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Drop Test??

ghgarzon

New member
Yes you can.


1. Use conservation of energy in order to determine final velocity just before touching ground.


2. Run a static analysis with constraints that represent where the object will hit the ground. Apply a colinear load with the direction of drop. Get the defelction caused by these set of loads & constraints. Now you can get an equivalent stiffnes, K, from the results of this static analysis. (K=Defl/Load)


3. Use the (1/2)*M*V^2 = (1/2)*K*X^2 to calculate the approximate deflection that the object will experience due to the kinetiv energy stored just before it hits ground.


4. Repeat 2 if the initial deflection is different than the one obtained in step 4.Also, carefull attention should be given to the constraints used. You probably need to run the analysis three times, one for each direction of coordinates; unless you know experimentally where the object hits the ground. Obviously, the set of constraints should only allow motion in the same direction that the load is applied.


Remember, all of this is linear approximation. Should you need a more accurate way of doing this, then you should really run the analysis with Abacus orother non-linearFEA software.


I hope this helps.


GH Garzon
 

hansu1968

New member
Thanks for your information.


One more question that I am wondering why I didn't see the termination time intervial in your procedure. Yes, the terminal velocity can be calculated from convertional formula, but how we are going to know the time when the object was hitting the ground.





Thanks.
 

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