1、MATERIALS SELECTIONECONOMIC,ENVIRON.,&DESIGN ISSUESISSUES TO ADDRESS.Price and availability of materials.How do we select materials based on optimal performance?Applications:-shafts under torsion -bars under tension -plates under bending -materials for a magnetic coil.NoImageChapter 22-2 Current Pri
2、ces on the web(a):-Short term trends:fluctuations due to supply/demand.-Long term trend:prices will increase as rich deposits are depleted.Materials require energy to process them:-Energy to produce materials(GJ/ton)Al PET Cu steel glass paper237(17)(b)103(13)(c)97(20)(b)20(d)13(e)9(f)-Cost of energ
3、y used in processing materials($/GJ)(g)elect resistance propane natural gas oil25 11 9 8 a http:/www.statcan.ca/english/pgdb/economy/primary/prim44.htm a http:/ b http:/www.automotive.copper.org/recyclability.htm c http:/ d http:/www.steel.org.facts/power/energy.htm e http:/eren.doe.gov/EE/industry_
4、glass.html f http:/www.aifq.qc.ca/english/industry/energy.html#1 g http:/www.wren.doe.gov/consumerinfo/rebriefs/cb5.htmlEnergy using recycled material indicated in green.PRICE AND AVAILABILITYNoImageChapter 22-3 Reference material:-Rolled A36 plain carbon steel.Relative cost,$,fluctuates less over t
5、ime than actual cost.Based on data in Appendix C,Callister,6e.AFRE,GFRE,&CFRE=Aramid,Glass,&Carbon fiber reinforced epoxy composites.$/kg($/kg)refmaterialRELATIVE COST,$,OF MATERIALS4 Bar must not lengthen by more than d under force F;must have initial length L.Maximize the Performance Index:-Stiffn
6、ess relation:-Mass of bar:Fc2 EdL(s=Ee)M Lc2 Eliminate the free design parameter,c:M FL2dE P Especified by applicationminimize for small M(stiff,light tension members)STIFF&LIGHT TENSION MEMBERS5 Bar must carry a force F without failing;must have initial length L.Maximize the Performance Index:-Stre
7、ngth relation:-Mass of bar:M Lc2 Eliminate the free design parameter,c:specified by applicationminimize for small M P sf(strong,light tension members)M FLNsf sfNFc2STRONG&LIGHT TENSION MEMBERS6 Bar must carry a moment,Mt;must have a length L.Maximize the Performance Index:-Strength relation:-Mass of
8、 bar:Eliminate the free design parameter,R:specified by applicationminimize for small M(strong,light torsion members)fN2MtR3 M R2L M 2 NMt2/3Lf2/3 P f2/3STRONG&LIGHT TORSION MEMBERSNoImageChapter 22-DATA:STRONG&LIGHT TENSION/TORSION MEMBERSIncreasing P for strong tension members Increasing P for str
9、ong torsion members 0.1 1 10 3 0 1 10 10 2 10 3 10 4 Density,(Mg/m 3)Strength,s f (MPa)slope=1 0.1 Metal alloys Steels Ceramics PMCs Polymers|grain grain wood Cermets slope=3/2 7Adapted from Fig.6.22,Callister 6e.(Fig.6.22 adapted from M.F.Ashby,Materials Selection in Mechanical Design,Butterworth-H
10、einemann Ltd.,1992.)NoImageChapter 22-0.1 1 10 3 0 0.1 1 10 10 2 10 3 10 4 Cermets Steels Density,(Mg/m 3)Strength,sf(MPa)slope=2 Increasing P for strong bending members Metal alloys Ceramics PMCs Polymers|grain grain wood 8 Maximize the Performance Index:P s1/2Adapted from Fig.6.22,Callister 6e.(Fi
11、g.6.22 adapted from M.F.Ashby,Materials Selection in Mechanical Design,Butterworth-Heinemann Ltd.,1992.)DATA:STRONG&LIGHTBENDING MEMBERSNoImageChapter 22-9 Other factors:-require sf 300MPa.-Rule out ceramics and glasses:KIc too small.Maximize the Performance Index:P f2/3 Numerical Data:Lightest:Carb
12、on fiber reinf.epoxy (CFRE)member.material CFRE(vf=0.65)GFRE(vf=0.65)Al alloy(2024-T6)Ti alloy(Ti-6Al-4V)4340 steel(oil quench&temper)(Mg/m3)1.5 2.0 2.8 4.4 7.8 P(MPa)2/3m3/Mg)73 52 16 15 11Data from Table 6.6,Callister 6e.f(MPa)1140 1060 300 525 780 DETAILED STUDY I:STRONG,LIGHT TORSION MEMBERSNoIm
