Time Step Less or Equal Zero Error

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

Hi Everyone, 

 

I am working with Radioss. I use TYPE 7 and TYPE 2 contact for this model (You can see from an image below). I set the Engine file as shown in image below.

In the beginning, Radioss run normally. But later found a problem, Time Step Less or Equal Zero Error.

(Previous model, I set nodal time step in engine file less than zero but Radioss run normally.)

Can anyone take a look into my model what's wrong. what change, I have to make.

 

Thank you in advance.

 

<?xml version="1.0" encoding="UTF-8"?>S__152936452.thumb.jpg.c2f6472fcf3001732966a154578ce5e2.jpgengine.png.768e4a6a9acfa0152008fdb788837c9b.png

1.png.f57bbf9532396a481fe814afbdce3f14.png2.png.e28ef60aa3c58a7c11a71737906fa9b0.png3.png.a5c36bc65ce987de6554ddfbecda3b51.png4.png.1f87300f6e159196ba9806ff3c4efcc6.png

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Answers

  • Simon Križnik
    Simon Križnik Altair Community Member
    edited March 2019

    Hi,

     

    From the engine out file we can  review what is causing very low time step.

    It can be an element, a node or an interface.

    •For an element, check the related material (especially its Young modulus and density in case of an elastic-plastic material; and its viscosity in case of a visco-elastic material). There must not be an error in the units system that this data is given in. 

    Check the size of the element, since elemental length is proportional to time step. If some elements are distorting badly during simulation it will lead to very low time step and the run will terminate. In this case use small strain formulation (in the property card).

    •For a node, check the characteristics of connected elements. If the node is on the master side or the slave side of an interface, this interface must be verified.

    •For an interface, the gap of the interface must be verified if some failure happens on the master or the slave side of the interface. Check the interfaces defined in the model for any penetrations.

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited March 2019

    @Ivan I checked the model follow your advice. But I still can't find the problem. Can you give me more advice?

    Thank you.

  • Simon Križnik
    Simon Križnik Altair Community Member
    edited March 2019

    I have already given generic advice. I will need access to the model for debugging. If you do not want to share it publicly you can send it to my email.

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited March 2019

    @Ivan I sent the model to your email

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited March 2019

    Ivan, Thank you for your response.

  • Kunal Hirudkar
    Kunal Hirudkar Altair Community Member
    edited September 2019

    Thank you for explanation..it helped me too.