ss_quiz_2

ss_quiz_2 - E-344 Spring 2006 Name Quiz 2 11 April 2006 ID...

Info iconThis preview shows pages 1–7. Sign up to view the full content.

View Full Document Right Arrow Icon
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Background image of page 2
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Background image of page 4
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Background image of page 6
Background image of page 7
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: E-344 Spring 2006 Name: Quiz 2 11 April, 2006 ID#: Honor Pledge: Wm number. 1. The tin-lead (Sn-Pb) phase diagram is given on the following page. (A) (10 pts) Determine: a. the melting temperature of pure Sn. 2%? °C b. the melting temperature of pure Pb. ’32} ° C c. The eutectic temperature and eutectic composition. TE : \<3 go C C“: J70 d. the lowest temperature where a Sn-Pb alloy can be liquid. \{g'c e. the maximum solid solubility of Sn dissolved into (Pb). J :70 $A (B) (10 pts) for an alloy of Sn — 26 at % Pb at a temperature of 182 °C, determine: (i) the phase or phases present; (ii) the composition of each phase(s); and (iii) how much of each phase is present. Also, sketch a possible microstructure characteristic of this specimen that you might observe using an optical microscope. \ \ ® (55 + LE5 -— d» + % © (9 CGL 1 MW Jo’a\>\° C‘s: 7a 3r\.5- 2&9 ,_ 0.6g \‘\ git: ‘Jfl‘g' L“ 4 _ who—Vt - 07¢? ______...—- %’ ‘bg‘ \’V\ \IOD / 85 90 95 80 70 WEIGHT PER CENT LEAD 60 20 30 40 50 10 2 1 0° ,uzazfimsfi 90 96.8 (98.1} — 100 Pb 80 0 7- D A OF. EL TD 2 N Em C 0 P 5R E . P1 0 C6 0M . 40.W.o TF An 0 .3 _ m _ 0 2 G 1 0% |____._____.._ 2. 4340 steel is a high-strength martensitic steel. Its fracture toughness and yield strength for two different tempering conditions are given in the table below. Suppose this steel is to be used as a strut in an aircraft landing gear where the peak tensile stress can be as high as 500 MPa. The W has a square 10 cm x 10 cm cross section. QYWT A. (10 pts) Assuming that when the strut is manufactured the minimum internal crack half width that can be detected by nondestructive evaluation methods is 1 mm, which of the two materials would be a better selection for the W application? Quantitatively justify your answer. mpg. sagas. B. (4 pt) What role does an internal crack play in brittle fracture? C. .(6 pts) What additional specific considerations might you have to take into account during your analysis of possible brittle failure if the strut is being designed for a 20 year lifetime with approximately 300 landing cycles annually?: Material ch (MPa—m”2 0), (MP3) 4340 steel 50.0 1640 Tempered at 260 °C 4340 steel 87.4 1420 Tempered at 425 “C ® LIL; 5W : SODV’Rfi = 1% MVO‘Q" \, '_ \ EON: WLS was: v,“ > 7,3 mm: thW/ \ ' “fins-11E $0M Mia 91 sweewmkw > $00 War. , / gww +5>8>u1kt\m. hamm— Tomb 5"» 0563 m: N WNW"! 0mm Coi~3‘=>“‘>‘m“;“"'”“x Waugh \bVCMt‘ We Canals" ® Pm) \HWL (JD—km MKS *5 NJ» the mus-Ya Wm WUW' (Q m mu. warm“? 020w New WM' use Mam \“r \T wear/es T00 unlit mauve ) WWII/W; cw OCCUR, Pr swab Coachmen-T52. 3 I____._____..._ 3. The monomer unit for poly(ethylene glycol) [PEG] is given in the adjacent diagram. ll . A. (5 pts) Suppose a sample of PEG has an average —- C ._C a | H molecular weight of 6800 g/mole. Estimate the average degree of polymerization. ; MSW: \6~ 2% w W4 WM Poly(ethylene glycol) trpr 7": ____.. B. (5 pts) PEG 6800 is soluble in water. Develop a brief argument justifying why this is so. \‘W'bVDCloJ swabs Form WW cam Mancng to» mono.» wows \D W Win C. (5 pts) In its form as a polymeric solid, PEG is a semicrystalline polymer. It’s glass transition temperature for PEG is about -30 °C and it's melting temperature is about 60 °C. Suppose the Viscosity is measured from two different l-gram samples of PEG at 100 0C. One sample has a molecular weight of 6800 g/mole and the other has a molecular weight of 200,000 g/mole. Are the viscosities of these two samples the same or different? If different, which is higher? Briefly justify your answer. W. ostogfhirfs woods EFL BW-PW'. 0%, b CM) MWLTK TVA-EC m “\SZasfi‘l or— W Zoo‘oao WT, M\\ W \k'Cfic‘J?» Pfiauush \‘V mus 30% p. (3W Fatwa at; iumamsma D. (5 pts) PEG can be converted to a hydrogel by covalently crosslinking different molecules together. Briefly describe how such a PEG hydrogel could be recycled. a coneumw CszsLi mm Va; PMBV‘OULK Com.