18 inch drop test equals to ??? g level shock/crash test? 1

[110303]

Hello my friends,

We had a pressure vessle which passed the 18 inch drop test onto the wood bench. Now we have a similar pressure vessle. But the requirement from the customer has changed to 20g shock crash test. I am trying to figure out a connection between the 18 inch drop test and the 20g shock test to determine which test is more critical. Could someone please help me?

Thank you in advance for your help and time.

 

[rb1957]

what about doing another 18" drop test with an accelerometer onboard ?

 

[110303]

Thanks a lot for the quick response. The 18 inch drop test was done by an outside test house. There is a lot involved with testing (test article, test house, cost, etc.). Right now I am looking for some analysis guidance. Help please.

 

[IRstuff]

The reason there is a bench handling test and a shock test is that they are NOT equatable

TTFN

 

[borjame]

I believe you would need to know the deceleration time of the original bench test to make any sort of comparison; knowing the speed at which the vessel hits the bench divided by the duration of the impact will give you the acceleration or g's. Wood allows a longer contact and decelration period, it's why some aerospace shops have wood floors between the machines, dropping a part on wood has less chance of breaking it. A 20G shock test sounds like a different beast.

 

[110303]

Thanks a lot for the response. Do you have any experiences about the magnitude of the deceleration time period might be? Could it be about 10ms or 100ms or 500ms or 1 min? I now understand it is the critical factor to obtain the acceleration of the object in the drop test.

Thanks again for your help.

Regards,

 

[corrosionman]

110303
As a total outsider to this problem can I offer following trhought. The 20 g drop test will subject the vessel to 20 g
at point of impact. Suppose vessel weighs 1 ton then the impact creats 20 ton point load. can you not somehow support vessel and apply a 20 ton point load to demonstrate its strength and rigidity? Your original question can not be solved because depending on rigidity of vessel and its size
some point may suffer a 20 g deceleration on impact, but other parts may not. Why not ask your Client what he means ?
Regards CM