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Tensile Deformation of Ductile Metal Animation Guide

A document explaining the concept of tensile deformation in ductile metals to an animator. The guide consists of 5 sections providing necessary details before starting the animation.

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Tensile Deformation of Ductile Metal Animation Guide

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  1. This is a document to explains the concept of Tensile Deformation a ductile metal to the animator. This will take you through a 5 section process to provide the necessary details to the animator before starting the animation. The legend on the left will indicate the current status of the document. The big Black coloured number will denote the current section, the Grey color would denote the completed sections, and the Turquoise color would denote the remaining sections. The slides having yellow background (like this one) are the 'Instruction slides' Welcome 1 2 3 4 5

  2. Tensile testing, also known as tension testing is a fundamental material science test in which a sample (ductile material) is subjected to uniaxial tension until failure‏. Properties that are directly measured via a tensile test are Young's Modulus, Yield Strength,  Ultimate Tensile Strength, Maximum elongation and Reduction in area Tensile Deformation of a ductile Metal Course Name: Mechanical Behavior of Materials Level(UG) Prerequisites': Understanding and knowledge of load and displacement Author Sudip Deb Mentor Prof P.Pant

  3. Learning Objectives • After interacting with this Learning Object, the learner will be able to: • Understand stress and strain. • Identify yield stress given any graph on stress and strain curves. • Identify strength given any graph on stress and strain curves. • Compare ductility of material given any graph on stress and strain curves.

  4. Definitions and Keywords 1 • Stress: Stress is defined as force per unit area. It has the same units as pressure, and in fact pressure is one special variety of stress. • Strain: Strain is defined as the amount of deformation an object experiences compared to its original size and shape. For example, if a block 10 cm on a side is stretched so that it becomes 11 cm long, the strain is (11-10)/10 or 0.1 (sometimes expressed in per cent, in this case 10 per cent.) Note that strain is dimensionless. • Elastic deformation: This type of deformation is reversible. Once the forces are no longer applied, the object returns to its original shape and size. • Plastic deformation: This type of deformation is not reversible. However, an object in the plastic deformation range will first have undergone elastic deformation, which is reversible, so the object will return part way to its original shape. 2 3 4 5

  5. Continued..: 1 • Ductility is a solid material's ability to deform under stress; this is often characterized by the material's ability to be stretched into a wire • Yield point:The first point at which permanent deformation of a stressed specimen begins to take place. This is a point on the stress-strain curve beyond which, strain no longer varies linearly with stress. • Ultimate Tensile Strength (UTS), often shortened to tensile strength (TS) or ultimate strength, is the maximum stress that a material can withstand while being stretched or pulled before necking. • Necking The reduction in diameter that occurs as a sample material is subjected to tensile stresses. • Fracture: This marks the end of the test, when the sample breaks. A break occurs after the material has reached the end of the elastic, and then plastic, deformation ranges. All materials will eventually fracture, if sufficient forces are applied 2 3 4 5

  6. Master Layout 1: 1 2 3 Spring 4 Graph 5 http://www.educationalelectronicsusa.com/p/gravitation_IV.htm

  7. Interactivity type (IO 1/IO 2)‏ Instruction to learners Boundary limits & options Instruction to animators Results and output • Graph 1: • As the learner drops the 200 gm. stone the first red dot appears and graph move to the first red dot. Spring stretches and when stone removed then spring returns to original size (zoomed image)‏ • As the learner drops the 450 gm. stone the 2nd red dot appears and graph moves there. Spring stretches and when stone removed then spring returns to original size. (zoomed image)‏ • As the learner drops the 750 gm. stone the 3rd red dot appears and graph moves there. Spring stretches and when stone removed then spring contracts a little but does not return to its original length. (zoomed image)‏ • As the learner drops the 2 kg stone the 4th red dot appears. The spring breaks across the middle. (zoomed image)‏ Drag and drop Drag the load to the spring balance and observe the spring 200 grams, 450 grams, 750 grams and 2 kg stones. • Stones appear one after another 200 gm. Then 450 gm. then 750 gm. and then 2 kg stone. • Once the child has placed the load the both the graph reading starts • After reading on graph shown, then remove button appears .Once the stone is removed the graph reaches its original state and next stone appears.. • Make sure to mark the deviation from normal by dotted line 1 Step 1: T1: Analogy of spring balance Zoomed image of the spring reading New stone shown here 2 Load Spring Displacement Remove Stone Graph 1 3 4 5

  8. Master Layout 2: Universal Testing Machine(UTM) 1 2 3 4 http://www.ndt-ed.org/EducationResources/CommunityCollege/Materials/Mechanical/Tensile.htm http://www.directindustry.com/prod/instron/tensile-compression-testing-machine-18463-41713.html 5

