External Forces Work

Subhu_21017
Subhu_21017 Altair Community Member
edited October 2020 in Community Q&A

HI All, 

I am running a crash analysis.

I have no external force applied to my model except initial velocity and gravity.

the model is set to impact on a rigidwall

Will the External Forces Work remains constant or increase or decrease??

 

 

THANKS in Advance

 

Regards,

SUBHU

 

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Answers

  • Subhu_21017
    Subhu_21017 Altair Community Member
    edited November 2017

    The External Work Forces is Decreasing. Is this Good??

     

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  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited November 2017

    Hi Subhu,

    External work is any external loading applied in the simulation.  This can include, Imposed movement (displacement, velocity or acceleration), force (/CLOAD or /GRAV), and pressure to name a few. Work by done an external force on a system is always a transfer of energy to some other form of energy and this negative work represents the transfer of energy during the simulation and this is fine.

     

  • jsk459
    jsk459 Altair Community Member
    edited May 2018

    Hi,

     

    Please let me know below mentioned energy relations are correct or not.

     

    External work = Internal energy+kinetic energy+contact energy+hourglass energy

    Total energy = Internal energy + kinetic energy

  • Nachiket Kadu_22143
    Nachiket Kadu_22143 Altair Community Member
    edited May 2018
    Altair Forum User said:

    Hi,

     

    Please let me know below mentioned energy relations are correct or not.

     

    External work = Internal energy+kinetic energy+contact energy+hourglass energy

    Total energy = Internal energy + kinetic energy

    @jsk459 Yes the above relation is correct.

  • Andy_20955
    Andy_20955 New Altair Community Member
    edited November 2019

     

     

     External work = Internal energy+kinetic energy+contact energy+hourglass energy

     

    This is NOT correct. 

    External Work includes the work from Imposed movement (displacement, velocity or acceleration), force (/CLOAD or /GRAV), and pressure.  It also include the frictional energy from a /RWALL (when FRIC!=0.0)

     

    If there are only an initial velocity, gravity and a rigid wall in the model then I would assume the high negative external work is caused by the friction on the rigid wall and maybe gravity.  It is difficult to say without seeing the model.

     

    Thank,

    Andy

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