OLOAD -Transient Analysis

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

Hi,

I am running transient run with sinusoidal loading. I have given table D1 as sinusoidal function of time in the form of values for once cycle. When I am checking the OLOAD i,e applied load.

I am getting a linear curve for some initial time and then curve follows sinusoidal path. Also at t=0. table d1 value is 0.5 but the same in force is zero.

Kindly let me know about this.

 

 

<?xml version="1.0" encoding="UTF-8"?>TABLE d1 values.JPG

<?xml version="1.0" encoding="UTF-8"?>OLOAD values.JPG

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Answers

  • gopal_rathore
    gopal_rathore Altair Community Member
    edited August 2017

    Hi,

    @Prakash Pagadala Kindly let me know about the above points?

     

    Thank you

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited August 2017

    Hi Gopal,

     

    Did you request for a set of nodes or for all?

     

    Do you have gravity with MTRAN/DTRAN analysis type? If yes, it is not supported for the same.

     

     

  • gopal_rathore
    gopal_rathore Altair Community Member
    edited August 2017

    Hi,

    I have requested for a set of nodes. I am not using gravity with DTRAN analysis

     

    Thank you

  • gopal_rathore
    gopal_rathore Altair Community Member
    edited August 2017

    Hi,

    @Prakash Pagadala I was not expecting the linear linear line in the Oload input load as my TABLE D1 represents a sinusoidal wave.The objective is to do a repeated cycle fatigue analysis and for the same I making a transient run for one cycle for fatigue calculation.

  • gopal_rathore
    gopal_rathore Altair Community Member
    edited August 2017

    Hi,

    I can understand the reason for the linearity in the start as the load is not zero at t=0 thus it takes a time step to reach the initial value. Can you give me a general guideline to for making a relation between no. of time steps , simulation time and time step size.

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited August 2017

    Hi Gopal,

     

    Do you mean for fatigue time history?

     

    Maybe Load Time History Compression on OptiStruct will guide.

     

     

  • gopal_rathore
    gopal_rathore Altair Community Member
    edited August 2017

    Hi,

    No I meant for transient analysis

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited August 2017

    Hi Gopal,

     

    Sorry for a late response. I think you can define analysis time step and end time using TSTEP. Where N in TSTEP  is number of time steps and DT is time increment. 

     

  • gopal_rathore
    gopal_rathore Altair Community Member
    edited August 2017

    Hi,

    I am clear with TSTEP load card.I wanted to know about how we decide the number of time steps for a particular time run. For eg. we have 1 sec of simulation run, no. of time steps can be any value from low ot high. So is there any general base don load variation and time as parameter.

     

    Thank you.

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited August 2017

    Hi Gopal,

     

    If it is explicit the element size affects the time step. 

     

    But in implicit I need to check with my experts... I shall get back to you after learning :)/emoticons/default_smile.png' srcset='/emoticons/smile@2x.png 2x' title=':)' width='20'> 

  • gopal_rathore
    gopal_rathore Altair Community Member
    edited August 2017

    Hi,

    Thank you for your response.:)/emoticons/default_smile.png' srcset='/emoticons/smile@2x.png 2x' title=':)' width='20' />

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