1. Nondestructive ApproachNondestructive Approach
to Evaluate Defects into Evaluate Defects in
Elements of AgriculturalElements of Agricultural
MachineryMachinery

2. Md. Nur-A-Alam
B. Sc. in Agril. Engg., MS in FPM, PGD-in-ICT
Bangladesh Agricultural University,
Mymensingh-2202
Presented ByPresented By
Slide 2 / 33

3. IntroductionIntroduction
▓ Farm machineries are major elements of farm
mechanization in Bangladesh
▓ Timeliness in farm operations is a crucial factor
for successful agricultural operations
▓ The failure of important parts like PTO/propeller
shaft, spline shaft, tine/blade etc. of farm
machineries especially tractor and power tiller
during the peak season causes various large
losses of revenue and inefficient utilization of
labor
Slide 3 / 33

4. Slide 4 /33
IntroductionIntroduction (Contd.)(Contd.)
Defective Engine Parts

5. IntroductionIntroduction (Contd.)(Contd.)
▓ Therefore, it is necessary to routine check-up,
inspection and diagnose of important parts of
agricultural machinery for getting proper
performance and timeliness operation
▓ lt is possible to adjust, repair and/or replace the
defective component/parts according to diagnose
results
Slide 5 / 33

6. JustificationJustification
▓ Non-destructive testing is a key inspection
criterion - across many fields of engineering
▓ ln agricultural machinery sector to maximize
efficiency, minimize downtime and improve
productivity
- reliable and accurate nondestructive
testing
- integrity assessment are essential
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7. JustificationJustification (Contd.)(Contd.)
▓ There is no available technique/method
to nondestructively evaluate/diagnose the
important parts of agricultural
machinery in Bangladesh
▓ The four-point probe potential drop (PD)
technique can be considered one of the
best candidates for the purpose
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8. ObjectivesObjectives
▓ To develop a laboratory based nondestructive
testing set up for evaluating of internal
defects/cracks in the important parts of
agricultural machinery
The specific objectives are:
i) To design and develop of a DC four-
point probe measuring system
ii) To detect internal cracks and defects of
machine parts nondestructively
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9. Objective-Methods Link
Objective Methods
1) To design and develop of a DC
four-point probe measuring
system
 Literature and document review
 Design and construction of probe
 Experimental set up
2) To detect internal cracks and
defects of machine parts
nondestructively
 Analyzing the data collected through
experiment
 Examine the defective material from
different sides to detect crack
 Development of a computer program
using a mathematical equation
related with voltage, resistivity and
input current
Materials and MethodsMaterials and Methods
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10. Materials Used in the Potential Drop Measurement System
Materials and MethodsMaterials and Methods
(Contd.)(Contd.)
Materials Specification/Capacity
Power Suppliers A Battery of 12 V
Ammeter Sfim Panel Meter; Model: SF-80, Range: AC/DC 50A
Multimeter Fluke 28 II True RMS Multimeter
Rheostat A variable rheostat having capacity of 25 Ampere
Electric wire 3-22, 1 core-10 yards
Insulating Materials Plastic fibre
Probe SS rod having diameter of (4 pcs)
Spring Having a diameter of (4 pcs)
Nut Having diameter of used on the fiber (4 pcs) and
having diameter of used on the thread of probe (4 pcs)
Bolt Use to keep probe set rigidly on sample (2 pcs)
Frame Wooden frame
Code::Blocks 12.11 To make a calculator according to above formula using C++
programming language to determine voltage drop
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inch
8
1
inch
8
3
inch
8
5
inch
8
1

11. Materials and MethodsMaterials and Methods
(Contd.)(Contd.)
Slide 11 / 33
Collar Tail Spring
Nuts
SS Rod

12. Materials and MethodsMaterials and Methods
(Contd.)(Contd.)
Slide 12 / 33
Assembly Drawing of the Probe
2D View of the Probe

