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Engineering Materials

Subject : engineering
Instructions:
  • Answer 50 questions in 15 minutes.
  • If you are not ready to take this test, you can study here.
  • Match each statement with the correct term.
  • Don't refresh. All questions and answers are randomly picked and ordered every time you load a test.

This is a study tool. The 3 wrong answers for each question are randomly chosen from answers to other questions. So, you might find at times the answers obvious, but you will see it re-enforces your understanding as you take the test each time.
1. (sigma)=F/Ai (rho)=(rho)'(1+(epsilon))






2. 1. Diamagnetic (Xm ~ 10^-5) - small and negative magnetic susceptibilities 2. Paramagnetic (Xm ~ 10^-4) - small and positive magnetic susceptibilities 3. Ferromagnetic - large magnetic susceptibilities 4. Ferrimagnetic (Xm as large as 10^6) - large m






3. Found in 26 metals and hundreds of alloys & compounds - Tc= critical temperature = termperature below which material is superconductive.






4. The ability of a material to absorb heat - Quantitatively: The energy required to produce a unit rise in temperature for one mole of a material.






5. With Increasing temperature - the saturation magnetization diminishes gradually and then abruptly drops to zero at Curie Temperature - Tc.






6. -> fluorescent light - electron transitions occur randomly - light waves are out of phase with each other.






7. Process by which metal atoms diffuse because of a potential.






8. 1. Fluorescent Lamp - tungstate or silicate coating on inside of tube emits white light due to UV light generated inside the tube. 2. TV screen - emits light as electron beam is scanned back and forth.






9. Because of ionic & covalent-type bonding.






10. Different orientation of cleavage planes in grains.






11. Without passing a current a continually varying magnetic field will cause a current to flow






12. Cracks propagate along grain boundaries.






13. heat flux = -(thermal conductivity)(temperature gradient) - Defines heat transfer by CONDUCTION

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14. Flaws and Defects - They concentrate stress locally to levels high enough to rupture bonds.






15. These are liquid crystal polymers- not your normal "crystal" -Rigid - rod shaped molecules are aligned even in liquid form.

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16. Typical loading conditions are _____ enough to break all inter-atomic bonds






17. They are used to assess properties of ceramics & glasses.






18. Diffuse image






19. This strength parameter is similar in magnitude to a tensile strength. Fracture occurs along the outermost sample edge - which is under a tensile load.






20. Increase temperature - increase in interatomic separation - thermal expansion






21. Wet: isotropic - under cut Dry: ansiotropic - directional






22. As the applied field (H) increases the magnetic domains change shape and size by movement of domain boundaries.






23. There is always some statistical distribution of flaws or defects.






24. Occurs at a single pore or other solid by refraction n = 1 for pore (air) n > 1 for the solid - n ~ 1.5 for glass - Scattering effect is maximized by pore/particle size within 400-700 nm range - Reason for Opacity in ceramics - glasses and polymers.






25. Second phase particles with n > glass.






26. 1. Insulators: Higher energy states NOT ACCESSIBLE due to gap 2. Semiconductors: Higher energy states separated by a smaller gap.






27. Allows you to calculate what happened G=F' x cos(lambda) - F=F' x cos(phi)






28. Hardness is the resistance of a material to deformation by indentation - Useful in quality control - Hardness can provide a qualitative assessment of strength - Hardness cannot be used to quantitatively infer strength or ductility.






29. Failure under cyclic stress 1. It can cause part failure - even though (sigma)max < (sigma)c 2. Causes ~90% of mechanical engineering failures.






30. Rho=F/A - tau=G/A . Depending on what angle the force is applied - and what angle the crystal is at - it takes different amounts of force to induce plastic deformation.






31. Width of smallest feature obtainable on Si surface






32. The size of the material changes with a change in temperature - polymers have the largest values






33. These materials are "attracted" to magnetic fields.






34. Stress concentration at a crack tips






35. Reflectiviy is between 0.90 and 0.95 - Metal surfaces appear shiny - Most of absorbed light is reflected at the same wavelength (NO REFRACTION) - Small fraction of light may be absorbed - Color of reflected light depends on wavelength distribution of






36. Metals are good conductors since their _______is only partially filled.






37. Another optical property - Depends on the wavelength of the visible spectrum.






38. Dimples on fracture surface correspond to microcavities that initiate crack formation.






39. Materials change size when temperature is changed






40. Degree of opacity depends on size and number of particles - Opacity of metals is the result of conduction electrons absorbing photons in the visible range.






41. For a metal - there is no ______ - only reflection






42. 1. General yielding occurs if flaw size a < a(critical) 2. Catastrophic fast fracture occurs if flaw size a > a(critical)






43. Superconductors expel magnetic fields - This is why a superconductor will float above a magnet.






44. 1. Ductility- % elongation - % reduction in area - may be of use in metal forming operations (e.g. - stretch forming). This is convenient for mechanical testing - but not very meaningful for most deformation processing. 2. Toughness- Area beneath str






45. Elastic means reversible! This is not a permanent deformation.






46. Measures impact energy 1. Strike a notched sample with an anvil 2. Measure how far the anvil travels following impact 3. Distance traveled is related to energy required to break the sample 4. Very high rate of loading. Makes materials more "brittle."






47. Measures Hardness 1. psia = 500 x HB 2. MPa = 3.45 x HB






48. 1. Hard disk drives (granular/perpendicular media) 2. Recording tape (particulate media)






49. - Metals that exhibit high ductility - exhibit high toughness. Ceramics are very strong - but have low ductility and low toughness - Polymers are very ductile but are not generally very strong in shear (compared to metals and ceramics). They have low






50. Is analogous to toughness.