December 16, 2020 at 12:27 pmPaulvhSubscriber
Currently I'm working on a static structural analysis with two models that describe the failure of individual material and the interface in a multi-material (PC) part. The individual material failure is modelled with the use of EKILL based on the ultimate plastic strain theory. The interface failure is modelled by a separation-distance based debonding (CZM) on contact elements.
The problem that I encounter in this simulation is the high occurence of element HDST violations, i.e. element distortions. To a degree this behavior is expected as when elements are killed via EKILL, their stiffness is reduced significantly, subjecting them to high degrees of deformation. I have however tried many approaches to minimize this effect, including:
- Model setup: decreased loading increments and increased amount of substeps (1mm displacement is loaded linearly ramped over 100 loadsteps, with each having minimum 5 and maximum 1*10^5 (!) substeps), varied CZM artificial damping factor, ensured contact pinball radius is at least the length of the contact gap at the completion of debonding.
- Mesh quality: varied between all mesh methods (multizone/quadrilateral/triangles), varied mesh size (ranging from 0.01mm to 1mm), introduced initial biased aspect ratios of elements that are to be stretched.
Unfortunately, none of the approaches minimizes the occurence of element distortions to an extend where the simulation is able to completely converge in a robust manner. Observing the force convergence solution output and the Newton-Raphson residual force plot (see figures), I can only conclude the simulation is prematurely halted because of the element distortion (highlighted in green in the NR plot).January 7, 2021 at 11:06 amAshish KhemkaForum ModeratornnWhat is the number of equilibrium iterations you are using? If you have not changed the same then can you try increasing the number of equilibrium iterations using the command in the Setup branch:nneqit,100 ! This increases the equlibrium iterationsnnRegards,nAshish KhemkanJanuary 7, 2021 at 2:02 pmPaulvhSubscriberHi Akhemka,nI have come across this suggestion on another forum as well and attempted with increased neqit,50. Unfortunately I noticed no changes. Thanks for thinking along though!nIn the meantime a promising change I have made was changing the discplacement boundary condition to a remote displacement boundary condition, allowing me to change its behaviour from rigid to deformable. Switching between these settings drastically affected the robustness of the model with limited effect on the results. nKind regards,nPaulnViewing 2 reply threads
Ansys Innovation Space
- The topic ‘Element distortion undetectable’ is closed to new replies.
Boost Ansys Fluent Simulations with AWS
Computational Fluid Dynamics (CFD) helps engineers design products in which the flow of fluid components is a significant challenge. These different use cases often require large complex models to solve on a traditional workstation. Click here to join this event to learn how to leverage Ansys Fluids on the cloud, thanks to Ansys Gateway powered by AWS.
Earth Rescue – An Ansys Online Series
The climate crisis is here. But so is the human ingenuity to fight it. Earth Rescue reveals what visionary companies are doing today to engineer radical new ideas in the fight against climate change. Click here to watch the first episode.
Subscribe to the Ansys Blog to get great new content about the power of simulation delivered right to your email on a weekly basis. With content from Ansys experts, partners and customers you will learn about product development advances, thought leadership and trends and tips to better use Ansys tools. Sign up here.Trending discussions
- How to do the frequency response of the nonlinear vibration of a flexible PCB?
- Importing Line and Solid Bodies from SpaceClaim to Mechanical
- how to open SendCommand in Ansys
- problems facing during solution
- Still facing the same issue
- Failed to move file from solver directory to scratch directory: file.rst
- Adaptive Sizing
- Stiffness factor
- Import DAT file
- Import pressure data (coordinates and value) to ansys workbench through excel
Top Rated Tags
© 2023 Copyright ANSYS, Inc. All rights reserved.Ansys does not support the usage of unauthorized Ansys software. Please visit www.ansys.com to obtain an official distribution.