Numerical Derivation of Buckling Knockdown Factors for Isogrid-Stiffened Cylinders with Various Shell Thickness Ratios

<table class="figure-group"><tr class="fig-image" id="a"><td><object data="https://static.hindawi.com/articles/ijae/volume-2020/9851984/figures/9851984.fig.0016a.svgz" name="9851984.fig.0016a" type="image/svg+xml"></object></td></tr><tr class="fig-caption"><td><b>(a) </b>Detailed model (<svg height="10.7866pt" id="M168" style="vertical-align:-2.150701pt" version="1.1" viewbox="-0.0498162 -8.6359 30.7076 10.7866" width="30.7076pt" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink"><g transform="matrix(.013,0,0,-0.013,0,0)"><path d="M699 368C699 549 574 666 407 666C186 666 23 488 23 277C23 113 129 -3 288 -13L307 -26C431 -111 501 -139 533 -147C559 -154 613 -163 658 -164L666 -141C597 -111 507 -66 430 -11L416 -1C580 42 699 190 699 368ZM601 371C601 227 518 54 381 22L354 40L278 24C175 47 120 145 120 269C120 451 235 631 398 631C540 631 601 521 601 371Z"></path></g><g transform="matrix(.013,0,0,-0.013,13.018,0)"><path d="M535 323V373H52V323H535ZM535 138V188H52V138H535Z"></path></g><g transform="matrix(.013,0,0,-0.013,24.281,0)"><path d="M153 550H386L412 615L406 623H120L82 318C104 327 142 338 184 338C294 338 347 275 347 187C347 112 305 39 221 39C160 39 119 71 97 89C88 97 80 96 71 90C59 80 50 67 49 57C48 45 52 36 66 23C80 9 123 -12 169 -12C221 -11 288 15 342 59C403 109 431 165 431 225C431 308 366 395 238 395C212 395 165 379 127 364L153 550Z"></path></g></svg> kN)</td></tr><tr class="fig-image" id="b"><td><object data="https://static.hindawi.com/articles/ijae/volume-2020/9851984/figures/9851984.fig.0016b.svgz" name="9851984.fig.0016b" type="image/svg+xml"></object></td></tr><tr class="fig-caption"><td><b>(b) </b>Equivalent model (<svg height="10.7866pt" id="M169" style="vertical-align:-2.150701pt" version="1.1" viewbox="-0.0498162 -8.6359 30.7076 10.7866" width="30.7076pt" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink"><g transform="matrix(.013,0,0,-0.013,0,0)"><path d="M699 368C699 549 574 666 407 666C186 666 23 488 23 277C23 113 129 -3 288 -13L307 -26C431 -111 501 -139 533 -147C559 -154 613 -163 658 -164L666 -141C597 -111 507 -66 430 -11L416 -1C580 42 699 190 699 368ZM601 371C601 227 518 54 381 22L354 40L278 24C175 47 120 145 120 269C120 451 235 631 398 631C540 631 601 521 601 371Z"></path></g><g transform="matrix(.013,0,0,-0.013,13.018,0)"><path d="M535 323V373H52V323H535ZM535 138V188H52V138H535Z"></path></g><g transform="matrix(.013,0,0,-0.013,24.281,0)"><path d="M153 550H386L412 615L406 623H120L82 318C104 327 142 338 184 338C294 338 347 275 347 187C347 112 305 39 221 39C160 39 119 71 97 89C88 97 80 96 71 90C59 80 50 67 49 57C48 45 52 36 66 23C80 9 123 -12 169 -12C221 -11 288 15 342 59C403 109 431 165 431 225C431 308 366 395 238 395C212 395 165 379 127 364L153 550Z"></path></g></svg> kN)</td></tr></table>

