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fasteners.md

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+# References
+
+- [Machinery's handbook](https://www.worldcat.org/title/machinerys-handbook/oclc/954734887) from [Industrial Press](https://books.industrialpress.com/machineryhandbook)
+- [NASA Fastener Design manual](https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19900009424.pdf) or [19900009424.pdf](19900009424.pdf) - somewhat dated materials since Cadium is no longer generally used but excellent overview of concepts
+- [NASA Standard 5020, Requirements for Threaded Fastening Systems in Spaceflight Hardware](https://standards.nasa.gov/standard/nasa/nasa-std-5020)
+- E. F. Bruhn. (1949). Analysis And Design Of Airplane Structures. Retrieved from http://archive.org/details/in.ernet.dli.2015.166811
+- Chambers, J. A. (1995). Preloaded joint analysis methodology for space flight systems. Retrieved from https://ntrs.nasa.gov/search.jsp?R=19960012183
+- Hemminger, E., Posey, A., & Dube, M. (2014). Torque Tension Testing of Fasteners used for NASA Flight Hardware Applications (p. 13). Presented at the Proceedings of the 42nd Aerospace Mechanisms Symposium, NASA Goddard Space Flight Center.
+- https://www.mcmaster.com/screws 
+
+# Material Selection
+
+18-8 stainless steel is low-cost and corrosion resistant, the strength of 70,000 psi is close to [SAE Grade 2 bolts](https://www.engineeringtoolbox.com/steel-bolts-sae-grades-d_1426.html). 
+A-286 Alloy is comparable strength to non-stainless bolts, but at a relatively higher cost. The minimum tensile strength of A-286 screws typically exceed SAE Grade 8.
+
+When a single bolt can't fail, a certified A286 alloy bolt is often called for. When there is redundancy and margin, more widely  available 18-8 is often more convenient and cost effective.
+
+# Style selection
+
+Vented Socket Head Screws increase cost and decrease choices but allow venting of blind holes to prevent gas build up in space/vacuum applications when the hole is not otherwise vented (the smallest screw hole that must be vented is somewhat fuzzy, but the fewer unvented holes the better).
+
+
+# Lubricant
+
+Lubricants that are vacuum safe and low-outgassing (see outgassing.nasa.gov), such as Braycote 601 EF can decrease the risk of galling.
+
+# Torque
+
+For detailed calculations and requirements see NASA Standard 5020. NASA [Tech Memo 19960012183](19960012183.pdf) introduces preloaded joints and also has a table of suggested torque values.
+
+*The quick and approximate approach*: Look up fastener clamping load and recommended torque on a table like the [Spaenaur Suggested Tightening](spaenaur%20-%20Suggested%20Tightening%20Torque1%20Values%20To%20Produce%20Cor.pdf) chart, taking care to use the lubricated column if applicable, and 18-8 bolts approximated as Grade 2 and A-286 approximated as Grade 8.
+
+The clamping load of the part should exceed the expected load on the joint being supported by a safety factor. e.g. a kilogram part expecting to see 30 g loads should and a minimum safety factor of three should be held with at least `1 [kg]*3*(30*9.8) m/s/s = 882 Newtons` (e.g. >198 lbs-force). 
+
+## Torque wrenches
+
+- torque values typically don't include the running torque and this will need to be estimated for the most accurate value.
+
+# Inserts
+
+ Nitronic 60 locking helical inserts are suggested for threading into aluminum. Inserts, such as locking helical inserts "helicoils", provide a locking mechanism to prevent screws from backing out, can increase strength, and the tolerable number of cycles of a joint.

hardware_testing.md

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+
+NASA resources:
+
+- NASA GEVS (General Environmental Verification Standard): https://standards.nasa.gov/standard/gsfc/gsfc-std-7000
+(also Milne, J. S., & Kaufman, D. S. (2003, January 1). General Environmental Verification Specification. Retrieved from https://ntrs.nasa.gov/search.jsp?R=20030106019)
+- Sounding Rocket Handbook. (2015). Wallops Flight Facility Wallops Island, Virginia, USA. Sounding Rockets Program Office Suborbital & Special Orbital Projects Directorate. Retrieved from http://sites.wff.nasa.gov/code810/files/SRHB.pdf
+- Chapter 4, `CubeSat 101: Basic Concepts and Processes for First-Time CubeSat Developers`. (2017). NASA. Retrieved from https://www.nasa.gov/sites/default/files/atoms/files/nasa_csli_cubesat_101_508.pdf
+
+
+Assorted commercial resources (not vetted or endorsed):
+
+- Spaceflight, Inc. Payload Users Guide. (n.d.). Spaceflight Industries, Suite 600 Seattle, WA 98109. Retrieved from http://spaceflight.com/wp-content/uploads/2015/05/SPUG-RevF.pdf
+- "The Matchmaking Platform for Test and Engineering Services in Aerospace" https://triasrnd.com/
+- Nanoracks IDD: http://nanoracks.com/wp-content/uploads/NanoRacks-CubeSat-Interface-Control-Document-CubeSat-Guide.pdf
+- Falcon 9 Payload users guide https://www.spaceflightnow.com/falcon9/001/f9guide.pdf