| The performance, durability and ultimate success of many devices under various contact and near-contact conditions (in close proximity of few nanometers), especially micro/nanodevices, is heavily influenced by surface mechanical properties and interfacial phenomena such as adhesion, friction and wear over multiple length scales. Scientific studies and design needs of such devices have led to the appearance of the new, interdisciplinary fields of nanotribology and nanomechanics.; In the first part of this work, three basic elements of nanotribology and nanomechanics were investigated, including nanomechanical properties, surface adhesion and effect of roughness on contact, adhesion and friction. On the measurement of nanomechanical properties, a high-resolution capacitive load-displacement transducer (force resolution of 3 nN and displacement resolution of 0.05 nm) and very sharp diamond indenters were developed and used to perform accurate measurements at sub-10 nm contact depths. Based on the interatomic Lennard-Jones potential, the widely used but ill-defined Lennard-Jones surface law was rigorously derived. Meanwhile, a finite element model using the surface elements to mimic van der Waals forces was also built to study adhesive contact, and the results were compared with various analytical models. The effect of surface roughness was discussed by introducing a normalized Weibull distribution to account for surface asymmetry as seen for many engineering surfaces. Effect of this asymmetry on contact, friction, and adhesion forces were studied by using this normalized Weibull distribution in a statistical microcontact model.; In the second part of this work, a systematic approach considering the above basic elements was used to investigate impact-induced contact damage of Head Disk Interfaces during operational shock. A contact mechanics based analysis with consideration of mechanical properties and thickness of various sub-micron thick surface layers, effect of adhesion, effect of roughness and flash temperature was performed to study the impact between slider corner and disk surface. The above contact mechanics based analysis was validated by a 3-dof, dynamic, thermomechanical finite element analysis. |
