Section B: Flashcards
Phases of a Spacecraft Structure?
Planning, Manufacture, Testing, Transportation, Launch, Appendage deployment, Operation, Re-entry
What Frequencies are avoided in design?
Natural frequency of the S/C and Low Frequency dynamics of the LV
What produces mechanical shocks?
LV separation, Satellite release mechanism, Fairing separation, Appendage deployment machanisms
How can mechanical shocks lead to failure
Breaking or altering electronics, optical devices, brittle materials, mechanisms.
How do you form an SRS?
Plotting the max acceleration of the output of a transient ground acceleration input for different natural frequencies.
What are the two features of an Acoustic Load?
Directivity and SPL.
What is OASPL?
The ratio between the mean square value of the actual pressure and a reference pressure.
What are the on-station requirements?
Handling vibrations, maintaining a vacuum, handling thermal cycles, deploying appendages.
Internal mechanisms that create microvibrations?
Rotating Devices (reaction wheel), Thermal Instruments (cryogenic cooler), thrusters
Method selection considerations?
Joint strength, Joint stiffness, Different Materials, Durability, Cost, Alignment, Access
Two + and - of Mechanical Fasteners.
+: Good for dissimilar, standard sizes. easy to install, versatile.
-: expensive, heavy, loses stiffness, stress concentrations.
Two + and - of Welds.
+: can contain fluid, inexpensive, maintains stiffness
-: warping, loss of strength, can’t disassemble
(reserved for attaching similar metals, stiffness-critical Al)
Two + and - of Bonding.
+: smooth surface, even load distribution, lightweight.
-: weak in tension, toxic, temperature limitations, quality, can’t disassemble.
What is Cb?
kb/(kf + kb)
What is the equation for shearing of a bolted joint?
Fs < (Ff*u)/SF
