Shell Buckling Design Criteria Based on Manufacturing Imperfection Signatures

Hilburger, Mark W.; Nemeth, Michael P.; Starnes, James H.

doi:10.2514/6.2003-1843

Cited by 28 publications

(20 citation statements)

References 20 publications

(16 reference statements)

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“…As inclusion of initial imperfections is of great importance when evaluating panel stability behaviour [27,[29][30]] the out-of-plane distortions of the experimental specimens in their test conditions were accurately measured using a Co-ordinate Measuring Machine (CMM). This data allowed the representation of actual test specimen geometric imperfections within the appropriate simulations.…”

Section: Imperfection Modellingmentioning

confidence: 99%

Non-prismatic sub-stiffening for stiffened panel plates—Stability behaviour and performance gains

Quinn

Murphy

McEwan

et al. 2010

Thin-Walled Structures

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(limit 100)Previous work has demonstrated the potential to introduce plate element sub-stiffening to increase the local stability and thus static strength performance of integrally machined aluminium alloy stiffened panels. The introduction of plate element prismatic sub-stiffening modifies local plate buckling behaviour and within realistic design constraints, may produce sizable performance gains with equivalent mass designs. This article examines through experimental and computational analysis the potential of non-prismatic sub-stiffening for tailoring local plate stability performance. Using non-prismatic sub-stiffening, the experimental work demonstrates potential initial buckling performance gains with equivalent mass designs (+185%), and computationally, potential mass savings with equivalent static strength performance designs (-9.4%). BackgroundThe structural configuration of transport vehicles typically includes the use of stiffened panels given their design potential for combined lightweight with high strength and stiffness.Stiffened panel structures generally comprise an external plate, divided and supported longitudinally and laterally by internal stiffeners. Additional weight-savings are possible if the sub-divided plate elements are allowed, and design to locally buckle at load levels below the ultimate required capacity of the structure. This characteristic is due to the stable postbuckling response of stiffened panels to compression and shear loading. The longitudinal and lateral stiffeners then carry additional loading to reach the ultimate capacity of the structure.Stiffened panel structures are therefore frequently designed with elastic plate buckling at load levels expected in-service or with plastic plate buckling at the maximum in-service loads and for ultimate collapse at factored load levels, which consider in-service loading plus an appropriate safety factor.Recent advances in the strength and damage tolerance characteristics of available materials offer opportunities for increased stiffened panel working and limit stresses, for example with next generation Aluminium-Lithium alloys [1]. To design to these higher working stresses it is on occasion desirable to increase the local panel plate element stability without increasing the volume of material at the cost of increased manufacturing complexity. Such improvement in local plate buckling performance is plausible by introducing plate element sub-stiffening[2]. The concept of plate sub-stiffening relies on the introduction of local plate element structural features which transform the plate into a panel and which if design correctly will result in increased stability. ACCEPTED MANUSCRIPT Page 3 of 40 Previous work -Prismatic sub-stiffeningThe concept of stiffened panel sub-stiffening has previously been experimentally demonstrated for 'thin', moderately loaded, post-buckling aerospace applications [8]. The experimental work focused on specimens with three longitudinal stiffeners and examined prismatic sub-stiffening concepts u...

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Section: Imperfection Modellingmentioning

confidence: 99%

Non-prismatic sub-stiffening for stiffened panel plates—Stability behaviour and performance gains

Quinn

Murphy

McEwan

et al. 2010

Thin-Walled Structures

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“…Moreover, the measured data in Ref. 5 indicates that as the wave number increases in either the axial or circumferential direction, the amplitude quickly diminishes.…”

Section: Imperfection Sensitivity Estimates For Composite Sandwicmentioning

confidence: 99%

“…Additionally, the Fourier cosine series representations of measured cylinder imperfections given in Ref. 5 indicate that the dominant waveform comprising the measured data (other than the elliptical waveform not considered herein) corresponds to the (1, 2) bifurcation mode with an amplitude equal to 20% of the wall thickness. Moreover, the measured data in Ref.…”

Section: Imperfection Sensitivity Estimates For Composite Sandwicmentioning

confidence: 99%

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Buckling Imperfection Sensitivity of Axially Compressed Orthotropic Cylinders

Schultz¹,

Nemeth²

2010

51st AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials ConferenceSelf Cite

8
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7
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Structural stability is a major consideration in the design of lightweight shell structures. However, the theoretical predictions of geometrically perfect structures often considerably over predict the buckling loads of inherently imperfect real structures. It is reasonably well understood how the shell geometry affects the imperfection sensitivity of axially compressed cylindrical shells; however, the effects of shell anisotropy on the imperfection sensitivity is less well understood. In the present paper, the development of an analytical model for assessing the imperfection sensitivity of axially compressed orthotropic cylinders is discussed. Results from the analytical model for four shell designs are compared with those from a general-purpose finite-element code, and good qualitative agreement is found. Reasons for discrepancies are discussed, and potential design implications of this line of research are discussed. = denotes an adjacent equilibrium state

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“…[4][5][6][7][8] However, there are many limitations to the current design recommendations for buckling-critical cylinders that have led to a recent reinvestment in shell buckling research and design technology development by several groups. [9][10][11][12] The primary limitations in the current design practice, cited by these R&D groups, includes the following, in no particular order:…”

Section: Introductionmentioning
confidence: 99%

Developing the Next Generation Shell Buckling Design Factors and Technologies
Hilburger
¹

2012
53rd AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials ConferenceSelf Cite
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Directorate. The SBKF project has the current goal of developing less-conservative, robust shell buckling design factors (a.k.a. knockdown factors) and design and analysis technologies for light-weight stiffened metallic launch vehicle (LV) structures. Preliminary design studies indicate that implementation of these new knockdown factors can enable significant reductions in mass and mass-growth in these vehicles and can help mitigate some of NASA's LV development and performance risks. In particular, it is expected that the results from this project will help reduce the reliance on testing, provide high-fidelity estimates of structural performance, reliability, robustness, and enable increased payload capability. The SBKF project objectives and approach used to develop and validate new design technologies are presented, and provide a glimpse into the future of design of the next generation of buckling-critical launch vehicle structures.

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Shell Buckling Design Criteria Based on Manufacturing Imperfection Signatures

Cited by 28 publications

References 20 publications

Non-prismatic sub-stiffening for stiffened panel plates—Stability behaviour and performance gains

Non-prismatic sub-stiffening for stiffened panel plates—Stability behaviour and performance gains

Buckling Imperfection Sensitivity of Axially Compressed Orthotropic Cylinders

Developing the Next Generation Shell Buckling Design Factors and Technologies

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