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Use of *SENSOR in LS-DYNA 971


A powerful new feature available in LS-DYNA version 971 is the *SENSOR keyword. To briefly summarize the Keyword Manual description, *SENSOR allows boundary conditions and various model entities to be activated/deactivated based on element, force, and/or node based criteria.

Options are available for modeling very elaborate systems, but we will focus on a very simple example which can be downloaded here: sensor.k. The cards of primary interest are as follows:

*SENSOR_DEFINE_NODE
1,5,29,Z,,COORD
*SENSOR_SWITCH
1,Sensor,1,LT,16
*SENSOR_CONTROL
1,DISC-ELE,1

The *SENSOR_DEFINE_NODE card instructs LS-DYNA to monitor the distance between two nodes in the global Z direction. The *SENSOR_SWITCH card determines when the result becomes less than a specified value. And when this occurs, the *SENSOR_CONTROL card deactivates the spring element in the model.

  • LucaB says:

    Hi,
    I’m trying to use di card but im not able to se the output. Where can I find the results? Have I to activate a particular Database_…?

  • Gareth says:

    Hi, I have been trying to use the Sensor cards to measure pressure change of an airbag upon impact, however it does not run, but without the sensor it does. Error message = “unexpected end of file” PE = 0 ….

    thanks

  • Suri Bala says:

    Gareth,

    It probably indicates an invalid format when using *SENSOR keywords. Can you please check the manaual to ensure the format meets the latest LS-DYNA specifications.

    Suri

  • Gareth says:

    Still does not work. Thanks though.

    I was wondering how can I measure pressure on an impact, e,g, I impact a box, and I want to find the pressure change inside like if I put a real pressure sensor inside the box and measuring the change in pressure (how to do it in Ls Dyna?)- many thanks

  • Suri Bala says:

    Gareth,

    Pressure is usually monitored using a solid element and ELOUT file should include this.

  • Trevor says:

    Hi Suri, so that what you mean is you select a element on the box to be solid and create a sensor on it. The ELOUT should then produce the pressure reading? Do you have an example of a pressure sensor

  • Ernesto Mottola says:

    Hello Suri

    thanks for providing this blog. I Googled for *SENSOR and this resource is one of the few showing up. Could you please check the link to the example you provide? Link seems to be broken.

    Moreover do you have any other examples? I am trying to switch between two discrete elements using *SENSOR (D1:On–>Off, D2:Off–>On on a certain condition) but I am having a hard time to get it working…

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