Unformatted text preview: ively, from the first
grid. Strain
Strain Gage Rosettes a b Basic rosette types, classified by grid orientation: (a) tee; (b) 45ºrectangular; (c) 60º delta c Strain
Strain Gage Rosettes
Rosettes are manufactured from different combinations of grid. Geometrically different, but functionally equivalent configurations
of rectangular and delta rosettes. Principal
Principal Strains and Directions
from Rosette Measurements
The equations for calculating principal strains from three rosette
strain measurements are derived from what is known as a “straintransformation” relationship. Principal
Principal Strains and Directions
from Rosette Measurements
By successively substituting into Equation (1) the angles for
the three grid directions, the strain sensed by each grid can
be expressed as follows: Principal
Principal Strains and Directions
from Rosette Measurements
By solving Equations (2) simultaneously for the unknown quantities
εP, εQ, and θ, the principal strains and angle can be expressed in terms
of the three measured strains. Angle θ represents the acute angle from the principal
axis to the reference grid of the rosette Principal
Principal Strains and Directions
from Rosette Measurements
Hooke’s law can be used to convert the principal strains into principal
stresses After applying Hooke’s law: Questions
Questions...
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 Fall '08
 JasonWeiss
 strain gage rosette, Gage Rosettes

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