Is there something wrong that I got the energy balance like this?

Paphatsorn
Paphatsorn Altair Community Member
edited December 2021 in Community Q&A

I am doing the drop weight impact test of composite plate according to ASTM D7136 standard in Radioss solver and have to compare the result with the test results. But there are some problems occur, the internal energy from the finite element not equal to 50 J when the ball crash to the plate like the value of kinetic energy at time = 0 s, the internal energy increares to 49 J when the impactor attack the plate and then it constant. The internal energy supposes to start with zero and then increase to 50 J according to the 1st law of Thermodynamics. 

Did I miss something or misunderstand with something? Please help me. Thank you in advance.

I will attach the model file too, in case of you want to check my set up in program.

This one is the results from simulation.

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and this one is the actual test results.

The internal energy from test is also weird, I did not test it by myself, I use the result from other groups. But I will check it up later.

image

This one is the energy comparison between simulation and actual tests.

image

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Answers

  • Rogerio Nakano_21179
    Rogerio Nakano_21179 New Altair Community Member
    edited December 2021

    Hi

     

    About the Radioss analysis:

    Some of the internal energy is transformed into contact energy and other type of energy

    Consider verify the other energy data you have in the T01.

     

    The TTE output is the total energy balance, except external work.

    TE consider only internal energy and translational kinetic energy.

     

    https://2021.help.altair.com/2021.2/hwsolvers/rad/topics/solvers/rad/time_histories_overview_starter_r.htm

     

    Also the curves are flat after some time because there is no gravity, therefore after contact interaction is not happening anymore the rebound velocity is constant.

     

     

    I hope this is helpful.

    Regards