1、This document represents the technical consensus of the developing group but does not yet have final NASA approval. JSC 65828 Rev. A STRUCTURAL DESIGN REQUIREMENTS AND FACTORS OF SAFETY FOR SPACEFLIGHT HARDWARE FOR HUMAN SPACEFLIGHT OCTOBER 2011 National Aeronautics and Space Administration Lyndon B
2、. Johnson Space Center Houston, Texas Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-JSC 65828 Rev. A This document represents the technical consensus of the developing group but does not yet have final NASA approval. Structural Design Requirements
3、and Factors of Safety for Spaceflight Hardware For Human Spaceflight October 21, 2011 Prepared By: /s/ Karen S. Bernstein Karen S. Bernstein Structures Branch Lyndon B. Johnson Space Center Approved By: /s/ Gregory F. Galbreath G. F. Galbreath Branch Chief, Structures Branch Lyndon B. Johnson Space
4、Center Approved By: /s/ Edgar O. Castro E. O. Castro Division Chief, Structural Engineering Division Lyndon B. Johnson Space Center National Aeronautics and Space Administration Lyndon B. Johnson Space Center Houston, Texas Provided by IHSNot for ResaleNo reproduction or networking permitted without
5、 license from IHS-,-,-JSC 65828 Rev. A This document represents the technical consensus of the developing group but does not yet have final NASA approval. REVISION HISTORY AND CHANGE LOG Rev. Date Originator Description Approval Draft 4/28/2010 K. S. Bernstein RFI Release 1 (Initial version of docum
6、ent to support RFI release of Commercial Crew Transportation Request for Information) Baseline 1/31/2011 K. S. Bernstein - An applicable document number was updated from JSC-65830 to NASA-STD-5020 and the title of the applicable document was revised. - Some of the content regarding structural design
7、 requirements for solid rocket motors was clarified. - “Derating” was changed to “design” in the section on fabric structures, and the definition of “derating” was removed from the glossary in section B. - The definition of “A basis” was revised in section B. A 10/21/2011 K. S. Bernstein A change wa
8、s made to the call-out for AIAA standards S-80 and S-081, which address metallic pressure vessels and composite overwrap pressure vessels. The words “the design requirements specified in” were deleted from each callout. Vendors are expected to use the entire standard, tailored at the point of applic
9、ation. In addition, this release of the document includes format changes to comply with configuration management processes at JSC, and editorial changes in the Forward to update the description of the document. The references to JSC 62550 were updated to NASA-STD-5018, which had not been released wh
10、en the structures standard was first published. The references to NASA-STD-5020 were reverted back to JSC 65830 because the NASA standard has not yet been released. Reference to the upcoming standard was added as a comment to the requirement. The references to JSC 65831 were updated to NASA-STD-5019
11、, which had not been released when the structures standard was first published. ES CCB Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-JSC 65828 Rev. A This document represents the technical consensus of the developing group but does not yet have fin
12、al NASA approval. Note: Dates reflect latest signature date of Revision. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-JSC 65828 Rev. A This document represents the technical consensus of the developing group but does not yet have final NASA approv
13、al. 1 FORWARD This is a standard published by the National Aeronautics and Space Administration (NASA) Johnson Space Center (JSC) that is intended to provide uniform structural design and factor of safety requirements in support of the development of human-rated spaceflight hardware. The material co
14、vered in this standard is based on the consensus judgment of a working group of structural engineers supporting the NASA JSC Structural Engineering Division, and founded on agency-wide consensus positions developed under the Constellation Program and lessons learned by the Space Shuttle Programs Str
15、uctures Working Group. The technical content of this standard is primarily based on the Constellation Program Structural Design and Verification Requirements (SDVR) document, CxP 70135 Change 004. It incorporates lessons learned from implementation of the SDVR within the CxP Orion and Ares projects,
16、 which highlighted a number of issues. The goal in writing this new standard was to maintain intent of the original requirement while reorganizing the content to improve document structure, clarify intent or remove redundancy. In some cases, requirements were removed because they are addressed in ot
17、her standards being released concurrently, for example the new standard for fasteners and mechanical joints. In addition, detailed rationale statements were added for each requirement to provide guidance on interpretation and, in some cases, a discussion of the recommended verification method. This
18、standard focuses on design and factor of safety requirements. Details related to methods of verification of each requirement will be negotiated and approved via the structural verification plan submitted to the Technical Authority at the responsible NASA center for review and approval. This standard
19、 was compiled with contributions from Rod Kujala/JSC, Karen Bernstein/JSC, Vince Fogt/JSC and Paul Romine/JSC. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-JSC 65828 Rev. A This document represents the technical consensus of the developing group b
20、ut does not yet have final NASA approval. 2 TABLE OF CONTENTS Contents Forward . 1 Table of Contents 2 List of Tables . 4 1 Introduction 5 1.1 Purpose 5 1.2 Applicability 5 1.3 Implementation . 6 1.3.1 Tailoring . 6 1.4 Constraints and Preconditions . 6 2 Documents . 7 2.1 Applicable Documents . 7 2
21、.2 Reference Documents . 7 2.3 Order of Precedence 8 3 Structural Requirements 9 3.1 Structural Assessment Program . 9 3.1.1 Structural Verification Plan 9 3.1.2 Stress Analysis 10 3.1.3 Structural Test Plans . 11 3.1.4 Structural Test Reports 11 3.2 Structural Design 11 3.2.1 Structural Strength .