“ pm- 9347' mm Rev/web, Pluraka 'CS‘VOSSUpEHL-Ll . '2 V91, \5 \\ WWWEVI NJ» \Mu MELT W WM. kw woeskwwé. wuwagm OUKUUT WSS\\ we mam tomb“: - I____.____....__ 4. (A) (12 pts) Using the stress-strain data presented below (figure 5), determine the elastic modulus, the yield stress, the ultimate tensile stress, and the percent elongation to failure for cortical bone. __._. \’) \ A OFFSE‘O? b \’ 200 Apparent Density __: \qb M?“ -----0.30‘ g/cc 150 - — — '0.90 3/60 6‘; : \‘50 %?a E“ we ——1.85 g/cc 0/, Quad; = 7. 2% g 100 85 50 a ' _. -_ U— - § a- ~ ~ — m _ a — _ _ ._ __. - —- "‘ C 5 \}D h at ‘ trabecular bone I E 00‘ 0 , . ‘ ----------------------- -- 0 25 1 \bj‘ G?“ \79 0.270 ‘ Strain (%) “T?” Fig. 5 Stress ~ strain curves for cortical and lrabecular bone. (B) (4 pts) Based on the data in figure 5, would you expect the indentation made by a hardness tester into cortical bone to be greater than, less than, or the same made by an identical test into trabecular bone? Briefly justify your answer. mad WBZUl/fin— K b3 O" 5" ‘3 B” Wain-MS elf/RUE y r 7 7 .'. W1 \wmw \U‘xo CMLM EM was H; kegs W W “3WD mess;ch sunk. (C) (4 pts) Suppose the initial gauge length of the cortical bone tensile specimen is 2 inches. What will be the gauge length after failure in tension? In the case of complete fracture into two separate pieces, ignore the air between the two fracture surfaces). W65 Wauxwlrfi. 39°:WUSH “)1, M X>Lflhc QNDM as 43-90mm NT :1 7520/0 H \aIOO/D : \I‘Zv/o A ‘ i N“. V" tween; I_i__.____.__ In the following multiple-choice problems, circle the one answer that BEST completes the sentence. 3 points per problem. No partial credit. 5. Suppose the stress-strain data described in the adjacent diagram were collected from a specimen of poly(ethylene) (PE), a specimen of 6063 Aluminum alloy; and a silicon nitride (Si3N4) ceramic. Which curve corresponds to which material? a. 1= PE; 2 = 6063 A1; 3 = (Si3N4) 6) 1 = (Si3N4), 2 = 6063 A1; 3 = PE; c. l = 6063 Al; 2 = (Si3N4), 3 = PE; (1. 1 = 6063 Al; 2 = PE; 3 = (Si3N4), 6. none of the above. 6. The viscosity of a thermoplastic polymer: a. is very low below Tg; b. increases with increasing temperature; @decreases linearly with increasing temperature; s a strong function of temperature; 6. none of the above. 7. Of the three schematic conformations below, the one possible for a for a flexible-chain macromolecular polymer like polyethylene is: 11 of the above 6. only b and c. a b C 9300‘” (9.0.“ 8. Rubber: a. has a low elastic modulus; b. can not be easily recycled due its crosslinks; c. typically cannot undergo much plastic deformation prior to failure; (1. is a type of polymer; all of the above. r_________...._ 9. Two brass samples are identical except that sampleA has a finer grain size than sample B. Specimen A has a higher yield stress than specimen B. b. Specimen B has a higher yield stress than specimen A. c. The two specimens have identical yield stresses. (1. The yield stresses may be different depending on the size of each specimen. 6. none of the above 10. A material’s resistance to fracture is best characterized by its: toughness; . yield strength; c. ductility; d. modulus; e. none of the above. 11. Consider a cold-worked metal that has been annealed at a temperature just below its melting point for 1 hour. Relative to the initial hardness, the annealed hardness would: a. be greater; b. be the same; be less; . depend on degree of doping; e. none of the above. 12. Hardness is usually determined by: a. compression experiments; b. the 0.2% offset analysis of tensile data; (9 indentation experiments; (:1. fracture—toughness measurements; e. none of the above. 13. The rate at which a typical solute atom moves (diffuses) in a crystal solvent: increases with increasing temperature; . decreases with increasing temperature; c. does not depend on temperature; (1. none of the above. 14. Based on the fact that Cu and Ni are completely soluble in each other, one can expect that Cu and Ni have similar: a) crystal structures; b) atomic radii; c) valence; d electronegativity; all of the above. ...
View Full Document

This note was uploaded on 10/03/2009 for the course E E344 taught by Professor Libera during the Spring '09 term at Stevens.

Page1 / 7

ss_quiz_2 - E-344 Spring 2006 Name Quiz 2 11 April 2006 ID...

This preview shows document pages 1 - 7. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online