TAGGED: ansys, droptest, droptestsimulation, lsdyna, pointmass


July 15, 2024 at 6:00 amzabee.kSubscriber
Hello,
I'm performing a drop test of a structure on to which a point mass of 10kg is acting. The mass of structure is 0.00225 kg and on to which a point mass of 10kg is acting. After solving, the kinetic energy of the system is less. it is equal to that of the structure but not with point mass. Wanted to know why im getting less kinetic energy and how to accont for the kinetic energy of the point mass.
Please find the attached images below for the reference.
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Regards,
Khan

July 15, 2024 at 3:51 pmRam GopisettiAnsys Employee
Hi Khan,Â
I am not sure why this disparity is causing, on a similar drop scenario as follows a ball of mass 5.1378e004 kg with a volume of 6.545e008 mÂ³ is added with a mass of 20kg and is been dropped with a velocity of 10 m/sÂ
As per my calculations, the total kinetic energy of the system is approximatelyÂ 1000.03 Joules where DYNA produced with a small difference as follows and ignoring the point mass the results are given in right, so there are no issues on the solver side, need to check the model for inaccuracies or in your hand calculations and see if you had summed up the total KE fromÂ $E_{total}=Epoint_{mass}+E_{ball}$
Cheers, RamÂ
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July 17, 2024 at 7:53 amzabee.kSubscriber
Hello Mr. Ram,
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I rechecked my calculation and model, everythings look good. Im attaching images below for your reference.
The sturcture is of mass 0.14218 kg with drop height being 1m which gives you the impact velocity of 4.4287 mps. I did the calculations and got K.E = 1.394J which is correct theoretically and ansys results. but when im adding a point mass of 10kg to the structure the K.E is 99.461 which im getting from energy summary graphs but not able to get the same under solution information K.E.
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Can you please help me understand why im not able to get results like you. You are able to get results separate for structure and also with point mass included. My results are only of structure with out point mass. Can you please share me how you are defining point mass.
and also wanted to know can we scope point mass to get velocity and acceleration. I tried scoping it but its not working.
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Regards

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