PS3

Question 1

What is meant by the terms “limit load”, “safety factor (or factor of safety)”, “proof level” and “ultimate level” as applied to spacecraft structural testing

Answer 1

The limit load is the maximum load expected to be applied to a structure.

The safety factor is a multiplying factor that is applied to the limits of material properties to account for variations in properties and degradation in use.

Proof level is the product of limit load and yield factor of safety (typically 1.1-1.25) –under which a structure must not sustain any significant deformation.

Ultimate level is the product of limit load and ultimate factor of safety (typically 1.25-1.5) –under which the structure must not rupture or undergo gross deformatio

Question 2

Briefly describe the form of a honeycomb panel and explain why they are used in spacecraft. State the advantages of a panel-based structural design

Answer 2

Spacecraft honeycomb panels comprise an aluminium honeycomb core, with thin aluminium of composite skins glued to each side. The honeycomb resists compression forces, but is weak in torsion (it can bend easily). The skins provide stiffness, the composite resulting an a stiff yet lightweight panel. Panel construction allows spacecraft equipment to be easily laid out and worked upon –easing manufacture