PSI - Issue 52

A.D. Cummings et al. / Procedia Structural Integrity 52 (2024) 762–784 A. Cummings / Structural Integrity Procedia 00 (2023) 000–000

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Table 2. Mechanical and impact properties of package body BS1503 224 430 LT40 Property Room Temperature ( ≈ 23 ◦ C)

Low Temperature (-40 ◦ C)

E [MPa]

205,000

209,000*

0.3

0.3

ν

3 ]

7,900

7,900 340* 509*

ρ [kg / m

σ y [MPa] σ uts [MPa]

290 466 0.34 N / A N / A

N / A

elong

Charpy [J] (A) Charpy [J] (B)

52 91

K mat is calculated from the master curve equation, Eqn J.5 BS7910 (2019):- K mat = 20 + { 11 + 77 exp [0 . 019( T − T 0 − T K )] }    25 B    0 . 25    ln    1 1 − p f       0 . 25 WhereT 0 is found from the following three equations:- Eqn J.6 BS7910 (2019):- T 27 J = T Cv − C 4 ln C v ( C us v − 27) 27( C us v − C v )

(1)

(2)

C is calculated from Eqn J.7 BS7910 (2019):-

C us v 14 . 3

σ y − 40 ◦ C

C = 34 ◦ C +

(3)

35 . 1 −

And Eqn J.4 BS7910 (2019) provides:-

1000 C us v

σ YRT 12

T 0 = T 27 J − 87 +

(4)

+

T 0 is then corrected to account for dynamic e ff ects by applying Eqn L.15 BS7910 (2019):-

T 0 , st ln ( ˙ K ) Γ − ln ( ˙ K )

(5)

∆ T 0 =

Where Γ is found from Eqn L.16 BS7910 (2019):- Γ= 9 . 9 exp       T 0 , st 190    1 . 66 +    σ y 722    1 . 09   

(6)

Where σ y is the yield stress at the T 0 , st temperature (estimated using equations in chapter 7 BS7910 (2019)) and ˙ K is estimated as Meyers (1994):-

K mat t f

˙ K =

(7)

The final value depends on the thickness of the member at the stressed location and the time to fracture, t f . In the centre of the package base and internal radius, which are highly stressed in a base down drop (as will be shown), K mat = 34MPa.m 0 . 5 andK mat = 33.6MPa.m 0 . 5 respectively. The master curve approach, originally developed for ferritic steels, has been validated for a similar grade of ma terial, ASTM A350 LF5 Norton et al. (2004). It is therefore expected that the fracture toughness estimates are conservative.