Nondestructive Nondestructive Approach to Evaluate Approach to Evaluate Defects in Elements of Defects in Elements of Agricultural MachineryAgricultural Machinery

Md. Nur-A-AlamB. Sc. in Agril. Engg., MS in FPM, PGD-in-ICT

Bangladesh Agricultural University, Mymensingh-2202

Presented ByPresented By

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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

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Introduction Introduction (Contd.)(Contd.)

Defective Engine Parts

Introduction Introduction (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

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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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Justification Justification (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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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 Slide 8 / 33

Objective-Methods Link

Objective Methods1) 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 Methods Materials and Methods

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Materials Used in the Potential Drop Measurement System

Materials and MethodsMaterials and Methods (Contd.)(Contd.)

Materials Specification/CapacityPower Suppliers A Battery of 12 VAmmeter Sfim Panel Meter; Model: SF-80, Range: AC/DC 50AMultimeter Fluke 28 II True RMS MultimeterRheostat A variable rheostat having capacity of 25 AmpereElectric wire 3-22, 1 core-10 yardsInsulating 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 frameCode::Blocks 12.11

To make a calculator according to above formula using C++ programming language to determine voltage drop Slide 10 / 33

inch81

inch83

inch85

inch81

Materials and MethodsMaterials and Methods (Contd.)(Contd.)

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Collar Tail Spring

Nuts

SS Rod

Materials and MethodsMaterials and Methods (Contd.)(Contd.)

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Assembly Drawing of the Probe

2D View of the Probe

Testing Materials MS Flat Bar SS Flat Bar CS Flat Bar

Probe

Materials and Methods Materials and Methods (Contd.)(Contd.)

Slide 13 / 33Experimental Set up with DC Current

Materials and Methods Materials and Methods (Contd.)(Contd.)

Voltage Drop CalculationV=IR (From Ohm’s Law)

Where,∆Φ = Voltage Dropρ = Resistivity of MetalI = Currentπ = ConstantS1 = Half Distance of Current ProbesS2 =Half Distance of Voltage Probes

22

21

1S-S

S×πI2=ΔΦ ρ

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Circuit Diagram

(a) (b)

Schematic Diagram of Crack free Sample Schematic Diagram of Single Cracked Sample

Crack free Sample Single Cracked Sample Twisted Sample

Crack TypeSingle Crack

Twisted

Materials and Methods Materials 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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Schematic Diagram of Crack free SampleSchematic Diagram of Cracked Sample

Crack Free Sample Single Cracked Sample

Experimental Design for Stainless Steel Flat Bar

Materials and Methods Materials 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 Depth1 mm2 mm3 mm

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Schematic Diagram of Crack free SampleSchematic Diagram of Cracked Sample

Crack Free Sample Single Cracked Sample

Experimental Design for Carbon Steel Flat Bar

Materials and Methods Materials 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 Depth1 mm2 mm3 mm

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ResultsResultsExperimental Result of Mild Steel Flat BarComparison of Voltage Drop on different conditions of MS Flat Bar

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Results Results (Contd.)(Contd.)Experimental Result of Mild Steel Flat BarEffect of Probe Spacing on Voltage Drop for Different Conditions of MS Flat Bar

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Results Results (Contd.)(Contd.)Experimental Result of Mild Steel Flat Bar

Resistivity for MS Flat Bar in Crack free Condition

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Current (A)

SpacingResistivity,

ρ (Ω-m)Sub-Average

Resistivity, ρ (Ω-m)

Average Resistivity, ρ (Ω-

m)S1

(cm)S2 (cm)

515.25 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

1015.25 2.5 1.13×10-4 1.2325×10

-4 12.5 2.5 1.03×10-4 17.75 5 1.54×10-4 15.25 5 1.23×10-4

1515.25 2.5 1.13×10-4 1.1725×10

-4 12.5 2.5 1.13×10-4 17.75 5 1.39×10-4 15.25 5 1.04×10-4

Results Results (Contd.)(Contd.)Experimental Result of Mild Steel Flat Bar

Resistivity in Different Current on MS Flat Bar

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Experimental Result of Stainless Steel Flat BarComparison of Voltage Drop on different conditions of SS Flat Bar

Results Results (Contd.)(Contd.)

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Experimental Result of Stainless Steel Flat BarEffect of Probe Spacing on Voltage Drop for Different Conditions of SS Flat Bar

Results Results (Contd.)(Contd.)

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Experimental Result of Stainless Steel Flat BarResistivity for SS Flat Bar in Crack free Condition

Results Results (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 5.0025×1

0-4

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-

4 12.5 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 3.2875×1

0-4 12.5 2.5 2.57×10-4

17.75 5 4.00×10-4 15.25 5 3.17×10-4

Experimental Result of Stainless Steel Flat BarResistivity in Different Current on SS Flat Bar

Results Results (Contd.)(Contd.)

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Experimental Result of Carbon Steel Flat BarComparison of Voltage Drop on different conditions of CS Flat Bar

Results Results (Contd.)(Contd.)

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Results Results (Contd.)(Contd.)Experimental Result of Carbon Steel Flat BarEffect of Probe Spacing on Voltage Drop for Different Conditions of CS Flat Bar

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Results Results (Contd.)(Contd.)Experimental Result of Carbon Steel Flat BarResistivity 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

1.545×10-4 12.5 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

1.52×10-4 12.5 2.5 1.50×10-4 17.75 5 1.82×10-4 15.25 5 1.34×10-4

Results Results (Contd.)(Contd.)Experimental Result of Carbon Steel Flat BarResistivity in Different Current on CS Flat Bar

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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

Discussion Discussion (Contd.)(Contd.)

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Two calculation procedure developed using code::blocks 12.11 (C++ programming language)

GUI for Resistivity Measurement

GUI for Voltage Drop Calculation

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

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Thanks for Your Patience