25-08-2017, 09:32 PM
DYNAMIC ANALYSIS OF HELICAL GEAR BY PHOTOELASTICITY
DYNAMIC ANALYSIS.pptx (Size: 92.64 KB / Downloads: 94)
INTRODUCTION
GEARS
A gear is a component within a transmission system that transmits rotational force to another gear or device with constant velocity ratio . It is used in nearly all applications where power transfer is required such as Automobiles,Industrial Equipments,etc.
It has been seen that while transmission of force the failure of gear takes place due to stress concentration and bending stresses at tooth root of gear. In order to avoid failure of gear, analysis of stress on gear is done by using different methods. PHOTOELASTICITY is one of the method for analysis.
PHOTOELASTICITY
Photoelasticity is an experimental technique for stress and strain analysis that is particularly useful for members having complicated geometry, complicated loading conditions, or both. For such cases, analytical methods (that is, strictly mathematical methods) may be impossible, and analysis by an experimental approach maybe more appropriate.
THREE DIMENTIONAL ANALYSIS
In three dimensional analysis , we get stresses in all three directions i.e. in X,Y & Z .This is the advantage of three dimensional analysis over the two dimensional analysis because in two dimensional analysis we get stress in only two directions i.e. in X & Y.But in certain complex problems we require stress in all three directions. Therefore three dimensional analysis in more advantageous.
DESIGN OF LOADING FRAME
The next step after casting the model is to design the loading frame.
It involves the following steps:
Load calculation: It involves calculating torque and tangential load acting on prototype of a helical gear. Trial and error method has been carried out to apply load on the model.
Design and construction of loading fixture: The design of loading frame is such a that it should simulate actual working conditions in helical gear operation.
STRESS FREEZING
After mounting a model on a loading frame , a model along with a loading frame is placed in the stress freezing oven.
A calibration disc is also placed in separate loading frame and kept in stress freezing oven.