22、11 3.2.2 Buckling and Crippling . 13 3.2.3 Structural Life 14 3.2.4 Metallic Structures . 15 3.2.5 Non-Metallic Structures . 15 3.2.6 Structural Soft Goods 16 3.2.7 Parachute and Parafoil Systems . 17 3.2.8 Pressurized Hardware . 17 3.2.9 Liquid Propulsion Engine Structures 20 3.2.10 Solid Rocket Mo
23、tors . 21 3.2.11 Rotating Machinery 21 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-JSC 65828 Rev. A This document represents the technical consensus of the developing group but does not yet have final NASA approval. 3 3.2.12 Wire Rope and Cables
24、. 22 3.2.13 Fasteners and Fastened Joints 22 3.2.14 Seals 23 3.3 Design Factors . 24 3.3.1 Factors of Safety . 24 3.3.2 Combined Loading 33 3.3.3 Life Factors 35 3.3.4 Bearing Factor for Joints Subjected to Hammering Action 36 3.4 Structural Loads and Environments . 36 3.4.1 Redistributed Loads . 36
25、 3.4.2 Loads Due to Friction (Relieving) 37 3.4.3 Loads Due to Friction (Additive) 37 3.4.4 Design Loads for Collapse . 37 3.5 Math Models. 38 3.5.1 Model Verification by Test . 38 3.5.2 Model Verification Test Factors . 38 3.5.3 Model Verification Test Correlation 39 3.6 Structural Materials 40 3.6
26、.1 Structural Material Allowable Properties 40 3.6.2 Material Design and Analysis Thickness . 40 3.6.3 Acceptable Dimensional Variations for Welded Joints . 40 A. Acronyms and Abbreviations . 41 B. Definitions 42 Provided by IHSNot for ResaleNo reproduction or networking permitted without license fr
27、om IHS-,-,-JSC 65828 Rev. A This document represents the technical consensus of the developing group but does not yet have final NASA approval. 4 LIST OF TABLES Table 3.3.1.2-1 - Minimum Factors of Safety for Metallic Flight Structures . 26 Table 3.3.1.2-2 Minimum Factors of Safety for Beryllium Str
28、uctures 26 Table 3.3.1.3-1 Minimum Factors of Safety for Non-metallic Flight Structures . 27 Table 3.3.1.4-1 Minimum Factors of Safety for Structural Soft Goods . 28 Table 3.3.1.5-1 Minimum Factors of Safety for Parachute and Parafoil Systems 28 Table 3.3.1.6-1 Minimum Factors of Safety for Pressuri
29、zed Hardware 29 Table 3.3.1.8-1 Minimum Factors of Safety for Solid Rocket Motors 31 Table 3.3.1.9-1 Minimum Factors of Safety for Rotating Machinery . 32 Table 3.3.1.10-1 Minimum Factors of Safety for Wire Ropes and Cables 33 Provided by IHSNot for ResaleNo reproduction or networking permitted with
30、out license from IHS-,-,-JSC 65828 Rev. A This document represents the technical consensus of the developing group but does not yet have final NASA approval. 5 1 INTRODUCTION 1.1 PURPOSE This document establishes the structural requirements for human-rated spaceflight hardware including launch vehic
31、les, spacecraft and payloads. These requirements are applicable to Government Furnished Equipment activities as well as all related contractor, subcontractor and commercial efforts. These requirements are not imposed on systems other than human-rated spacecraft, such as ground test articles, but may
32、 be tailored for use in specific cases where it is prudent to do so such as for personnel safety or when assets are at risk. The requirements in this document are focused on design rather than verification. Implementation of the requirements is expected to be described in a Structural Verification P
33、lan (SVP), which should describe the verification of each structural item for the applicable requirements. The SVP may also document unique verifications that meet or exceed these requirements with NASA Technical Authority approval. 1.2 APPLICABILITY This document recommends engineering practices fo
34、r NASA programs and projects. It may be cited in contract, program, and other Agency documents as a technical requirement. Determining the suitability of this standard and its provisions is the responsibility of program/project management and the performing organization. This standard is applicable
35、to the development of new hardware. Applicability to existing hardware with previous flight history will be addressed in the program Systems Requirements Document (SRD). Project-specific tailoring may generate other project-specific requirements that are derivatives of this standard. Other program s
