Initial energy not equal to total energy

Altair Forum User
Altair Forum User
Altair Employee
edited November 2020 in Community Q&A

Dear all

       I have created a model, which has an intial velocity 1252mm/s to impact on a plate. And the impact object mass is 147.7 Kg.

In my opinion the intial energy is 0.5*147.7Kg*(1252mm/s)^2 =115814.416 J  

      But when I plot the energy in hypergraph, the energy is about 277717 J . I don't know why they are different. I have uploaded the model I used.

could you help me? Thanks!

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Answers

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited July 2016

    Hi,

     

    Total energy is a sum of internal energy ,kinetic energy, contact energy, etc... Can you plot only the IE and KE and check?

     

    I am unable to plot the curve as my version doesn't support your files,

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited July 2016
    Altair Forum User said:

    Hi,

     

    Total energy is a sum of internal energy ,kinetic energy, contact energy, etc... Can you plot only the IE and KE and check?

     

    I am unable to plot the curve as my version doesn't support your files,

    Yes, I plot KE and IE,

    due to conservation of energy, the total energy should match with initial kinetic energy.

    but the result shows they are not match. I don't know why?<?xml version="1.0" encoding="UTF-8"?>a.jpg

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited July 2016

    Hi,

     

    I think I am missing something.

     

    Imagine you are doing a drop test. By virtue of its height you have PE at T=0.

     

    Now when the object falls on the ground you will KE and the PE will be. Here PE is converted to KE (assuming there are no other forms of energy).

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited July 2016
    Altair Forum User said:

    Hi,

     

    Total energy is a sum of internal energy ,kinetic energy, contact energy, etc... Can you plot only the IE and KE and check?

     

    I am unable to plot the curve as my version doesn't support your files,

    yes, I made a drop test. In order to increase analysis time, I added an initial velocity to the object. but the energy is same.

    The question is that the energy is not match with output energy.why?

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited July 2016

    Hi,

     

    Add Gravity and calculate the intial PE and compare

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited July 2016
    Altair Forum User said:

    Hi,

     

    Add Gravity and calculate the intial PE and compare

    hi,

         I added gravity, but the result is not reasonable. It shows that the total energy increased and the internal energy increased from 0.

    <?xml version="1.0" encoding="UTF-8"?>bb.jpg

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