| Nanoscale phenomena have received significant interest over the past two decades due to the discovery of a number of novel properties at this scale which have a strong impact on the mechanical behavior and properties of nanomaterials. One of the key underlying mechanisms is the surface stress effect, which is due to under-coordinated bonding environment of surface atoms. As far as the general bulk material is concerned, the surface stress effect is not significant because mechanical contribution from free surface is negligible compared to that of bulk volume. However, when the characteristic length scale decreases, the ratio of surface area to volume increases, which leads to a strong surface stress effect. Traditional continuum models fail to capture the size-dependent elastic properties and behavior of nanomaterials because they do not capture nanoscale free surface effects such as surface stresses. Molecular Dynamic (MD) simulations have shown capability to capture nano-behaviors but are often not computationally tractable. In order to investigate small scale mechanical behaviors efficiently, many new computational models have arisen. Surface Cauchy Born (SCB) model is one of competing surface models which can capture the surface stress effect accurately and has computational merits because it is implemented within the frame of standard Finite Element Analysis (FEA). Based on SCB model, several issues with significant surface stress effects are investigated in this thesis: (1) Resonant mass sensing of nanomaterials; (2) Coupled thermo-mechanical behavior of nanomaterials; (3) Bending properties of FCC metal nanowires; (4) Instability analysis of nanomaterials. |
