Lab 9 introduces several methods of measuring strain, primarily with strain gages. The different methods are compared. Strain Definitions Strain is a measure of deformation. Normal strains turn squares into rectangles with all the corners remaining right angles. Shear strains , denoted by g , measure the angle change of the corners of a square.
Shear strains turn squares into diamonds.
This example shows how the orientation of the coordinate system influences the perceived strain in an object. The blue square changes to a rectangle. Therefore only normal strains would be apparent for the coordinate orientation shown. The red square changes to a diamond. For the coordinate system rotated 45 o , shear strains would appear to dominate.