Approximated objective does not match with response at first iteration (ioerr(1897))

Beginner93
Beginner93 Altair Community Member
edited October 2020 in Community Q&A

Hello,

 

since a few days i´m trying to do a nonlinear quasi static topography optimization of an simple l-braket and want to form a bead. It has to be nonlinear, because later there will be contacts and other stuff in the complete model.

It´s the first time i´m doing this, so i´m pretty inexperienced. I alway got the same error, approximated objective does not match with response at first iteration (errorcode 1897). I´ve tooked some screenshots with my settings.

 

It would be really nice if someone knows where my problem is.

Thanks and greetings,

Luca

<?xml version="1.0" encoding="UTF-8"?>Error.png

<?xml version="1.0" encoding="UTF-8"?>LoadStep.png

<?xml version="1.0" encoding="UTF-8"?>NLPARM.png

<?xml version="1.0" encoding="UTF-8"?>Objective.png

<?xml version="1.0" encoding="UTF-8"?>Response.png

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Answers

  • Rahul Rajan_21763
    Rahul Rajan_21763 New Altair Community Member
    edited February 2019

    Can you also share the .out file of the run?

  • Beginner93
    Beginner93 Altair Community Member
    edited February 2019

    Of course. Here it is.

    Unable to find an attachment - read this blog

  • Beginner93
    Beginner93 Altair Community Member
    edited February 2019

    Hi, doesn´t anyone have an idea?

    It´s really important.

     

    Thanks

  • Rahul Rajan_21763
    Rahul Rajan_21763 New Altair Community Member
    edited February 2019

    Is it possible to share fem file to take a quick look?Will try running this in OptiStruct 2018 version.

  • Beginner93
    Beginner93 Altair Community Member
    edited February 2019
    Altair Forum User said:

    Is it possible to share fem file to take a quick look?Will try running this in OptiStruct 2018 version.

    As i already told, it´s only an example for me. Later there will be another component on the bottom with a contact between these two parts.

    Unable to find an attachment - read this blog

  • Rahul Rajan_21763
    Rahul Rajan_21763 New Altair Community Member
    edited February 2019

    Shared model gives same error on 2018 version. However if you don't consider MATS1, then it runs fine

  • Beginner93
    Beginner93 Altair Community Member
    edited February 2019

    Thanks for your help.

     

    I thought for a nonlinear analysis and optimization MATS1 is necessary. Otherwise there is no difference between linear and nonlinear?

    Is it even possible to reduce the max stress with an optimization in a quasi static nonlinear subcase and the optistruct solver?

  • Rahul Rajan_21763
    Rahul Rajan_21763 New Altair Community Member
    edited February 2019

    I am checking this internally and update you soon.

  • Rahul Rajan_21763
    Rahul Rajan_21763 New Altair Community Member
    edited February 2019

    Please use stress response as constraints only which could be more meaningful than minmax.

  • Beginner93
    Beginner93 Altair Community Member
    edited February 2019

    So i should delete my objective in the optimization? In this case the optimization don´t start and the error 'no objective defined' occur.

    Maybe i don´t get you right.

  • Rahul Rajan_21763
    Rahul Rajan_21763 New Altair Community Member
    edited February 2019

    Linear should work fine with stress as constraint and even with minmax.My colleague suggested to use 2019 internal beta build.

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