functionally\ngraded (FG) nanobeams are investigated. This study reports the changes in the\ngeometry and dynamics of FG nanobeams because of changes in their surface\ntextures and/or surface mechanical properties. A new model for FG nanobeams\nwith engineering surfaces is developed. This engineering surface is considered\nas a different material phase with a surface texture (waviness and roughness).\nThe initial curvatures of cantilever, simple supported, and clamped-clamped FG\nnanobeams due to surface residual stresses are determined. Moreover, their\nnatural frequencies and mode shapes are derived depending on surface integrity.\nThe initial curvatures of FG beams are obtained increasing with an increase in\nthe slope of the surface texture and/or a decrease in the heights of the\nsurface roughness. Moreover, it is observed that the natural frequencies of FG\nbeams may decrease or increase due surface integrity depending on the boundary\nconditions. Thus, as a first prospect, the surface roughness allows the\nvibration energy to propagation over the beam length and hence its natural\nfrequency decreases resulting in a zero-frequency mode. As for the other\nprospect, surface roughness inhibits the propagation of the vibration energy\nthrough the beam length leading to a mode localization. It is revealed that a\nmode localization is accompanied with an increase in the natural frequency of\nthe nanobeam. The proposed surface integrity model for FG nanobeams is compared\nwith Gurtin-Murdoch surface elasticity model. The results demonstrate that the\nsurface integrity model is preferred over the former model where it accounts\nfor, both, surface texture and surface mechanical properties effects. However,\nGurtin-Murdoch model assumes smooth surfaces of nanobeams which leads to\nunder/overestimations of their mechanics.\n