The surface tooth wear which occurs at the gear contact region due to inadequate contact strength of the tooth is one of the predominant modes of gear failures. Currently, higher contact ratio spur gears are increasingly used in power transmission applications such as aircraft, wind turbine, automobiles and compact tracked vehicles due to their high load carrying capacity.  In this work, the di...

In internal combustion engines, exhaust valve and its seat gain considerable temperature as the hot gases exit through them. So, the rate of heat transfer should be under control. In this study, the contact heat transfer coefficient has been estimated. An experimental study on an Air-Cooled internal combustion engine cylinder head has been considered. Using the measured temperatures of sensors ...

PURPOSE To investigate the release of surface-active agents (surfactants) from unworn soft contact lenses (SCLs) and their influence on the lens surface wettability in vitro. METHODS Surface tension (ST) of blister pack solutions was measured by pendant-drop technique. STs at the air-aqueous interface and contact angles (CAs) of four conventional and seven silicone hydrogel SCLs were evaluate...

As the most important working area of gear, teeth play the role of transmitting load and power. Tooth line and tooth profile are the two main characteristics of the tooth surface, which affect the shape of the tooth surface, tooth meshing characteristics and contact characteristics. Taking the elliptical cylinder gear pair in the reversing device of a new type of drum pumping unit as the resear...

Nanoparticles made of biodegradable polymers has become the best approach for nanoparticle making due to their compatibility with the human body. New glycerol adipate polymers with hydroxyl group substituted with different percent of acyl group, sited as figures within the abbreviated name in the text, and triptophan were synthesized and proposed to be used in the preparction of dexamethason ph...

The current work considers the multi-scale nature of surface roughness in a new model that predicts the real area of contact and surface separation as functions of load. This work is based upon a previous rough surfacemulti-scale contactmodelwhichused stackedelastic–plastic spheres tomodel themultiple scales of roughness. Instead, this work uses stacked 3D sinusoids to represent the asperities ...

Friction is a classical field that goes back to Leonardo da Vinci, Guilliame Amonton, and Charles Augustin de Coulomb. Amonton found that friction force is proportional to normal load, but surprisingly is independent of the area of the apparent contact surface. This observation is known as the Amonton’s paradox. The apparent contact surface is the geometric object surface projected to the conta...

It has been shown experimentally that boundary friction is proportional to load (commonly known as Amontons’ law) for more than 500 years, and the fact it holds true over many scales (from microns kilometres, from nano-Newtons Mega-Newtons) materials which deform both elastically plastically subject of much research, in order fully understand its wide applicability (and also find any deviations...