11-01-2013, 04:20 PM
The Effect of Relative Humidity and Roughness on the Friction Coefficientunder Horizontal Vibration
The Effect of Relative Humidity.pptx (Size: 249.2 KB / Downloads: 39)
Introduction
This topic has been introduced itself by its name which is “The Effect of Relative Humidity and Roughness on the Friction Coefficient under Horizontal Vibration .“ We discussed about this topic in a experimentally way. To do so, a pin-on-disc apparatus having facility of vibrating the test samples at different direction is designed and fabricated. The direction of vibration is horizontal. Horizontal vibration is created along (longitudinal direction) and perpendicular (transverse direction) to the sliding direction. The experimental setup has the facility to vary the amplitudes and frequencies of vibration while velocity of vibration is kept constant.
Relative humidity
Relative humidity is a term used to describe the amount of water vapor that exists in a gaseous mixture of air and water vapor.
Relation between Relative humidity and Friction coefficient
Friction coefficient is proportional to the applied load.
2. The measured friction coefficient was affected by environment RH depending on applied load.
3. For low applied load, the friction coefficient varies following humidity alteration of testing environment, i.e., increase in humidity increases the friction coefficient, while for high applied load, there was observed no variation on friction coefficient
Decrease and Increase of Frictional Force
A decrease in frictional force can be obtained through:
(a)Resonance between the natural frequency of the contacting asperities and that of the external vibration,
(b) Reversal of the friction vector,
© Superposition between static and dynamic load, which means that a lower tangential force is needed to initiate the sliding of materials in the friction surface .
(d) Local transformation of vibration energy into heat energy in the friction surface, so that the yield point of the material is lowered.
An increase in the frictional force can be obtained through:
(a) viscous damping of the friction surface,
(b) increased adhesion or micro welding (pick-ups) between the materials
© deformation and material hardening of the material