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Torsion Tests to Study Plastic Deformation in Ductile Materials

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Conference

2017 ASEE Annual Conference & Exposition

Location

Columbus, Ohio

Publication Date

June 24, 2017

Start Date

June 24, 2017

End Date

June 28, 2017

Conference Session

Teaching Statics, Dynamics, and Mechanics of Materials

Tagged Division

Mechanics

Page Count

18

DOI

10.18260/1-2--29032

Permanent URL

https://peer.asee.org/29032

Download Count

7150

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Paper Authors

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Somnath Chattopadhyay University at Buffalo, SUNY

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Dr. Somnath Chattopadhyay teaches mechanics, manufacturing and design at the University at Buffalo. He has authored a text on Pressure Vessel s and till recently was an Associate Editor of the ASME Journal of Pressure Vessel Technology. His research interests are in the areas of fatigue and fracture of metals, carbon nanotubes, multi-scale material modeling and engineering education. He had a very successful industrial career with Westinghouse Electric where he directed and performed structural design of power generation equipment and is a registered professional engineer. He received his Ph.D. in mechanics from Princeton University.

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Jerry Qu University at Buffalo

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Jerry Qu is currently a senior undergraduate student at the University at Buffalo’s School of Engineering and Applied Sciences. He is pursing a Bachelors of Science in Industrial and Systems Engineering.

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Adres Nuri University at Buffalo

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Adres Nuri is currently a senior undergraduate student at the State University of New York at Buffalo. He will be graduating in May 2017 with a Bachelor of Science in Mechanical Engineering.

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Syed Ali Hasan University at Buffalo

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I am currently a senior undergraduate student at the University at Buffalo’s School of Engineering and Applied Sciences. I am pursing a Bachelors of Science in Computer Science and a Bachelors of Science in Mechanical Engineering.

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Nilanjan Kundu University at Buffalo

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Nilanjan Kundu is currently a senior pursuing a Bachelor of Science in Mechanical Engineering at the University at Buffalo's School of Engineering and Applied Sciences.

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Abstract

This project is an experimental study on plastic deformation in ductile materials such as aluminum and steel. The object is to stimulate interest in engineering undergraduate students the importance of plasticity in structural design and metal forming. It is proposed as a supplemental lab activity for the junior level Mechanics of Materials course. Torsion tests were performed on circular cylindrical bars to obtain torque-twist curves (the torsional shear stress vs torsional shear strain plots). The shear modulus, G, and the 0.2% offset yield shear strength, k, were estimated from these curves. The bars were twisted well into their plastic regions, and as the elastic/plastic torsion continued, the torques seemed to approach their limiting values. Experimental estimates for the limiting torques were in reasonable agreement with the values predicted by the so-called sand heap analogy. This states that the stress surface for a fully plastic cross-section is obtained by piling dry sand on a horizontal base whose shape is identical to the cross-section of the bar. For a circular cross-section, the sand heap is a cone, and the limiting torque is equal to (k a /G) times the volume of the cone, where a is the radius. The specimens were twisted to a predetermined maximum value. The directions of twist were subsequently reversed. After unloading and reloading from the initial loading phase, the materials seemed to yield in the reverse direction with lesser yield strength values. This shows that the plastic deformation for metallic materials is one direction affects plastic deformation in the reve

Chattopadhyay, S., & Qu, J., & Nuri, A., & Hasan, S. A., & Kundu, N. (2017, June), Torsion Tests to Study Plastic Deformation in Ductile Materials Paper presented at 2017 ASEE Annual Conference & Exposition, Columbus, Ohio. 10.18260/1-2--29032

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