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CPP301Core Project-II

Design and development of horizontal tensile testing machine (5kN)

Under the supervision of:Dr. Dhiraj Kumar Mahajan

A Presentation bySajeed Mahaboob (2011ME1111) Krishanu Sarkar (2012MEB1102)

MOTIVATION• Tensile tests are performed to achieve material parameters such as UTS, yield strength, % elongation, % area reduction and young’s modulus.• These important parameters obtained are useful for selection of engineering materials for many applications.•Need of horizontal tensile machine for testing in different environment conditions.•Miniaturized (Horizontal, Max 5kN)

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TENSILE TESTING PRINCIPLE

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Figure 1 : A typical Engineering Stress- Strain Diagram for a Ductile Material

(Engineering stress)=F/

Necking starts (local deformation) : applied engineering stress is equal to ultimate tensile stress (i.e )

Yielding (uniform deformation) :

E: Young’s modulusOnly in elastic region,

COMPONENTS IN OUR PROJECT

• Lead screw (Trapezoidal)• Load cell (S-Type)• Stepper motor• Strain gauge•Gripping units• Base and supporting plates• Spur gears• Ball Bearings• Controllers

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TRAPEZOIDAL LEAD SCREW: SELECTION

• Trapezoidal lead screw is selected over square thread, as it has higher load carrying capacity.• Better power transmission • Parameter selected using criteria, Tensile and compression D

Buckling =

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LOAD CELL: SELECTION

• S-BEAM type LOAD CELL• Less expensive than others • 500kg capacity available

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Figure 4: Assembled view of S type Load Cell (http://www.ipaindia.com/products/double-s-load-cell/)

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SPECIFICATION OF LOAD CELL

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TORQUE REQUIREMENT

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GEAR DESIGN

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• Constraints: Center to center distance is 50 mm• Torque ratio: 1000/800 (calculated)• Bore diameter: 19mm for driving and 15mm for driven gear.

• Results based on calculations

STEPPER MOTOR SELECTION• Lesser price than servo motor of same size• Positions are discrete steps in its revolution cycle•Degree of rotation need to be as much as less for accurate results•More current , the more torque is generated by the motor

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Figure 5 : typical stepper motor(https://simple.wikipedia.org/wiki/Stepper_motor#/media/File:Nema_17_Stepper_Motor.jpg)

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STEPPER MOTOR DESCRIPTION

GRIPPING DEVICE SELECTION

• Holds the specimen up to maximum load capacity

• Should minimize both slippage and uneven stress distribution

• Self-aligning

• Slippage and necking of the specimen into the grip should be avoided

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Figure 4: 5kN vice grip (http://www.elis.it/lloyd-pdf/Lloyd_Grips-catalogo.pdf)

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OLD DESIGN

SCHEMATIC DESIGN• Components are-

1. Lead screw with nut 2. Load cell3. Frame4. Gripping units5. Spur gears6. Stepper motor7. Bearing 8. controllers

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ASTM E-8M: “Standard Test Methods for Tension Testing of Metallic Materials.”

Rectangular tension test specimens (ASTM 370).

RESULTS

The functional requirements of the machine are as follows:•Maximum stroke: 600 mm• Maximum tensile force: 5kN• Diameter of trapezoidal lead screw = 20 mm• Pitch = 4 mm• Sample size: 1 mm thick, gauge cross-section area of 10 , and

gauge length 100 mm (Sample: Aluminium alloy 6061-T6 ()• 5kN vice grip is used • S-type load cell is used

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REFERENCES…[1] RUSSELL C.HIBBELER, Mechanics of materials, 9th edition.

[2] Woong Lim & Ho-Kyung Kim, Design and development of a miniaturised tensile testing machine, Global Journal of Engineering Education, Volume 15, Number 1, 2013

[3] Shigley, Mechanical Engineering Design, Richard G. Budynas

[4] Machine Design by V L. Maleev and Hartman

[5] https://en.wikipedia.org/wiki/Tensile_testing

[6] https://en.wikipedia.org/wiki/Linear_encoder

[7] http://www.ipaindia.com/products/double-s-load-cell/

[8] http://www.elis.it/lloyd-pdf/Lloyd_Grips-catalogo.pdf

[9] http://www.motionusa.com.s3-website-us-east-1.amazonaws.com/nook/BallScrews/PowerTrac_Full_Catalog.pdf

[10] http://www.festo.com/net/SupportPortal/Files/10257/Festo_10_Tips_servos_steppers.pdf

[11] https://simple.wikipedia.org/wiki/File:Nema_17_Stepper_Motor.jpg

[12] ASTM E-8M: “Standard Test Methods for Tension Testing of Metallic Materials.” http://compass.astm.org/EDIT/html_annot.cgi?E8+15a

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Thank you!

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