Buckling Imperfection Sensitivity of Conical Sandwich Composite Structures for Launch-Vehicles

Sleight, David W.; Satyanarayana, Arunkumar; Li, Yingyong; Schultz, Marc R.

doi:10.2514/6.2018-1696

Cited by 8 publications

(3 citation statements)

References 8 publications

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“…A comprehensive overview regarding this project is for example given in [2]. Recently, comprehensive imperfection sensitivity studies for cylindrical [41] and conical [42], [43] composite shells were published which indicate that the current NASA recommendations for composite shells may be very conservative for modern launch-vehicle structures. Consequently, it was suggested to investigate the buckling response of composite shells through buckling tests and analytical predictions.…”

Section: Introductionmentioning

confidence: 99%

Buckling analysis of an imperfection-insensitive hybrid composite cylinder under axial compression – numerical simulation, destructive and non-destructive experimental testing

Wagner

Petersen

Khakimova³

et al. 2019

Composite Structures

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Thin-walled shells like cylinders are primary structures in launch-vehicle systems. When subjected to axial loading these shells are prone to buckling. The corresponding critical load heavily depends on deviations from the ideal shell shape. In general, these deviations are defined as geometric imperfections and although imperfections exhibit comparatively low amplitudes, they can significantly reduce the critical load. Considering the influence of geometric imperfections adequately into the design process of thin-walled shells poses major challenges for structural design. An alternative to robust design of thin-walled shell by accurate consideration of geometric imperfections is the development of a robust or imperfection-insensitive shell architecture. In this article a special hybrid cylinder is presented and analyzed. The composite shell design is based on an interstage structure of the Ariane 6 by MT Aerospace and has special CFRP belts which are intended to reduce the imperfection sensitivity of the shell. The shell was tested at the German Aerospace Center in Braunschweig and the corresponding results are presented and described. The hybrid cylinder was analyzed with the Southwell-method and geometrically nonlinear finite element analyzes. The results show that the Southwell-method delivers conservative buckling load estimations and that the CFRP belts reduce the imperfection sensitivity significantly.

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Section: Introductionmentioning

confidence: 99%

Buckling analysis of an imperfection-insensitive hybrid composite cylinder under axial compression – numerical simulation, destructive and non-destructive experimental testing

Wagner

Petersen

Khakimova³

et al. 2019

Composite Structures

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“…The same design requirements may also apply to payload adapters. The buckling of composite cylinders and cones has been investigated for current aerospace applications [e.g., [2][3][4][5][6][7][8]. Designs for traditional manufacturing methods typically use heavy circumferential rings to join conical and cylindrical structures.…”

Section: Introductionmentioning

confidence: 99%

Testing of a Composite Conical-Cylindrical Shell

Rudd

Schultz

Gardner

et al. 2023

AIAA SCITECH 2023 Forum

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Launch-vehicle shell structures, which can be comprised of both cylindrical and conical sections, are known to be susceptible to buckling due to their large radius-to-thickness ratios. The advancements in composite manufacturing and numerical methods have enabled designers to consider more nontraditional shapes, such as connecting the conical and cylindrical sections with a toroidal transition to create a single-piece conical-cylindrical shell. This single-piece construction eliminates the need for a heavy interface ring between sections and has the potential to save mass. To better understand the buckling behavior, a composite conical-cylindrical shell was designed, fabricated, and tested. Prior to test, a finite element model that included thickness variations and radial imperfections was created. The test article buckled elastically at 251.8 kN, approximately 8.8% higher than the predicted buckling load of 231.4 kN Continued research in conical-cylindrical structures has the potential to expand the design space for launch-vehicle structures and lead to improved designs and reduced weight.

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“…A comprehensive overview regarding this project is for example given in [2]. Recently, comprehensive imperfection sensitivity studies for cylindrical [25] and conical [40], [41] sandwich composite shells were published which indicate that the current NASA recommendations for composite shells may be very conservative for modern launch-vehicle structures. Consequently, it was suggested to investigate the buckling response of composite sandwich shells through buckling tests and analytical predictions.…”

Section: Introductionmentioning

confidence: 99%

Decision tree-based machine learning to optimize the laminate stacking of composite cylinders for maximum buckling load and minimum imperfection sensitivity

Wagner

Köke

Dähne

et al. 2019

Composite Structures

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Köke, H.; Dähne, S.; Hühne, C.; Niemann, S.; Khakimova, R. Decision tree-based machine learning to optimize the laminate stacking of composite cylinders for maximum buckling load and minimum imperfection sensitivity, Composite Structures AbstractLaunch-vehicle primary structures like cylindrical shells are increasingly being built as monolithic composite and sandwich composite shells. These imperfection sensitive shells are subjected to axial compression due to the weight of the upper structural elements and tend to buckle under axial compression. In the case of composite shells the buckling load and imperfection sensitivity depend on the laminate stacking sequence.Within this paper multi-objective optimizations for the laminate stacking sequence of composite cylinder under axial compression are performed. The optimization is based on different geometric imperfection types and a brute force approach for three different ply angles. Decision tree-based machine learning is applied to derive general design recommendations which lead to maximum buckling load and a minimum imperfection sensitivity.The design recommendation are based on the relative membrane, bending, in-plane shear and twisting stiffnesses. Several optimal laminate stacking sequences are generated and compared with similar laminate configurations from literature. The results show that the design recommendations of this article lead to high-performance cylinders which outperform comparable composite shells considerably. The results of this article may be the basis for future lightweight design of sandwich and monolithic composite cylinders of modern launch-vehicle primary structures. t Wall thickness of cylindrical shells tply Ply thickness u Axial shortening  Ply angle  Ply angle  Ply angle  knockdown factor Wilkins [1975]

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Buckling Imperfection Sensitivity of Conical Sandwich Composite Structures for Launch-Vehicles

Cited by 8 publications

References 8 publications

Buckling analysis of an imperfection-insensitive hybrid composite cylinder under axial compression – numerical simulation, destructive and non-destructive experimental testing

Buckling analysis of an imperfection-insensitive hybrid composite cylinder under axial compression – numerical simulation, destructive and non-destructive experimental testing

Testing of a Composite Conical-Cylindrical Shell

Decision tree-based machine learning to optimize the laminate stacking of composite cylinders for maximum buckling load and minimum imperfection sensitivity

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