13、ageChapter 22-10 Minimize Cost:Cost Index M$/P(since M 1/P)Numerical Data:Lowest cost:4340 steel(oil quench&temper)material CFRE(vf=0.65)GFRE(vf=0.65)Al alloy(2024-T6)Ti alloy(Ti-6Al-4V)4340 steel(oil quench&temper)$80 40 15 110 5P(MPa)2/3m3/Mg)73 52 16 15 11($/P)x100 112 76 93 748 46 Need to consid
14、er machining,joining costs also.Data from Table 6.7,Callister 6e.DETAILED STUDY I:STRONG,LOW COST TORSION MEMBERSNoImageChapter 22-11 Background(2):High magnetic fields permit study of:-electron energy levels,-conditions for superconductivity -conversion of insulators into conductors.Largest Example
15、:-short pulse of 800,000 gauss (Earths magnetic field:0.5 Gauss)Technical Challenges:-Intense resistive heating can melt the coil.-Lorentz stress can exceed the material strength.Goal:Select an optimal coil material.(1)Based on discussions with Greg Boebinger,Dwight Rickel,and James Sims,National Hi
16、gh Magnetic Field Lab(NHMFL),Los Alamos National Labs,NM(April,2002).(2)See G.Boebinger,Al Passner,and Joze Bevk,Building World Record Magnets,Scientific American,pp.58-66,June 1995,for more information.Pulsed magnetic capable of 600,000 gauss field during 20ms period.Fractured magnet coil.(Photos t
17、aken at NHMFL,Los Alamos National Labs,NM(Apr.2002)by P.M.Anderson)DETAILED STUDY II:OPTIMAL MAGNET COIL MATERIALNoImageChapter 22-12 Applied magnetic field,H:H=N I/L Lorentz hoop stress:Resistive heating:(adiabatic)s I oHRA(sfN)temp increase during current pulse of Dt DT I2eA2cvDt(DTmax)Magnetic fi
18、eld points out of plane.elect.resistivityspecific heat Forcelength I oHLORENTZ STRESS&HEATINGNoImageChapter 22-13 Mass of coil:M=dAL Eliminate free design parameters A,I from the stress&heating equations(previous slide):Applied magnetic field:H=N I/L H2M12R2LoNsfd-Stress requirement specified by app
19、licationPerformance Index P1:maximize for large H2/M HDtMDTmax2 RL1dcvespecified by applicationPerformance Index P2:maximize for large Ht1/2/M-Heating requirement MAGNET COIL:PERFORMANCE INDEX NoImageChapter 22-14 Relative cost of coil:$=$M Eliminate M from the stress&heating equations:Applied magne
20、tic field:H=N I/L-Stress requirement specified by applicationCost Index C1:maximize for large H2/$specified by applicationCost Index C2:maximize for large Ht1/2/$-Heating requirement HDt$DTmax2 RL1d$cve H2$12R2LoNsfd$MAGNET COIL:COST INDEX NoImageChapter 22-15 Data from Appendices B and C,Callister
21、6e:Material 1020 steel(an)1100 Al(an)7075 Al(T6)11000 Cu(an)17200 Be-Cu(st)71500 Cu-Ni(hr)Pt Ag(an)Ni 200 units sf 395 90 572 220 475 380 145 170 462 MPa d 7.85 2.71 2.80 8.89 8.25 8.94 21.5 10.5 8.89 g/cm3$0.8 12.3 13.4 7.9 51.4 12.9 1.8e4 271 31.4 -cv 486 904 960 385 420 380 132 235 456 J/kg-K e 1
22、.60 0.29 0.52 0.17 0.57 3.75 1.06 0.15 0.95 W-m3 P1 50 33 204 25 58 43 7 16 52 sf/d P2 2 21 15 5 3 1 19 1 2 (cv/e)0.5 d C1 63 3 15 3 1 3 1 1 2 P1/$C2 2.5 1.7 1.1 0.6 0.1 0.1 0.1 0.1 0.1 P2/$Avg.values used.an=annealed;T6=heat treated&aged;st=solution heat treated;hr=hot rolled Lightest for a given H
23、:7075 Al(T6)Lightest for a given H(Dt)0.5:1100 Al(an)Lowest cost for a given H:1020 steel(an)Lowest cost for a given H(Dt)0.5:1020 steel(an)C2 C1 P2 P1 INDICES FOR A COIL MATERIALNoImageChapter 22-16 Material costs fluctuate but rise over the long term as:-rich deposits are depleted,-energy costs in
24、crease.Recycled materials reduce energy use significantly.Materials are selected based on:-performance or cost indices.Examples:-design of minimum mass,maximum strength of:shafts under torsion,bars under tension,plates under bending,-selection of materials to optimize more than one property:material for a magnet coil.analysis does not include cost of operating the magnet.SUMMARY
