ME 220 Washington State University Bridge Truss Experiment Lab Report See Instruction, I would like to get a lab report for Materials laboratory, I will up

ME 220 Washington State University Bridge Truss Experiment Lab Report See Instruction, I would like to get a lab report for Materials laboratory, I will upload the lab manual and the data and the report guidline. Bridge Truss – Jun 29,
3
B
8
D
-49.2 µStrain
(-51.4 µStrain)
1
2
5
-51.2 µStrain
(-51.4 µStrain)
53.4 µStrain
(51.4 µStrain)
6
-13.2 µStrain
(-12.8 µStrain)
4
A
F
-62.5 µStrain
(-64.3 µStrain)
9
12.9 µStrain
(12.8 µStrain)
64.5 µStrain
(64.3 µStrain)
7
24.6 µStrain
(25.7 µStrain)
R1
-16.66 LBS
C
-64.6 µStrain
(-64.3 µStrain)
11
55.3 µStrain
(57.9 µStrain)
P1
12.5 LBS
10
E
32.6 µStrain
(32.1 µStrain)
P2
25 LBS
G
R2
-20.83 LBS
Tension Compression Loads
Loads
P1
P2
25 Pounds
50 Pounds
member
member
No Load
1
2
Initial voltage (V) -0.0030198 -2.6593813
Initial strain (in/in)
0
0
Date 7/23/2020
Poisson’s Ratio
0.32
Gage Factor
2.100
member
member
member
member
member
3
4
5
6
7
-0.005779 -0.0053892 -0.0049036 -0.0042041 -0.0054136
0
0
0
0
0
Strains
Loads added:
1
2
3
4
5
6
7
Voltage (V)
-0.0026399 -2.6597673 -0.0054133 -0.0055718 -0.0048053 -0.0042998 -0.0058239
Strain Gage Voltage 7.098E-05 -7.413E-05 6.833E-05 -3.411E-05 1.836E-05 -1.788E-05 -7.667E-05
Micro Strain (in/in) -51.212147 53.483378 -49.296332 24.612358 -13.247019 12.90355 55.321757
(X 10-6)
(Strain Values in Parenthesis are Theoretical)
truss element length: 13″
truss material: Al
Tube O.D.
Tube Wall
Area in2
Young’s Modulus
0.375
0.035
10000000
member
member
member
8
9
10
-0.0030731 -0.00747385 -0.0006312
0
0
0
Strain Gage
Excitation
member
11
Voltage (V)
-0.005943497
5.3515682
0
8
9
10
-0.0026091 -0.00795293 -0.0001515
8.67E-05 -8.9527E-05 8.965E-05
-62.549911 64.5966536 -64.676358
11
-0.006185753
-4.52729E-05
32.6651702
5.3515467
ME220 – Mechanics of Materials Laboratory
TEST TITLE: Bridge Truss Experiment
NAME:
(refer to lab manual pp. 63-74)
1. Summary (1/12) (The summary should be succinct (limited to one page), but contain
the following four pieces of information, namely, the purpose of the experiment;
experimental methods; results; and conclusion.)
2. Calculations (8/12)
1. List the truss properties as follows.
TRUSS PROPERTIES
Truss Material
Young’s Modulus
psi
Member Cross-Sectional Area
sq. inches
Gage Factor
Test Loads:
P1 =
lb.
P2 = _______________ lb.
2. Using the analysis techniques that you learned from Statics or Mechanics of
Materials, determine forces and strains caused in the members, 1(AB), 3(BD),
5(CD), 7 (CE), 11(EG), by load P1 and P2 acting together.
3. Construct graphically the vector force polygon for joints C & E. The polygon
must close because the joint is in equilibrium.
4. Present the experimental data and the calculation results in the following
format.
Member
Member Strain
Member Strain
Percentage
(calculated)
(Experiment)
error
in/in
in/in
2
5. Compare the above results with those determined experimentally.
3. Discussion (2/12)
1. How well do the analytical and experimental results compare? And What are
the reasons for the differences in the analytical and experimental values?
2. Does it appear that bending loads are present in any member? Why may this
occur?
4. Conclusion (1/12)
3
ME220 : Materials Laboratory
Bridge truss Experiment
Prof. Jow Ding
Summer 2020
ME220 : Materials Laboratory
Objective: Use experiment to determine the strain and stress on selected
truss members and compare with the theoretical results.
Theoretical Analysis:
• Carry out force analysis to determine the internal forces (F) on specified
truss members.

• Determine stress: = / where = ( )( – ).

• Determine strain: = / , where = × psi for aluminum.
Experiment:
The device to be used for measuring local strain is “strain gage”
ME220 : Materials Laboratory
What is strain gage and how does it work?
• Strain gage is essentially a conductor wire whose resistance changes with
elongation or strain.
• Strain gage is glued to the structure at the point of interest and thus
experiences the same strain as the structure.
• By establishing a correlation between resistance change and strain
experienced by the strain gage, i.e. calibration, strain of the structure can
be determined by the measured resistance change of strain gage and
calibration relation.
ME220 : Materials Laboratory
The resistance of an electrical conductor R (in ohms) varies according
to the relation
l : conductor length, cm.

A : conductor cross-sectional area, 2
=

: resistivity of conductor material, ohm-cm.
=

=
=

=

=
2

4

+ d

+
+

1

+ ρ ( )=

−( )

+

− ( / 2 )

=2

)

−(

= ∶ axial strain along the strain gage direction

= ∶ transverse strain along the perpendicular direction

ME220 : Materials Laboratory

− = ∶ ′

=

+

− 2 =
=

+(1 + 2 )
/ /
=
+ 1 + 2

F is provided by the strain gage manufacturer.
ME220 : Materials Laboratory
Measurement of resistance change by Wheatstone bridge circuit:
When R2R3=R1R4, G=0; The circuit is balanced.
ME220 : Materials Laboratory
ME220 : Materials Laboratory
Measurement of resistance change by Wheatstone bridge circuit:
= −
=

(1 + 2 )
( ) −( ) −

ME220 : Materials Laboratory
Construct graphically the vector force polygon for joints C & E
ME220 : Materials Laboratory
Thin-walled pressure experiment:
• Mount the strain gage on the beverage can.
• Open the can and record the strain gage reading.
• Use the data to determine the pressure inside the can.

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