Stress analysis of nanostructures using a finite element method

Stress analysis facilitates the optimal design of micro/nanoelectromechanical system (MEMS/NEMS) devices for reliability. A finite element method was used to study nanostructures with different geometries and materials. By comparing the load-displacement responses obtained from the modelling and the actual experiments, it was concluded that an elastic model can be used. The numerical model was used to analyse the effect of surface roughness and scratches on stresses. Bending stresses as a function of beam geometry and load location, which is useful for beam design, were obtained. Beams with surface roughness in the form of semicircular and grooved asperities and scratches with various aspect ratios were modelled with the load present at the centre of the beam as well as at different offsets. Asperity and scratch locations were also varied so as to ascertain their effect on bending stresses. It was observed that the asperities and scratches increase the bending tensile stresses which could lead to failure of MEMS/NEMS devices. The loading was varied on the beams and the material was assumed to be pure elastic, elastic-plastic and elastic-perfectly plastic to observe the variations in the bending stresses and displacements. The results of the analysis can be useful to designers to develop the most suitable geometry for nanostructures.