Appendix G.Calculations From Three Strain Gauges, At 60 degrees, On a Circular Pipe

Appendix_G00260.png

 

Figure 19: Three Strain Gauges Mounted on a Circular Pipe Diagram

Average_Axial_Strain.png

 

equation 17: Average Axial Strain

Maximum_Bending_Strain_Around_the_YY_Axis.png

 

equation 18: Maximum Bending Strain Around the YY Axis

Maximum_Bending_Strain_Around_the_XX_Axis.png

 

equation 19: Maximum Bending Strain Around the XX Axis

Maximum_Strain.png

 

equation 20: Maximum Strain

Example:

Let Appendix_G00263.png = 20, Appendix_G00266.png = 192 and Appendix_G00269.png = 88 (all tensile strains)

Average Axial Strain, A = (20 + 192 + 88) / 3 = 100 microstrain tension

X = ±(104 / 1.732) = ±60

Y = ±(300 / 3 - 20) = ±80

tanq = 80 / 60 = 1.333 and q = 53 degrees from the X axis

P = ±[60 x 0.6 + 80 x 0.8] + 100 = 200 microstrain, tensile, 0 microstrain minimum