MEEN 475 Midterm
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Texas A&M University *
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475
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Material Science
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Feb 20, 2024
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r /_ MEEN47S Materials in Design Fall 2023 Name: e You have 50 minutes Midterm Exam « This is a work-alone, closed-book, no-notes exam. ¢ You may use a ruler and a calculator. o « Turn off all other electronic devices other than your PC. Your camera should be on. « No Questions: If you think a problem is wrongly worded or there is a mistake or missing information, state what you think the mistake or missing information is and what assumption you are going to make and then continue. « Failure to follow the Honor Code will result in automatic failure of the course. “I have read and understand the exam Rules & Restrictions” ’ ; . F ; i “On my honor, as an Aggie, | have neither given nor Egefled unauthorized aid on this academic work Signa Questions Point Value Score Problem 1 24 Problem 2 20 Problem 3 30 Problem 4 26 Total
MEEN 475 Materials in Design Fall 2023 Problem 1 (24 pts.) T/F (Truel/False): 2 pts. each @ - Increasing the content of Niquel on a Cooper-Niquel alloy increases the yield strength. © _F_ Inlow carbon steels, increasing the C content generally decreases the strength. 3. _T_ Investment casting involves melting out a wax pattern and filling the resulting cavity with metal. C L_ In slip casting, a shell or preform is heated and compressed by an external gas pressure. 133 5. 1 Ina material selection process, the material index had the following term:(f'_) . The p slope is 3 onthe p—E chart where density is on the x-axis of the chart. 6. _[ Ina hypothetical material selection process, the objective was to minimize the weight and free variable was the t-thickness. The following is an acceptable equation to select the material 1/2 . 12t P from the charts: m= {?j (L)(EE] i ] (7> 1_Few polymers can be used above 200°C 8. T In the material cost analysis the Cv.ris simply pCm Multiple Choice (8 pts. 2 pts. each) (one correct answer) 1. Fiber reinforced composite materials parts can be made by: a. Extrusion b. Injection molding (c_Filament winding d. Blow molding 2. Metals have a wide range of strengths on the p—¢c because: a. They have high melting points. (b Their strength depends on composition and processing. c. They generally have low elastic modulus. d. They have high densities. 3. Which of the following materials is most likely not suitable for use in a 300 °C application? a. Metals. (6> Polymers. c. Glasses. d. Ceramics. 4. Which material is the best choice for a high strength, high stiffness and low weight application? 3) Carbon fiber reinforced composites. . Polymers. c. Rigid polymer foams. d. Concrete.
MEEN 475 Materials in Design Fall 2023 Problem 2 (20 pts.) tile assembly and for ducting for Channel sections for window frames, for slide-together sections for versa rder is for 100,000 such sections, electrical wiring can be complex in shape. Figure 1 shows an example. The o A each 1 m in length and weighing 1.2 kg, with a minimum section of 4 mm. Atolerance of 0.2 mm and a surface_ w must be achieved without any additional finishing operation. (a) List the constraints, leave the objective blank and “Choice of process” is the free variable. (b) Use the charts of Chapter 7 to identify 2 possible processes to make the casing. Figure 1: Channel Cross Section Shape an aluminum section with a complex profile weut |2k, e punimum Seekiow Hmm Folevauce o 0. o curfree vougmess less Jum ® /00,000 batehy Function Constraints length 1 ® Mo a&ol{'houa'( J\M's‘l“.f] OPefld’wM Objective . Free variables | e Choice of process r es” g H \O> eossfio\( {JfOCtiSS M s awogg,blp f;rocegj beCaqu T on all of) the cnrts 3\/\@6"( 'fiwm;ufi 5 afOSS,EI( p/C((’SL loecaise 3 ¥ fiv\lls whuh ok Hie V‘w\:je’&
