9 Aerospace Structures
Introduction
Now that some understanding of the anatomy of flight vehicles has been gained, it is logical to examine their structural design characteristics in greater depth. While aerodynamics provides the foundation for atmospheric flight, an aircraft must also possess a suitably shaped structure capable of withstanding all imposed loads, whether aerodynamic, engine-induced, or those arising from the undercarriage during landing, including both vertical and side loads. Any aerospace structure must therefore be not only strong and lightweight, but also robust and durable. A clear appreciation of the available structural design options, along with their inherent constraints, is essential for achieving these objectives.
Many structural design goals and engineering challenges for spacecraft are similar to those for aircraft, particularly the need for optimally shaped structures made from high-strength, lightweight materials. However, spacecraft often require specialized materials capable of withstanding extreme thermal environments, especially during atmospheric re-entry when kinetic heating becomes severe. Likewise, supersonic aircraft may demand structural features that allow controlled expansion under aerodynamic heating, thereby preventing the buildup of excessive internal stresses.
Learning Objectives Appreciate the history and evolution of aerospace flight structures.
Understand the primary loads on an airframe, such as tension, compression, bending, torsion, and shear.
Know how aircraft structures are constructed, including spars, ribs, stringers, skin, etc.
Understand the principles behind the finite element method (FEM) and why it is used in designing structurally efficient aerospace structures.
Be aware of some of the challenges in airframe design, including avoiding buckling and fatigue, as well as incorporating structural redundancy to enhance safety and reliability.
Brief History of Aerospace Structures
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