  9. Interactivity type (IO 1/IO 2)‏ Instruction to learners Boundary limits & options Instruction to animators Text to be displayed Drop down Notice the initial length L0 and the initial area of the specimen A0. Click on red button to start the experiment Stress: 250 MPa Options: 250 MPa 475 MPa 530 MPa 700 MPa 800 Mpa 600 MPa • Mark and show L0 andA0 in the sample • Show the sample being placed in the UTM • Show the zoomed up Lo part of the rod in between the machine clasps. • Show instruction to learner 2. • The learner clicks on the red button • As the red button is clicked the value in black box starts increasing arithmetically and it just stops at the boundary values for 2 sec to mark the significant change in the material elongation and the stress-strain graph where the corresponding red dot glows . • Stress is Load / cross sectional area (A0)‏ • Strain is defined as the change in length/ original length on application of load. • L1- L0 • L0 Step 2: 1 T1: Tensile Test for ductile material - stress – strain curve Stress Magnified image of the specimen being elongated 2 Load value Clasps START 3 4 5

  10. A0 L4 L3 A rod L2 A rod L1 L0 Crack Original Stretched 3 Stretched 2 Stretched 1 Master Layout 3: 1 2 3 Stretched Fracture http://www.ndt-ed.org/EducationResources/CommunityCollege/Materials/Mechanical/Tensile.htm http://www.directindustry.com/prod/instron/tensile-compression-testing-machine-18463-41713.html 4 This is the state of the zoomed sample between the clasps as the load is continuously increased the various length of the sample are as shown NOTE: This is for reference of the animator not to be shown in original animation. Please show the images as given in the following slides. 5

  11. A0 A rod L0 Original Boundary limits & options Text to be displayed Instruction to animators Stress is a function of Load / cross sectional area (A0)‏ Strain is defined as the change in length/ original length on application of load. L1- L0 L0 3. As the value of the load is well within the elastic region no significant change in the structure of the ductile sample. Stress: 250 MPa Limits: 250 MPa 475 MPa 530 MPa 700 MPa 800 Mpa 600 MPa • Once the red button in the step 2 is clicked the loading process starts . • The value in the load box is set to 0 by default and once loading is started its value starts increasing arithmetically unless it reaches the boundary value of 250 MPa. • While the loading continues the texts 1 and 2 appear to the learner • At this value the loading stops for two seconds and the first red dot appears in the graph and the graph moves there and the fig 1.1 is shown as the state of the specimen • The text 3 is displayed to the learner • After the loading phenomenon then again loading starts from 250MPa again. Step 3.1: 1 T1: Tensile Test for ductile material - stress – strain curve Stress 2 Fig 1.1 3 4 5

  12. A0 L0 Original Boundary limits & options Text to be displayed Instruction to animators • As the value of the load still within the elastic region no significant change in the structure of the ductile sample and if load removed the material can regain its original state . Stress: 475 MPa Limits: 250 MPa 475 MPa 530 MPa 700 MPa 800 Mpa 600 MPa • After the pervious step the loading again resumes and the load meter continues until the value in it reaches 475 MPa where it stops for 2 sec and the orange dot appears on the graph and the graph moves there. • Once it reaches 475 MPa. Fig 1.2 represents the zoomed state of the sample without any significant deformation (change) • Text is displayed to the learner. Step 3.2: 1 T1: Stress – Strain curve- Elastic deformation Stress 2 Fig 1.2 3 4 5

  13. A rod L1 Boundary limits & options Text to be displayed Instruction to animators • The maximum elastic limit of the sample has been reached and plastic deformation in the sample has started as length increased from Lo to L1 . Stress: 530MPa Limits: 250 MPa 475 MPa 530 MPa 700 MPa 800 Mpa 600 MPa • After the pervious step the loading again resumes and the load meter continues until the value in it reaches 530 MPa where it stops for 2 sec and the yellow dot appears on the graph and the graph moves there here a slight curve is seen in the graph and hence the curve is zoomed up and showed to the learner as the Yield Strength point. • Once it reaches 530MPa. Fig 1.3 represents the zoomed state of the sample which shows a increase in the length from Lo to L1 by about 1 cm • Text is displayed to the learner. Step 3.3: 1 T1: Stress – Strain curve- Plastic deformation Stress 2 Stretched Fig 1.3 3 4 5

  14. L2 Stretched 1 Boundary limits & options Text to be displayed Instruction to animators • As the plastic deformation of the sample continues the length now increases from L1 to L2 cm the material cannot regain its original state even if the load is removed Stress: 700MPa Limits: 250 MPa 475 MPa 530 MPa 700 MPa 800 Mpa 600 MPa • After the pervious step the loading again resumes and the load meter continues until the value in it reaches 700 MPa where it stops for 2 sec and the green dot appears on the graph and the graph moves there • Once it reaches 700MPa. Fig 1.4 represents the zoomed state of the sample which shows a increase in the length from L1 to L2 by about 1 cm • Text is displayed to the learner. Step 3.4: 1 T1: Stress – Strain curve- Plastic deformation Stress 2 3 Fig 1.4 4 5

