If you need assistance, please send an email to forum at 4hv dot org. To ensure your email is not marked as spam, please include the phrase "4hv help" in the subject line. You can also find assistance via IRC, at irc.shadowworld.net, room #hvcomm.
Support 4hv.org!
Donate:
4hv.org is hosted on a dedicated server. Unfortunately, this server costs and we rely on the help of site members to keep 4hv.org running. Please consider donating. We will place your name on the thanks list and you'll be helping to keep 4hv.org alive and free for everyone. Members whose names appear in red bold have donated recently. Green bold denotes those who have recently donated to keep the server carbon neutral.
Special Thanks To:
Aaron Holmes
Aaron Wheeler
Adam Horden
Alan Scrimgeour
Andre
Andrew Haynes
Anonymous000
asabase
Austin Weil
barney
Barry
Bert Hickman
Bill Kukowski
Blitzorn
Brandon Paradelas
Bruce Bowling
BubeeMike
Byong Park
Cesiumsponge
Chris F.
Chris Hooper
Corey Worthington
Derek Woodroffe
Dalus
Dan Strother
Daniel Davis
Daniel Uhrenholt
datasheetarchive
Dave Billington
Dave Marshall
David F.
Dennis Rogers
drelectrix
Dr. John Gudenas
Dr. Spark
E.TexasTesla
eastvoltresearch
Eirik Taylor
Erik Dyakov
Erlend^SE
Finn Hammer
Firebug24k
GalliumMan
Gary Peterson
George Slade
GhostNull
Gordon Mcknight
Graham Armitage
Grant
GreySoul
Henry H
IamSmooth
In memory of Leo Powning
Jacob Cash
James Howells
James Pawson
Jeff Greenfield
Jeff Thomas
Jesse Frost
Jim Mitchell
jlr134
Joe Mastroianni
John Forcina
John Oberg
John Willcutt
Jon Newcomb
klugesmith
Leslie Wright
Lutz Hoffman
Mads Barnkob
Martin King
Mats Karlsson
Matt Gibson
Matthew Guidry
mbd
Michael D'Angelo
Mikkel
mileswaldron
mister_rf
Neil Foster
Nick de Smith
Nick Soroka
nicklenorp
Nik
Norman Stanley
Patrick Coleman
Paul Brodie
Paul Jordan
Paul Montgomery
Ped
Peter Krogen
Peter Terren
PhilGood
Richard Feldman
Robert Bush
Royce Bailey
Scott Fusare
Scott Newman
smiffy
Stella
Steven Busic
Steve Conner
Steve Jones
Steve Ward
Sulaiman
Thomas Coyle
Thomas A. Wallace
Thomas W
Timo
Torch
Ulf Jonsson
vasil
Vaxian
vladi mazzilli
wastehl
Weston
William Kim
William N.
William Stehl
Wesley Venis
The aforementioned have contributed financially to the continuing triumph of 4hv.org. They are deserving of my most heartfelt thanks.
Registered Member #2431
Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639
Are there examples of electronic devices surviving high G-loads? I can only think of artillery like the M982 GPS guided round, and solid state flight recorders.
I dont think the G and Newton units are directly convertible, right? Im trying to calculate the G-force collision of a drone with a 747 or large aircraft. I guess i should be using the work-energy principle method.
Registered Member #27
Joined: Fri Feb 03 2006, 02:20AM
Location: Hyperborea
Posts: 2058
Two off topic posts disappeared.
Part II: Posting
A. Stay on topic. When posting in a thread, look at two things. The subject, and the first post. Those two give you an idea of what is and what isn't okay in the thread.
E. Make sure each post has a point. Unless you're in the chatting board, there's no need for a one-liner post that doesn't have any real content.
-----------
DIP chips can reliably survive 30 000 G if mounted correctly. If your drone should hit a hard surface at 900 km/h you would need about 10 cm crumple zone to reach a comparable value so it seems to be possible in theory if you can stop the card from flexing too much.
Registered Member #2939
Joined: Fri Jun 25 2010, 04:25AM
Location:
Posts: 615
What do you consider high G? When I was designing military training equipment we had a laser + electronics that mounted on a gun barrel, and had to survive 800G shock loading on every shot. Biggest risk item was the crystal for the micro. I don't recall seeing any issues.
Registered Member #65
Joined: Thu Feb 09 2006, 06:43AM
Location:
Posts: 1155
@Patrick Normal micro SDHC memory cards are mostly wafer silicon by volume, and easily fracture when bent. Yet given its relatively low mass, there is a high probability it would remain functional for awhile if bonded to something rigid. For example, most high Mach aircraft use aluminium bonded PCBs coated with transparent fire retardant silicones to mitigate vibration fatigue. NASA has done extensive work documenting mechanical board failure modes, and JPL built on many of these same design principles.
Note, some chips already follow JESD22-B104C or Mil-Std-883: Where method 2002.5 Cond. E is defined as 10000g’s for 0.2ms for several iterations. Just remember from basic principles F=m*a, which suggests a lower mass package like 0402 & QFN are usually less likely to pull itself off a board or break glue bonds. Note, the solder heel fillet inspection process is very important for meeting this kind of standard.
You may find many materials exhibit piezoelectric properties under physical perturbation. For example, tapping some scope probe lead wires or cheap ceramic components can generate noise.
Registered Member #65
Joined: Thu Feb 09 2006, 06:43AM
Location:
Posts: 1155
Aluminium in PCB laminations is not that exotic these days, and can be ordered without the via holes forming fissures. Less mundane delivery vehicles where SOICs tear their own pins off if the heel is wrong, will often use this type of board for critical electronics. Coatings are another issue that can vary depending on the equipment, but flame retardant silicone dips/sprays are popular.
Note metal foams (invented at Bjorksten Lab in the 50's) were designed for impact absorption, and thus the force peaks are much less energetic.
Registered Member #72
Joined: Thu Feb 09 2006, 08:29AM
Location: UK St. Albans
Posts: 1659
It's quite easy to do one's head in hoping and poking with 'do I pot it in epoxy, or something squdgy?' sort of questions.
The basic physics is quite straightforward however. You can always transform the situation into something moving being brought to rest, this seems to be the easiest way to reason about it. All the massy parts of the system will have a known amount of kinetic energy initially. This will be dissipated by them doing work on the lossy parts of the system, the crumple zone if there is an explicit structure, material losses or fractures if there isn't. The length of the crumple zone defines how much time and distance they have to do this, which controls the force. Getting the force from housing to the massy parts is the job of of a compliant system, and as you know a mass/compliant system has a resonant frequency. The ratio of stiffness and dissipation per unit displacement will indicate whether your system is heavily or lightly damped.
Put in those system terms, it's usually easier to figure out upper/lower bounds for things, and for which bits need to be stiff/lossy/light/long etc.
Registered Member #3324
Joined: Sun Oct 17 2010, 06:57PM
Location:
Posts: 1276
It would be interesting to do some actual physical tests... the problem is trying to accelerate your item up to 167m/s...
Carbon did bring up a very interesting point regarding the peizo electric functions of ceramics... I woulder just how high the voltages could go from a high velocity impact such as described and how much of a concern it would be.
I would imagine the best way of securing the electronics to survive such a high velocity impact would be either securing the unit with springs in a steel case, or a material similar to what is in IGBTs.
This site is powered by e107, which is released under the GNU GPL License. All work on this site, except where otherwise noted, is licensed under a Creative Commons Attribution-ShareAlike 2.5 License. By submitting any information to this site, you agree that anything submitted will be so licensed. Please read our Disclaimer and Policies page for information on your rights and responsibilities regarding this site.