Element 11074 located in Body has become highly distorted

    • bxddstl

      Professor, ,I am a novice.I have a simulation of the pressure effect of the crude in the tank on a balloon with antifreeze. The crude in the tank, the balloon in the crude (1 mm thick rubber), and the antifreeze in the balloon (ethylene glycol) are all made by volume extraction, so they fit perfectly together.I made it using system coupling, but when I chose to click Update in system coupling, the system told me:

      (DP 0) Element 14132 located in Body "SYSalloon" (and maybe other elements) has become highly distorted. You may select the offending object and/or geometry via RMB on this warning in the Messages window. Excessive distortion of elements is usually a symptom indicating the need for corrective action elsewhere. Try incrementing the load more slowly (increase the number of substeps or decrease the time step size). You may need to improve your mesh to obtain elements with better aspect ratios. Also consider the behavior of materials, contact pairs, and/or constraint equations. If this message appears in the first iteration of first substep, be sure to perform element shape checking. Named Selections for the offending element can be created via the Identify Element Violations property on the Solution Information Object.

      But later, when I set the material of balloon into structure steel, the system coupling was successful. So I would like to ask why? Is it because the rubber material ,so the balloon deformed too much and directly damaged it?(But I remember someone else on youtube with abaqus doing a similar simulation. A rubber balloon shouldn't be damaged in this case, should it?)Or is there a problem with the contact between the balloon and its adjacent surfaces when it deforms?Other possibilities I didn't think of?

      Can you help me?

      ","embedType":"youtube","name":"A Transient Structural SYS SpaceClaim 2021 03","frameSrc":"https://www.youtube.com/embed/2CXRHk4S1Dw?feature=oembed&autoplay=1"}">
    • Stephen Orlando
      Ansys Employee
      Hi there,nWhen running System Coupling and it stops running, the first thing to do is examine the output files for each solver to look for clues to what happened. For Fluent, look at the transcript .trn file. For Mechanical, look at the .out file. For CFX, look at the .out file. Also, look at the System Coupling log file, .scl.nnI recommend going over this tutorial in the Ansys documentation that shows a 2-way FSI simulation with Fluent and Mechanical.https://ansyshelp.ansys.com/account/secured?returnurl=/Views/Secured/corp/v202/en/sysc_tut/sysc_tut_oscplate_wb_fluent.htmlnSystem Coupling Tutorials \\ Tutorials with Workbench-Setup Workflows \\ Tutorials with Workbench Setup and Execution \\ Oscillating Plate FSI with Fluent and MechanicalnnYou can also look at the following for a similar tutorial but run with the System Coupling GUI outside of Workbench. The new System Coupling GUI (run outside of Workbench) is available by searching for System Coupling 2019R3 (or newer) in the Windows Start menu.https://ansyshelp.ansys.com/account/secured?returnurl=/Views/Secured/corp/v211/en/sysc_tut/sysc_tut_reedvalve_fluent.htmlnnFSI simulations with very soft materials or membranes are prone to numerical instabilities. In 2020R1 we have introduced a stabilization method in System Coupling called the Quasi-Newton Stabilization Algorithm. Note that this has to be used with the new System Coupling GUI or Command Line Interface that is run outside of Workbench. More information here:https://ansyshelp.ansys.com/account/secured?returnurl=/Views/Secured/corp/v211/en/sysc_ug/sysc_gen_scservice_dt_supplemental_iqnils.htmlnSystem Coupling User's Guide \\ System Coupling Data Transfers \\ Supplemental Processing Algorithms \\ Quasi-Newton Stabilization AlgorithmnnIt is very important to build up the FSI simulation in stages as opposed to setting up the 2-way FSI right at the start. This document Best Practices for Coupled Fluid-Structure Interaction (FSI) describes this process and is available here:https://ansyshelp.ansys.com/account/secured?returnurl=/Views/Secured/corp/v211/en/sysc_ug/sysc_bestpractices_fsi.htmlnSystem Coupling User's Guide \\ Best Practices for System Coupling \\ Best Practices for Coupled Fluid-Structure Interaction (FSI)nnSteven
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