<div>Deformed shapes of the isogrid-stiffened cylinder (<span class="nowrap"><svg height="12.5612pt" id="M167" style="vertical-align:-3.27287pt" version="1.1" viewbox="-0.0498162 -9.28833 61.2595 12.5612" width="61.2595pt" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink"><g transform="matrix(.013,0,0,-0.013,0,0)"><path d="M610 18C585 26 567 34 540 68C517 97 499 128 476 171C452 215 425 276 413 304C496 332 570 394 570 494C570 555 545 595 509 619S419 650 364 650H139L133 622C216 615 219 612 203 527L129 132C112 40 105 36 23 28L17 0H279L285 28C199 34 194 40 211 132L239 284H284C320 284 334 275 351 236C374 182 394 140 420 93C459 23 495 -1 592 -8H600L610 18ZM480 485C480 424 449 372 403 342C374 323 338 316 293 316H245L291 562C296 589 301 601 311 608S337 618 358 618C432 618 480 575 480 485Z"></path></g><g transform="matrix(.013,0,0,-0.013,8.151,0)"><path d="M368 703H309L44 -163H104L368 703Z"></path></g><g transform="matrix(.013,0,0,-0.013,13.512,0)"><path d="M324 430H196L233 583L223 592L145 529L120 430H54L29 396L31 388H111L56 126C33 15 54 -12 77 -12C137 -12 214 57 250 95L233 119C208 92 155 59 138 59C126 59 120 70 131 125L186 390L298 394L324 430Z"></path></g><g transform="matrix(.0091,0,0,-0.0091,17.88,3.132)"><path d="M380 106C343 72 306 56 265 56C195 56 116 112 115 248C235 252 361 262 377 265C396 269 400 277 400 297C400 374 333 449 250 449H249C198 449 144 421 103 376S37 269 37 201C37 88 109 -12 232 -12C263 -12 332 6 395 84L380 106ZM225 412C281 412 315 364 314 312C314 297 308 292 290 292C232 290 176 289 120 289C135 370 180 412 225 412Z"></path></g><g transform="matrix(.0091,0,0,-0.0091,21.748,3.132)"><path d="M99 437H52L25 408L28 397H99V104C99 38 91 32 32 26V0H246V25C185 32 178 38 178 104V397H365V104C365 38 358 32 303 25V0H526V25C451 32 444 37 444 104V397H555C565 404 568 428 563 437H444V471C443 562 453 609 466 629C476 647 492 661 518 661C551 661 581 639 600 620C609 611 619 612 629 620C637 626 647 636 650 644C654 654 654 666 645 677C627 697 597 710 564 712C521 707 476 686 432 642C412 664 374 688 316 690C269 685 230 668 190 636C139 596 120 551 111 525C104 505 99 477 99 449V437ZM365 437H178V461C178 537 192 580 209 605C223 627 245 648 283 648C336 648 374 615 394 585C384 566 378 550 374 533C369 516 365 488 365 456V437Z"></path></g><g transform="matrix(.013,0,0,-0.013,31.017,0)"><path d="M535 323V373H52V323H535ZM535 138V188H52V138H535Z"></path></g><g transform="matrix(.013,0,0,-0.013,42.279,0)"><path d="M384 0V27C293 34 287 42 287 114V635C232 613 172 594 109 583V559L157 557C201 555 205 550 205 499V114C205 42 199 34 109 27V0H384Z"></path></g><g transform="matrix(.013,0,0,-0.013,48.519,0)"><path d="M412 140C382 77 369 73 315 73H129L270 222C362 320 402 379 402 466C402 571 322 635 234 635C177 635 130 609 99 576L42 495L64 475C90 514 133 568 201 568C274 568 318 519 318 435C318 349 255 267 193 193C144 135 87 78 32 23V0H405C417 45 427 89 440 131L412 140Z"></path></g><g transform="matrix(.013,0,0,-0.013,54.759,0)"><path d="M412 140C382 77 369 73 315 73H129L270 222C362 320 402 379 402 466C402 571 322 635 234 635C177 635 130 609 99 576L42 495L64 475C90 514 133 568 201 568C274 568 318 519 318 435C318 349 255 267 193 193C144 135 87 78 32 23V0H405C417 45 427 89 440 131L412 140Z"></path></g></svg>).</span></div>

International Journal of Aerospace Engineering

fig16

Figure 16

Figure 16: Numerical Derivation of Buckling Knockdown Factors for Isogrid-Stiffened Cylinders with Various Shell Thickness Ratios 