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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. - A magnetic field is induced in the material B= Magnetic Induction (tesla) inside the material mu= permeability of a solid






2. 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.






3. 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.






4. Specific heat = energy input/(mass*temperature change)






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






6. Allows flow of electrons in one direction only (useful to convert alternating current to direct current) - Result: no net current flow






7. 1. Necking 2. Cavity formation 3. Cavity coalescence to form cracks 4. Crack propagation (growth) 5. Fracture






8. A high index of refraction (n value) allows for multiple internal reactions.






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






10. Diffuse image






11. The Magnetization of the material - and is essentially the dipole moment per unit volume. It is proportional to the applied field. Xm is the magnetic susceptibility.






12. 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






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






14. Is analogous to toughness.






15. 1. Yield = ratio of functional chips to total # of chips - Most yield loss during wafer processing - b/c of complex 2. Reliability - No device has infinite lifetime. Statistical methods to predict expected lifetime - Failure mechanisms: Diffusion reg






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






17. Loss of image transmission - You get no image - There is no light transmission - and therefore reflects - scatters - or absorbs ALL of it. Both mirrors and carbon black are opaque.






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






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






20. (sigma)=K(sigma)^n . K = strength coefficient - n = work hardening rate or strain hardening exponent. Large n value increases strength and hardness.






21. Cp: Heat capacity at constant pressure Cv: Heat capacity at constant volume.






22. # of thermally generated electrons = # of holes (broken bonds)






23. High toughness; material resists crack propagation.






24. No appreciable plastic deformation. The crack propagates very fast; nearly perpendicular to applied stress. Cracks often propagate along specific crystal planes or boundaries.






25. If a material has ________ - then the field generated by those moments must be added to the induced field.






26. Plastic means permanent! When a small load is applied - bonds stretch & planes shear. Then when the load is no longer applied - the planes are still sheared.






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






28. 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.






29. Growing interconnections to connect devices -Low electrical resistance - good adhesion to dielectric insulators.






30. Occur due to: restrained thermal expansion/contraction -temperature gradients that lead to differential dimensional changes sigma = Thermal Stress






31. Large coercivities - Used for permanent magnets - Add particles/voids to inhibit domain wall motion - Example: tungsten steel






32. 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.






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






34. Small Coercivities - Used for electric motors - Example: commercial iron 99.95 Fe






35. 1. Ability of the material to absorb energy prior to fracture 2. Short term dynamic stressing - Car collisions - Bullets - Athletic equipment 3. This is different than toughness; energy necessary to push a crack (flaw) through a material 4. Useful in






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






37. Defines the ability of a material to resist fracture even when a flaw exists - Directly depends on size of flaw and material properties - K(ic) is a materials constant






38. (sigma)=F/Ai (rho)=(rho)'(1+(epsilon))






39. Occur when lots of dislocations move.






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






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






42. Is reflected - absorbed - scattered - and/or transmitted: Io=It+Ia+Ir+Is






43. 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."






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






45. - 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






46. Sigma=ln(li/lo)






47. - The emission of light from a substance due to the absorption of energy. (Could be radiation - mechanical - or chemical energy. Could also be energetic particles.) - Traps and activator levels are produced by impurity additions to the material - Whe






48. Becomes harder (more strain) to stretch (elongate)






49. Transmitted light distorts electron clouds - The velocity of light in a material is lower than in a vacuum - Adding large ions to glass decreases the speed of light in the glass - Light can be "bent" (or refracted) as it passes through a transparent






50. The ability of a material to transport heat - Atomic Perspective: Atomic vibrations and free electrons in hotter regions transport energy to cooler regions - Metals have the largest values