Trying to compare two different weights during drop through analysis.

AI Thread Summary
The discussion revolves around analyzing the drop test survivability of two parts, weighing 10 pounds and 13 pounds, packaged in foam. The user has test data for part A indicating it survives a drop from 5 feet, and seeks to extrapolate this for part B without direct testing. Initial calculations involve kinetic energy and force related to foam deflection, but the user struggles with incorporating foam damping into the analysis. A participant suggests that if deflection beyond 0.25 inches indicates failure, part B's lower energy (65 ft-lb) compared to the foam's threshold (90 ft-lb) suggests it should also be safe. The conversation highlights the importance of understanding energy transfer and material properties in drop test analysis.
Spoolx
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Hi guys,
I am working on a project at work where we make part a which weighs 10 pounds and part b which weighs 13 pounds.

Parts a and b both get packaged in a foam container. I have test data on part a that says it will survive drop tests, I was hoping to do analysis to say part b will also survive the drop test without actually having to test part b.
The drop height is 5 feet. The foam has a specification where it takes 90lbf to deflect it .25 inch

My initial calculation was to find the kinetic energy of both, and then divide by the displacement to find the force, however obviously the foam padding adds some sort of damping to the equation. So I really don't know how to solve this problem.
When I do my KE equation I can't figure out how to get rid of the ft from the numerator as I need lbs to calculate deflection of the foam.

Any help is greatly appreciated.

Thanks
 
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what is the condition for failure?

right off the bat, we can say part a does 5*10=50ftlb and part b does 5*13=65ftlb.
Is deflection greater than .25" the failure condition? If so, you can see that part b is < 90ftlb, and therefore ok.

does that help?
 

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