13. Testing Materials
 MS Flat Bar
 SS Flat Bar
 CS Flat Bar
ProbeProbe
Materials and MethodsMaterials and Methods
(Contd.)(Contd.)
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Experimental Set up with DC CurrentExperimental Set up with DC Current

14. Materials and MethodsMaterials and Methods
(Contd.)(Contd.)
Voltage Drop Calculation
V=IR (From Ohm’s Law)
Where,
∆Φ = Voltage Drop
ρ = Resistivity of Metal
I = Current
π = Constant
S1 = Half Distance of Current Probes
S2 =Half Distance of Voltage Probes
2
2
2
1
1
S-S
S
×
π
I2
=ΔΦ
ρ
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Circuit Diagram

15. (a) (b)
Schematic Diagram of Crack free Sample Schematic Diagram of Single Cracked Sample
Crack free Sample Single Cracked Sample Twisted Sample
Crack Type
Single Crack
Twisted
Materials and MethodsMaterials and Methods
(Contd.)(Contd.)
Experimental Design for Mild Steel Flat Bar
Dimension: 18 cm×2.5 cm×4 mm
Spacing: S1 = 15.25 cm and S2 = 2.5 cm
S1 = 12. 50 cm and S2 = 2.5 cm
S1 = 17.75 cm and S2 = 5 cm
S1 = 15.25 cm and S2 = 5 cm
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16. Schematic Diagram of Crack free Sample Schematic Diagram of Cracked Sample
Crack Free Sample Single Cracked Sample
Experimental Design for Stainless Steel Flat Bar
Materials and MethodsMaterials and Methods
(Contd.)(Contd.)
Dimension: 18 cm×3.75 cm×4 mm
Spacing: S1 = 15.25 cm and S2 = 2.5 cm
S1 = 12. 50 cm and S2 = 2.5 cm
S1 = 17.75 cm and S2 = 5 cm
S1 = 15.25 cm and S2 = 5 cm
Crack Depth
1 mm
2 mm
3 mm
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17. Schematic Diagram of Crack free Sample Schematic Diagram of Cracked Sample
Crack Free Sample Single Cracked Sample
Experimental Design for Carbon Steel Flat Bar
Materials and MethodsMaterials and Methods
(Contd.)(Contd.)
Dimension: 18 cm×2.5 cm×6 mm
Spacing: S1=15.25 cm and S2=2.5 cm
S1=12. 50 cm and S2=2.5 cm
S1=17.75 cm and S2=5 cm
S1=15.25 cm and S2=5 cm
Crack Depth
1 mm
2 mm
3 mm
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18. ResultsResults
Experimental Result of Mild Steel Flat Bar
Comparison of Voltage Drop on different conditions of MS Flat Bar
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19. ResultsResults (Contd.)(Contd.)
Experimental Result of Mild Steel Flat Bar
Effect of Probe Spacing on Voltage Drop for Different Conditions of MS Flat Bar
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20. ResultsResults (Contd.)(Contd.)
Experimental Result of Mild Steel Flat Bar
Resistivity for MS Flat Bar in Crack free Condition
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Current
(A)
Spacing
Resistivity, ρ
(Ω-m)
Sub-Average
Resistivity, ρ (Ω-m)
Average Resistivity,
ρ (Ω-m)S1 (cm) S2 (cm)
5
15.25 2.5 1.70×10-4
1.5975×10-4
1.33×10-4
12.5 2.5 1.31×10-4
17.75 5 1.82×10-4
15.25 5 1.56×10-4
10
15.25 2.5 1.13×10-4
1.2325×10-412.5 2.5 1.03×10-4
17.75 5 1.54×10-4
15.25 5 1.23×10-4
15
15.25 2.5 1.13×10-4
1.1725×10-412.5 2.5 1.13×10-4
17.75 5 1.39×10-4
15.25 5 1.04×10-4

