Page 231 - Biaxial Multiaxial Fatigue and Fracture

Critical Plane-Energy Based Approach for Assessment of Biaxial Fatigue Damage where ... 215

The total damage in a block loading history is calculated by accumulating the parameter for the
block loading history consisting of three 01 Cycles st+p2nd+ p3rd).
Table 2 lists 0-angles, at which the largest Mohr's circles are obtained for various block
loading histories shown in Fig 1.
Table 2. The most damaging planes obtained for various block loading histories.

Histories a 0-angles (degrees) of most damaging planes of 01 cycles
e1 02 03 04 05 06
Al-A2 1 90 270 --- --- _-- -__
Bl-B2 2 100 250 470 620 --- -__
B3-B4 2 90 270 450 630 --- -__
Cl-C2 3 80 270 460 620 810 1000
c3-c4 3 110 260 460 620 800 1000

FATIGUE LEE RESULTS AND CORRELATIONS

Stress amplitude-number of blocks to failure
Figures 7a-7c present the number of blocks to failure versus the magnitude of biaxial stress
amplitude for the load histories tabulated in Table 2.

..................................................
(In-phase loading) B2(a=2)
............................... ..... . ............................. ................ w C2(n=3)

.! ... ?.....!..'. '.L .....
40 .......... I ....... t .... I .....e*oadin.

: Including transverse I
-
rneanstrtrx j
-I
........... L .....
..................... I ....... .... ..... "..... A. ,...I \-I ,
L ........ 6cj
I
I 0' lo-( 1 o6
Number of blocks to failure
Fig. 7. Stress amplitude versus number of blocks to failure for various biaxial fatigue tests.