  15. Boundary limits & options Text to be displayed Instruction to animators • The Ultimate Tensile Strength of the material has been reached and is indicated by the blue dot any further loading could lead to breaking of the metal Stress: 800MPa Limits: 250 MPa 475 MPa 530 MPa 700 MPa 800 Mpa 600 MPa • After the pervious step the loading again resumes and the load meter continues until the value in it reaches 800MPa where it stops and the blue dot appears on the graph and the graph moves there • Once it reaches 800MPa. Fig 1.5 represents the zoomed state of the sample which shows a increase in the length from L2to L3 by about 1 cm • Also mark and show the phenomenon of necking to learner by a zoomed image of the necked region • Text is displayed to the learner. • At this point the value of the load meter becomes 0 and a new dialog appears on the screen represented in blue asking the learner whether he wishes to load further . Step 3.4: 1 T1: Stress – Strain curve – Ultimate tensile stress Stress Necking 2 3 Load further Fig 1.5 4 5

  16. L4 Crack Stretched 3 Boundary limits & options Text to be displayed Instruction to animators Cracks being formed on the sample Facture or FailureThe material starts to crack once it has crossed its ultimate tensile strength until the point of complete failure or fracture of the material. Stress: 600MPa Limits: 250 MPa 475 MPa 530 MPa 700 MPa 800 Mpa 600 MPa • If the learner clips the load further button the loading again starts in the load meter from 0 • Once it reaches 500MPa.simulatneously crack formation starts in the ample as shown in Fig 1.6 and the crack propagates with increasing load. • Text 1is displayed to the learner. • As the value of the load meter becomes 600 MPa. The fracture of the sample takes place with a breaking sound and Fid 1.7 is displayed to the learner along with text 2 and the graph further moves and then rests at the breaking strength shown by the red dot • Text 2 is displayed Step 3.5: 1 T1: Stress – Strain curve – Ultimate tensile stress Stress 2 3 Fracture Fig 1.6 Fig 1.7 4 5

  17. APPENDIX 1 Self- Assessment Questionnaire for Learners • Please provide a set of questions that a user can answer based on the LO. They can be of the following types: • These questions should be 5 in number and can be of objective type (like MCQ, Match the columns, Yes or No, Sequencing, Odd One Out). • The questions can also be open-ended. The user would be asked to think about the question. The author is requested to provide hints if possible, but a full answer is not necessary. • One can include questions, for which the user will need to interact with the LO (with certain parameters) in order to answer it. • It is better to avoid questions based purely on recall.

  18. APPENDIX 1 Master Layout 4: 1 T1: Stress – Strain curve - New material 2 3 4 5

  19. Interactivity type (IO 1/IO 2)‏ Instruction to learners Questions Instruction to animators Results and Output Choose ( one try)‏ Read the question and select the correct answer. What does the red dot in the graph depict? Options: Yield point, fracture point. • Show the graph with the two dots. If yield point is clicked then Correct! that is the yield point for the given material stress and strain curve. If incorrect then show ‘ Yield point depicts a change in the curve from a linear elastic curve to a plastic curve. This point onwards strain increases faster than stress. ’ APPENDIX 1 Q1: T1: Stress – Strain curve - New material

  20. Interactivity type (IO 1/IO 2)‏ Instruction to learners Questions Instruction to animators Results and Output Click ( one try)‏ Read the question and click on the correct area in the graph. Locate the ultimate tensile strength of this material. CHANGE PLOTTO MAKE UTS MORE OBVIOUS • Show the graph without the yellow dot of master layout 4. If the learner click in the area of the yellow dot it is correct. Correct that is the ultimate tensile strength for the given material stress and strain curve. If the learner click anywhere outside the dot region then show ‘Tensile strength, is the maximum engineering stress level reached in a tension test’ APPENDIX 1 Q2: T1: Stress – Strain curve

  21. Punch Sheet of metal Die Punch Sheet of metal Die Sheet of metal Punch Cup Die APPENDIX 1 Master Layout 5: T1: Cup formation

  22. Punch Sheet of metal Die Interactivity type (IO 1/IO 2)‏ Instruction to learners Questions Instruction to animators Results and Output Choose( one try)‏ Read the question and click on the correct answer If you are given a sheet of metal to convert to a Cup, which deformation would you choose? Options: Plastic deformation, Elastic deformation. • Show the sheet of metal. • If the elastic region is chosen • Show the punch dropping on the sheet of metal forming the Cup. • Once punch removed show it spring back to the sheet of metal. • If the plastic region is chosen • Show the punch dropping on the sheet of metal forming the Cup. • Once punch removed show the Cup as it is. If plastic deformation is clicked then Correct! In plastic deformation the material changes shape. If incorrect then show ‘In elastic deformation, when the stress is reduced, the material will return to its original shape’ APPENDIX 1 Q3: T1: Cup formation from a sheet of metal