21. ResultsResults (Contd.)(Contd.)
Experimental Result of Mild Steel Flat Bar
Resistivity in Different Current on MS Flat Bar
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22. Experimental Result of Stainless Steel Flat Bar
Comparison of Voltage Drop on different conditions of SS Flat Bar
ResultsResults (Contd.)(Contd.)
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23. Experimental Result of Stainless Steel Flat Bar
Effect of Probe Spacing on Voltage Drop for Different Conditions of SS Flat Bar
ResultsResults (Contd.)(Contd.)
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24. Experimental Result of Stainless Steel Flat Bar
Resistivity for SS Flat Bar in Crack free Condition
ResultsResults (Contd.)(Contd.)
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Current
(A)
Spacing
Resistivity, ρ
(Ω-m)
Sub-Average
Resistivity, ρ (Ω-
m)
Average Resistivity,
ρ (Ω-m)S1 (cm) S2 (cm)
5
15.25 2.5 5.11×10-4
5.0025×10-4
3.915×10-
4
12.5 2.5 3.58×10-4
17.75 5 5.83×10-4
15.25 5 4.95×10-4
10
15.25 2.5 3.55×10-4
3.455×10-412.5 2.5 2.54×10-4
17.75 5 4.28 ×10-4
15.25 5 3.45×10-4
15
15.25 2.5 3.41×10-4
3.2875×10-412.5 2.5 2.57×10-4
17.75 5 4.00×10-4

25. Experimental Result of Stainless Steel Flat Bar
Resistivity in Different Current on SS Flat Bar
ResultsResults (Contd.)(Contd.)
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26. Experimental Result of Carbon Steel Flat Bar
Comparison of Voltage Drop on different conditions of CS Flat Bar
ResultsResults (Contd.)(Contd.)
Slide 26 / 33

27. ResultsResults (Contd.)(Contd.)
Experimental Result of Carbon Steel Flat Bar
Effect of Probe Spacing on Voltage Drop for Different Conditions of CS Flat Bar
Slide 27 / 33

28. ResultsResults (Contd.)(Contd.)
Experimental Result of Carbon Steel Flat Bar
Resistivity Table for CS Flat Bar in Crack free Condition
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Current
(A)
Spacing
Resistivity, ρ
(Ω-m)
Sub-Average
Resistivity, ρ (Ω-m)
Average Resistivity, ρ
(Ω-m)S1 (cm) S2 (cm)
5
15.25 2.5 2.27×10-4
2.1475×10-4
1.7375×10-4
12.5 2.5 1.69×10-4
17.75 5 2.55×10-4
15.25 5 2.08×10-4
10
15.25 2.5 1.56×10-4
1.545×10-412.5 2.5 1.13×10-4
17.75 5 2.00×10-4
15.25 5 1.49×10-4
15
15.25 2.5 1.42×10-4
1.52×10-412.5 2.5 1.50×10-4
17.75 5 1.82×10-4
15.25 5 1.34×10-4

29. ResultsResults (Contd.)(Contd.)
Experimental Result of Carbon Steel Flat Bar
Resistivity in Different Current on CS Flat Bar
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30. DiscussionDiscussion
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 The voltage drop increases with the increasing resistance in
current flow path
 The resistivity of the materials differs slightly for same condition
 The resistivity depends on the material composition and
properties
Both Mathematically and Experimentally
∆Φ of 15.25 cm and 2.5 cm spacing < ∆Φ of 12.50 cm and 2.5 cm
spacing
∆Φ of 17.75 cm and 5 cm spacing < ∆Φ of 15.25 cm and 5 cm spacing

31. DiscussionDiscussion (Contd.)(Contd.)
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Two calculation procedure developed using code::blocks
12.11 (C++ programming language)
GUI for Resistivity MeasurementGUI for Voltage Drop Calculation

32. ConclusionsConclusions
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 A low-current experimental setup for Voltage Drop
measurements was developed
 Variation of voltage drop on the same sample before
and after cracking indicates the presence of defects
 The evaluation is made by a simple, non-iterative
formula
 The developed technique is capable to detect any
inhomogeneity (defects) and to determine resistivity
 A simple computer based calculator was made to
find out the resistivity and voltage drop according to
the formula

35. Slide 35 / 33
Thanks for
Your