The Phan-Thien and Tanner Model Applied to Thin Film Spherical Coordinates: Applications for Lubrication of Hip Joint Replacement

2008 ◽  
Vol 130 (2) ◽  
Author(s):  
John Tichy ◽  
Benyebka Bou-Saïd
Keyword(s):  
Joint Replacement ◽  
Load Capacity ◽  
Squeezing Flow ◽  
Spherical Coordinates ◽  
Hip Joint Replacement ◽  
Ptt Model ◽  
Confined Fluid ◽  
Load Carrying ◽  
Human Joints ◽  
Viscoelastic Modeling

The Phan-Thien and Tanner (PTT) model is one of the most widely used rheological models. It can properly describe the common characteristics of viscoelastic non-Newtonian fluids. There is evidence that synovial fluid in human joints, which also lubricates artificial joints, is viscoelastic. Modeling the geometry of the total hip replacement, the PTT model is applied in spherical coordinates for a thin confined fluid film. A modified Reynolds equation is developed for this geometry. Several simplified illustrative problems are solved. The effect of the edge boundary condition on load-carrying normal stress is discussed. Solutions are also obtained for a simple squeezing flow. The effect of both the relaxation time and the PTT shear parameter is to reduce the load relative to a Newtonian fluid with the same viscosity. This implies that the Newtonian model is not conservative and may overpredict the load capacity. The PTT theory is a good candidate model to use for joint replacement lubrication. It is well regarded and derivable from molecular considerations. The most important non-Newtonian characteristics can be described with only three primary material parameters.

The PTT Model in Hip Joint Replacement: Shock Loading

2005 ◽  
Author(s):  
John Tichy ◽  
Benyebka Bou-Sai¨d
Keyword(s):  
Shock Loading ◽  
Vertical Jump ◽  
Rheological Models ◽  
Artificial Joints ◽  
Hip Joint Replacement ◽  
Flow Models ◽  
Ptt Model ◽  
Confined Fluid ◽  
The Common ◽  
Human Joints

The Phan-Thien Tanner (PTT) model is one of the most widely used rheological models. It can properly describe all the common characteristics of viscoelastic non-Newtonian fluids. Synovial fluid of human joints, which also lubricates artificial joints, is well known to be highly viscoelastic. Thus it is reasonable to attempt to describe such joint behavior using non-Newtonian flow models. Modeling the geometry of the total hip replacement, the PTT model is applied in spherical coordinates to a thin confined fluid film. As an illustrative problem, the case of a sudden impulsive start of simple squeezing motion is solved, similar to landing on one’s feet after a vertical jump. The phenomena of shear thinning, stress relaxation, and stress overshoot are all exhibited.

scholarly journals Risk forecasting of the femoral head dislocation and its prophylaxis at total hip joint replacement

2018 ◽  
Vol 0 (1) ◽  
pp. 79-85
Author(s):  
Volodymyr Filipenko ◽  
Vera Kolesnichenko ◽  
Volodymyr Mezentsev ◽  
Oleh Ovchynnikov
Keyword(s):  
Femoral Head ◽  
Hip Joint ◽  
Joint Replacement ◽  
Hip Joint Replacement ◽  
Total Hip ◽  
Risk Forecasting

scholarly journals The Assessment of Using CFRP to Enhance the Behavior of High Strength Reinforced Concrete Corbels

2021 ◽  
Vol 28 (1) ◽  
pp. 71-83
Author(s):  
Mazin Abdulrahman ◽  
Shakir Salih ◽  
Rusul Abduljabbar
Keyword(s):  
Reinforced Concrete ◽  
Ultimate Strength ◽  
Load Capacity ◽  
High Strength ◽  
Load Carrying Capacity ◽  
Test Results ◽  
Ultimate Load Capacity ◽  
Load Carrying ◽  
Externally Bonded ◽  
Effective Depth

In this research, an experimental study is conducted to investigate the behavior and strength of high strength reinforced concrete corbels externally bonded with CFRP fabric sheets and Plates with different patterns taking into account the effect of adopted variables in enhancing the ultimate strength; the effect of shear span to effective depth (a/d), configuration, type and amount of bonding. Eleven high strength reinforced corbels were cast and tested under vertical loads. Test results showed there was an improvement in the behavior and load carrying capacity of all strengthened corbels. An increasing in the ultimate strength of strengthened corbel by inclined CFRP strips reached to (92.1%) while the increasing reached to (84.21%) for using one horizontal CFRP Plates compared to un-strengthened reference specimen. Also, it can be conducted that the increase of (a/d) ratio from (0.6 to 0.8) resulted in decreasing by 21.05% in ultimate load capacity of corbels and from (0.4 to 0.6) by 31.25% and 58.69% in cracking and ultimate loads respectively Using CFRP .

Performance of a Short Multi-Grooved Capillary Compensated Hydrostatic Journal Bearing

1968 ◽  
Vol 183 (16) ◽  
pp. 107-115
Author(s):  
J. K. Patrick ◽  
N. N. S. Chen
Keyword(s):  
Journal Bearing ◽  
Load Capacity ◽  
Flow Characteristics ◽  
Lubricating Oil ◽  
Load Carrying Capacity ◽  
Straight Line ◽  
Load Carrying ◽  
Capillary Type ◽  
First Time ◽  
Oil Film Pressure

This paper presents the results of an extensive experimental investigation into the performance of a short multi-grooved bearing subjected to a range of static and alternating loads. Lubricating oil was supplied, at pressures of up to 2000 lb/in2, to capillary type restrictors connected to 10 closed-end axial grooves in the bearing. The bearing had a length/diameter ratio of 1/3 and operated with a journal speed and load frequency of 327 c/min. Measured load capacity, stiffness, and flow characteristics indicate that bearings of this type have a significant load-carrying capacity at zero journal speed and that the load capacity is increased by journal rotation. A feature of the journal behaviour under alternating loads is the movement of the journal centre along a straight line coincident with the load plane. The extensive oil film pressure surveys indicate for the first time the pressure distribution within narrow hydrostatic bearings and provide a basis for a realistic theoretical analysis of this type of bearing.

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