Description

This new 3-day course is a companion course to “Space Mission Structures: From Concept to Launch” (SMS). SMS gives the big picture of spaceflight structures development, while SDA goes into much more detail on design and analysis of aerospace structures and is not specific to spacecraft; most of the course applies to aircraft as well. Although we recommend people start with SMS and follow with SDA, SMS is not a prerequisite.

Subjects include statics and mechanics of materials (with emphasis on practical applications), strength analysis (with emphasis on empirical and semi-empirical methods rather than sole reliance on finite element analysis), fatigue analysis (with practical applications), and structural design (philosophy, material selection, types of structures and their considerations, methods of attachment, and guidelines). 

Participants should be prepared to work class problems.

Prior acquisition of the instructor’s 850-page reference book, Spacecraft Structures and Mechanisms: From Concept to Launch [1995], is recommended but not required..

Who Should Attend:

Structural and mechanical design engineers, stress analysts, and others interested in the topic.

Course Outline:

1.    Structural Requirements and Design Criteria

- Structural requirements:  what they are and what they are not

- Typical structural functions and constraints

- How flight loading environments affect the structure

- Standards and criteria

- Top-level criteria for strength

- Other commonly used structural design criteria

2.    Review of Statics and Free-Body Diagrams

- Static equilibrium and free-body diagrams

- Benefits of a statically determinate interface

- Examples and class problems

- Relationship between load and displacement

3.    Mechanics of Materials

- Stress and strain

- Combined state of stress

- Beams and bending stress

- Unsymmetrical bending

- Torsion and the effects of warping constraint

- Thermal effects

4.    Strength Analysis

- Accounting for variation in material strength:  allowable stresses

- Revisiting the margin of safety

- Interaction of stresses; failure theories

- Failure in practice

- The benefits of ductility

- Understanding stress analysis from the engineer’s perspective

- Common pitfalls and case histories

- An effective process for strength analysis

- Failure modes for fastened joints

- Exercise:  identifying potential failure modes

- Forms of buckling

- Elastic buckling of columns

- Inelastic buckling and eccentric loading

- Buckling of plates and shells

5.    Fatigue of Metals

- What is fatigue?

- Brief history of fatigue failures and ensuing research

- What causes fatigue?

- Crack initation and growth

- Stress concentration factors

- Terms defining a loading cycle

- Presentation of fatigue data

- High-cycle (stress-life) vs. low-cycle (strain-life) fatigue

- Palmgren-Miner rule

- The Goodman method and equivalent alternating stress

- Linear-elastic fracture mechanics

- Fracture control

- Generating a loading spectrum

- Designing to avoid fatigue failure

6.    Structural Design

- Opening thoughts on structural design

- Material selection

- Types of structures and important things to understand when designing them

• Beams
• Trusses and frames
• Forms of lightweight panels and shells
• Monocoque and semi-monocoque cylinders
• Skin-stringer and panel-frame structures

- Methods of attachment

- Reducing cost by reducing the number of parts

- Designing an adaptable structure

- Summary of Sec. 6:  Structural design guidelines

Instructor(s):

Tom Sarafin is President and Chief Engineer of Instar Engineering and Consulting, Inc. He has worked full time in the space industry since 1979 as a structural engineer, a mechanical systems engineer, a project manager, and a consultant.  Since founding Instar in 1993, he’s consulted for NASA, DARPA, the DOD Space Test Program, Lockheed Martin, DigitalGlobe (Maxar), Sierra Nevada Corp, Spaceflight Industries, Millennium Space Systems (Boeing), and other organizations.  He was a key member of the team that developed NASA-STD-5020, “Requirements for Threaded Fastening Systems in Spaceflight Hardware” (March 2012).  He is the editor and principal author of Spacecraft Structures and Mechanisms:  From Concept to Launch and is a contributing author to Space Mission Analysis and Design.  He’s also the principal author of a series of papers titled “Vibration Testing of Small Satellites.”  Since 1995, he has taught over 300 courses to more than 6000 engineers and managers in the aerospace industry.