Shell Buckling Knockdown Factors

Metadata Updated: July 17, 2020

The Shell Buckling Knockdown Factor (SBKF) Project, NASA Engineering and Safety Center[HTML_REMOVED](NESC) Assessment #: 07-010-E, was established in March of 2007 by the NESC in[HTML_REMOVED]collaboration with the former NASA Constellation Program (CxP) and now the Space Launch System (SLS) Program. The SBKF Project has the goal of[HTML_REMOVED]developing and experimentally validating improved (i.e., less-conservative, more robust)[HTML_REMOVED]analysis-based shell buckling design factors (a.k.a., knockdown factors (KDFs)) and developing[HTML_REMOVED]design recommendations for launch vehicle structures. Shell buckling knockdown factors have been historically based on test data from laboratory-scale[HTML_REMOVED]test articles obtained from the 1930s through the 1960s. The knockdown factors are used to account[HTML_REMOVED]for the differences observed between the theoretical buckling load and the buckling load obtained[HTML_REMOVED]from test. However, these test-based KDFs may not be relevant for modern launch- vehicle designs,[HTML_REMOVED]and are likely overly conservative for many designs. Significant advances in structural stability[HTML_REMOVED]theory, high-fidelity analysis methods, manufacturing, and testing are[HTML_REMOVED]enabling the development of new, less conservative, robust analysis-based knockdown factors for[HTML_REMOVED]modern structural concepts. Preliminary design studies indicate that implementation of new[HTML_REMOVED]knockdown factors can enable significant weight savings in these vehicles and will help mitigate[HTML_REMOVED]some of NASA[HTML_REMOVED]s launch-vehicle development and performance risks, by reducing reliance on[HTML_REMOVED]large-scale testing, and providing high-fidelity estimates of as-built structural performance,[HTML_REMOVED]increased payload capability, and improved structural reliability.To achieve its KDF development and implementation goals, the SBKF Project is engaged in several[HTML_REMOVED]work areas including launch-vehicle design trade studies, subcomponent and component level design,[HTML_REMOVED]analysis and structural testing, and shell buckling design technology development including[HTML_REMOVED]analysis-method development, analysis benchmarking and standardization, and analysis-based KDF[HTML_REMOVED]development. Finite-element analysis is used extensively in all these work areas. In particular,[HTML_REMOVED]there are four main categories analyses conducted by SBKF and include:1) high-fidelity structural simulations, 2) imperfection sensitivity studies, 3) test article[HTML_REMOVED]design and analysis and 4) exploratory studies. Each of these types of analysis may have different[HTML_REMOVED]analysis objectives and utilize different modeling approaches that depend on the results required[HTML_REMOVED]to meet the Project needs. A description of the four main categories follows.[HTML_REMOVED]High-fidelity structural simulationsHigh-fidelity structural simulations are defined as simulations that can predict accurately the[HTML_REMOVED]complex behavior of a structural component or an assembly of components (e.g., virtual structural[HTML_REMOVED]test) and often require a significant level of modeling detail and knowledge of the structural[HTML_REMOVED]system (e.g., its physical behavior and expected variability). Models are considered high-fidelity[HTML_REMOVED]if results predicted with these models correlate with[HTML_REMOVED]test data to within a small range of variance and represent accurately the true physical behavior[HTML_REMOVED]of the structure. The permissible amount of variance is determined based on the analysis[HTML_REMOVED]requirements defined by the Project in accordance with the intended end use of the predicted data.[HTML_REMOVED]High-fidelity shell buckling analysis objectives considered by the SBKF Project often require the[HTML_REMOVED]accurate prediction of stiffnesses, local and global deformations, strains, load paths and[HTML_REMOVED]buckling-induced load redistribution, and buckling and failure loads and modes. To achieve these[HTML_REMOVED]analysis goals, the models typically must accurately represent loading and boundary conditions, and[HTML_REMOVED]expected or measured geometric and material varia

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Public: This dataset is intended for public access and use. License: No license information was provided. If this work was prepared by an officer or employee of the United States government as part of that person's official duties it is considered a U.S. Government Work.

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Metadata Created Date August 1, 2018
Metadata Updated Date July 17, 2020

Metadata Source

Harvested from NASA Data.json

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Resource Type Dataset
Metadata Created Date August 1, 2018
Metadata Updated Date July 17, 2020
Publisher Space Technology Mission Directorate
Unique Identifier TECHPORT_33077
Public Access Level public
Bureau Code 026:00
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Metadata Catalog ID
Schema Version
Catalog Describedby
Harvest Object Id e260a497-0f92-4261-8474-4ed921e7c00b
Harvest Source Id 39e4ad2a-47ca-4507-8258-852babd0fd99
Harvest Source Title NASA Data.json
Data First Published 2018-06-26
Homepage URL
Data Last Modified 2020-01-29
Program Code 026:027
Source Datajson Identifier True
Source Hash 9f536635c61a7177720c178e89b1d713b6d1aa47
Source Schema Version 1.1

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