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Registered Member #2431
Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639
I was told of this description in Steinberg's Vibration book for electronic equipment. This works if the ground being struck is stiff.
G=sqrt((2*h*k)/W)
Where,
h is drop height in inches k is the stiffness of your structure in lb/in W is the weight of the structure in lbs G is the (a/g), where a is the acceleration and g is the acceleration of gravity.
but Id like to figure out a simple G force calculation. Is It as simple as g=h/d where: h = is the height in meters. d = distance of deceleration in meters.
so if my drones descend from 3 meters, and crumple (like a Volovo) to a stop within 5cm, then the g-load would be 60 g's ? But theres a wrinkle. The three drone losses im investigating, all move toward a ridged surface at a constant 2 m/s despite falling from different heights. So the vertical speed is not a classical free fall.
So what value do i use for "h" ?
I choose the value of 5cm because the shedding of mass (crap breaking off) eases the fall, ive seen it at the center of mass during the crash, just for a fraction of a second. i wish i could measure it.
It feels like im missing a squared value or more some where.
Im interested in the quick g-load for evaluating the circuit boards and inertial components. semiconductor survivability after the rest of the machine was destroyed is what im interested in.
Registered Member #193
Joined: Fri Feb 17 2006, 07:04AM
Location: sheffield
Posts: 1022
An answer to "So what value do i use for "h" ? " is the height it would have to fall from where, neglecting air resistance, it would hit the ground at 2 m/s.
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Calculating G-impulse of Drone Collisions with Ground.
