Mechanical Engineering

# How to calculate shock absorber constants from known c and k values

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We are trying to put a spring-damper system on a drone to act as landing gear (very small scale, only about 300 grams total). We created a MATLAB simulation to describe spring and damper constants, taking into account drone weight, free fall height, and stroke length of the spring-damper. The simulation tells us k constants, c constants, damping ratios, and compression lengths for an input maximum acceleration, stroke length, mass, and fall height. Those are the constants we then need to find a spring damper (aka shock absorbers) for. The issue is, the datasheets associated with commercially available shock absorbers don't have these constants. I have linked two datasheets for reference.

One datasheet we have found uses constants of: Max in.-lbs/cycle (Nm/cycle), Max in.-lbs/hour (Nm/hour), Max Velocity in/sec (m/sec), and max reaction force lbf (N). In this case, what is the meaning of these variables? i.e. is Max Velocity an impact velocity? That would be perfect for our free fall application. Or is it velocity of the stroke of the shock absorber? How do we take c, k, and damping ratios and calculate these values? Datasheet found here: https://www.toolots.com/ea-non-adjustable-hydraulic-shock-absorber-25-64-stroke-length.html#productDetails

Another datasheet uses different variables: Load (kg), Max absorption energy J (kgf * m), Speed Range (m/s), and extension force N (kgf). In this case, is the Load a continuous load? Is the speed Range the speed of the physical stroke? Is the extension force a direct F = k*x relationship? Datasheet here: https://www.grainger.com/ec/pdf/36JM64_1.pdf

Hopefully you can either give me some advice on how to approach these variables or some equations on how to calculate them. Any help is appreciated. Thanks!

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