الفهرس 
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Abstract
Due to vastly increased use of artificial shoulder joint, it is important to obtain meaningful design data that data will enable the designer to predict fail and safe behavior of artificial joint. The main problem of artificial shoulder joint from engineering view point is the tribological behavior of this joint, where the best way to minimize wear and surface damage in the joint is to separate the solid surface by a film of lubricant. If lubricant film fail the condition will act as two surfaces in direct contact and the mechanism of friction and wear will be presented. So that, in present study a further contribution to in-vitro investigation of the tribological behavior of artificial shoulder is studied. This is performed by the following steps:
1)- Construct and design test rig to simulate shoulder joint kinematically and in shape.
2)- The joint is examined under different conditions of loads, speeds and ball materials. Temperature distribution and fluid film profile through the contact area between the ball and the socket are to be measured. Unworn and worn surfaces of balls and sockets, is also studied to determine the mechanism of wear.
Test results showed that; through the contact area, between the ball and the socket, under relatively low load and speed, squeeze film of lubricant is generated to separate the surface of the joint and the load transfer through the fluid film, wear would be diminished and the temperature distribution through the contact area is recorded to be minimum in values.
As the applied load increases film thickness decreases until the lubrication regime changes to a mixed lubrication, then to a boundary lubrication where thin layer of lubricant molecules adhesive to joint surface s will prevent seizure of the joint surfaces, and the temperature recorded is increased. Squeeze film generated in the case of viscous vegetable lubricant is thicker than that in saline solution, also viscous fluid withstand higher load without fail of lubrication regime.
Temperature distribution through the contact area between the ball and the socket is affected by the applied load, operating speed and ball material, where as the applied load or speed increase yield an increase in temperature. The temperature rise ceramic-polymer joint is less than that in the case of stainless-ploymer joint.
Surface roughness of unworn joint surfaces has been found to have a much effect on tribological performances of artificial joint, where the mode of lubrication, real area of contact, friction and wear depend on surfaces roughness.
The joint of ceramic ball and polymer socket has much less wear than that of stainless steel ball on polymer socket , the decrease in polymer socket thickness articulating against ceramic ball is less by 8-11 time than that in polymer socket against Stainless-Steel ball.