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Calculation for Matereal C19400 annealed strip

Ang LeeApril 9, 2010

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C19400based on “Metal handbook,9th edition, volu 2, pp 311-313

97.5 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 maxfor 100% contact with C194

Temperature=607 K (MAX) 50% (closed to 0% case contact with c19400

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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

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Thermal stress_Sth 100% contact case

100 % contact, Beam sectionSth~17 ksi < 36 ksi, ok

100% contact , top 1” plateSth ~14 ksi << 36 ksi ok and also < 18 ksi (yield ) ok

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Thermal stress_Sth 100% contact case

• For 100% contact case (most likely case) , C19400 should be fine.

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C19400_50% contact case

50% contact, beam section Thermal stress _ Sth

50% contact for the beam section, 1/3” from bottom

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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 plate1/3” from the bottom, Sth is quite low is 11 ksi << 36 ksi and 18 ksi

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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).

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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.

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Structure calculation by using 0.33” as top plate

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Buckling SF (vacuum load) by using 0.33” as top plate

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Thermal stress _50 % contact

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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.