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Calculation for Matereal C19400 annealed strip . Ang Lee April 9, 2010. C19400 based on “Metal handbook,9 th edition, volu 2, pp 311-313 97.5 Cu,2.4Fe,0.13 Zn,0.03 P K=260 W/ mK , c=386 J/kg K, alpx =1.6.3e-6/C up 300c, Sy =18.4 ksi at 500 F and 17.8 ksi 550 F.
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Calculation for Matereal C19400 annealed strip Ang Lee April 9, 2010
C19400based on “Metal handbook,9th edition, volu 2, pp 311-31397.5 Cu,2.4Fe,0.13 Zn,0.03 PK=260 W/mK, c=386 J/kg K, alpx=1.6.3e-6/C up 300c,Sy=18.4 ksi at 500 F and 17.8 ksi 550 F Temperature =418 K max for 100% contact with C194 Temperature=607 K (MAX) 50% (closed to 0% case contact with c19400
C19400 • From “Metals handbook,9th Ed, Vol 2, pp311-313, K=264 W/mK and Sy=~18 ksi (T=550 F)_Table 40 “typical elevated-temperature property of annealed C19400 strip • ASME II,part D, Table Y1,c19400 ,SB-543 gives Syield=18 ksi at T=450 F • Allowable Sm=Sy*2/3=18*2/3=12 ksi for structure load • For the thermal stress, 3*Sm=36 ksi
Thermal stress_Sth100% contact case 100 % contact, Beam section Sth~17 ksi < 36 ksi, ok 100% contact , top 1” plate Sth ~14 ksi << 36 ksi ok and also < 18 ksi (yield ) ok
Thermal stress_Sth100% contact case • For 100% contact case (most likely case) , C19400 should be fine.
C19400_50% contact case 50% contact, beam section Thermal stress _ Sth 50% contact for the beam section, 1/3” from bottom
Thermal stress for 50 % contact 50% contact case, for top plate 1”, 90 % area, thermal stress is less 24 ksi, in fact, 1/3” from bottom, thermal stress is only 11 ksi (see left picture 50 % contact, for the top plate 1/3” from the bottom, Sth is quite low is 11 ksi << 36 ksi and 18 ksi
C19400__50% contact_top 1” plate • In fact, the bottom 1/3” area, the thermal stress is less < 11 ksi. • It is well below the allowable for the thermal stress (36 ksi) and even below to the Sy=18 ksi. • Therefore, we could reasonable assuming 2/3 of top plate is mainly for the heat distribution and 1/3 of the bottom section will be used for the structure purpose ( stress due 15 psi and safety factor for buckling).
Stress due to the structure loadby assuming 1/3” as top plate thickness • As we’ve assumed the top 0.66” is only for the heat distribution, then the structure calculation should be done by using the 1/3” at the bottom only. • The stress calculation (0.33” thick for top plate) indicates that Smax=1.9 ksi << Sm=2/3*18=12 ksi • And SF for buckling, due 15 psi , is SF=82, which is more than sufficient.
Conclusion for C19400 • It is very good choice for a combination of high strength and good conductivity application. • It works for 100% contact case (most likely) and it also works for 50% case (most pessimistic case since it is very close to 0% contact). • Since current design has 1” thick top plate. The structure calculation indicates the 1/3” should be more than enough for the structure load. Then, 2/3” can be considered as the purpose of the heat distribution only.