Trans RINA, Vol 154, Part A2, Intl J Maritime Eng, Apr-Jun 2012
reason might that the stiffeners suffer lateral buckling and then induce panel failure for the FS2-A panels, which are classified as column failure as shown in Figure 13 and 14. The plate and the stiffeners collapse as a unit, which is needed to avoid by strong the stiffeners. For the LS2-A, BS2-A and US2-A panels, the plates occur buckling,
and then induce stiffeners failure. collapse modes are plate-induced failure mode.
100 200 300 400 500
0 US2
3Bay-C1 3Bay-C2 3Bay-C3 3Bay-C4 2Bay1-C5 2Bay1-C6 2Bay2-C7 2Bay2-C8 1Bay-C9
0 2 4 6 8 10 12 14 dL/L(103
) Figure 12 Average stress-shortening curves for US2-A 1 NODAL SOLUTION
STEP=1 SUB =26 TIME=.226274 SEQV
Y (AVG)
DMX =.027007 SMN =.125E+08 SMX =.690E+09
MX MN Z X
MAY 12 2010 00:49:09
(a) LS2-A (b) US2-A Figure 14 Equivalent stresses after collapse for C5
Table 6 Ultimate strengths for the three bays model (MPa) Case
C1 .125E+08 BS2-A3 (a) FS2-A (b) BS2-A 1 NODAL SOLUTION
STEP=1 SUB =11 TIME=.166743 SEQV
Z (AVG)
DMX =.007946 SMN =.207E+07 SMX =.690E+09
MN Y MX X
APR 8 2010 23:53:14
.878E+08 .163E+09 .238E+09 .314E+09 .389E+09 .464E+09 .539E+09 .615E+09 .690E+09 .207E+07 US2-A3 (a) LS2-A (b) US2-A Figure 13 Equivalent stresses after collapse for C3
The slopes of average stress-shortening curves during loading are similar in the FE analyses except 1bay-C9. The boundary condition
affects both the collapse
behaviours and the ultimate strength. However, this influence depends on the stiffener type to some degree. For the FS2-A panels, the average stress-shortening curves during unloading for the C5 and C6 condition are similar for the 1/2+1+1/2 bays model, but drop more slowly than the other cases. For the BS2-A and LS2-A panels, the average stress-shortening curves
during
unloading are similar between different configurations. For the US2-A panels, the average stress-shortening curves during unloading are similar for the C5, C6, C7 and C8 configurations, but drop more slowly than the other 3 bays model configurations.
A-72 .785E+08 .155E+09 .231E+09 .308E+09 .384E+09 .461E+09 .537E+09 .614E+09 .690E+09
FS2-A FS2-B FS2-C FS2-D FS2-E BS2-A BS2-B BS2-C BS2-D BS2-E LS2-A LS2-B LS2-C LS2-D LS2-E US2-A US2-B US2-C US2-D US2-E
C2 C3 C4
455 475 549 517 427 505 546 514 452 515 545 515 375 533 545 512 349 539 545 515 484 484 509 486 497 505 509 487 466 510 509 487 440 520 508 487 424 514 507 487 465 475 487 472 493 493 489 472 496 470 471 471 496 496 479 471 495 496 492 471 399 417 445 426 394 445 444 430 421 441 443 422 412 448 446 422 413 447 451 422
Figure 15 shows the ultimate strength of the three bays model with the C1 condition. From the results shown, increasing the width of the panels, namely the number of the stiffeners or the length of the frames, decreases the ultimate
strength of the stiffened panels. The
displacement in the z direction of the frame is not equal to zero, as shown in Figures 16, which increases with increasing the B0. This is caused by the stiffness of the
©2012: The Royal Institution of Naval Architects Their
For the stiffened panels under consideration, the FS and US series is more sensitive than the BS and LS series to the boundary condition and the geometric model during unloading. The external one side bay in the 3 bays model supply more flexible constraint for the middle bay than external half side bay in the 1/2+1+1/2 bays model. This causes the different equivalent stress between the 3 and 1/2+1+1/2 bays model as shown in Figure 13 and 14.
(a) FS2-A
(b) BS2-A
Stress (Mpa)
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