MTS Series 609 Alignment Fixture - Manual (Page 49)

Calculating Bending Strain—Notched Flat Thick
Series 609 Alignment Fixture Product Information Specimen Preparation 49
Calculating Bending Strain—Notched Flat Thick Specimens
This section shows how to calculate the bending strain for flat specimens with
four gages at each level.
Gage Placement
1. Calculate the bending strains for each level.
Use these formulas to find the x axis (B
x
) and y axis (B
y
) bending strains of
each level:
Where: ε
1
through ε
8
are the strain readings from gages 1 through 8
Bu
x
is the bending strain of the x axis of the upper gages
Bl
x
is the bending strain of the x axis of the lower gages
Bu
y
is the bending strain of the y axis of the upper gages
Bl
y
is the bending strain of the y axis of the lower gages
Do not ignore the sign of negative numbers.
2. Calculate the average axial strain for each level.
Use this formula to find the average axial strain (A):
Where: ε
1
– ε
8
are the strain readings from gages 1 through 8
Au is the average strain of the upper gages
Al is the average strain of the lower gages
3. Calculate the percent bending strain for each level.
Use this formula to find the percent bending strain (PBS):
Bu
x
ε
1
ε
3
–
2
---------------- =
Bu
y
ε
2
ε
4
–
2
---------------- =
Bl
x
ε
5
ε
7
–
2
---------------- =
Bl
y
ε
6
ε
8
–
2
---------------- =
Upper Gages Lower Gages
Au
ε
1
ε
2
ε
3
ε
4
+ + +
4
--------------------------------------- = Al
ε
5
ε
6
ε
7
ε
8
+ + +
4
--------------------------------------- =
Upper Gages Lower Gages