PSI - Issue 76

D. Kaschube et al. / Procedia Structural Integrity 76 (2026) 19–26

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Table 1: Summary of constant amplitude strain-controlled fatigue tests for CMF manufactured Ti-6Al-4V under fully-reversed and mean strain conditions

R ε

R σ

N f

R ε

R σ

N f

ε a

σ a

σ m

ε a

σ a

σ m

[ − ] [ − ]

[ MPa ] [ MPa ] [ − ]

[ − ]

[ − ] [ − ]

[ MPa ] [ MPa ] [ − ]

[ − ]

-1 0.0080 772 -19

-1.05 304

−∞ 0.0047 546 -220 -2.35 7747 −∞ 0.0049 569 -243 -2.49 12291 −∞ 0.0044 516 -277 -3.31 29274 −∞ 0.0045 522 -278 -3.28 30827 −∞ 0.0046 538 -278 -3.15 33021 −∞ 0.0040 502 -357 -5.92 92179 −∞ 0.0040 497 -373 -7.01 312142

-1 0.0065 807 -114 -1.33 330

-1 0.0075 755 -12 -1 0.0069 705 5 -1 0.0063 669 -70 -1 0.0058 585 -9 -1 0.0044 452 23 -1 0.0038 429 -90 -1 0.0031 331 10 -1 0.0025 266 58

-1.03 438 -0.99 759 -1.23 1270 -1.03 1323

-1 0.0053 639 -163 -1.69 1843

-0.90 12389 0 0.0079 805 39

-0.91 144

-1.53 22657 0 0.0059 648 118 -0.69 540 -0.94 38858 0 0.0044 488 218 -0.38 1840

-0.64 44865 0 0.0032 361 252 -0.18 7877 -1 0.0033 372 -111 -1.85 46409 0 0.0027 288 199 -0.18 11299 −∞ 0.0083 878 -116 -1.30 81 0 0.0022 247 103 -0.41 27697 −∞ 0.0077 821 -139 -1.41 284 0 0.0019 226 93 -0.42 40450 −∞ 0.0078 788 -142 -1.44 288 0 0.0018 210 58 -0.57 59309 −∞ 0.0066 752 -144 -1.47 864 0 0.0016 183 152 -0.09 75515 −∞ 0.0054 645 -212 -1.98 2315 0 0.0015 165 129 -0.12 125927 −∞ 0.0054 610 -206 -2.02 2602 0 0.0013 150 87 -0.26 294999 −∞ 0.0047 579 -233 -2.35 6288

Table 2: Static and fatigue parameters used for further evaluation of the mean strain influence

σ ′ f

ε ′ f

E

b

c

σ u

σ y

[ MPa ] [ MPa ] [ − ] [ MPa ] [ MPa ] 116000 2464.0 -0.1715 0.0711 -0.6098 1042.5 941.8 [ − ] [ − ]

10 − 2

10 − 3 Strain amplitude ε a

10 − 2 Strain amplitude ε a

ε a ε a , el ε a , pl

R ε = − 1 R ε = 0 R ε = −∞

10 − 3

10 2

10 3

10 4

10 1

10 2

10 3

10 4

10 5

10 5

10 6

Reversals to failure N f

Reversals to failure N f

(a) Strain-life plot of fully-reversed fatigue data including the corresponding elastic and plastic strain data and fits.

(b) Comparison of strain amplitude versus fatigue life data for strain-controlled fatigue tests with di ff erent R ε .

Fig. 2: Strain-life plots according to Co ffi n-Manson for di ff erent values of R ε , including fully reversed test data.

an influence, but due to the hardening behaviour of the material, this only becomes apparent above approx. 10 4 load cycles. It is therefore essential to take mean strain into account. The extent to which the existing models can be applied is shown in Figures 3b to 3e.