Where – MTS Series 609 Alignment Fixture User Manual
Page 52
Series 609 Alignment Fixture Product Information
52
Calculating Bending Strain—Notched Thin Flat
Specimen Preparation
Calculating Bending Strain—Notched Thin Flat Specimens
This section shows how to calculate the bending strain for round 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
w is the width of the specimen.
d is the distance from the specimen edge to the middle of the gage
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 percent bending strain for each level.
Use this formula to find the percent bending strain (PBS):
Where:
See the previous definitions.
3. Determine which axis is bending.
Bu
x
1
4
--- ε
1
ε
2
ε
3
–
ε
4
–
+
(
)
=
Bu
y
w
4
----
ε
1
ε
2
ε
3
–
ε
4
–
+
w 2d
–
---------------------------------------
⎝
⎠
⎛
⎞
=
Bl
x
1
4
--- ε
5
ε
6
ε
7
–
ε
8
–
+
(
)
=
Bl
y
w
4
----
ε
5
ε
6
ε
7
–
ε
8
–
+
w 2d
–
---------------------------------------
⎝
⎠
⎛
⎞
=
Upper Gages
Lower Gages
PBS
x
4 Bu
x
(
)
ε
1
ε
2
ε
3
ε
4
+
+
+
--------------------------------------- 100
×
=
PBS
x
4 Bl
x
(
)
ε
5
ε
6
ε
7
ε
8
+
+
+
--------------------------------------- 100
×
=
PBS
y
4 Bu
y
(
)
ε
1
ε
2
ε
3
ε
4
+
+
+
--------------------------------------- 100
×
=
PBS
y
4 Bl
y
(
)
ε
5
ε
6
ε
7
ε
8
+
+
+
--------------------------------------- 100
×
=
Upper Gages
Lower Gages