What should engineers consider for selecting total knee replacement
Design Against Fluctuating Loads
Machine elements are subjected to varieties of loads, some components are subjected to static loads, while some machine components are subjected to fluctuating loads, whose load magnitude tends to fluctuate. The components of a machine, when rotating at a high speed, are subjected to a high degree of load, which fluctuates from a high value to a low value. For the machine elements under the action of static loads, static failure theories are applied to know the safe and hazardous working conditions and regions. However, most of the machine elements are subjected to variable or fluctuating stresses, due to the nature of load that fluctuates from high magnitude to low magnitude. Also, the nature of the loads is repetitive. For instance, shafts, bearings, cams and followers, and so on.
Design Against Fluctuating Load
Stress is defined as force per unit area. When there is localization of huge stresses in mechanical components, due to irregularities present in components and sudden changes in cross-section is known as stress concentration. For example, groves, keyways, screw threads, oil holes, splines etc. are irregularities.
What should engineers consider for selecting total knee replacement
In the situation of deteriorated knee joint, artificial prosthesis may be required. This artificial prosthesis must possess certain properties for their applicability. The engineers responsible for selecting materials for these application look for following properties:
- Compatibility of material with human tissue: The material which is to be implanted as knee joint replacement should be absolutely compatible with the organic tissues of human body. The material should be non reactant and non-toxic to human blood, human tissue over time.
- The corrosion resistant properties of the material: The material is to be so chosen that it doesn’t react with the oxygen present in the blood and become corroded. The corrosion, if occurs, may result in complete failure of the joint. Thus, an engineer should focus on the corrosion resistant properties of the material.
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