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—— o Sand casting Die casting | Investment casting Cerntritugal casting Materiqls i Design Fall 2023 | AN shapes ) e f'?{liflm\ s f;]n | ( c«.,:]l.;;} — —— Dt e ) () ) Sy = @ ) Die casting Invostment casting Centifugal casting Bloctro-machining iy f B o | — | 1000 = mtal == coamc = = composte wA® = mstel = Corwmic s polymer == composite o jon thickness mm) Sand casting| I T Dee casting | — | | ¢ ) Pvestment castrg | | Sa;d casting 5 [ i Low-preseure casting L [ | e casting Forgng | lvestmentcastimg = Extrusion| | 4 Centrifugal casting ) & 3 Shest forming | | Forging | ] 28] Powder methods | | S N [ Extrusion | 2 5 Bloctro-machining| seetmm——(— | Sheet forming | 31 Comventional machining e e e e e S — Powder methods o e ) P g lrvs-;:rcu\q e e e l | B Machini’) e p— ‘ € mokding| 7 et fectro- ! [ § Cormpressson moding | i - Rl 1 | [ Machining fee. - - - Rl e I, 3 g Rotational moking —— | | Injection moulding e » Thermo-formng —_— ‘ Blow moulding s i Polymer casting - | Compression moulding S ————— g & PO disabiskapysd R B = Rotational moukding N— | £ S Flemant vinding e e e e o Thermo-forming [ 3 5 Lay-p mahods | Polymer casting | Veoumbeg| 2 [ RIS =T | Resin-transfor moulding | . 107 102 ot 100 10 Filament winding ! ] Lay-up methods 5 “ | g — — = 1 Vacuum bag [ g Ackhasivos | | Additive manufacture fe s +- - | 1 3 Wekdng. metals I | - . - Vieiding, polymers | 1 10 10? 10° 10 10 10° 10 | Economic batch size (units) = metel e corami: «m polymar.. s composie nm, = melsl = comic we polymer = COmposte MFA1S
MEEN 475 Materials in Design Fall 2023 Problem 3 (30 pts.) A 25-mm diameter by 150-mm long cylindrical component will be made of a carbon fiber reinforced polymer (CERP) instead of wood to reduce its weight significantly. The wood has a Young’s Modulus (E) of 10 GPa and a strength (o7) of 70 MPa. A CFRP with a modulus of 100 GPa has been selected. (a) What s the strength of the CFRP if its o1/E is the same as that of the wood? (b) If the displacement (8) due to a tensile load (F) and the length (L) of the cylindrical component remains the same, what is the radius of the CFRP component? E S=FL/AE g = f A is the cross-sectional area F= 5 A r 1 ) 0) d=aSmw £z OGR =T0 MPs e B DS OA e (700-18 )70 = |SOmw 1 F: 5L{qx\0bN Af'Trl GP 70’0 - 0.07 E 1010 5: % ?P o0.07 - : - : (100 401)050'»5) = U/O'p—)iég’/b’) qu= 00T ¢ Q tret) (10710 = 0.07-090 0°) Gr c=) (10016 Seeap = 00 MP | ical 1000/ Modulus -strength | | Technica Atai and potymars: yd s, o, ] Ceramics, glasses: modulus of ruphure, MOR 1 Elastomers: tonsile lear strength, oy Composdes: lensie feiure. o 100 = - Yield before 0 = " > g1 [T & Nontechnical N . [c) i :Z_\ 2 = ceramics 7 ’ F Weod = s crnvrcompcfllru/'l, L2 E] Phencic ol g Selie 3 - 7 mers st el iet 8 | vl strain ‘ & 2oy el E L] K PMMA - Ao 4 0 =10 Foams |, . PG, 5k 2 1 < A 3 5 a® -3 P - +%5%°]( Deven . ” A guidedinos | .° /’,:'/; T B 2 4"1, ,1 . 0.17 A Ja B g2 I3 Buckling » before yield - \ Elastomers ! 10° | was i - 3 ! 0 1 10 100 1000 10,000 5 Strength, o; (MPa)
e MEEN 475 Materials in Design Problem 4 (26 pts.) Identify the cheapest metal satisfying all of the following conditions e without decomposition up to 150 °C o E%4/p>0.0423 (GPa)*/*/(kg/m?), e p < 7000kg/m3 and e strength o¢> 300 MPa conditions? Show search region, lines and list the possible metals in each chart used. E% Young's mmth - Dmsdy) v OOHZS - 1000 f 100 £ ro.0M>f e e / :‘O E *0. wave spoed .- 10°mvs E=arld ] e foams, 's modulus. /7:\(70 ANO, e Tiatoys ililp fon— V! lloys ) )——4,-0« S0y ) Metals 95-1 Lead soys apys ichnical . 5 ' NS e - 1000 E—lolg':"p 5\ o v 7l - ) gt = - s astoms = 10, c=W% T : i / I Poyurtfane i &y oo iscprene _ ¥ | (Q_,,z-,mm\m R foamns o (8 o \/ L "7 Elastomers Pre ne N a0 10t 410 mE | )4 . 10 100 1000 10,000 Density p (kg/m°) G T TS N " [Max service temperature Silcen carbide : [t Auminum nirida Ziconia Coramic foams o Tungsten sfoys Boron caibide ?_ 15001 ¥ Aumina 4 Siica glass 2 Nickek-based Sticon naride 4 suparaloys | Brick, 2 | Tungsten caibide g 1000 1~ 3 s "’ |,ourlmm ic Staniess stedt | 2 ¢ ‘ icon g Low alloy steel £ s00] Trarwmatoys | PTFE Polyester, ngd H g O /&uw yester, gk K /I PA pp PUR £ Cu-alioys "lllm "- PEPS /" pvel ) /yu &% fi]f"hnylfim)fi.) 0 Neoprane 2Zn-alloys PET ABS by Potymer foams| Lead alloys Meotals Polymers | Ceramics Hybrids MFA 03 T T -
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MEEN 475 Materials in Design Fall 2023 10,000 f=———— Strength - Density Metals and pob wength, o, nplire, MOF 1000 s e gth, o, 100 Natural Woods ! N matorials ~__ : V. b\ - i Figid polymer foams N, minimum mass design < hxitie potmec -+ ,q” h\l_v'l" A 00 1000 10,000 Density p (kg/m’) y TR TP Technic: Modulus - Relative cost/volume Stardoss stools . SN B WC cel s 10,000 s Cé 2 ,\,cL——;s W aloys — — (- AN Nontechnical S { ceramics = - X Melalz_‘ 3 o L E Concgs N\ > cre = 4 I 'S conostes w104 — ' H E] 3 & - 14 ° c 3 Guide lines for > minimum cost ! ol edesion’=/f 0.01 4/ A 00 0.01 100 Relative cost per unit volume C, 5 ! Losed ofl nese chowds and Fre wlu'\remcflm Yo meted needs Yo WMeel e ek metll e M