  23. Stress Stress Strain Strain APPENDIX 1 Master Layout 7: T1: Slope and stiffness Plastic spring Steel spring

  24. Stress Stress Strain Strain Interactivity type (IO 1/IO 2)‏ Instruction to learners Questions Instruction to animators Results and Output Choose( one try)‏ Read the question and click on the correct answer A man applying the same strength to pull both the springs. Which of the springs would be more stiff? Options: Steel spring, Plastic spring • show a mans hand on the sides of the springs. • Show text 1. • Show the question. • After learner clicks on the option show the plastic spring stretching a lot (50 mm). • And the steel spring stretching 1 mm. • Show the two graphs 1. Stiffness is resistance of a material to elastic deformation. (Correct answer is steel spring)‏ (If correct then show) ‘You are correct conform your answer by clicking on view the animation. (If incorrect then show) ‘ You are incorrect clarify your thinking by clicking on view the animation. APPENDIX 1 Q4: T1: Slope and Stiffness Steel spring Plastic spring View the animation http://www.go-ride.com/SPD/2-25-x-500--12510000-1105570016.jsp , http://www.fotosearch.com/ITS363/itf272059/

  25. Interactivity type (IO 1/IO 2)‏ Instruction to learners Questions Instruction to animators Results and Output and text to be displayed Choose( one try)‏ Read the question and click on the correct answer Which of the following is more ductile? Options: chalk, silver wire • Show text 1. • Show the question. 1. Ductility is the maximum elongation before failure/ fracture. (Correct answer is silver wire)‏ (If correct then show) ‘You are correct silver wire is more ductile than chalk’ (If incorrect then show) ‘ Chalk breaks faster and is more brittle’ APPENDIX 1 Q5: T1: Ductility Question: Silver wire chalk http://www.laventure.net/tourist/cables.htm , http://youngvision.blogspot.com/2009/02/where-chalk-faced-children-play.html

  26. Interactivity type (IO 1/IO 2)‏ Instruction to learners Questions Instruction to animators Results and Output Drag and drop Drag and drop the stress – strain curve its appropriate material. Options: chalk, silver wire • graph 1 is for chalk and graph 2 for silver wire. Correct answer is graph 1 for chalk and graph 2 for silver wire: If incorrect answer show ‘Try again!’ If correct the show ‘Therefore a material that takes more stress before failure or fracture the higher is its ductility.’ APPENDIX 1 Q6: T1: Ductility Ductility Ductility

  27. 1 Instruction to Animators 2 • Master layout 1 shows a spring balance measuring stones of different types. Initially as the load increases the elongation of the spring increases. • Then later as the stress increases the strain also increases but the spring comes back to its original shape up to the elastic limit. • Later as more stress increases the strain stays almost the same but the spring does not go to its original shape. • And when even more stress is added the spring which is more than the maximum stress that could be withstood by the spring it breaks from the centre. • After that we load a ductile specimen on the Universal Testing Machine and observe the stress-strain graph closely. 3 4 5

  28. APPENDIX 2 Linksfor further reading Reference websites: http://www.ndt-ed.org/EducationResources/CommunityCollege/Materials/Mechanical/Tensile.htm http://www.engineersedge.com/strength_of_materials.htm http://www.feppd.org/ICB-Dent/campus/biomechanics_in_dentistry/ldv_data/basic.htm http://www.ndt-ed.org/EducationResources/CommunityCollege/Materials/Mechanical/Tensile.htm http://www.feppd.org/ICB-Dent/campus/biomechanics_in_dentistry/ldv_data/basic.htm Video References: http://www.youtube.com/watch?v=67fSwIjYJ-E&feature=related http://www.youtube.com/watch?v=JRLybNsJN20 Books: Mechanical Metallurgy – George E. Dieter Research papers:

  29. APPENDIX 3 Summary • Elastic deformation: • The stress and strain initially increase with a linear relationship. • In this region of the curve, when the stress is reduced, the material will return to its original shape. • Yieldpoint: From this point on in the tensile test, some permanent deformation occurs in the specimen. • Plastic deformation: The material will not return to its original, unstressed condition when the load is removed. • The ultimate tensile strength (UTS) or, more simply, the tensile strength, is the maximum engineering stress level reached in a tension test. • Failure/ Fracture: The point at which the material breaks. • Stiffness is resistance of a material to elastic deformation. The higher the elastic slope the higher the stiffness of the material. • Ductility is the maximum elongation before failure/ fracture.

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