36、tandards such as International Space Station (ISS) requirements may also be applicable. For ISS specific events refer to the SSP 50808, International Space Station (ISS) to Commercial Orbital Transportation Services (COTS) Interface Requirements Document (IRD). The requirements specifically excluded
37、 from this standard are materials and processes, design loads determination, fracture control, glass, fasteners, liquid propulsion engines greater than 6000 lbs thrust, ISS specific events, ground support equipment and facilities. Appropriate standards should be used for these topics, as applicable.
38、 The scope of this document is to define the structural design requirements for primary and secondary structures sometimes also called safety critical structures. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-JSC 65828 Rev. A This document represen
39、ts the technical consensus of the developing group but does not yet have final NASA approval. 6 1.3 IMPLEMENTATION The convention used in this document to distinguish between requirements and goals is as follows: “shall” is used to indicate requirements that must be implemented and verified, and “sh
40、ould” is used to indicate goals that must be addressed by the design but do not need to be verified. Each “shall” requirement is contained in its own subsection and indicated with a unique number using the format: STRxxxx for traceability purposes. The purpose of the Rationale statement is to indica
41、te why the requirement is needed, the basis for its inclusion in a requirements document, and to provide context and examples to stakeholders. It is important to note that the rationales are not binding and only provide supporting information. 1.3.1 Tailoring The responsible NASA Center will charter
42、 a Loads and Structures Panel (LSP) for reviewing and approving the implementation of the requirements of this document. The LSP is the responsible NASA Technical Authority for the program for structural design requirements. In the event that a particular requirement of this document cannot be met f
43、or a specific component, alternative tailored requirements may be proposed. Tailored requirements must be demonstrated to be “risk neutral” per the program risk assessment process. Risk neutral approaches have equivalent risk to the requirements in this document. The approach will be approved by the
44、 NASA LSP and documented in the SVP. 1.4 CONSTRAINTS AND PRECONDITIONS The criteria of this document were developed in the context of structural designs that are amenable to engineering analyses by current state-of-the-art methods and conforming to standard aerospace industry practices. More specifi
45、cally, the designs are assumed to use materials having mechanical properties that are well characterized for the intended service environments and all design conditions. For reusable and multi-mission hardware, these criteria are applicable throughout the service life and all of the missions. Design
46、 considerations should include material property degradation under the service environments. Material allowables should be chosen to minimize the probability of structural failure due to material variability. Allowables should be based on sufficient material tests to establish values on a statistica
47、l basis. Further, the service environments and limit loads should be well defined. Aerospace standard manufacturing and process controls should be used in hardware fabrication and handling. Test hardware should be representative of the flight configuration. Provided by IHSNot for ResaleNo reproducti
48、on or networking permitted without license from IHS-,-,-JSC 65828 Rev. A This document represents the technical consensus of the developing group but does not yet have final NASA approval. 7 2 DOCUMENTS The documents listed as applicable documents contain provisions that constitute requirements of this standard as cited in the text of Section 3. Reference documents are provided for additional information or to provide guidance to meet the requirements in Section 3 but are not levied as requirements. The applicable documents are accessible via the NASA Technical Standards System a
