Study of contact and friction at multiple length scales is necessary for the effective design and analysis of surfaces in sliding microand nano-electromechanical systems (MEMS/NEMS). As loading forces decrease in such applications, the size of the asperity contacts tends to decrease into the nano scale regime. Also with the increase in surface area to volume ratio in such systems, the surface f...

Discussions of energy dissipation during friction processes have captured the attention of engineers and scientists for over 300 years. Why then do we know so little about either dissipation or friction processes? A simple answer is that we cannot see what is taking place at the interface during sliding. Recently, however, devices such as the atomic force microscope have been used to perform fr...

Contact modelling, simulation, and analysis of mechanical systems with friction need proper treatments due to the non-smooth nature of the contact phenomenon. Two main approaches to deal with the contact problems are constraint and compliant based formulations [3]. In constraint based approaches, the problem is formulated by imposing the kinematic unilateral constraints between bodies in contac...

This paper presents an impact planning strategy to bat 2D objects to a target with or without contact friction. In the frictionless case, a closed-form solution is analyzed, simulated, and validated via the task of a WAM Arm batting a hexagonal object. Contact friction introduces a continuum of solutions, from which we select the one that expends the minimum kinetic energy of the manipulator. S...

The porosity of uniaxially compacted cohesive powders depends on the applied stress (including gravity). The case, where these stresses are weak, is considered. The compaction results in a porosity which is a function of sliding, rolling and torsion friction. By contact dynamics simulations it is shown that the influences of contact torques (static rolling and torsion friction) on the porosity ...

Single asperity friction experiments using atomic force microscopy (AFM) have been conducted on chemical vapor deposited (CVD) graphene grown on polycrystalline copper foils. Graphene substantially lowers the friction force experienced by the sliding asperity of a silicon AFM tip compared to the surrounding oxidized copper surface by a factor ranging from 1.5 to 7 over loads from the adhesive m...

This paper describes a new friction model, called the “brush model“, suitable for haptic rendering in virtual environments. A novel two-layer multiasperity surface contact model is presented that provides real-time rendering of friction forces at haptic refresh rates. This new friction model has several advantages; of particular importance is the accuracy with which it handles static friction a...

This work identifies damping parameters from compliantcontact vibration systems using energy dissipation concept. To develop the identification algorithms, the energy loss as registered in the force-displacement relationship of the real system is balanced against that of a theoretical model incorporating with an idealized compliant contact. Two approaches, including one based on the harmonic re...

This paper investigates the use of different soft contact and friction models, in Simulink, in the context of legged locomotion. The main criterion for assessing the models is the number of integration steps that are taken using variable step integration methods. The variables that are considered for the comparisons are the type of contact and friction models, the integration method, the desire...

In forming processes contact friction significantly influence metal flow, stress-strain state and process parameters. Furthermore, tribological conditions influence workpiece surface quality and its dimensional precision. This paper presents research results of the influence of contact friction coefficient on a workpiece surface quality in ring upsetting by flat plates. Workpiece surface roughn...