December 19, 2022 at 8:52 pmSwen GroenSubscriber
Currently I am working on the modelling of a cable-driven soft continuum robot. I am running into some issues though regarding my boundary conditions and the results.
I am running a static structural with large deformation turned on.
The model consists of 4 parts. 1 silicon base with 4 cylindrical holes in which 3 wires run (stainless steel), modelled as beams. The silicon is modelled with a mooney-rivlin non-linear model. During actuation of the robot the cables are being pulled, resulting in the deformation of the silicon and therefore the movement of my actuator.
I have the ends of the wires as a fixed joint at the end of the silicon part with a frictionless contact region between the wire and the cylindrical holes it is running through.
For the meshing I use 2 sizing steps. 1 for the base and 1 for all the wires.
However, When I run the model and show the results the silicon deforms as anticipated however, the wires are straight and are not deforming and get a message the contact region might have been broken.
I have tried the following alternatives:
Model the wires as a solid but there is no convergence in this method, regardless of mesh-size.
Model the beams as
Model the contact regions as:
Use cylindrical joints for the majority of the wires and cylindrical fits with flexible and deformable behaviour but I get these results which is not like expected or physically possible:
I know the model is possible seeing published results using the beam method and solid method (Abaqus):
December 20, 2022 at 1:13 pmpeteroznewmanSubscriber
Use Frictional Contact between Beams and holes as the model that will be the easiest to converge.
After you have meshed and defined the contact, insert a Contact Tool under the Connections folder and Generate Initial Contact Status. You need to see that the contact is Near Open or Closed. If it is Far Open, you will need to increase the Pinball Radius until it changes.
Under Analysis Settings, you turn on Auto Time Stepping. Set the Inital and Minimum Substeps to 100 and the Maximum Substeps to 1000.
January 11, 2023 at 12:22 pmAniketAnsys Employee
January 11, 2023 at 6:01 pmSwen GroenSubscriber
Thank you for the replies. I have been working on the pinball radius and some models, but the issue keeps persisting. I have the contact as Near Open but it still breaks the contact condition. I will add the offset to see whether that helps.
- You must be logged in to reply to this topic.
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.
- Solver Pivot Warning in Beam Element Model
- Saving & sharing of Working project files in .wbpz format
- Understanding Force Convergence Solution Output
- User manual
- An Unknown error occurred during solution. Check the Solver Output…..
- What is the difference between bonded contact region and fixed joint
- The solver engine was unable to converge on a solution for the nonlinear problem as constrained.
- whether have the difference between using contact and target bodies
- Defining rigid body and contact
- Colors and Mesh Display
© 2023 Copyright ANSYS, Inc. All rights reserved.