Increase in demand on Models containing Contracts with Friction

Andy@LamteqSolutions
Andy@LamteqSolutions Altair Community Member
edited October 2020 in Community Q&A

Hello,

 

I have been having issues with a model containing contacts and friction. The model is relatively straight forward, a multiple mast model with wearpads and contacts between pad faces and adjacent mast sections.

 

When the contact is set to property type slide N2S, the analysis demands around 47GB for In-Core Solution. However when the type is set to static friction coeff = 0.15, the in-core demand becomes 80GB. The model on my pc then typically fails because MUMPS demands significantly more RAM.

 

I've tried adjusting the search distance and using a PCONT card to define friction with little impact on MUMPS demand.

 

Any suggestions?

I currently have one PARAM card... PARAM,EXPERTNL,CNTSTB 

 

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Answers

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited May 2017

    Hi Andy,

     

    How big is the model in terms of number of nodes?

     

    Can you run without friction and search distance set to auto?

  • Andy@LamteqSolutions
    Andy@LamteqSolutions Altair Community Member
    edited May 2017

    Hello Prakash,

     

    Number of nodes = 772,243

    Elements = 776,988 (vast majority QUAD4).

     

    With search distance set to auto, I assume you mean no distance specified.

     

    Yes it runs with those settings

     

     

     

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited May 2017

    Hi

    How are you calculating the search distance?

    It is twice the average edge length on the master surface when using contact type Slide.

  • Andy@LamteqSolutions
    Andy@LamteqSolutions Altair Community Member
    edited May 2017

    I measured it as 2mm

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited May 2017

    Hi Andy,

     

     I think the problem is with Search Distance. Can you run with Auto,

    Meanwhile I will check with experts about the issue.

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited May 2017

    Can you provide details about analysis?

  • Andy@LamteqSolutions
    Andy@LamteqSolutions Altair Community Member
    edited November 2020

    Many thanks Prakash,

     

    It is still complaining of memory requirement. A curious thing is that .out file is disagreeing with the optistruct run screen... .out (attached) suggests only 41GB ram required for in-core whilst the optistruct states 80GB

     

     

     

    <?xml version="1.0" encoding="UTF-8"?>OPTISTRUCT RUN SCREEN.JPG

    <?xml version="1.0" encoding="UTF-8"?>OPTISTRUCT RUN SCREEN2.JPG

    Unable to find an attachment - read this blog

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited May 2017

    @Andy,


    Is the .out and screen shot are for same run and same model?

    I both cases the memory is not sufficient, though.

  • Andy@LamteqSolutions
    Andy@LamteqSolutions Altair Community Member
    edited May 2017

    That's correct, they are both same models

  • Andy@LamteqSolutions
    Andy@LamteqSolutions Altair Community Member
    edited May 2017

    Are there any parameter cards which can be used to help?

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited May 2017

    @Andy@LamteqSolutions

     

    One way is to increase the RAM.

     

    Maybe you can change the mesh size, have a finer mesh where contact is required and coarse at areas of non-interest, have contacts only where necessary

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