Conversion of frictional work into thermal energy, frictional heating, is frequently encountered in the sliding of complying solids. Depending on rubbing conditions (dry, lubricated, normal load, sliding speed, and thermal properties of the rubbing components), the released heat can cause significant rise in the temperatures of the sliding interface. Contact temperatures influence sliding behaviour. The low sliding friction of ice and snow is due to the presence of a thin lubricating layer of melt water which results from frictional heating of contacting ice crystals. Surface temperatures may also cause transitions in the wear regime exhibited by a sliding solid (i.e., from severe to mild or vice versa). The transition is related to the kinetics of heat transfer within the mechanically affected zones of each of the rubbing components.
The analysis of thermal energy release in sliding friction, and accurate prediction of temperature rise in rubbing, is a complex endeavour. This is due to the interdependence of all the factors involved. Energy conversion and heat release during friction involve a high degree of coupling between the thermal and mechanical states of the rubbing materials. This coupling often introduces mathematical difficulties in theoretical calculations, and many uncertainties in measurements. As such, the theory of heat transfer in sliding is often based on the premise that the mechanical state of the surface (stress, strain, etc) is independent of the thermal state. This assumption is not necessarily adequacies for developing a predictive theory of wear.
Foundations of thermal analysis in sliding date back to the early decades of the twentieth century. The first measurement of the interface temperature rise was performed by Shore, and independently by Bowden and Ridler, in 1925, whereas Blok, Holm and Rosenthal introduced the first theoretical analysis in 1930s. These early efforts initiated a branch of research that investigates thermal effects in rubbing known as “thermotribology.” Additionally, such works constitute, in the most part, the foundation of many analyses. Since that time much progress has taken place in the field: many researchers have proposed advanced models and considerable progress in instrumentation has taken place. Applications continue to challenge the envelope of conventional analysis especially when miniaturized systems are considered.
This special issue seeks to document developments within “thermotribology” since its inception. Central to the theme is inclusion of future trends and advanced efforts that discuss, remedy, or criticize conventional theoretical and experimental approaches.
Suitable topics include, but are not limited to, the following:
- Theoretical modeling of temperature rise phenomena in sliding
- Measurement of temperature rise in tribo-contacts (machining, dry and wet sliding)
- Thermal effects in lubricated contacts
- Effect of temperature on tribological response of sliding solids (transition in wear regime, frictional behaviour, etc.)
- Numerical simulations of temperature rise in lightly and heavily loaded contacts
- Flash temperature theory
- Inverse methods applied to measurement and prediction of temperatures reached in sliding
- Thermal effect at the micron and submicron levels
- Review of experimental and theoretical methods
- Irreversible Thermodynamics applied to friction and wear
- Thermal effects in data storage devices and MEMS
Submission: 30 June 2011